Engineering Design Handbook - Explosive Series, Explosive Trains
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AD-777 482 ENGINEERING DESIGN HANDBOOK. EXPLOSIVES SERIES. EXPLOSIVE TRAINS Army Materiel Alexandria, January
Command Virginia
1974
Reproduced From Best Available Copy
DISTRIBUTED BY:
Natbonal Technical Information Servi•o U. S. DEPARTMEhT OF COMMERCE 5285 Port Royal Road, Springfield Va. 22151
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*AMCP 706-179
DEPARTMENT OF THE ARMY HEADQUARTERS UNITED STATES ARMY MATERIEL COMMAND 5001 Eisenhower Ave. Alexandria, VA 22304
15 January 19,4
AMC ;AMPHLET No.
706-179
ENGINEERING DESIGN HANDBOOK EXPLOSIVE TRAINS Page
Paragraph
xiii xvi xix xxiii
LIST OF ILLISTRATIONS .......... LIST OF TABL ES .................. LIST OF SYMBOLS ................. PREFACE ......................... PART ONE - FUNDAMENTAL PRINCIPLES CHAPTER i. EXPLOSIVE CHARGES AS COMPONENTS OF WEAPON SYSTEMS 1-I 1-1!.1 I -1.2 1 - 1.2,1 1-1.2.2 1-1.2.3 1- 1.2.4 1-1.3 1-1.3.1 1-1.3.2 I - 1.4 1-2 1-2.1 1-2.1.1 1-2.1.2 i --:. i.3 1- 2.2 1-2.2.1 1-2.2.2 1--2.2.3 1-2.2.4
T17i
Introduction ....................... Purpose ......................... The Explosive Train ................ Functions and Types .............. Low Explosive Train .............
. .
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I-1 1-1 1- 1 1- I 1-2 !-2
High Exnlosive Train ............
1-3 Typical High Explosive Train ...... 1-4 Explosives ....................... .1-4 Low Explosive. ................. 1-4 High Explosives ................. 1-4 Bases for Selecting Explosive Charges . 1-7 Systems Approach to Ammunition ...... 1-7 Vehicular Aspects ................. 1.--7 General ....................... 1-7 Aerodynamic Heating ............ 1 -9 Acceleration .................... I-I0 Structural Aspects ................. Neglecting the Strength of the 1-10 . Expl, isive .................... Consequences of Structural Failure 1-10 of Explosive Charges ........... Structural Components as Sources 1-1I of Fragments ................. Interaction of Structure With 1-!I Explosive Materials ............
pamphlet supewbe.du AMCP 706-179, March 1963.-
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,.-p-.nirred by
NATIONAL TECHNICAL INFORMATION SERVICE U S
*
' 't O! Cnimoruce Springfield VA 22151
.. . ..
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AMCP 706-179
TABLE OF CONTENTS (Con't.) Paragiaph I -2.3
1-2.3.1 1-2.3.2 1-2.3.3 1-2.4 1-2.4.1 1-2.4.2 1-2.4.3 1-3 1-3.1 1-3.2 ! -3.3 1-3.4 1-3.5
Page Mechanical Aspects ................
1.-.. 1I
Functioning .................... Location With Respect to Target .... Safing and Arming Devices ........ Electrical Aspects .................. Environments ..................... Possible Initiation of the Main Bursting Charge ............... Electnc Initiators Exposed to Spurious Signals ............... General Design Considerations ........... Reliability ....................... Safety ...................... ... Economics ........... Standardization ................... Human Factors Engineering .......... References .........................
1 -1l 1 --12 1-12 .1-13 1-13 .
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-13 I -13 ! -13 1-14 1-14 1-15 1-15 1-16 1-16
CHAPTER 2. EXPLOSIVE REACTIONS AND iNITIATION 2-1 2-1.1 2-1.2 2-! .3 2-1.4 2-2 2-2.1 2-2.1.1 2-2.1.2 2-2.1.2.1 2-2.1.2.2 2-2.1.3 2-2.2 2-2.3 2-2.3.1 2-2.3.2 2-2.3.3 2-3 2-3.1 2-3.2 2-3.2.1
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Thermal Decomposition and Burning .... Thetmal Decomposition ............ Reaction Kinetics .................. The "HIot Spot" Theory of Initiation . Deflagration ...................... Detonation .......... ............. Transition from Deflagration to Detonation .................... Transition Process ............... Growth of Detonation in Primary High Explosives ............... Lead Styphnate ............... Lead Azide .................. Growth of Detonation in Secondary High Expiosives ............... Shock Waves ...................... Detonation Waves ................. Equations of Sta^. .............. Chapman-Jouguet Conditions for Ideal Detonation .............. Actual Detonation ............... Initiation .......................... Establishing a Self-propagating Reaction ...................... Initiation by Heat ................. Hot Wire Electric Initiators .......
-1 2-1 2-2 2-3 2-5 2-6 2-6 2-6 2-7 2-2 7 2--7 2-7 2-9 2-11 2-11 2-12 2-13 2-15 2-15 2-17 2-17
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I.
AMCP 706-179
TABLE OF CONTENTS (Con't.) Page
Paragraph 2- 3.2.2 2--3,2.3
. Conductive Film ELlctrit- Initiators Mix Electric Conductive Explosive ...... .............. Initiators
2-3.2.4 2-3.2.5 2-3.2.6 2-3.3 2-- 3.3.
Gas ......... -ot 2il Transtr Transmitsioul of dot Patitles........ Adiabatic Compression ............ Initiation by Impact ................ Impact Sensitivity Measured With Laboratory Machines ........... Stab Initiation .................. Percussion Initiation .............. Initiation by Other Means .......... ... F'iction ..................... Electric Sparks .................. Exploding Wires ................. Laser and Light ................. Spontaneous Detonation .......... Shock Through a Bulkhead ........
2-3.3.2 2-3.3.3 2-3.4 2-3.4.1 2-3.4.2 2 -3.4.3 2-3.4.4 2-3.4.5 2-3.4.6
.
References ..........................
2-18 .-19 2-1Q 2--20 2-20 2--21 2-21 2-21 2-22 -23 2-23 2-24 .2-24 2-26 2-26 2-26 2 -27
CHAPTER 3. DETONATION TRANSFER AND OUTPUT
SAnother
v S3-2.1.2
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3-1 3-1.1 3 - 1.2 3-2 3-2.1 3-2.1.1 3 - 2.2 3-2.2.1 3-2.2.2 3--2.2.3 3-2.2.4 3-2.2.5 3-2.3 3-3 3-3.1 3-3.2 3-3.2.1 "3-3.2.2 3-3.3
Effectiveness of One Charge in Initiating ......................... Detonation Propagation ........... Dimensional Interactions ............ Sensitivity to Initiation .............. Sensitivity Tests ............... Standard Tests .................. Gap Tests ...................... Variables Affecting Sensitivity ........ Loading Density ................ Let-to4ot Variations ............. ........... Additives ........... Confinement .................. Gaps and Barriers .............. Misaiigud Charges ................ Output ............................ Nature of Explosive Output ........... Effect of Charge Configuration ...... The Detonation Front ............ Wave Shaping .................. Blast ............................
3-1 3-1 33-3 3-3 3-3 3-4 3-6 3-6 3-1 3-7 3-8 3-10 3-10 3-I0 3-1 3-1I 3-12 3 13 3-14 3-14 3-16
Fragmentation .................... Fragmentation Characteristics . Controlled Fragmentation .........
3-3.4 3-3.4.1 3-3.4.2
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AMCP 706-179
"IABLEOF Paragraph 3 3.5 3--3.5.1 3 3.5.2 3-3.5.3
CONTENTS (Con't.) Page 3 16 3 -16
Other Output Effects................ Underwater .................... Underground ....... ........... Shaprd Charge ................... References .........................
3.. 17 3 17 3 -18
CHAPTER 4. ENVIRONMENTAL RESPONSE 4 1 4 -2 4-2.1 4 -2.1. 4-2.1.2 4 2.1.3 4--2.1.4 4 2.1.5
4 -2.2 4-2.2.1 4-2.2.2 4-2.2.3 4--2.3 4 2 3.1 4 -2.3.2 4-2.4 4-3
b
4--3.1
"4-3.2
4 -3.2.1 4-3.2.2 4-3.2.3 4-3.3 4-3.3.1 4-3.3.2 4-3.4 4-3.4.1 4-3.4.2 4-3.4.3 4-3-4.4 *
Military R -quirements ................. Temperature ....................... High Temperature Storage .......... Chemical Decomposition .......... Dimensional Chitnge .............. ...... Explosive Property Change Exudation .....................
4--I 4-2 4-2 4 --2 4-4 4-5 4 -5
Effect-; in Initiators .................
4 -5
4-6 4-6 4-7 4-8 4--8 4-8 4-9 4-10 4--i1
.... .......... Cook-X'* ......... Threshold Coaditions ............ Cook-off Experiments ........... Simulatic,, of Aerodynamic Heating. • Other Eftectq of High Temperature Use. Melting ol Explosives ............ Sensitization ... ................ Low Temperature Storage and Use .... Environment ....................... Chemical Interactiiens .....
............
........... Simnulatiot. of Impact .. Laboratory Impact Tests .......... .... Bullet Impact .............. Mass Impact .................... Setback Acceletation ................ The Occurrence of Setback ........ The Setback Mechanism .......... .. Other Effects ................. Vibration ...................... Friction ....................... Electricity ...................... irradiation ..................... ............... References .........
.
4_11 .-
4- 12 -1- 12 4-12 4-13 4- 14 4-14 4-14 4-16 4-16 4--16 4-16 4-17 4- 17
PART TWO - DESIGN CONSIDERATIONS CHAPTER 5. PRIMERS ANYD DETONATORS 5--I 5-1.1 5 - 1.2
Description and Selection ............... Introduction ..................... Function and Construction ..........
5-.1 5-.1 5.-i
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AMCP 706-1 79
TABLE OF CONTEiTS (Con't.) Page 5 2
Paragraph initiator TyP s ....................
5 .1.3
Stab Initiatols .....
5 -1.3.1 5 -1.3.2 5 -1.3.3 51.3.4 5 -1.3.5 5 -1.3.6 5-1.3.7 5 -1.4 5--2 5- 2.1 5--2.1. 5 -2.1.2 5-2.1.3 5-2.2 5 --2.2.1 5 -2.2.2 5 2.2.3 55-2.3 5-2.3.1 5-2.3.2 5-2.3.3 5-2.4 5-2.4.1
S5-2.4.2.4 [.
5-2.4.2 5-2.4.2.1 5- 2.4.2.2 5-2.4.2.3 -2.4.2-5
555-2.4.3 -2.4.2 -2.4.3.1I -5
.
.................
Percussion Primers ................ Flash Detonators ................ .. Relays ...................... ............... Electric Initiators ... Squibs .................... ........ Types Initiator of Grouping . .. Bases for Selecting an Initiator Type ................. Characteristics Input Stab Initia ors .................... Initiation ...................... Effects of 11isk and Cup Thickness Effects of Test Apparatus ......... Percussion Primers ............... .. Initiatioi .................... ............ ('ups Sealing Disks and Other Variables ................. Flash Detonators .................. Initiation ..................... Effect of Explosive at Input Fndi .... Effect of Construction at Input End . Electric Initators5................-9 Input Sensitivity ................. Hot Bridgewire Initiators ........... Flash Charge Explosives ......... Biridgewire Resistance .......... Firing Energy atid Power ........ Rzsponse Times ............... "ypical Design P, oblem ......... ..... Dimensions Bridgewihe n n arid e s~Initiators Bridgewihe Brd e-13Di Exploding
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5-9 5-9 5-9 5-10 5.-to 5-1l 5 -12 5-13
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. 5.. -14 5-14 5 -14 5-14 5-15 5.-.15
Materials .................. Explosive Matenals ............ Film Bridge Initiators ............. Initiation Mechanism ........... Graphite Bridge Films .......... Conductive Mix Initiators .........
S5--2.4.3.2 5-2.4.4 5-2.4.4.1 5-2.4.4.2 5-2.4.5 5-2.4.6 5-2.4.7 5-2.5 5-3 5-3.1 5-3.2 5-3.2.1 5-3.2.2
Spark Gap Ir,itiators ............. ................... Squibs .... Through-buikhedd i,,,tiators ......... Output ............................ Outptut of Primeis ................. . Output of Detonators ............ .-.. Output Detonator of Parameters Measurement of Detonator Output •
5 -2 5 2 5 2 5 2 5 2 5.. 3 5 -3 '4-4 5 -6 5 -6 5 -6 5 5. 6 5 -7 5 7 5 -7 5 5--8 5-8 5-8 5 -8
.
5--IS 5-15 5 -16 5-16 . 5.. -16 5-18 5-18 5-19 V
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AMCP 706119
TABLE OF CONTENpj'$ (1Con't.) Parag' a;;h
5 3...3 5 3.?.; 5 3..: 5 3.2.3 3
5- 3.2.3.4 5 3.2.3.5 5 4
5 4.3
5 -22 -23 53 -24 5 -24 ';5-24
.........
5-25 5--25
CHAPTER t. DELAY ELEMENTS Description .........................
6- 1.1
6-2.2.2
5 21 5 21 5 21 5 -22
.....
Bridging Techniques .............. Soldered Bridges on Raised Terminals ................... Flush Soldered Bridges ......... Welded Bridgc Graphite Film bridges .......... Bridgewire Materials .............. Spark Gap Plugs ................. Flash and Spotting Charges ........ References .........................
6-I
6.-.2.2...
Dim nsions ................ Loading Densiiy of Ixplsiv, Conlfnctnent of Explosives .... ('onstruction and Fabrication
Electric lnitiato:s. hIitiator Plugs........
5-4.4.2.2 5 -4.4.2.3 5 .4.4..4 5 -4.4.3 5 -4.4.4 5-4.4.5
6-2.1.5 6-2.2
9;x plosive Quanjtities and
Stab and F!ash Initiators ..... Percussoiii Primers .
5-4.4 5 4.4.1 5--4.4-2 5 4.4.2.1
6--2.1.4
5 -19 . 5 1. 5 2t
Mt clunica' luiti:1tors ...............
5-4.3.1 5 4.3.2
6-2 6 -2.1 6--2.1.1 6-2.1.2 6- 2.1.3
Lxplo.ivc1 Used in Dclon atQ,.• ...... Int:'riiditc Charges ........... Base Ch:,rF's ..
... Initiator ('ups . .... Yixlosic Loadir;g ................
5 4.1 5 4.2
6 - .2 6-1.2.1 6-1.2.2 6-1.2.3 6- 1.2.4
Page
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Function and Construction .......... Delay Types ..................... Obturated (Scaled) Delays.." Vented Delays.................. Ring-type Delay ................ Delays Achieved by Methods Olher Than Controlled Rate Burning
...
Delay Compositions ................... Gas-producing Delay Charges ......... Loading Pressure ................ Pellet Support ................... Eflects of Moisture and Temperature. Obturated Delays .............. Vented Delays .................... Gasless Delay Charges .............. Delay Co.positions .............. Ignition Powders ................
vi
ILe
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-25
5-25 5-25 25 .5 5......... -26 5-26 5..5 -26 5-26 5-27
6-1 6-I 6-I 6-1 6-2 6-3
6-3 6-3 6-3 6-4 6-4 6-56-5 6-5 6-6
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AMCP 706-179
TABLE OF CONTENTS (Con't.) Paragi ph
Page Properties of Delay and Ignition Powders .....................
6 2.2.3
.
6..
6 .6 Properties of interest ............ (, 7 Burning Rates ................. Lffccts of lempera-ure and 6 8 Storage .................... 6 9 Effects of Reduced Pressure ...... 6 9 Effects of Acceleration ......... 6 9 Particle Size .................. o 9 Design, Fabrication, and Loading .... 6 9 Loading Pressure .............. 6 9 Column Diameter .............. .. 10 Wall Thickness................... 6.-10 Design Principles ..................... 6 10 Obturated vs Vented Design .......... 6 II Design Rules of Thumb ............. 6 -iI .... References .......................
6 2.2.3.1 6 2.2.3.2 6 -2.2 3.3 t 2.2.3.4 6 2.2.3.5 6 -2-2.3.6 6 2.2.4 6-2.2.4.1 6-2.2.4.2 6 -2.2.4.3 6-3 6--3.1 6 -3.2
ClIAPTER 7. LEADS AND BOOSTERS
"
.............. Description .......... General ......................... Fanctions ................. Leads .........................
7 -l! 7 -1.1 7 -1.2 7-1.2.1 -- 1i.2.2 7- 1.3 7-2 7-2.1
,o s ca .......................
7-2.2 7-2.2.1 7 -2.2.2 7 -2.3 7-2.4 7-2.5 7-3 7-3. I 7-3.2 7-3.3 7-3.4
.....
7 -l 7 --1 77--I 7-1
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Explosives ....................... Design Considerations ................ Relation to Fuze Design ............ Leads ........................... Length ........................ Diameter and Confinement ........ Boosters ......................... Charge Density Effects .............. Output Wave Profile ................ Construction and Fabrication .......... Loading Techniques ................. Short Leads ...................... Long Leads ...................... Boosters ......................... References .........................
7. -2 7 -4 7-4 7-5 7. -5 7-5 7 -6 7.-7 '.7-8 7-9 7 -9 7-10 7. -11 7-1I 7-13
CHAPTER 8. MAIN BURSTING CHARGES
k
8-I 8-1.1 8-1.2
Description ........................ Function ........................ Typical Main Bursting Charges ........
8-1 8-i 8--I vii
ti "4f,'. . . . . . . . . . . . - . . . . .. . . .
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AMCP 706-179
TABLE OF CONTENTS lCon't.) Paragraph 8 8
1.2.1 1.2.2
8
1.2.3
8
1.2.4
Page Iligh Explosive (111) Ammunition ... High E.xplosive Antitank (I l.AT) and Iligh Explosive Plastic (11iii') Ansinm nition ................. Chenmical Amii nii oi ............ hligh ixplosive Inceindiary II) Anm unliltion ..........
8 1.2.5 8 1.3 8 2 8
2.1
8 2 8 2
.......
8
Cluster Ammumilion ........... Size and Weight ................... Explosivcs ......................... Ixplesivc Loading ................. Inert Sinluhnts ................... Initiation .......................... Scnsilivity ........................ Booster Position .................. AuXiliary Boosterb aid Boosted
8
Confinemernt .................... References .........................
.
Suriounds. .....................
-4.4
2
8 2 8 2 8 4
Selrction ........................
8 2.2 8 2.3 8 3 8-3.1 8 -3.2 8 3.3
1
8
8
4
8 8 8 8 8
5 (, 6 6 7
8
7
8 7 8 8
CHAPTER 9. OlIER EXPLOSIVE CHARGES 9-1 9 -1.1 9-1.2
Actuators ......... ................ Description ...................... Output Characteristics..................
9. -I1 9 1 9 2
9 !-
0.. .. . . .. High-explosive Bolts .............. Low-explosive Bolts .............. Explosive Nuts .................. . Demolition Devices and Accessories ...... Destructors ...................... Explosive Cords, Caps, and Sheets ..... Explosive Cord .................. .. Flexible Linear Shaped Charge ...... Blasting Caps .................. Sheet Explosive ................. Demolition Blocks .................
9 3 9 -3 9 -4 9 -4 9 4 9 5 9 -5 9 -6 9-6 9 -6 9-6
References ..............
9 -7
9--1.3.1 9-1.3.2 9-1.3.3 9-2 9-2-1 9 -2.2 9-2.2.1 9-2.2.2 9-2.2.3 9-2.2.4 9--2.3
CHAPTER 10. LOADIN(, AND FABRICATION 10-I 10-2 10-2.1
viii
"--I
Process Selection .................... Casting ................ ............ Projectile Prepasatior ..............
.
10-1 . 10-1 . 10-1
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AMCP 706-170
TABLE OF CONTENTS (Con't.) Paragraph 10 2.2 10 10 10 I0 10 IC 10 10
2.2.1 2.2.2 2.2.3 2.3 2.4 2.4.1 2.4.2 2.4.3
10 10 10 10 10 10 10 10 10 10 10 10. 10
2.4.4 2.4.5 2.4., 3 3.1 3.1.1 3.1.2 3.1.3 3.1.4 3.1.5 3.2 . 3.2.1 3.2.2
!0
3.2.3
10 10 10 10 10 10 10 10 10 10110 10
3.2.4 4 4.1 4.2 5 5.1 5.2 .5.3 5.4 6 6.1 t6.2
10 -6.2.1 10 -6.2.2 10-6.2.3
Page I[ltcct o" Casting Procedure oni Charge Characteristics .................. . Porosity and Cavitation ........... Crystal Si.c .................... UJnifori-nity of('onposition . ...... Standard Casting Procedure ........... Some Special Casting Techniques ...... Pellet Casting ................... Vacuum Melting and Casting ....... Vibr ation, Jolting, and Ce'ntrifugal (asting ...................... Controlled Cooling ........... .. Extrusion ...................... Liquid Explosives ................ Pressing ........................... Standard Procedures ............... Measurement of Explosive Charges . Direct Pressing in Case ............ Stop vs Pressure Load-ing .......... Pelletizing ..................... Reconsolidation ................ Special Procedures ..... ........ .... Vacuum Pressing ................ Hot Pressing .................... ydsr!:*.tiz and 1.B atos
I-
II
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0 .10 I..) 0 . 0 10 10 10
... ,c
Pulsating Pressures ............... Finishing Operations ............... . M achining ....................... Cementing of Compound Charges ..... Suitability ......................... Availability ...................... Output Characteristics ..... ........ Sensitivity ....................... Chemical and Physical Properties ...... Quality Assurance ................... Bases for Tolerances ................ Factors Affecting Quality of Explosive "CTharges ........................ Density ........................ Cracks and Cavi:ies .............. Composition Variation ............ References .........................
2 2
2 2 2 3 3 3
I0 4 10 4 10 4 10 4 10 4 10 4 10 4 10 .5 10 ( 10 9 10 -10 10 -10 10 10 10 10 1.0
1
10 11 10-12 10 -12 10-13 I1.. 0 -13 10 13 10 14 10 -14 10-15 10-16 I.0.10-16 I.0 -17 I0 -17 10-18 10-18 10-18
CHAPTER I I. PACKING, STORING. AND SHIPPING I- I
Packing ...........................
!.l -1
jtt
ix
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~
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AMCP 706.179 TABLE CF CONTENTS (Con't.) I'arl~t
pllPage
I I I
G~cnclal . .. . . .. .. .. . ...
I.2
Packl ig of I xplom ve 11am G( IIo
I ?.1I 11
1.2 3
I! I
.3 1.3I. I
I
II fit!; . .. lC
. . ..
..
. . . . . . .
.I';'ckig (Consideratious ........... i:.rl,1 g f Small ! pIilos;vw m
p............... neinlIs
II
Packing o1 Related Mat ai .......... D1iI1 lEx plosives .................
.3.2
Ass St ligg .
2
aml-led AiIim liitaoi ..........................
2.1
1lizard (lasitication
-22
Sotl
3
1 I3 1 3
.
sii............. .on
......
Sliippi g ('o sidlrratiuis .......
Truc- '! lanspo-t ....
33.3 3.3.4
12 - I 22} -I.I
I2.
IA%?Aln
llu',
('oisiderations 'n LvalatiOln
.
.
12-1.2 ? 1.2.1 12-!.2.2 12-1.2.3 12-1.2.4
uiltistical Tes( Methods ............. General Considerations ........... Staircase Method, hle Brurecton lest. Frankl'ou Run-down Method ...... Iobit, Normit, and Logit Pro'edures.
2-2
Testing Techniq
12-2. I 12- 2,.l I
s .......
................
Ex plosi-.,c Materials ................ General .......................
2-2.1P2 2-2.1.2.1 12-2.1.2.2 12-2.1.2.3
II
II . II I.I o
.............
12 -1.1.5
12- I .1.2 12-1.1.3 12 --I.1.4
5
5
n ......
lSal'ety and Reliability Proceturcs Statistical In ferences ............. IFrqluency Distriutulions .......... Confldence Levels ............... Reliability Ietrittination from Mean and IXviatio, ............ Optimiization ...............
12 -12.
11
5
..............
f=
4
II II
Ship ira sport .................. Air I"ransport .................. Rcfcrencs .......... ...............
'IIA P~iEP
3
1
...
('onsiderations for Specific Modes of Slipping ........ ............ It il "i AIIspor t ..................
3.3.2
1. I1
llarari (.lamisficaition
3.3.1
3 3
1 ..
Shippingl . ................
1I 3.1 II -3.2 I I 3.3 II II II II
. . ..
....
Ialard 'Cl-.sfilncatlh n .............
(o
1
..
. ...
Sensitivity .................... Impact Test ....... ........ Friction Peqdultim Test ......... Rifle 13lleIt Impact Test .........
.
...
1.2.112 1......- I 12 -1 .1.2-21 12-4
12 4 12 6 12- o 12 -i 1 2-7 12-8 12-8 .12
8
12-8 12 -8 12 -9 12-9 12-•1) 12--10
X
t,
-
-
-"- . . f
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AMCP 706 171
TABLE OF CONTLNIS (Con't.) Ia! ap ;ij'3h
I,'Pa
32 2.1.2.4
3\I'I X
12
12 2.1. 2., 12 2.1 2.7 12 2.I.2,
(.;a st,. .............................. Scilauc lIt'csstur" ICA ........... Inilicl Vu lIic l ltly I S1 .. u11l, r l' I l ." ..............
1-
.(cok .. i ] cilptlaill 'I "I 1 l','tliostallic SC'lI.lL'it M I)y
2.1.2.5
2.1.2 It)
12 2.1 "1.11 12 2ý1.2.1. 12 2-1.2 0. 1:
1•
2.1.2.14
"I "1 "1 12 2
2. 1.4 2.2
12 12 12 32
2-.t 2.2.2 2.2.2.3 2.2 2 2 2.2..3 2.2.3 2.3 2.3.1 2.3.3 1 2.3.3.2 2.3.1.3
S.2 32 32 1 12 12 12
....
t1 ...... . ..
.v
I ,'t
I() 10 II I I
12 II 12 1. "'1 12
......
12
13
........ ....... ......... [oiln , h ity . ... ...... l atio-mii P~rc2sst , . ..... .... 1h11 " .......... .........
12 I
12
12 1 I2
13 1 45
2 12 12 12 I" 12
35 IS 1'% 15 ( I,
12 12
1I 16
12
I
O utl'
1a1s3 t ............. .......... M trtl ................. "l'lilaIl IcS! .......... ........ I..•.u l-i -atcl Siock .... ... ...... SU Nibl[!)" •............. .... ... In l'ut..... ....................... Mrclhani:al Iniiitim,,r .............. lhcggili hinait..ON ................ (tn itlstn r Ilchargc ....... Voltag" StilsitivIy. .............. Stealdy (C'uiilt t lun tio..'lli .3;ll Galp, -alnd IhaI t% ................ O ultiui .......................... Iktolllaigo.......................3 SindIest .... ....... Irad Disk Ilest .............. S10t0 De l lt leht ...............
..... . ...
..
IXMtoe
?t'ssr"
W a•%lls~ of sh
Mhit- dation 1) t.IIOr mAut, -Ci,',r'•. ..
Nondelonatlng ltcnlS ........... r. PIillT O Ll11lt ......... Slpecial Primer Outpiut Parameters ................. Nlcliallical Output .. Iltjsirolnll crt .....................
....
References ............................ GLOSSARY. ..
....
....................
.
.
12 --2.3.1.7
12 2.3.2.3 32 2.4
I
2 2 12
Aluninimn Pent l et'............ llopkinmo'i liar Ictl ........ ... of tle Ali Shiotk c .......
2.3. 32 - 2 .3..1 23 12 2.3-'.2
III
.2
32 2.33.. .4 12 2-3-1..5 37 -2-3 I. .-lvkity
12
2
.
cll' ial I hernial Anal , ... 1khrtnotliO I 1t~llli.l|.Anal)ii}, ....... Itot W RICIgnition I t .......... 1lhct mal lDkttna|l,1111)
12 2. ...3 12 .1 .IX'ona • .I .3.. 12 2 1.3.4 12 .1B.3.5 - 2 '1lollisutk 2...1 _7
Q,,,•,,t 1C1i3'C lat•"t I,'.. s ..
12 2 12 12
17 17. I? I I2 12 IX 1 2 I.1s 12 3') 32 -' 12
r2
I
lI
J 1S 20 20
1.
.....
12 3 2 I 2
2 21
12
221
21
I
xi
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AMCP 706-179
TABLE OF CONTENTS (Con't.) Paragraph
R-1 R-2 R-3 R -4
Page GENERAL REFERENCES ............
R.-- 1
Introduction ....................... General Reference ................... Journal Articles of the JANAF Fuze Committee Pertaining to Explosive Trains .................. Military Specifications on Explosives and Explosive Compositions ..........
R--R-- I
IN D EX ............................
xii
-
5
I. .
R-2 R-3 L--
"-V
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AMCP 706-179
LIST OF ILLUSTRATIONS Fig. No.
Title
Page
1- I I -2
Typical Low Explosive Train ................. Typical Iligh Explosive Train ...... ...........
1 -2 1 .3
2 1 2- 2
Computed Explosive Reaction Rates ........... Arrangement Used in Observations of Detonation Growth ...................... Formation and Incipient Decay of Shock Wave "fromWave of Finite Amplitude ............. Energy-power Relationship for Various Initiators .............................. Typical Effect of Bridgewire Volume on Input Characteristics .......................... Threshold Comiditions for Initiation of Various Explosives in a Shock Tube ................ Initiation by Adiabatic Compression ........... Input Sensitivity vs Explosion Temperature ...... Standard Firing Pin for Stab Initiators ........ Energy-velocity Relationship for Percussion Prim ers ................................ Schematic of Typical TBI ...................
2 -3
2- 3 2-4 2-5 2 -6 2-7 2--8 2-9 2- 10 2-1 i 3- I 3-2 3-3
3-4,
3-5 3-6 3-7 3-8 3-9 3-10 3-11 3-12 3-13 3-i4 3-15
Streak Camera Record of Detonation .......... Critical Gap as a Function of Column Diameter Critical Axial Air Gaps Across Which Detonation Is Transmitted Between Lead Azidcnfl and.nsp" Tetryl .................... 3 - ,'a ll S , . "a~ Ai,,
2-7 2 -I1 2 -- 16 2-- 17 2--20 2-21 2-22 2-22 2-23 2-27
..
,,p Test ....................
Minimum Priming Charge and Gap for Critical Propagation ............................ Small Scale Lucite Gap Test .................. Effect of Voids on Booster Sensitivity (Wax Gap Test) .............................. Effect of Voids on Booster Sensitivity (Lucite Gap Test) .............................. Effect of Acceptor Confining Material upon Sensitivity in an Air Gap Test .............. Gap Sensitivity Related to Density and Hardness of Acceptor Confining Medium ............. Arrangement for Propagation of Misaligned Charges ............................... Line Wave Generator of the Manifold Type ...... Line Wave Generator of Sheet Explosive Line Wave Generator of Warped Sheet of . ... .. Explosive ................... Pressure-time Relationship of Exp . .............. Blast .................
3.-2 3-2
3-3 3- 5 3-5 3-6 3-7 3-8 3-9 3-10 3-Il 3-...... 13 3-13 3--14
Sxiii
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AMCP 706-179
LIST OF ILLUSTRATIONS (Con't.) Fig. No. 4
I
4 -2 4-3
4-4 4 --5
Page
Postulated Condition for Initiator Failure Caused by Wire-explosive Separation ......... Test of a Booster in Simulated Missile Flight Cook-offCharacteristic- of Three Explosives .....
4 -6 4-7 4 8
Simulated Aerodynamic Heat Test ............ Typical 1ime-acceleration Curve for Projectile While in Gun ...........................
4-10 4- Id
5- 1
Typical Priners and Detonators (Mechanical) ....
5--3
5-2 5--3 5 -4 5 .5 5-6 5 -7 5 -8
Typical Explosive Relays .................... Typical Primers andi Detonators (Electrical) ...... Electric "Mini" Detonator ................... Electric Squib, M2 ......................... Stab-electric Detonator, T29 ................. Functioning Times of Hot Wire Bridge Initiators. Initial TBI Configuration for Saturn V Launch Vehicle ........... .................... Comparison of TBI Parameters ............... Coined Bottom Cup ........................ Punch Trimming of Initiator Cups ............. Ini!iator Cup Crimping ......................
5--3 5-4 5 -5 5-6 5-6 5-13
5--9 5-10 5- 11 5- 12 6- 1 6-1
--3 6-4 6-5 6-6 6-7 6-8 7-1 7--2 7-3 7-4 7-5 7-'-6 7-7 7-8 7-9 7-10
r
Title
7-1I
5 -17 5-18 5-23 5-23 5-24
Obturated Delay Element of Bomb Fuze, ANM IOOA2 ............................ Electric Delay Detonator, MARK 35 MOD ! .... Electric Delay Detonator, T65 ................. Sealing Methods fot Vented Delays ............ Fuze M54 ................................ Pressure Type Delay ........................ Support of Delay Pellet ..................... Characteristics of an Obturated Black Powder Delay Element ...........................
6-2 6 3 6 -3 6-3 6-4 6-4 6-3 6-6
Booster, M21A4 .......................... 2.75-in. HEAT Rocket With Spit-back Explosive System ........................ 20 mm Fuze, M505 ........................ Critical Conditions for Detonation of Lead ...... Lead Pellets Held in Place by Staked-in Closure Disk ............................ Lead Retained by a Feature of Fuze Design ...... Lead Retained by a Cup .................... Fxplosive Loaded by Breaking Off Excess ....... Lead End Coated With Sealant ................ Lead Cup Crimped in Place .................. Chamfered Booster Pellet ....................
7-2 7-3 7-4 7-7 7-!1 7-11 7-12 7-12 7-12 7-12 7-13
xiv
.
-
_
a_
Jrmm-
•Odi-n
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AMCP 706-179 LIST OF ILLUSTRATIONS (Con't.) Fig. No.
Title
Page
7-12
Improper Charging of Cup ...................
8-_I 8- 2 8-3 8-4 8-5 8-6
High Explosive Projectile .................... Armor-piercing Projectile .................... General Purpose Bomb ...................... Antitank Mine, M15 ....................... High Explosive Antitank Proiectile ............ Burster Type Chemical Projectile ..............
8-2 8-3 8-3 8-4 8--4 8-5
9- 1 9-2 9-3 9-4 9-5 9-6
9-2 9-2 9-3 -4 9-4
9-7
Motor, Dimple, T3EI ...... ................ Motor, Bellows, T5E I ...................... Driver, Explosive, MARK 12 MOD 0 ........... Switch, Squib Actuated, Non Delay, XM60 ...... Pyroswitch ............................... Explosive Bolt in Which Reflected Tension Waves A-e Utilized o....................... .... Destructor, Universal, d0 M ..................
10-1 10-2 10--3 10-4
Vacuum Casting Kettle ..................... Sco3p Loading ............................ Charging Plate Loading ..................... Detonator Loading Tool ....................
10-5 10-6 10-7 10-8
10-7 10-8 10-9 l1-i I
10-9 10--10
Tool for Direct Loading of Component ......... Nomograph of Loading Pressure and Density .... Pelleting Presses ........................... Vacuum Pressing Apparatus .................. Hydrostatic Press Principle .................. Isostatic Press Principle .....................
11-I 11-2
Packing Box for Small Explosive Components . Illustration of Data in Ref. 4 .................
1.. 11-3 11-5
12-1
Cumulative Frequt -icy Distribution for a Normally Distributed Population ............ Skewed Fiequency Distribution Typical of Impact Sensitivity. Data ................... Picatinny Arsenal Impact Test Apparatus ....... Gap Test Set-up ........................... Apparatus Which Simulates Setback Pressure .... Thermogram of Ammonium Nitrate ........... Method of d'Autriche for the Measurement of Detonation Velocity ...................... Typical Condenser Discharge Firiag Circuit for Testing Electric Initiators .................. Principle of Hopkinson Bar Measurement of Detonator Output ....................... Arrangement for Detonator Safety Test .........
12-2 1"2-3 12-4 12-5 12-6 12-7 12-8 12-9 12-10
7-13
9-5 9-5
I
10-4 10-5 10-5 10-6
10-12 10-12
12-3 12-3 12-9 12-11 12-12 12-13 12-14 12-18 12-20 12-22 xv
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AMrP 706179 LIST OF TABLES Table No.
Title
I- I 1-2
Common High Explosive Materials ............ Values of Acceleration in Ammunition ..........
1-5 -10
2-1 2-2
Ignition and Explosion Temperatures .......... Values of the Const•.nt G in Eq. 2-3 ............
2-4 2-6
2-3
Optimum Loading Densities and Particle Sizes
2-4 2-5 2-6
for Growth of Detonation in RDX, HMX, and PETN ............................. Detonation Velocity Constants for Eq. 2-17 ..... Detonation Conditions, Calculated and Measured Sensitivity of Various Explosives in Wire Bridge Initiators .............................. Effect of Loading Pressure on Initiator
2 -7
Sensitivity .............................
b
2- 19
2--23
Initiation of Explosion by Friction of PETN in the Prtsence of Grit ......................
2-24
2-9
Threshold Ignition Energies ..................
2-25
3- I
Densities and Shock Velocities in Various M etals ................................ Typical Results of Booster Sensitivity Test ...... Initiation Sensitivity Measured by Several Tests .. Relation of Decibangs to Gap Thickness ........ Sensitivities of Some Explosives According to the Small Scale Lucite Gap Test ................ Effcct of 5 Pecrint D-2 Wax on the Booster
3-6
Sensitivity of Various Cast Explosives (Wax Gap Test) ......................... 3-7 3-8 3-9 4-1 4-2
4-3 4-4 4-5 4-6
xvi
2-8 2-13 2-14
2--8
3-2 3-3 3-4 3-5
t
Page
Aik Gap Sensitivity Related to Acoustic Impedance of Acceptor Confining Medium ............. Sensitivity for Various Spacer Materials (Wax ...... Gap Test) ........................ Gurney Constants for Common Explosives Environmental Requirements for Military Materiel ............................... Relative Sensitivities of Explosives According to Standard Labcratory Tests of Ground Sam ples ............................... Sensitivity of Explosives to Hazards of Use ...... Cook-off Tests of Standard and Modified M47 ... Detonators ........................ TNT Impact Sensitivity Variation With Temperature ............................ Compatibility of Common Explosives and M etals ................................
3-4 3-4 3-5 3-6 3-7
3-8 3-9 3-1I 3-15
4-2
4-3 4-4 4-9 4-9 4-12
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AMCP 706-179
LIST OF TABLES (Con't.) Table No.
4-7 4-8 4-9 4-10
Title
Page
Bullet Sensitivity of 50/50 Pentolite ............ Temperatures Reached by Air When Compressed Adiabatically ........................... Critical Setback Pressures of Explosives of Various Base Separations .................. Data Obtained From Explosives After Exposure to Gamma Radiation .....................
4-13 4-15 4-15 4-18
5-I
Common Priming Compositions ...
5-2
Effects of Cup or Sealing Disk on Sensitivity
5-3 5-4
Resistivities of Bridgewire Materials ............. Firing Times of Hot Bridgewire Initiators ........
5-5
Heats of Explosion and Detonation Pressures ..
6-- I 6-2
Gasless Delay Compositions in Current Use ......
6--7
Ignition Powders for Gasless Delay Elements .... Burning Rates of Gasless Delay Compositions ....
6-8 6-8
6-3
6-4 6-5
7- I
5--7 5........... ....
Effect of Loading Pressure on BaCrO 4 -B Compositions .......................... Failure Diameter Variation of Manganese Compositions at -65'F ...................
5-8
5-10 5- 12 .
5-21
6-10 6-10
Failure Diameters of Lead and Booster Explosives .............................
7-6
8-1
Preferred Use of Main Explosives ...............
8-6
10-1 10-2
Loading Density of Various Explosives ......... Fundamental Characteristics of Explosive Compounds ............................ Fundamental Characteristics of High Explosive M ixtures ..............................
10-3
12-I
Safety and Reliability Related to Deviations From the Mean .........................
10-7 10-15 10-16 12-5
r xvi i/xviii
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AMCP 705-179
LIST OF SYMBOLS
'
I
1
A
constant, Hz or dimensionless
A'
0 atom, sec/ K inverse function of the resistance to motion of an
a
acceleration, g
8/
Brinell hardness
B
constant
C
capacitance, pF
C
heat capacity, W-sec/°C or Cal/g-"C
co
velocity of sound, ft/sec
D
detonation velocity, ft/sec
d
diameter, in.
E
activation energy, cal/mole
E
modulus of elasticity, 'b/in."
E
voltage, V
VI
Gurney constant, ft/sec
F
constant
G
empi-ical constant
G
gap, in.
g
ft/sect acceleration due to giavity,
h
thickness, in. or cm
I
curn.nt, A
is
current to fire lead styphnate, A
K
constant
k
thermal conductivity, cal/sec-em-{*C xix
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AMCP 706-179
LIST OF SYMBOLS (Con't.)
r
k'
reaction rate, lzf
L
length, in.
.A
Maclh number
a:l
mlass;
n
numbe;
n
polytropic exponent
P
pressure, psi
R
burning rate, ft/sec
R
resistance, ohm
R
roentgen
R
universal gas constant, cal/°K-niole
r
ratdius, in.
rw
bridgewire resistivity, mictrohi-cm
T
temperature, 0K, 'C, or OF
I
time, sec
u
velocity of material relative to undisturbed medium, ft/sec
V
voltage, V
V
volume, in?3
V
velocity, ft/sec
V
velocity of material relative to the wave front, ft/sec
W
weight, lb or mg
w
energy, erg
X
sensitivity stimulus, gap decibang
af
3 covolume of gas, in.
7
cooling rate coefficient, W/°C
xx
V
-
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.AMCP 706-179
LIST OF SYMBOLS (Con't.) !.7
failu re rate
Sratio *
of sliecitic heats
JA
(7--
+)/y, I)
p
density, g/cm 13
SUBSCRIPTS a
acceptor charge
C
case, charge. cord
d
delay composition, detonation
SI
firing temperature
I
ideal, insulation
Slong
,
A•l
confining medium
"I m •
measured, metal
la
reference condition, initial
p
priming composition
r
recovery, reference
$
sho'-, Vfagnation
I
threshold, test specimen, transmitted, total
w
wire
p
xxi/xxii
(a
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AMCP 706-179
PREFACE The Engincerti'' l)esignI Ilandbool,:; of the US Army lNateriel Command have e'volved over a number of year, for the purpose of naking readil,' availablc basic inforiialion. Iccliiical datia, and practicý-l guides for Ilie development of military equipnmLnt. The present handbook is one olfa slries on explosives. This publication is the, first revision of the Handbook, !.plosiw-c Traims Extensive changps were made to uipdate the volthnc. Illustrations of sanllile devices, references, and test data were brought tip to date. Outdated material was replaced with current inforniation and tile organiz;1tion was' clhmilged to conform to present practice. A new ehaptrr was added on packing, shipping. and .tonng and the treatment of main chairges, safe'ty, setback and testing techniques was enlarged. Tuis handbook presents theoretical and practical data pertaintig to explosive trains. It includes consideration of the various elements which. in considerable variation. may constitute the explosive train of an itemh. The main charge of an explosive item, such as projectile or warhead filler, is also covered. Data arc given on the physical and explosive charaTcteristics of' typical explosives and references are cited in which additional data are found. Coverage includes development of the complete explosive train, from elements suitable for initiation of the explosive reaction to the promotion of effective functioning of the final, output element. The nature of the explosive reaction, method of transfer of detonation and ineasurenment of ou:out are discussed. Design principles and data pertaining to primers, detonators, delay elements, leads, boosters, main charges and specialized explosive elements are covered. The effects of environmental conditions -nd ... steps to be taken to avoid difficulties arc discussed. . Prepared as an aid to ammunition desibners, this handbook should also be of benefit to scientists and engineers engaged in other basically related planning and interpretation of experiments and tests concerning the performance of ammunition or ammunition components. The handbook wai prepared by The Franklin Institute Research Laboaratories, Philadelphia, Pennsylvania. It was written for tie Engineering Handbook Office of Duke University, prime contractor to tile Army Research Office-Durham. Its preparation was under the technical guidance and coordination of a special committee with representation from Picatinny Arsenal and Frankford Arsenal of the Munitions Command, and tile Ballistic Research Laboratories. Chairman of this committee was Mr. Donald Seeger of Picatinny Arsenal.
.
xiiin
"N,
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AMCP 706-179
"The Lnginecring D)csign Handbooks fall into two husic categories. those approved for release and sale, and those classified for security rIvaesns. The Army Matericl ('omnmand policy is to release these Inrginecering D)esign Handbooks to other DOD activities and their conlractors and other cGovernm;ent agencies in accoidwice with currcnt Armny Regulation 70-31. dated 9 September 1960. It will be nott'd that the majority of these Handbooks can te obtained from the National Technical Information Service (NTIS). Procedure%for acquiring these Hlandbooks follow: a. Activities within AMC, D)O) agencies, and Government agencies other than •OD having need for the Hlandbooks should lirect their request on an official form to: Commander Letterkenny Army Depot ATWN. AMXLE-ATD Chambersburp, PA 17201 b. Contractors and universities mast foiward their requests to: National Technical Information Service Department of Commerce Springfield, VA 22151 (Requests for classified documents must be sent, with appropriate "Need to Know" justification, to Letterkenny Army Depot.) Comments and suggestions oil this Handbook arc welcome and should be addressed to: Commander US Army Materiel Command ATTN- AMCRD-TV Alexandria, VA 22304 (DA Forms 2028. Recommeutdcd Changes. to Publication,. which aic avahd•tie through normnal pnlblic•tions supply channels, imui be used for
xxiv
L.~. .
,I
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AMCP 706-179
EXPLOSIVE TRAINS'
PART ONE - FUNDAMENTAL PRINCIPLES CHAPTER 1 EXPLOSIVE CHARGES AS COMPONENTS OF WEAPON SYSTEMS 1-1 INTRODUCTION
1-1.2 THE EXPLOSIVE TRAIN
1-1.1 PURPOSE
1-1.2.1 FUNCTIONS AND TYPES
This handbook is one in the series of Engineering Design Handbooks dealing with explosives. it covers the principles and factors applicable to the design of the various individual elements that arc parts of an explosive train. These elements include primers, detonators, relays, delays, leads, boosters and ;main bursting charges. In addition, principles and factors involved in the design of explosive items such as actuate.rs, explosive switches and destructors, that are usually not elements of the main explosive train of a military item, are mentioned, particularly where the principexplosive tradiffer
An explosive train is an assembly of coinbistible and explosis elements arranged in the order of decreaN sensitivity, inside a fuze. projectile, bomb, gun chlamber, ur the liket. The function of the explosive train is to ;zccoomplish the controlled augmentation of a small impulse into onc of suitable cnergy to cause the im=in charge of the ammunition to function.
Strain.
•
The phenomena of initiation, deflagration, and detonation and their interaction with effects produced in surrounding materials are discussed with particular emphasis on those aspects that are important to designers of explosive charges Also discussed are evaluation procedures, loading methods, and the effects of design upon the probability of accidental initiation, upon reliability, and upon the useful life of an item. 4Revised by Gunthei Cohn, 11w h:jankLi
LAbortiorici. Philadelphia, Penna.
Institute RSeag;h
Explosive trains may be divided into two general classes. h mg ea bplsre draivd s and ltow explosive trains, according to the type of used in the main charge. An explosive train may also he designated ,.Lcording to the item in which it is assembled or to which it pertains. One of the most common examplcs of the high explosive trains is the frize explosive train. If the bursting charge is added, it is commonly called a bursting charge explosive train. A common example of the low explosive train is the propelling charge expkoslve train-
tFor more delailed definitions of exs.loiive mateail, meethe
(,Iomuy at the end of this handbook.
i-! I
hot gases% anrd Iy of prldeN.
2. Artiri wlirretiatr- chiarge oft primlary high e xpIosi\;V Ior OS ct iriiiniitIiil lead azide ) in briling It) de tonawIhIich li t:n I tanstioui Irinhi; Itinl takes pla;ce. i. A secoirdairy high explosive charge (f'or eat'\;rit'i. RI)X) (flnat iztiisilies thle shock out et1Uiroiri tire jii;teiiied i3t C1eiiagV , riid
4. A main cOtiarg consisting ol a secondary iiighi explosive (for exam~iple, TNT) that pro-
t-1.2.2 L.0W EXPLOSIVE TRAIN
diiccs tire desired effecct.
A low ex plosive t rain; iii its simiplestI has oril> I)1wo esse ii1;.1i clerricr1its
Au;xilfiary eclnenit ts that are almtrost always cinclirted in artl explosive tramn for convenienct: oh- diesigin and for stpeciali purposes are:4
1.- A prinria ry ex plosive chirgia ii thle to tin of,p1 liter-, igliliter, or ignirtion charge,. and ii2.
-
A marin propelling or other gas gelierat-
lIn adtdrtionr, thre trail; Itia hrave a delay cerIrt )O1rusi1til Ilopovide a litl (InCIdelay lre is a iniitia tor cartridge. shown ill Fig. 1-1 typical losv explosive train. It consists of' a printr, delay elemeneit.aindniiair charge. trans nd oher Pronilig chrgeexplsiv low explosive trainis ;are covcrc:d in detail in Rjf. I. othierwise niriicaed. tile term Hxlsr train; in this handbook signiifies a high t'vjili sire fruin;.
-Unless
F
1. Leadls arid relays to t rairsni I explosive reactions between spatially separated dclicrs
2- hDelay or time clenlierit to increase the interval beitwee i activation of the first explo' sivce cime nt and funet ioning of the main chiarge, and 3. A booster that is senIsitive enough; to be Initiated by relatively small output of a secondary hi1gh explosive charge arid powerful ciritight to initiate the itnsenisitive secondary high explosive usually used for the main charge. At times it is possible to combine several functions of these elemrents into a single unit.
~Numenical ;ocirelmcc% r
at tire codol e..ct chapter r lme
WIhei arranging thre elemerits in the trin, tile
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F AMCP 766 179
r"Na PON
M)?
DETOATIO
ROTOR-
PAIMN
CHAN"E
.- Ii4?ER1004TE CHAN"E ON Sam C~INOE
-
RX BOOSTERCHARK
FUL~
~
~
PROJECTILET-.~..tl
0 iý4
(A)
TOP OFF'CkhAW
Oi
-0) UNARMED
ARMED
Figure 1-2. Typical High Explosive Train more sensitive compoinenit. ate always scparated from the more powerful by a sating and g d3In A number of auxiliary elements are used in some military devices, viz., aciuators. explosive bolts, and destructors. Complete explosive trains in themselves, they are designed to perform a specific task. 1-1.2.4 TYPICAL HIGH EXPLOSIVE TRAIN Fig. 1-2 shows a simple high explosive train. Pictured in schematic form is the M505 Nose Fuze that is used with 20 mm ammunition. The fuze is shown in both armed and unarmed conditions but details of mechanical construction have been omitted. While important, these features are beyond the scope
o0 this liandhook (Cfur da as.;c•bly dra-.... this fuze, see Fig. 7-3).
of
the armed condition, the fuze is r'ady to function. When it strikes the target, the following sequence of actions take place: 1. The stab firing pin strikes the input end of the M47 Detnator, piercing the thin metal disk and pushing into the primer charge. This stabbing causes a reaction to be initiated in the primer charge. 2. The primer charge initiates the intermediatr charge of lead azide that is also contained in the detonator. Here the action is accelerated and converted to a detonation. 3. The detonation of the lead azide is transmitted to the RDX base charge of the detonator and is amplified.
1-3
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AMCP 706-179
4. Tile RDX boos(er and top off charges ,if any, serve to amplify tile detonatton wave to insure proper initiation of the main charge in the projectileIn a superquick fuze. such as this one, this entire sequence takes place in only a few microseconds, whereas in a fuze having delayed actiun. the interval between activation of the primer charge and explosion ot the main charge may be as much as several hundred .nillispconcs. Such a delay may be "introduced by a special pyrotechnic charge, "whichburns at a definite rate, between primer and intermediate charges. The rotor in which the detonator is assambled is aligned with the remainder of the explosive tr;in through the action of linear Sand rotational forces encountered during propelling die projectile from the gun. In the unarmed view tFig. 1-2(B)) the fuze is in the sale or out-of-line position. The purpose of this safety feature of fuzes is to isolate physically the more sensitive explosives of the explosive train from the main charge. Since the more sensitive explosives are more susceptible to accidental initiation, they will not propagate to the inam charge, if initiated, when they are in the out-of-line position (see par. 1-2,3.3). 1-1.3 EXPLOSIVES A detailed discussion of explosive materials is not within the scope of this handbook. For information on explosive chemistry, see Ref. 2 and for information on explosives used by the military, see Refs.* b, c, and d. On the other hand, the explosive train designer requires an intimate knowledge of what explosives to use and how these explosives react. Explosives are divided into two groups, low and high. 1-1.3.1 LOW EXPLOSIVES An explosive is classified as a low explosive when the rate of advance of the chemical
r '
.q are listed i the end of this handbook.
1-4
t
ltend c*
t
reaction zone into the unreacted explosive is less than the velocity of sound through tile undisturbed material. When used in its nomial manner. low explosive burns or deflagrates rather than detonates. Low explosives arc divided into two groups- I ) gas-producing low explosive including propellants. certain primer mixtures, igniter mixtures, black powder, photoflash powders, and certain delay compositions, and (2) nongas-producing low explosives including the gasless type delay compositions. The reaction of low expl,.=•ves is covered in par. 2-1. In fuze explosive liains, low explosives are limited to priming compositions (see Table 5-1) and delay compositions (see Table 61). 1-1.3.2 HIGH EXPLOSIVES An explosive is classified as a high explosive when the rate of advance of the chemical reaction zone into the unreacted explosive exceeds the velocity of sound through this explosive. This rate of advance is termed the detonation rate for the explosive under consideration. High explosives are divided into the groups: (1) primary high explosives that are characterized by their extreme sensitivity to initiation by both heat and shock, and (2) secondary high explosives that at. initiated only by relatively high intensity shock. The reaction of high explosives is covered in pisr. 2-2. Common high explosive materials are summarized in Table 1-1. Fundamental properties are listed in Tables 10-2 and 10-3 and the Military Specification numbers for these materials are listed in par. R-4. 1-1.4 BASES FOR SELECTING EXPLOSIVE CHARGES When the designer is ready to build an explosive train, he must make a number of decisions. Before he can select the explosive charges, he must have a clear idea of the input stimulus that will be used to start Ihis system and of the final output the system is to have. Between these two extremes, he mnust assem-
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AMCP 706-179 TABLE 1-1
COMMON HIGH EXPLOSIVE MATERIALS AcceptaMe
Use Only for
Use
Nomally UJed
for Mixtures
Primer
Lead arlde Lead styphnate
Antimony sulfide Barium nitrate
Dinzodinltrophenol (DDNP) Mannitol hexanltrata
basic or
Lead sulfocyanate
Nltrostarch
normal
Nitrocellulose Tetr-cene
Oetonetor*
Lead AzIde HMX PETN RDX
Special Applicailons
Sameras above
Tetryl
Lead or Booster
Comp. A-5 DIPAM HNS PBXN-5 RDX
Cyclotol Pentolite Pressed TNT PETN
Tetryl
'+ :"H6
Main Carge
Comp. A-3 Comp. 8
Comp. C-A
HBX3 Minol-2 Octol ¢
3mp. A4 Comp. B-3,8B4,8B-5 Cyclotol OBA-22M PBXN-101, 103
TNT
Trltonal If the detonator includes the function of a primer, It will contain one or more of the primary explosives. ble a variety of explosive components. This complete system will then make up the explosive train. Since the objectiqe of the explosive train is to function the main bursting charge, it is logical to consider it first. This charge is designed so as to deliver the output that is "required of the ammunition. While the output is invariably specified for all design requirements, it is usually given in terms that the explosive charge designer cannot use directly. Specifications start with the user who has a to defeat a tank, to cause personnel casualties, or to produce a signal. Next, the ammunition designer translates these needs into terms of specific ammunition. He may call for a 90
mm HEAT round to be fired from a recoilless rifle, a nonmetallic mine to be triggered by foot pressure, or a marker projectile delivering a red smoke puff lasting for 20 sec. At this point, the explosive charge designer takes over. He will specify the weight and configuration of the main high explosive charge in the HEAT projectile, the amount of charge in the mine and, together with the ammunition designer, will fix the size of the mine to result in the desired effects, or he will specify the weight and configuration of the HE burster charge and the composition of the. chemicals to produce the smoke puff. Where the design calls for high explosives in a projectile, bomb, or the like for which caliber is either specified or the shape of which is fixed by ballistic considerations, the 1-5
x--+
.-
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AMCP 706-179
task of designing the output charge is fairly straightforward, The -given container is filied with as much explosive as will fit. Seventy percent of the total weight of a light-case bomb, for example, is high explosive filler, Design principles for blast (par. 3-3.3) and for fragmentation (par. 3-3.4) are well established. Explosives for chemical charges must burst the case and efficiently disseminate the contents. The design of main charges is discussed in pars. 8-2 and 8-3. At the other end of the train is the initiator. Selection and design of the proper first element in the explosive train is probably the most difficult step. For this reason, this subject is treated in depth by itself (par. 5-1 .4). The design of initiators is covered in pars. 5-1 to 5-4. It is a basic safety requirement in ammunition that the initiator be kept cut of line so that the train will not propagate in the event of accidental functioning of the sensitive initiator. While the explosive charge designer is definitely concerned with such safety devices, they are not included in this handbook. The design, construction, layout, and evaluation of the various safety and arming devices are covered in texts on fuze designs. Ile next element to be considered is the booster charge. Most high explosive ammunition has boosters. The booster is that chai4e which is sensitive enough to be actuated by the small explosive elements on the one hand and powerful enough to cause detonation of the main explosive on the other hand. Tetryl, RDX, and HMX are common explosives which have these properties. The booster ctarge is best placed into a cavity of the main charge (the fuze well). The design of boosters is covered in pars. 7-1 to 7-3. From the standpoint of train propagation, a booster pellet is all that is required. However, for reasons of safety and versatility, some military ammunition calls for a complete booster containing its own detonator and out-of-line arming device. This secondary 1-6
train is designed in the same manner as the main train. So far, we have considered main charges 2nd boosters at the output end and initiators at the input end- These three form the basic elements required in every train. If the explosive train is for a small device, no additional charges are necessary. Additional charges are added only to fill a particular need. Note also that blasting caps, which contain a large output charge, obviate a.booster in demolition charges. If there is to be a time interval between initiation and functioning of the train, a delay element is inserted. Often a relay is required at the end of the delay to transform the deflagration of the burning delay into a detonation wave. Delay elements are described in pars. 6-1 to 6-3. A common explosive train charge is the lead. Because of the geometry required to achieve bore safety, detonator (or relay) and booster are separated too far for the detonation wave to travel. This gap is filled with a lead. Leads contain the same explosiMs Ls boosters. Leads are covered in pars. 7-1 to 7-3. Sometimes functions other than initiation of the main charge are required. Actuators exert a force through a small distance to activate controls or to close switches. Small and reliable, they are ideally suited for remote control. Explosive bolts and destructors are other examples of devices serving auxiliary functions. These designs are covered in pars. 9- and 9-2. Good design practice must be applied to all explosive charges and to their assembly into a train. Charges must be of the proper geometry and sensitivity and must have the correct density and confinement as discussed in par. 3-2.2. They must be compatible with other explosives and with metal parts. They must be safe to handle and must stand the extremes of temperature in storage and use as discussed in pars. 4-1 to 4-3. The design of explosivc
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AMCP 706-179
,
charges that make up safe and reliable trains has not yet been reduced to a formula. Rather, it requires considerable experience, The design of unusual trains, in particular, should never be attempted by a novice, After the design is completed, the train is ready for thorough test and evaluation as discussed in par. 12-2. 1-2 SYSTEMS APPROACH TO AMMUNITION 1-2.1 VEHICULAR ASPECTS 1-2.1.1 GENERAL Most ammunition is projected to its target over appreciable distances. Both maximum velocities and ranges continue to increase with improvements in propellants and design. Four aspects of this motion must be considered by the designer of explesive charges: 1. Range and accuracy of a projectile depend upon its aerodynamic characteristics. The external contours dictated by aerodynamic considerations are a limitation upon size and shape of the explosive system, 2. It is sometimes necessary to adapt the design of explosive charges in order to distribute the weight properly for flight stability, 3. Velocities and flight times of many modem missiles are such that aerodynamic heating has introduced a whole new set of explosive-charge-design problems. 4. Acceleration forces during launching. flight, and impact are the principal sources of the structural loading of ammunition. In addition to these more or less general consequences of the functioning of military items as vehicles, it is necessary for the designer of explosive charges to consider special circumstances that may arise as a result of transport systems. Accelerations due to the mechanical action of rapid-fire guns
"'t
and launchers are sometimes quite appreciable and have been known to produce undesirable results when they were not taken into consideration during design. Chambers of rapidfire weapons are heated in the course of long bursts to temperatures that can cause functioning of rounds that remain in them when fiting stops. The limitations on .xplosive charge design imposed by the first two listed aspects are those of dimensions and spatial configuration. They are usually clearly stated in design specifications or military requirements for explosive charges. Effects of aerodynamic heating and acceleration forces, however, usually are not obvious from a glance at the drawings. Frequently, they can inf ience the functioning of ammunition. 1-2.1.2 AERODYNAMIC HEATING Not only must an explosive system withstand high temperatures without premature functioning, it must also function effectively and reliably during or after such exposure. Insulation of explosive charges can be quite effective because the exposure time is usually so short that, with reduced heat transfer rates, the heat capacity of the explosive is sufficient to keep the temperature within bounds. However, as velocities and ranges continue to increase, the necessary amount of insulation may ino-ease to a point where it seriously reduces the effectiveness of a warhead, both by displacing explosive and by wrapping it in a highly effective shock attenuator. The effects of high temperatures upon explosives are discussed in more detail in par. 4-2. Some of the newer explosives that are more heat resistant are not castable. The use of these materials will necessitate design changes in the carrier to facilitate either (I) consolidation of the explosive charge or (2) assembly of preformed explosive charges. The determination of temperature profiles within ammunition items affected by aerodynamic heating is difficult, complex, and quite beyond the scope of the present discussion. It is, however, frequently possible for a 1-7
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AMCP 706-179
designer, by means of a few quick calculations using a simplified model of his system, to obtain a gross answer regarding the need for more detailed calculations, the substitution of explosives, or the insulation of explosive charges. The discussion that follows is intended as an aid in making such approximate calculations.
The flow conditions about an object moving through the atmosphere are most simple if they are considered in terms of a coordinate system moving with the object. In such a system, the undisturbed air is an infinite stream moving at a velocity of magnitude equal to that of the object in a system of fixed coordinates. Quite clearly, tne object impedes this flow of air. By Bemoulh's principle (conservation of momentum) any reduction of the velocity of part of the stream must be accompanied by an increase in pressure. Rapid compression of a gas causes its temperature to rise. The highest temperature that may be anticipated in any point in such a system, called the stagnation temperature Ts, is that of air which has been brought to rect with respect to the object T,
T1, (1I + 0.2W), K
(I-1)
whete T.
stagnation temperature, 'K =
M
temperature of the undisturbed atmosphere, °K Mach number
If the stagnation temperature is below that at which the explosive charge will suffer any ill effects, as discussed in pars. 4-2.2 and 42.3, there is no problem of aerodynamic heating. A stagnation temperature high enough to have deleterious effects upon the explosive is not necessarily reason to take special messures. Only a small fraction of the surface of a moving object is exposed to air at the
1-8t
stagnation temperature, The 'boundary layer of air in contact with the surface at points where there is an appreciable tangential flow component approaches a reco'ery temperature that is well below the stagnation temperature. Typical relationships of recovery temperatures T, to stagnation temperatures are
r,
-T
0.8 to 0.9 T,
(1-2)
To
where T, = recovery temperature, *K. The value of this ratio varies with velocity, position, and shape of the object. Most ammunition that flies at speeds at which the stagination temperature of atmospheric air is sufficient to have undesirable effects upon explosives does so for a limited time. The question as to whether the explosive materials will reach undesirably high temperatures during such an interval can be answered only by considering the heat flow into and within each component in detail. As the stagnation tempeiatures rise relative to those at which explosives are stable and as designs become more intricate, the means of resolving doubts regarding whether explosive charges wi!l survive aerodyamic heating become more laborious and less positive. The introduction of a heat barrier may turn out to be the only way in which these doubts may be removed. In some cases a simple barrier will be effective not only in protecting the explosive but it also will reduce the heat transfer analysis to simple arithmetic. For example, if a thin layer of insulation is applied to the outside of the metal case of an explosive charge, it may be assumed as a first approximation that the metal loses no heat to the explosive, that the surface coefficient of heat transfer is infinite, and that the heat capacity of the insulation is negligible. If these assumptions are made, then the heating rate of the case is
', ,,:,vl, ll
r I ,,i"1(
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ID
AMCP 706-179
_dTT_ T dt
hh,C.
)k.
,
2. If possible without compromising other c
0
sfeatures
of this design, choose an explosive that will survive this temperature,
where
T, = refercrnce temperature, *C
3. If doubt remains regarding survival of aerodynamic heating, make a conservative estimate of the heating rate based either on a simplified model or experimental data for an
I
analogous system, and
T, = case temperature, °C
= time. sec S te4. ki = thermal conductivity of insulation, cal/sec-cm-°C kc = thickness or case, cm
If doubt remains at this point, give serious consideration to the use of insulation or heat sinks. 5- Testing of the system may be required.
h, = thickness of insulation, cm C, = heat capacity of case, cal/g-*C Pc = density of case material, gjcm 3
Note that all of the assumptions are conservative in the sense that they tend to make the calculated temperature rise more rapid than the real one. Thus, if these calculations lead to the conclusion that the protection against aerodynamic heating is adequate, it may be accepted with a miniumum of doubt. *
Where the combination of temperature, time, space, and weight limitations results in inadequate protection of explosive materials, the use of heats of evaporation and fusion to the effective capacity of heat sinks has been suggested. Both the fusion of low melting alloys and the dehydration of salts have been suggested as therfnal buffers. Some salts have the added virtue of expanding with dehydration to form porous insulation media.
Sincrease Shydrated
I
jdynamic
A reasonable course for an explosive charge designer, confronted with a possible aeroheating problem, might be as follows: 1. Compute the maximum stagnation temperature to which a round might be expesed,
1-2.1.3 ACCELERATION As vehicles, ammunition items must, of course, be accelerated. In some instances the magnitudes of the accelerations are great. To the designer of explosive charges, accelerations are a source of structural loading which applies inherently to all masses including that of the exp!ostve material. Acccc!.io. s asso"ciated with changes in the momentum along the line of flight are always variable, usually impulsive, while centrifugal accelerations of spin-stabilized projectiles remain nearly steady during the time of flight. When considering the effects of acceleration of ammunition, its variability must also be considered. On the one hand, it is often possible to reduce peaks by use of shock absorber principles. On the other hand, the rapid changes can result in impact forces of much greater magnitude than those due to the direct effects of gross acceleration. In considering these effects, the designer should obtain the beat estimate available of the time-acceleration function to which his device will be subjected. Table 1-2 lists the magnitudes of some typical accelerations of amminition. 1-9
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AMCP 706-179
TABLE 1-2
distribution on the container that is very different from that computed by assuming the explosive to behave as a liquid.
AMMUNITION Ammunition and Condltion of
ExpoMsre Projectile
3. In Typical Peak
Acceleration. a
Direction
tk
when fired in gun
Prolectile piercing armor Projectile loaded Into automatic gun Projectile loaded Into artillery Rocket or missile, normal launch Rocket or milstle. gun launched Milsile steering Missile flight vibration Mine water entry
50,000 -150,000 -1,0D0 10.000 100 30,000 40 10 -2,500
Axial Axial Gr Oblique Axial
many applications, explosive
per-
formance could be improved by a smaller
metal-to-explosive ratio from that dictated by design in which the strength of the explosive is neglected. Improvement may also result from a different spatial configuration in which the strength of the explosive is utilized. 4. Some applications require metal so thin
Transverse
and soft as to have little value as a structural member.
Axial Axial Transverse Random Axial
5. The resistance to deformation and eventual failure of an explosive material under stress could result in impact forces much higher than those calculated using the hydrostatic approximation.
Note: Forward acceleration is convtntionally assigned
a positive value.
For these reasons it is always best, and sometimes necessary, to design an explosive item as a composite structure or, at least, to consider the effects of its behavior as such.
1-2.2 STRUCTURAL ASPECTS
1-2.2.1 NEGLECTING THE STRENGTH OF THE EXPLOSIVE To sustain accelerations and still retain their functional capability as explosive charges and mechanisms, ammunition must be
designed with full recognition of its functions as a structure. The time-h-inored practice of neglecting the strength of the explosive material, i.e., of designing the container to hold a liquid of the density of the explosive, can greatly simplify structural design and is generally quite conservative. It may not always result in the best design and, in some cases, it -s inapplicable because:
1-2.2.2 CONSEQUENCES OF STRUCTURAL FAILURE OF EXPLOSIVE
C•HARGF$ Obviously, those chaiges whose output characteristics are closely associated with
1. The strengths of explosives are far from negligible and those of some materials are quite appreciable. The strengths of cast explosives are on the order of 2000 psi (compressive) and 200 psi (tensile). Those of plastic
their geometrical configurations, such as shaped charges, will not function properly if the geometry is altered by structural failure. Other consequences of structural failure may be more serious when they occur. Although available evidence indicates that high mechanical stresses are, in themselves, incapable of initiating explosive reactions, movement under high stress-particularly the rather sudden movement resulting from a structural failure-provides a mechanism for the development of hot spots that may become reaction nuclei (see par. 2-1.3). Where the failure results in the relative movement of two adjacent metal members with explosive in
bonded explosives are somewhat higher.
between, action similar to an impact or fric-
2. The resistance of the explosive material to plastic deformation can result in a load
tion sensitivity test (where the explosives am pinched, ground, or impacted) may result in premature initiation.
(
1-10
.. .. ..
.--..(C'..;..
/
..
..
"
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AMCP 708-179
The initiating trains of ammunition are generally composed of a series of rather small charges that communicate detonation only when properly spaced and accurately aligned. Hence, a structural failure can result in either premature functioning or complete failure. 1-2.2.3 STRUCTURAL COMPONENTS AS SOURCES OF FRAGMENTS In many types of ammunition, notably artillery fragmentation projectiles, the case serves two somewhat contradictor) functions: that of the principal structural member and that of the source of fragments. In the one role it has to hold together under high gun acceleration and centrifugal stresses; in the other it must fly apart in a prescribed manner. The high strength that holds it together in the gun also absorbs a significant amount of the energy liberated when the explosive detonates. The choice of a structure and configuration conducive to optimum fragmentation may unduly weaken it. The charge-to-
t
case weight ratio that is best for fragmentation may afford too little metal for structural stability. In addition, the aerodynamic considerations of stability and range are involved, The design of such a projectile is a compror--se of interor, externor. and terminal ballistic considerations (discussed in par. 3-3). In other types of fragment-producing ammu-n, where structural or aerodynamic con•ations are less stringent, the designer has freeJom to adapt shape, construction, ":aierial to obtain optimum fragmentaA,-- 'R. 1-2.2.4 INTERACTION OF S ""6TH EXPLOSIVE M. I •';AS lition to the interaction oi c:xplesives 1. and inert parts to form a composite structure and their interaction to produce output effects, important interactions between explosives and inerts are involved in initiation. growth, and propagation of detonation. The pinching, grinding, and impact resulting from the relative movement of inert components in contact with explosives are, of course, essential phases of the operation of stab and
K '".t
N;
-f
percussion initiators. The phenomena involved in such initiation processes are discussed in par. 2-3. The importan-e of confinement in every phase of the initiation, growth, and propagation of explosive reactions cannot be overstressed. A change in the confining medium can change the critical value of a dimension by a factor of ten or more. Various aspects of the effects of confinement upon explosive reactions arý discussed in practically all paiagraphs of this handbook. Consideration of the role of an explosive material as a component of the structure and of its interaction with, inert structural components from the conceptual stage onward probably will avoid some problems in the testing and evaluation stages. 1-2.3 MECHANICAL ASPECTS 1-2.3.1 FUNCTIONING sense that their useful output is in the form of mechanical work, charges are mechanical devices. the explosive charge designer must also conider those .spects of the mechanical functioning of ammunition which are involved in plac:ng it in the desired location with respect to its target, safeguarding against operation until it gets there, and initiating the reaction at the defired place and time. Both the effects of these preliminary mechanical functions on the explosives and the effects of the presence of the explosives on the functioning must be considered. Because mechanical functioning generally occurs after the ammunition has been launched, the necessary energy must be either stored in or derived from the after-launch environment of the ammunition. In the generally explosive However,
Forms of stored energy which have been used include elastic (cocked springs, compressed gases), chemical (batteries, propellants, explosives), magnetic (permanent magnets), and electrical (charged condensers, Environmental elements). piezoelectric I-I 1
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AMCP 706-179
*
r
sources include aerodynamic or hydrodynamic forces incidental to the motion of the auninliu nition through the ambient Ifluid; acceleration forces related to launching. spin, water entry. And target impact; hydrostatic forces due to changes in ambient pressure. magnetic forces related to movement with respect to the earth's field; electrical forces related to environmental potential differences (electrostatic in air and electrolytic in sea water); and thermal and radiation effects. Quite clearly, the range of forces represented is so great that exceptional precautions are necessary at the one extreme to retain nearly frictionless movement and, at the other, to protect the dormant mechanism, structure, and explosive charges from damage. For details on both stored and after-launcl. forces, see Ref. g.
1-2.3.3 SAFING AND ARMING DEVICES
1-2.3.2 LOCATION WITH RESPECT TO TARGET
The armin* requirements h've made necessary in some instances the use of forces that are so weak as to place very high standards oni
The mechanical functions involved in placing tile ammunition in the desired location with respect to its target might be considered as part of its functioning as a vehicle. [lowever, th•se tunc!ions under consideration here are not so clearly vehicular functions as propulsion and flight of the item. They include such varied activities as separation of stages in multistaged weapons, jump-up action of certain antipersonnel weapons, and opening of parachutes. Some of these functions are accomplished by means of explosive actuators (par. 9-1). Where such devices are used, it is a concern of the designers of other components to safeguard against their premature initiation or other damage. In other "instances, where the source (such as movement of a small bellows under the action of hydrostatic pressure) makes only a small quantity of energy available, precautions are necessary to prevent an increase in the frictional loading of the system resulting from the distortion of the weapon case. due either to dimensional instability of the explosive material or to differential thermal expansion.
tolerances, finishes and balance of moving parts. some of which carry explosive components. The designer of explosive components for use in safine .mid arming :ntcha;ia;i musi be particularly careful to safeguard against dimensional instability of the explosive material. Any design change that results in a change in mass or in mass distribution should be considered carefuily in the light of its effect upon tile functioning of inertial arming systems, including rotors of fuzes for spinstabilized devices. The effect of chlanges in mass distribution caused by arming operations may sometimes require exanlination by an exterior ballistician.
1-12
It is a basic require ncit that uizes have two independent safing f.'aturcs, whenceer possible, either of which is capl-le of preventing an unintended dctoiation before the ammunition is projccted 3 - "lhe 1iphilosophy is based on the low probability that two featurte will fail siMulta:||couily. If possible. both safing features should be 'f'ail safe" and each should be actuated by a separate force. Where launching forces are used, arming must be delayed until a safe distance is attained between the ammunition dnd the point of launching. These principles-combined with the wide variety of launching. propulsion, and stabilization means used, the range of afterlaunch environments, and the- inventivc ingenuity of fuze designers -have resulted in a proliferation of arming devices and schemes (see Ref. g).
The design of a safing and arming mechanism is a three way compromise among reliability, quality control, anti compactness. If the components are large enough, they can be reliable even if they vary greatly from item to item, and quite safe if far enough apart in the unarmed state. To meet the increasing demand for miniaturization, it will be necessary to improve con tinually (I) the standards
(
-1
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AMCP 706-179
of reproducibility of output. (2) the sensi-
1-2.4.3 ELECTRIC INITIATORS EXPOSED
tivity of explosive comuponents, and (3) the techniques for their evaluation. The designer of the mechanism must lean heavily on the explosive component designer becausc the basic dimensions of the mechanisnm depend upon the characteristics of the explosive components.
TO SPURIOUS SIGNALS The very nature of the design and firing mechanism of electric initiators makes themi vulnerable to spurious electrical signals such as RF energy, lightning, and electrostatic charges. Pick-tip of such signals (an cause premature initiation or possibly dudding and thereby reduce perfornance reliability. Because of the extensive use of electrical initiators in modern weapon systems, great care must be takin to design them sO as to reduce this vulnerability.
1-2.4 ELECTRICAL ASPECTS 1-2.4.1 ENVIRONMENTS The complexity of our electrical environnmene is staggering. Practically every insulator has a static charge. Any two dissimilar pieces of metal, wet with slightly impure water, maký- a battery ofsorts. Weld them together
.
SMethods
Several solutions have been proposed to alleviate this problem in the design stage4 The designer of ammunition can minimize the hazard of initition caused by the electrical
and change their temperature and we have a thermal generator. Every spark plug, every switch, every thunderstorm, and all the stars keep broadcasting transients. lience, all
environment by following these general design practicesf
ammunition has, as does everything else, all sorts of small currents running through it at random at all times. In general, these currents remain so small as to have negligible heating effect. Under certain conditions, fairly high cnnents are possible. Electrostatic disuharges and surges due to nearby strokes of lightning Scan alsoofbhardening develop weapon appreciable currents. systems against Re ofare discussed in detail in Ref 4.
all electric circuits subject to hazard.
1-2.4.2 POSSIBLE INITIATION OF THE MAIN BURSTING CHARGE If, at some point in a circuit, spurious currents are concentrattd in a relatively small path in intimate contact with explosive material, it is ronceiv.1ble that a hot spot might develop and fonn a reaction nucleus. Analysis of such systems is too complex to undertake. This is particularly true in view of the lack of evidence that such accidentally
formed electric initiators have been the cause of accidents. It is well, however, to check a design for conditions that are obviously conducive to such effects,
I. Use of complete electrical shielding on
2. Design of components that are speciuically resistant to the spurous signals including, where applicable, the special schemes dissussed in par. 5-4.4. 1. o:
Proper
analysis
3 . r e simulation r simula correct
and
testing
oftion service
under a
unde ria electrical
environments to determine the susceptibility of a system to electrical hazards. 1-3 GENERAL DESIGN CONSIDERATIONS While the design of the explosive component that makes up an explosive train is not a simple task, it should not be considered overwhelming. The various chapters in this handbook discuss the principles of explosive components and treat the design of specific devices. In addition to the special information given, a number of general design factors must be kept in mind. These factors-applicab e to
engineering design in general-are important in the design of each system component. Knowledge of the general factors, the design requirements, and the relation of the explo-
1-13
JL_
I
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AMCP 706-179
sive component to the system permits cfficiency in design and the possibility of tradeoffs that may improve performance. The general factors include reliability, safety, standardization, and human economics, factors engineering. 1-3.1 RIELIABILITY Reliability is a measure of the extent to which a device behaves as it was designed to behave during the usually short period between launching. firing, or being emplaced. and completion of its mission. Obviously. reliability of ammunition and of its com'ponents is of key importance. Weapons arc useless if they don't function as intended,
,
Reliability is defined in statistical terms. It is the probability that material will perform its intended function for a specified period under stated conditions. The problem with explosive components is more severe than that of other items for two reasons. First, they are a small part of a complex system. Since the probability that all of the components in a system will function is the product of the probabilities of the individual components, the lnctioning probabiAiy ofc^"xpio sives must be high, higher than that of the total system. This requirement calls for high reliability of explosives. Secondly explosives are one-shot devices that cannot be tested repeatedly. Special work-or-fail methods of analysis have been developed; they are described in par. 12-1.2. The evaluation of materiel, including estimation of its reliability, is usually carried out by an organization, or at least a group, other than the design group. Difficulties between these groups can be resolved more readily if the designer of explosive devices is famifiar with the techniques used by evaluators, uses similar techniques to assure himself that his designs are reliable, and designs devices and systems in which reliability is as nearly inherent as possible. A frw general suggestions can be made for the designer:
I. Whenever po.sible, use stanuuiu Loutponents with established quality level and other reliability vriteria at least as high as that required by the application. 2. Wherver possible, particularly in more nomplex ,nd cxpensivc materiel, use redundant systems. 3. Specify nmaterial,
for which the propertics of importance t,, your application are well known and reproducible. Keep in mind that the average value for a parameter may be less important for design purposes than the extreme valus. 4. As far as possible, design items in such a manner that defects which affect reliability can be detected by means of nondestructive tests or inspection. 1-3.2
;AFETY
Safety is a basic consideration throughout item life. We are concerned with the extent to which a device can possibly be made to operate prematurely by any accidental sequence of events that might occur at any time between the start of its fabrication and As approach to the targel While safety also is defined statistically, the approach to safety is somewhat different front that applied to reliability. The keystone of this approach is the fail-safe principle. Essentially, this principle states that any sequence of events other than that to which a round is subjected in normal operation shall result in failure rather than detonation of the round. Compliance with the fail-safe principle usually is accomplished mechanically, and is the reason most mililary devices must be considered as mechanisinis. In terms of added bulk, weight, and complexity-which can be translated into terms of reliability, effectiveness, and logistics-safety is expensive. Hence, the problem of safety is a double one. The designer must be cert in that his device is safe and yet impose the least
"•
1-14
-
0
t
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AMCP 708-179 inlpai rm:lcit ot l fncti oning c)st.
all at minimumn
The preceding remarks on safety emphasize the protection again:it premature functioning of the initiation package. flowevet, this is only one aspectl of system safety. Another example of safety is tnhat of protecting against direct initiation of main charge or booster by impulses incidental to handling, shipping, storage or launching, and accidcent: that miay occur during these operations. The vulnerability of ammunition to initiation by accident or enemy fire can seriously restrict its tactical usefulness or greatly complicate problems of storage, handling, and transportation, System design can ieduce this vulnerability by affording mechanical protection, !upport, and confinement. Hence, safety is not a separate problem but an integral part of explosive charge design.
1-3.3 ECONOMICS The assessmIenlt of a wcapon system involves the comparison of its value with its cost- The value per round may be considered to bc tile produot of the military value of the damragc of which a round of ammunition is capable and the probability that a given round will inflict this dammage. The cost of a round of ammunition includes the cost of delivering it to its target aN well as that of producing it Each of these quantities is. in itself, a complex combination of diverse factors that may ir.clude aspects of statistics. military strategy and tactics, and all bran'ches of engineering. The process of comparing alternative solutions to stated requirements in the terms of the value received (effectiveness) for the resources expended (costs) is called the Costi Effecriveness
r
A number of policies, rules, and safety codes that apply to various types of material have been promulgated. In view of the variety of these codes, it is well for a designer to examine in advance the %atety enteria That will be applicable to his design. The designer should be familiar with the foliowing general safety inforniation: I. The basic reference for safety is the Safer), Manual'. 2. It is a basic requirement that fuzes have two independen' satfing features, whenever possible, either of which is capable of preventing atm unintended detonation before the ammunition is projected 3 3. For safety considerations during packing, storing, and shipping, see pars. 1I-I, 11-2. and 11-3, respectively. 4. The standard tests devised to examine the safety of explosive components are discussed in par. 12-2-4.
*[
5. Requirements for the system safety program are covered in ML-STJ-882 6 .
analysis.
Basically,
a choice
must be made between maximizing accomplishment of the objective for a given cost or minimizing the cost for achieving a given objective'. 1-3.4 STANDARDIZATION The decision as to whether to adapt a system design to the use of a standardized component or to design a new component especially adapttd to a system is often one of the most difficult a designer has to make. On the one hand, a new item often has been developed because, in thle layout stage of design, it took less effort to sketch in somethipg that fi t*he dimensions than to find oui what wis avn-ilable. On the other hand, the hard and fast resolution to use only shelf itcnss has resulted in systems that are app'-ciably inferior to the best attainable with r:gad to safety, reliability, effectiveness, or coinpz:c(ncss, and in the perpetuation of ob.ilete items. As a general rule, the standard item must always be given first preference and must be coadered carefully. An important reason in expiluive charge design i, the cost arid time 1-15
(-
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AMCP 706-179
required to qa arid 12-2).
new Items (see pars. 12-1
tem. Many explosive comlponents arc s1uall. intricatc devices. ('are must be takitl to avoid t,;itorcs t hatI te•.d to i'.l rodtL.cL" lilunta icriot.
MIL-STI)-320 lists a;tindalrdied series of dimoe nsi ons for i1tewly developed detonlv ors, primers, and leads and for their components.
I:aulty assemblies cused by such enrors as lnissi nI parts ot parts plaLed tp~itpc-downi can
1-3.5 HUMAN FACTORS ENGINEERING
handled behind barriers for rasons of safety hnso that close scrutiny is difficult !o acconiplish.
The science that analyzes Iman.lls rohle in
affect severely ultimate perlormance. Runteltier also that explosive componcntis ofteni are
inan-machine systenms is called hullatn factors
cigineering. Man's capabilities and, morc important, his lintitations must be given careful cotnsideration. This topic, as it relates to fuies, is covered in AMCP 706-210W.
rhe
design of explosive compon.ientlS is also withI human factors engineering lest any shortcomings of the comlpotnents affect the fuze, ammunition, or weapon sysconcerned
Erratic perfornlanic in a particular delay %%.is once t ,.,Cd tO a tprobleln of hutllo at t rai factors engineering. A manual assembly operation called for inserting 5 delay pellets into a deep cup, eicti pellet being separated by white tissue paper. Opcrators tended to lose count sc, that cupls containetd from 4 to (6 pellets. The prohletn was solved by using tissue paper of different colors for each layer.
REFERENCES a-g Lettered references are listed in the General Peferences at the end of this liiaidbook.
4. AMCP 700-235, F-nginecring Design tlandbook, Hlarde-ning Weapon Sy)stems Against RAf Energy,
I. AM'-P 706-270. Etngineering Design ilandbook, PropellantA ctuar-d Devices.
S. AMCR 385-100 Saijtiy Miaiul, Army Materiel Cotmtand, April 1970.
2. Tadeus U~rbanski, (Tuvnistri and Ted'htoologr of Explosive's. Pergatnon Press, London, Vol. 1 1964; Vol. 2, 1965; Vol. 3, 1967. 3. MIL -STD 1316, Fuz-. Design SaJelt', C0itria For, Dept. of Dcfense, 17 Septembet 1970.
1-16
6. MIL -STD 882, System Sufi't' Program Jor Sustlims and Associatrd Subs.is'tms" and Lquipment, Dept. of Defense, 15 July 199. 7. Robert N. Grosse. An Iputro(tjction to Research Cost-EJffrctiv'.'ess Aual)y-si, Analysis Corp., McLean, Va., July 1965 (AD-622 112).
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AM(CP 706 179
CHAPTER 2 EXPLOSIVE REACTIONS AND INITiATION
2-1 THERMAL DECOMPOSITION AND BURNING
2-1.1 THERMAL DECOMPOS!TION l'plopin-iss .1W suibstin,:c or imistur oit Niiht ances vsid ic lw) leit:lide ito onlerc-go at Lipid h cmi atclim a01amgt' with oim all on side su1pply- of ox ygeni with tilenliberation til large qwlt i tits of cnergy ge'nerall y acconlipalici i' by lit' evolutiion tif Iiot ga.cs. A% mt'tastiable materi'liis. they decompose at all lim pc ratumres above absolute itro. Thie rates tit ttccomposiliotn arc djrtect Itimictions of temiiperatuire- lor explosives of practical inlteret. tile tlc~oliptosit ion rateCs. ilt norimal temperatuores of Storage. lit dli ng, anid t ransiotat iti . are iletligitily small. As tile temoperatutre is in%:reascd at tw hiiundred dkegteCS, tile rtites of' II icI iiii dlc~oi posmiton aiia.u n :;ogi'.tifcao I lecOs- T'he sell-heating of' thle explosive by tile heat evolvetd inl this (exotihcomic) rcactiom tendit)totrtiicr raise tile temperature ant" inras cheraction rate. Where sitch circuoc si:lntt'5~ resullt ill a runlaway, reaction, a thermal explosion may p' tilt' Ret. I also presents a thorough %otus i tile hchavior of explosivcs.
-suich
rin
I'll- traction ot a typiQAl chorget il Solid exploive, rigorously conxitrcrcd inl it-, rilti' matt: det ail, is so comnpit'x as ito tic y quan tiLatwv description. Fortunately. holWCver. 1:1C Sypic ii situation is such that cone ot anot ii c aspect of tile behaviot oit tile material is %k, doiminanit thiat ot her aspe cts il ay tic di isni ssed as s1econ1d order e ffect%- IHence. although gradulal therinal deccomposit ion. ic t'lagratio n. and de.tonat ion are usuaiily ochin icjhy similhit ploievses. their physic ai caulses and mani test a' tions are so difltern t that the iy may bec tinderstood best bý coimsiderink thliem a% distinct phenomnca. hleats of c~ombustion and detoniptionm arc different initial p)iascs or tic lagea tion, whiichl can be %:oiisidered as burning or oxidationi. Some cxptosivcs. however. are not readily combustible. I'li rates of' the rmal decom posit ion and deilamgiatioin arc related direcciv ilo tempera-
Most expltosive reactions, whether intcn* timnal or aLcc ide ital. result tront highly local' liitd hieatiing that inifialme% it sellt-prtopagaiting reaction' Inl such ai reaction tile hteal libcrated by flme rceaionl ot thle explo~sive atl One pouiit ill .i charFge raises, tile Minpfratil(C lin adjacent material siifficiently to cause it to reacti at a similar rate. The mnodes tond rtites of
lnre and pressure white detonation is related preastire. All thice reactions restilt lit tile ilicrcase kif both temperature and pre'2--e.tv It follows thait anly -charge of explosive, if vontained so as to pfetveflt expansion or losses of matter or enkrgy, will evenmtuailly explode. It the tempe raltire is unifomin lhrotmt'iout thle charge, thle reactionl will be a pill thermal explosion where eacti elemenit 01 vol time expienences tile Samle Selt'aecc~crating temiperattire rise. More usually. any valriations in templeraltire will tend ito exaggerate themselves so that thle seif'licating reaction will ruinI amway at the hottest point front whic tti def'lagration, iItit 1171 SCll-accelerating. Will
sell'propagating reactions So protouitdly at'tcct [thc ipable phenomncia associated with tile funlctionling ot explosives that these pheinomeina canl hardly be considert'd extept terms oftilicst' mode%and rates.
propagate. Thle self-accelerating deflagration is characterized by a simiilarly accelferating rise iii pressure, wvhichi is propagated throuigh tile tumracted explosive as a conipressioli Wave. It' thle Charge is large enlough, lihe wave mlay
Ito
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AMCP 706-179
develop into a shock of sufficient amplitude to propagate as a detonation.
E = activation crergy, cal/mole R = universal gas constant, cal/°K-mole
2-1.2 REACTION KINETICS Perhaps the reaction of an explosive material can be understood best by trying to visualize an explosive molecule. Such a molecule is a structure containing atoms that have very strong affinities for one another, and that are prevented from responding to these affinities by their places in the structure. The positions of atoms within the structure of a molecule and that of molecules within the crystal are fixed, not by rigid links, but by equilibrium of electrostatic and quantummechanical exchange forces. Unless the tem.perature is absolute zero, each atom vibrates about its equilibrium position with a random motion under the influence of the similar random motions of its neighbors. These random motions, which are characteristic of thermal phenomena, apply to the partition of energy between molecules and between atoms of each molecule. The average energy of molecular agitation is proportional to temperature. If, at any given absolute temperature, the agitational energy exceeds the activation energy, the atom may escape from its position in the molecule and be free to assume more congenial relationships. This uproar increases the agitation of neighboring molecules, that is to say, the reaction proceeds with the evolution of heat. The reaction rate then is the frequency with which the agitational energy of individual molecules exceeds the activation energy k'()= ATe-EI(RT)
(2-1)
where k' = reaction rate, Hz T = absolute temperature, OK A' = inverse function of the restraint to motion of an atom, sec/°K 2-2
The classic Arrhenius equation sets A 'T = A for small temperature ranges k'(T) = Ae-t(RT)
(2-2)
where A = Arrhenius constant, Hz Eq. 2-2 is used more commonly to relrresent the temperature dependence of chemical reactions. For the temperature range of most experiments, the difference between Eqs. 2-1 and 2-2 is not distinguishable (see Fig. 2-1). The qualitative implications of the Arrhenius equation deserve the consideration of all who deal with explosives. Since E for military explosives has a value between 10,000 and 100,000, while R is approximately two, a small percentage change in temperature results in an order of magnitude change in reaction rate. The sharply detined temperatures that many experimenters have associated with decomposition, ignition, or exp!osion (see Table 2 -1d) are quite readily explained in terms of these equations and the relatively himited range of rates that may be measured by most experimental techniques. (The ignition temperatures shown in the table are computed; the explosion temperatures are experimental.) The Arrhenius equation expresses a characteristic (temperature) of explosives which has, perhaps, a greater influence upon the initiation process than any other attribute. For example, the reaction rate of a typical explosive with an activation energy of 50,000 calories per gram mole, at 800 0C is more than ten times its reaction rate at 700'C. The experimental determination of the constants of Eqs. 2-1 and 2-2 for various explosives is complicated by the effects of reaction products, phase changes and multiple reactions, as well as by the heat transfer considerations. The reactions of most of the
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AMCP 706-179
to
fits most experimental data so well that many investigators have ignored the complicating influences and derived more or less empirical Arrhenius constants from plots of the loga-
10
rithm of the rate, or of a rate-dependent quantity, as a function o" the reciprocal
04
temperature. For the explosive charge designer, the most consequences of theoretical studies of thermal decomposition problems are the development of (!) a more valid basis for qualitative thinking, and (2) coordinate systems within which most experimental data form recognizable patterns. When ;onfronted with an explosive charge design problem, a suggested approach to a realistic solution consists of the following two steps:
100 ouseful
W for o
1. Obtain, either from available literature or specifically designed tests, experimental for situations that simulate as closely as in service. possible those to be encountered
-) to Aedata
S•
2-1
[EQUATI ON
S'r) ý A#-''t -"r f 5oooo)-. EQUATION 2-0, ARR)NIUS
2. Interpolate between d3ta points using coordinates of inverse temperature, and loganthms of times, rates, or dimensions. These
-.-
lto•coordinates
lot
may also be used for extrapolation. However, extreme care should be exercised when extrapolating because abrupt changes in the decomposition rate (soch as those due tG melting of a component of an explosive material) may occur outside of the
A AND A' ARE ADJUSTED TO GIVE EQUAL RATES AT5000K
)O
[
!
range of expe'iniental data. 2-1.3 THE "HOT SPOT" THEORY OF INITIATION
I TEMPERATURE,
The view that nonuniformity of heat distribution is essential to the usual initiation process has been called the "hot spot" theory of initiation. In explosive initiators, the energy available is concentrated by the use of small diameter firing pin points and, in electrical devices by dissipating the energy in short and highly constricted paths. The addition of grit to primer mixes serves a similar function. Not only is nonuniformity of energy distribution essential to most initiation processes, but it is an important factor in
-K
Figure2-1. Computed Explosive Reaction Rates
Sgenerally
commonly used explosives are either accelerated (autocatalysis) or retarded (autostabiliiation) by the presence of their reaction products'. Because of these difficulties, accepted reaction kinetics constants for explosives are not available. However, the exponential form of the Arrhenius equation
2-3
L _
_ __
_
_
__
__
__
__
_
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.- MCP 706-179
TABLE 2-1 IGNITION AND EXPLOSION TEMPERATURES t Explosion Temperaturea, 0C
Themal IiMilto 0
Fmplolve
Temperature', C
0.1 we
1 sec
5 $ea
10 se
bete.HMX
-
380
327
Decomposes
306
Composition B
-
526
368
278
Decompsues
255
Cyclonite IRDX)
-
406
316
260
Decomposes
240
Heleite (EDNA) Lead Azide Lead Styphnate Nttrmlycerln (Liquid) Pentolite, 50/50
335 250
265 386 -
216 356 -
189 340 282
Decomposes Explodes Explodes
178 >335 276
-
-
222
Explodes
-
-
290
266
220
Decomposes
240
PETN (Penteerythritol Tetrenitrate) Silver Azide
215 160
272 310 -
244 -
225 290 100
Decomposes Explodes -
211 -
-. -
340 570
314 520
257 475
Ignites Decompoms
238 465
200
Tauscene Tetryl TNT (Trinitrotoluen)
-
-
*Computed t Experimental the growth and propagation of practically all chemical explosive reactions used in ordnance.
with dimensional changes and since the volumetric specific heats of solids vary only slightly from one to another, the minimum energy required to initiate an explosive device is nearly proportional to the volume of material th't is hete•d by the input energy pulse- It must be stressed that this is an approximation that should be applied only to comparisons of performance within initiators of the same type initiated in a specific
Because of the exponential nature of the Arrheni•is equation (Eq. 2-2). the raction rate inevitably reaches a level such that heat is liberated faster than it can be lost. From this point on, the reaction is self-accelerating and quite rapidly becomes explosive,
S~manner.
Although a general equation that includes
"consideration
of all of the complicating factors would be completely intractable, the use of simplified models makes possible solutions which contribute to the understanding of the initiation process. However, simplifications must be used cautiously. For example, it frequently appears that each explosive has a critical initiation temperature that is independent of dimensions. Although more extensive experiments or more detailed analyses have usually shown it to be an approximation that applies to only a specific class of initiator, this relationship can be a useful design
Since the energy available for the initiation of military explosives is usually limited, initia.lion systems are designed to concentrate this energy, as heat, in a relatively small volume. Obviously it won't stay that way. The smaller the voltime in which a quantity of heat is concentrated, the faster it is dispersed, other factors remaining similar. In order to concentrate a given amount of heat in a nucleus of a given volume, the heating must take place in a time which is short compared with the cooling time of the nucleus. If the rate at which energy is introduced, i.e., the input
tool if its limitations are kept in mind.
power, is reduced to a low enough level, the
Perhaps the most important implication of the foregoing is that, since in any type of system, the critical temperature varies so little
losses will establish equilibrium with the sum of the input power and the heat generated by the reaction. An infinite quantity of energy
I|
2-4
I S/...
.
."
!.--..
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AMRP 706-179
will not cause initiation under such equilibrium conditions. Up to this point, the present discussion has been concerned with the establishment of reaction nuclei. Once reaction is established at a nucleus, the useful functioning of an initiator requires that the reaction be propagated to the remainder of the explosive cl.arge of the initiator and thence to the next component of the explosive system. Similarly, the consequences of accidental initiation depend upon such propagation. The same heat transfer mechanisms whereby heat is dissipated from a prospective reaction nucleus ate necessary for the propagation of the reaction from an established nucleus. However, conditions that promote sensitivity to one or another stimulus will sometimes cause failure of propagation if carried to extremes. Heat may be transmitted by conduction, convection, radiation, and what might be called thermodynamic heat transfer. All of these mechanisms are involved in the reaction of explosives, but their relative importance varies greatly and changes as the reaction progresses.
b
Sstances,
Sunreacted
S
2-1.4 DEFLAGRATION
The reaction products of most splid explosives are largely gaseous. Most 6f the important aspects of the behavior of these materials are related to this phase change at the time of rt iction. The surface burning rate is determined by the rate at which heat is transferred from the hot, gaseous reaction products to the unreacted solid explosive material- (The local reaction rate is quite probably related to temperature by the Arrhenius equation, but the very steep temperature gradient is reflected in a much steeper reaction-rate gradient, so that the reaction zone is almost vanishitgly '-thin.)The rate at which heat is transferred between a gas and a solid is the product of the difference between their temperatures and a surface coefficient. The surface coefficient is a function of the flow conditions in the gas and its thermodynamic properties, and is directly proportional to pressure. When a solid explosive burns, temperature increase, flow conditions, and thermodynamic properties of its reaction products are near'y constant. Thus, the rate at which heat is transferred from the products to the explosive and, consequently, the surface burning rate should be directly proportional to the pressure. For some it is, but for most the situation is somewhat more complex.
The very rapid burning of which explosives are capable (by virtue of containing all of the needed for the completion of their
The reaction of many, perhaps most, explosive compounds takes place in the gaseous phase. The rate of surface burning in such
The process referred to as thermodynamic heat transfer is mi-eof the most important mechanisms involved in explosive reactions. The cooling of reaction products, due to abiabatic expansion can, under some circumquench a reaction. Conversely, explosives can be heated by compression to reaction-inducing temperatures. When the compression is of sufficient magnmtude and suddenness to cause a signiticant increase in temperature, it is generally propagated through the material as a shock wave. Detonation, the ultimate goal of high explosive systems, is a type of reaction propagation which depends upon this mechanism to transfer the heat of reaction to the unreacted explosive.
3:materials
,
,
reaction) is known as deflagration. Deflagration is distinguished from detonation by its subsonic propagation rate, from which it may be implied that shock waves are not important factors in tht propagation. Deflagration of a gas may be described quantitatively in terms of thermodynamics and hydrodynamics. That of solid explosives is more complex and, for real situations, is subject to only qualitative description. Empirical relationships, which art quite reasonable consequences of the mechanisms indicated in the qualptative description, are sufficiently useful for predicting the course of this type of reaction.
S.elements
2-5
LN
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AMCP 706-179 TABLE 2-2 VALUES OF THE CONSTANlT 0 IN EQ. 2-3 Exploe
a x ll
Ammonlum Picret Teiyyl TNT PETN ROX
6.25 8.7 12.5 21 21
Sis
cases is essentially the rate at which the surface erodes due to sublmation. This in turn is proportional to the rate of heat transfer divided by the heat of sublimation, Since the heat of sublimation of the solid usually increases with increasing ambient pressure, the increase of the surface burning rate with increasing pressure is somewhat less than linear. A relationship between burning rate and pressure which has been found to apply to the surface burning of a number of solid explosives and propellants is R = GP, ft/sec
(2-3)
in determining the course of the reaction. In a completely enclosed case, pressure continues to build up and burning rate continues to increase until the case bursts oc the explosive expended. The explosion that results is entirely due to the sudden release of gases when the case bursts- If the case has a leak, orifice, or nozzle, conditior's of equilibrium arc possible in which the rate at which gases are evolved equals that at which they flow from the container. For rockets, in which stability of this kind is extremely important, the effort is made to develop propellants for which the exponent n of Eq. 2-3 is as low as possible. In explosive components, the instability that results from the high values of Pi associated with porous explosives is an important factor in the rapid acceleration of reaction propagation, a part of the function of such elements. 2-2 DFTONATION 2-2.1 TRANSITION FROM DEFLAGRA"fIONTO DETONATION
where R =burning rate, ft/sec
SThe G = empirical constant P = pressure, lbfin-a n = polytropic constant, dimensionless The exponent n is less than one. Surface irregularities may increase the burning rate by increasing the surface area and by introducing a component of flow parallel to the surface, thus increasing the surface coefficient of heat transfer. Table 2-2" lists constants for Eq. 2-3 for various common military explosives,
*
The pressure depenience of the rate of surface burning, and the fact that gas is evolved at a rate proportional to the surface burning rate, result in a situation where the confinement afforded by the case of an explosive charge is the most important factor
2-6
2-2.1.1 TRANSIT!ON PRO-CESSS trznsition from deflagration to detonation is generally divided into three stages (I) deflagration. (2) low order detonation, and (3) high order detonation. The transitioy. from one to the other of these stages is usually quite sudden and is influenced greatly by three factors, particle size of the material, porosity, and confinemcnt provided by the envitonment. The process of transition from the first stage can be described on the basis of the following concepts: The deflagration reaction rate accelerates rapidly if the particle size is of the right magnitude. When confined, this increased reaction rate results in increased pressure that propagates as a shock wave in the unreacted explosive. As the shock wave becomes of increasing strength, shock heating will cause a fast enough reaction to sustain the shock which then propagates as a low
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I
I
tI
AMCP 706-179
7--
ý"=
a
,. :,/y'-:. / -and, '
.~',I .I.
I,
*.
, /.
-
Figure 2-2. ArrangementUsed in Observations of Detonation Growth
{
compared with the stable eate of over 4000 m sec for these loading conditions. The
growth is apparently continuous, though slow in a few experiments, approached its maximum rate in several inches. Because of its low rate growth to detonation, lead styphnate is not used as a detonating charge, but to increase the sensitivity of the initial charge, where its reprcducible ignitibility is an advantage. 2-2.1.2.2 LEAD AZIDE
order detonation. This low order detonation then propagates as a shock wave which, if reinforced by sufficient energy, will accelerate
!t is true that the growth of detonation in lead aziae is so much more rapid, even when loaded at very high pressures. ,that experi-
to produce a high order detonation (see aiso Ref. k).
ments in which detonation growth and "dead pressing" can be obmerved in most other explosives would lead to this conclusion. 11nwever, these properlies of lead azide, cornbined with the ever rising pressures for ruggedization and miniaturization, have resuited in the evolution of designs for which these assertions must be reexamined.
Particle size influences the acceleration rate of the reaction as does particle porosity because of their effect on the surface area that is exposed to the hot gaseous reaction. Experibnentation has shown that for each "particle size there is a critical pressure ot which the increase in burning rate with increasing pressure is faster than linears. Tt-is ritical pressure is inversely related to particle size.
tI
2-21.2 GROWTH OF DETONATION IN PRIMARY HIGH EXPLOSIVES In a series of experiments using the arrangement shown in Fig. 2-2', containers were sectioned after firing and the expansion of the bore was taken as a measure of the vigor of detonation. The arrangement was also used to measure propagation velocities. Lead styphnate and lead azide were tested. 2-2.1.2.1 LEAD STYPHNATE
Dextrinated lead azide made the transition from burning to detonation quite suddenlyý for all combinations of loading pressure, confinement, and initiation. However, when pressei to densities above 95% of maximum theoretical (requiting 20,000 - 25,000 p'i loading pressure) and mildly iritiated, it would detonate at rates of 1400-1100 rn/sec compared with an approximate rate of 3000 m/sec obtaiticd at lower densities. 2-2.1.3 GROWTH OF DETONATION IN SECONDARY HIGH EXPLOSIVES One of the principal features that distinguishes a secondary explosive from a primary explosive is its much smallet propensity for completing the transition from
The growth of reaction in lead styphnate
burning to detonation. As in primary explo-
was very gradual in all instances. It grew fastest (as indicated by the taper of the bore) in material pressed at 4000 to 3000 psi. Under these conditions, the maximum measured propagation rate for the second inch of column was about 2000 m/sec, which may be
sives, this transition is affected by the interaction of a number of factors including charge size, state of aggregation, confinement, and vigor of initiation. However, for any given combination, the transition is much slower and many charges, evqu main bursting
2-7
'S.
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AMCP 706-170 TABLE 2.3 OPTIMUM LOADING DENSITIES AND PARTICLE SIZES FOR GROWTH OF DETONATION INRDX. HMX. AND PETI Optimum Loading Dae~y
Optmum Pas
o*Dnsity. 9eoc
Explosive
Grnulastion
RDX HMX (tirst sample) HMX (second sample) PETN
Unsleved 250-136 micron (Not Determined) 420 micron
1.29 1.26 1.59
Micron Range 251-124 2b1-124 76- 53 124- 76
0eSin-
USS sieve cut 60.120 60.120 200-270 120-200
Burning Length, cm 1.2 1.9
1.4 0.2
charges, are so small as to be consumed by low order detonation before the transition can take place. Such main charges are, of course, much safer to handle and use than those in which the transition will take place. In addition to the assessment of hazards of main charge detonation after accidental ignition. the growth of detonation in secondary high explosives has been investigated by those who are interested in the development of safer detonators. The latter have made signifi-
In other experiments it has been established that tile growth of detonation in a column of secondary explosive is aicelerated by the insertion of a barrier followed by an air gap' (see also par. 3-2.2.5). It might be expected that tile explosive material, particle size, loading density. dimensions and confinement on both sides of the barrier-gap cornbination interact with the material and thickness of tile barrier and the dimensions of the gap to detenuine the burning distance A
cant contributions in the determination of optimum .onditions for the most rapid growth of detsn_-tion in some of the more
the faztorial experiment to determine optimum combination would be a formidable program.
sensitive svunidty 11igh. cxplosivcs.
I
Experiments similai to that illustrated in Fig. 2-2 have been carried out with columns of PETN. RDX and FMX. A refinement was the use of coaxial ionization probes that
Growth of detonation has been observed in a number of cast e:plosivess. In Pentolite cnd DINA (diethylnitrsnmine dinitrate), high order detonation was ctablished in 10 to IS cm. In Composition 13, the propagation rate grew to
could be fed in through small radial holes at fairly frequent intervals along the length without utidaly affecting the confinement. Velocity measurements obtained with these probes, and oscilloscopes and timers established the correlation between bore deforma-
about 3000 m/sec, at which point the cDntainer apparently shattered. relieving the pressure and allowing the reaction to decay. In TNT, tile reaction grew so little in ] 2-i.. columns that the containers were practically undamaged, and the propagation rates so low,
tion and propagation velocity. The lengths of
600 to 1000 m/sec. that it was difficult to
columns required to grow to detonation, referred to as burning lengths, were determined for a number of combinations of
obtain satisfactory records. By increasing the length to 34.5 in. and finally to 58.5 in., it was possible to observe the growth of the
particle size and loading density. Hardly
propagation velocity to about 2000 m/sec.
design data, these lengths may be taken as indications of development goals. For each explosive, optimum values were indicated for each of these variables at which the burning length reached a minimum value (see Table
The increase was quite retsilar but seemed to be accelerating toward the end. The question as to whether the r, action would continue to accelerate, stabilize at a low order detonation. or burst the tube and die out has not yet been
2-31 ).
answered.
2-8
(
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AMCP 706-179
2-2.2 SHOCK WAVES
and
Detonation is a mode of propagation of reaction in which the energy that initiates the
reaction is transmitted
to the unreacted
material in the form of a shock wave. It has been referred to as a reactive shock. The discussion that follows of nonreactive shocks serves as a preface to that of detonation. Shock waves, like acoustic waves, are a special class of compression-displacement of such waves waves. Although the behavior varies with their amplitude, their ws've form, and the properties of the media in which they propagate, many relationships that derive from fundamental physical laws are the same for practically all cases. Although the typical wave attenuates as it propagates, this attenuation is so slow compared with the associated transitions that the wave may be assumed to be stable when examining its detailed structure. It is convenient, at the beginning, to assume an infinite plane wave in which only movements and changes along the axis of propagation are significant.
P - P
poD = pv = p(D - u)
udm
=
Poudx
(2-6)
Eqs. 2-4 and 2-6 may be combined and , -pAPPoA
p)
]
('22-7)
where
v = velocity of materia! relative to the wave front u = velocity of material relative to the undisturbed medium m = mass P
- pressure
t
= time
x = distance trav,!Ied by shock wave in
p = density undisturbed medium
Refer to the paragraph that follows for a discussion of unitsd s u In using Eqs. 2-4 to 2-7 in thc estimation of shock conditions, two convenient systems of units may be derived from the CGS system. The use of gram as a unit of mass and cm as a unit of length results in densities in g/Cm 3 . These densities are numerically equal to the specific gravities of the materials that are
t2-4)
given in most handbooks- The use of the second as the unit of time and the dyne as the unit of force results, foi the usual shock or detonation calculations, 2in velocities (cm/sec) and pressures (dyne/cm r) expressed in numbers so large as to elude intuitive grasp.
(25)
Pressures expressed in bars (106 dynercm 2 )
The impulse applied is (P- PC.)dt
p foDu
rearranged to obtain
Consider, now.! wave propsaarine through a stationary medium. In a system moving with the wave, the conservation of matter demands plane perpendicular to the axis be equal to that passing through each other such plane. In other words, the pr( t of density and velocity is a constant at all points along the axis. In this system of coordinates, the undisturbed medium approaches the wave front at Savelocity equal in magnitude to that at which the wave propagates in the stationary medium. The velocity of the material relative to the wave front is, of course, equal to the difference between the propagation velocity and the velocity of the material at any point relative to the undisturbed medium. Thus, the equation of continuity 'b •1 e fo,.
= p udx/dt
2-9
".,.
-
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-
-.
-
-
7
~ ~--
-
-
AMCP 706-179
and times in milliseconds can be combined with masses in grams and distances in ccntimeters in which these equations may be used witnout numerical cotificients. The system of gram, centimeter, microsecond, and megabar is also compatible and may be even more convenient, Eqs. 2-4 to 2-7 apply quite generally to all pressure-displacement waves for which the assumption of equilibrium is valid. The relationship among pressure, "olume. and temperature is known as the equation of state of a material. Acoustic waves are those of such small amplitude that the volume change is negligible and AP/Ar. is more accurately expressed as dP/dp. Thus, the sound velocity c0 is expressed as =
VFp
(2-8)
By combining Eq. 1-8 with the ideal gas laws, the familiar equation for the velocity of sound in an ideal gas is found c.
(2-9)
For elastic solids and liquids the expression becomes co
-(2-10)
where ¢o = sound velocity =- ratio of the specific heat at constant
pressure to that at constant volume, dimensionless R E
universal gas constant
to result in a significant change in the compressibility. i.e., dPldp changes significantly) may, if the pressure rise is continuous in time and space, be considered a succession of sound waves each moving in the medium compressed by its predecessor. The sound velocity may change as the medium is compressed, causing a distortion of the wave as it progresses. For example, in a gas, the temperattire rise with compression causes the higher amplitude portion of the wave to propagate faster, outrunning the other portions until it reaches the front (see Fig. 2-3). The discontinuity of pressure density, particle velocity, and temperature which results is known as a shock. The equations of state of solids are more complex so that the modification of wave forms at pressures beyond their elastic limits varies from one material to another. Shock waves ot certain amplitudes degenerate in some solids. When compressed sufficiently, however, all matter becomes less compressible so that compression waves, if they are of sufficient amplitude, will develop into shock waves in any medium. A curve, commonly known as the Hugoniot curve, may be used with Eqs. 24 to 2-7 to define the conditions behind the shock wave" .The Hugoniot curve is the locus of end points of shock compressions. The propagation velocity should never be computed from the slope of the Hugoniot curve but always from that of a chord connecting the initial point with the final point using Eq. 2-7. For ideal gases, the equation of the Hugoniot curve is P
Refer to previous discussion for units. Waves of finite amplitude (those in which the compression of the medium is sufficient
(22-p. (
-
Po - OP
"o where i
= elastic modulus appropriate to the material and mode of propagation
p
-
2
=
(,
--
!)1(7+ 1).
Since the Hugoniot compression results in a larger temperature rise than does adiabatic compression, the gas becomes less compressible as the strength of the shock increases. It is thus apparent from Eq. 2-7 that the velocity of a shock is a direct function of its strength. For situations where the density is
2-10
-,.V
.....
.~...
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AMCP 706 179
6
SIYMMETRICAL
WAVE OF FINITE AMPLITUOE
PEAK. PROPASATINS At HIONEN VEL0TY, MOVES TOWARDO FRONT 01iTOR1TINI WAVE POM
018006TIUITY $HC
S~OVERTAKE P A
WAVE
HOIC
Im** DIRECTION OF PROPFMATION
FRONMT
IONVWA
Figure 2.3. Formation and Incipient Decay of Shock Wave from Wave of Finite Amplitude so close to the limiting value (po/A) that variations with pressure may be neglected, Eq. 2-6 may be rearranged to give P
Sin
0 D2(1 -A)
(2-12)
|kinu Fa. 7-I 1 and the ea. laws. the relationSshp may be expressed in terms el the Mach number M which is the ratio (Die0 ) of the shock propagation velocity to sound velocity the undisturbed medium P/Po = MI(I +u)
(2-13)
All of the conditions behind the shock may thus be calculated for an ideal gas combinations of Eqs. 2-4, 2-6, and 2-13.
products of the detonation of military high explosives under conditions in the detonation head. The rate of propagation of pressure displacement waves is proportional to the square root of the resitance of the medinium of propagation to changes in density. This relationship, as it applies to various types of wave in various media, is expressed in Eqs. 2-7 through 2-10. Eqs. 2-9 and 2-10 for elastic waves are essentially ready to use- The constants for various materials are readily available in general scientific and engineering handbooksk: As the amplitudes of the waves increase
2.2.3 DETONATION WAVES
and their forms change, the relationship becomes more complex. For shu:k conditions, the irreversible heating of the Hugoniot com-
2-2.3.1 EQUATIONS OF STATE
pression, Eq. 2-11, describes relationship between pressure and density.
Military designers have particular interest in
the behavior of gases under two special sets of -
r2-11
With the further increase in amplitude
circumstances: (I) atmospheric air subjected
usually associated
to explosive shock, and (2) the reaction
solid explosives, other factors add their in-
with the detonation of
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AMCP 706-179
fluence to that of tih Ilugoniot heating to modify the pr,:ssurc-density relationship further. These factors involve inter- and intramolecular and atomic forces that derive from relatively simple electrostatic and quantum mechanical principles. However, they acquire a considerable degree of complexity by thle time they have been combined to obtain tile attraction and repulsion functions for a single species of atom. 11.nee, calculation of the behavior of strong shock!, and the detonation of solid explosives is carried out using one or another of several empirical relationships.
conditions in solid explosives are variants of Eq. 2-15 in which accounl is taken of tile compressibility of molecales and, in some cases, of their thennal expansion 3 . However, none of the equations proposed are adapted to simple, direct calculation.
Precise calculations of the thermodynamic behavior of atmospheric air under strong shock conditions have been made and presented in tabular form
where n and K are constants, is as accurate an approximation as any. The exact value of n depends upon composition and loading 'density of the explosive. For high perfonnance military explosives, tile average value of n is close to three.
For higher densities, the volume occupied by the molecules (or, more accurately, that in which the electrostatic repulsive forces are significant) is an appreciable fraction of the total volume available. If the molecules are assumed to be incompressible solids, the ideal gas equation of state FV • RT
(2-14)
becomes P(V
RT
(2-15)
For the early stages of expansion, which are of interest in connection wilh most military applications, the pressure-volunme relationship PV'
- K
(2-16)
2-2.3.2 CHAPMAN-JOUGUET CONDITIONS FOR IDEAL DETONATION The thermohydrodynamic theory of Chapman and Jouguet is concerned with the transition, insofar as it affects the propagation of deionauion (the Chapman-Jouguet point), between conditions in the unreacted explosive and those at the completion of the reaction.
V = volume
Of the various conditions associated with the detonation of an explosive, the rate of propagation D is the most easily measured. Many precise experimental data are available relating detonation velocity to density. In general, for military explosives, the relationship is quite accurately represented by the
R = universal gas constant
equation
-a)
where P
- pressure
T = absolute temperature ce = covolume of the gas, the volume occupied by the molecules The dimensions will depend on the system of units employed. The equations of state which have been applied to the computation of detonation 2-12
D = F + Gpo, cm/tysec
(2-17)
where F and G are con.tants characteristic of the explosive, Table 2-43 lists the constants of Eq. 2-17 for a number of common military explosives. Data of this sort, relating detonation velocity to density, have been used to detennine equation-of-state constants for the reaction
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AMCP ;06 179
TABLE 2-4 DETONATION VELOCITY CONSTANTS
SDETONATON
EQ.
of reaction and cquation ol stale, Ihese laws COmpltelty defitc t . condittitson ot de totia-
Cion
F.
in Ihis one-diinecnsional model. which is
G, 4
Explosive
an//Inc cm /Anc
an
ideal detloiation. Real charges, of courst.
Amel, 60/50
0095
0415
Cyclonitc (RDX) Explosive D (Ammonium Picrate) [-taleite (EDNA) Lead Azide
0.249 0.155 0.203 0.286
three finilte dimetisiotns. It might he questioned whether coisideration of the infinity plane wave has practical significance. lit fact. idceal detonationt is closely aijiproxiwhen te dinensions ol a charge and
Nitrogucnidne Pentolite, 50/50 PETN (Penteerythriiol Tetranitrate)
0.144 0.238 0.160
0.344 0.328 0.056
Picric Acid Tetlyl
0.221 0.237
0.306 0.325
TTetrytotl, 6535
unulsual inastmuch as reaction tone lengths ol
0.166
0.340
many ,xplosives have becn estimnated to be oft'
STNT
0.1"18
0.323
the order of millitcterN or cvci less). Nearly ideal and definitely nonideal detonation arc both quite common in military perforitautce.
(Trinituotoluenel
0.402 0.310 0.395
products of detonation reactions. These conslants, in turn, have been) used witlh appro-
i
also dcscrirbed a• all infinite plane wave and a%
have
mated the radius of cAirvaturc of the deloiatioi ite: large whent c:mpcard with the front reaction ronte leigth c (a situa.tion whic'h is iiol
priate equations of state in the computation of the Chapman-Jouguet cotiditiotis for many e xplosivv's. More recently, techniques have
Detonation may be termed nonideal whent Kite radial flow of energy and material is Suf'ficient to alffec t signili~tantly tile condc -
been developed wilereby the movements of metal plates in contact with explosive charges
tions at the Chapinan-Jouguel point. As a result of the interdependenace of these j'onditions with the velocity of propagation, such effects are manifest in velocity variations. Either convergent or divergent flowdetonation results in nonideal detonation, Convergcni ;s rare except in cases where it is induced by
canl be measured precisely and reduced to pressure-time data for detonation. In Table of parameters of the 2Chapman-Jouguct - 5 " calculated values condition are given for various explosives. Experimental dat4, where available. are included for comparison. For organic high ,explosive compounlds, the particle velocity is nearly one-fourth of the detonation velocity Thus Eq. 2-6 becomes approximately P 0 =D/4
1,2-18)
specialized designs. Divergence, however. occurs at mIost intcrfatcc., with inert materIals. Tile most common shape of charges used for experimental observations of detonation is a long cylinder. It such charges. the effects of raaial losses of energy and material become apparent as the diameter is reduced. For this reason L
Note that in Table 2-5 the pressures puted empirically using Eq. 2-18 agree measured values nearly as well as those the more rigorous theory, certainly enough for most design purposes.
-
2-2.3.3 ACTUAL DETONATION
contwith using well
such effects have conie to be known as
diameter effects. Observable diaticter effects include reduction of t(le detonation velocity and failure of detonation. A rigorous quantitative theory that takes into account all of the complicating factors
........
would be quite useless. It would be too cumbersome for a reasonable computer pro-
The previous discussion of detonation has been concerned with a one-dimensional model. In suth a niodul, the conservation laws assume the simple forms of Eqs. 2-4, 2-6, and 2-7. Combined with data regarding the energy
gram even if sufficient experimental data were available to establish values for the many physical constants and properties involved.
S.
.
-
...
......
r
Many theories and models have been based
27-13
c-, ,,,-
- .. , -
k
J j
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AMCP 705-179 TABLE 2-5 DETONATION CONDITIONS, CALCULATED AND MEASURED Loadiwig Detonation Velocilty D, anIpeeC Density P0, Calculated Measured /cm,
5s9l~
11.7112 1.762 1.80 1.743 1.756 1.6.4 1.58 0.624
Composition~ B Cyctonite (RDX) Cyclonite IRDX) Cyclotot, 76/25 8 22 Cyclotot, 7 / 'TN'T TNT TNT *Fromi Eq. 2-10.
-
0.87b -
0.829 0.1395 -
0.802 0.862 -
0.825 -
0.695 0."88 0.380
on a groiup ot atssumptions regarditng the '35. cot'itrotting inechuniniis and processes b~ach of the thteories is ain attempt to der;.v a quiantitaitive description of" actual detonlation fromn a consideration (if a rtiam igcableý numtber
C-J Praewrf P. mopber Calculaetd Meatired 0.275' 0.327* 0.349 0.297' 0.311 0.2066 O.190* 0.026
Pardcie Velocity.
ripa Calculated Measured
0.2930p326
O.W4 0.313 0.213 0.177 0.177 -
-
0,224 -
-
0.216 -
-
0.218 0.155 0.163
0.11
-
0.2111 0.178
3. It ihe diameter of a chargc is 100 small.
detonation will fail to propagate. Failure diameter% for common explosives are listed in Tables M02 and 10-3.
of ffhe ampects of the process. Still, thie solutions remlain oplx
4. ilie properties of surrounding media call substantially alter diameter effects. For
genlecal theory is lacking, it
been observed at diameters of the order of 0.5
com~lex.en:arple.
Eivert
though a
is possible 0- make qualitative pivdi'.tiuii5 oO thle behavior of actual detoniations on thle
basis of thle following generalities: 1. Other factors reminiming constanlt, charges of smalt cross section detonAate at lower velocities than those of larger cross section. 2. The formula
DID,
I -KIr
(2-19)
where D =dEtonation velocity D,
ideal detonation Nelucity
r= rddius of charge
ma.;y be used to interpolate or extrapolate detonation velocitV data in the ranlge where D)ID, = 0.95 or more2-14
failure of detonation inl TNT has
while detonation at ha~s nfo br nearly ideal velocity has been observed for
charges one-tenth this size when confined in steel or brass' 5 - As might he expected front h~q. 2-6. thle shock Impedance p0 flu is a good criterion for thle efttvciveitess of the confining medium. Thle best confining mealiutn
is a
mismlatch with the explosive so as to reflect thle maxiniujoi energy back to the detonation products. 5. Velocities of' nonideal detonations are affected by particl, s.;-, of the cx, 'osive. Caiticall diameter% and detonation velocity losses art reduced for tine particle sizes. For sonic materials inl certain ranges, it appears that tile ratio of charge dimension to average particle dimension is mote significant than either absolute dimension. In cast explosives, techniques conducive to fine crystallization reduce diameter effects.
6. Particle size distribution is also a factor in diameter effects. Detonation velocities are
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AMCP 706-1 79 tiighet aijil lailuicth iaclmetr smaller !-or uniformi part i.Ic si ,s thItani lor mi xiture-s o1 partiCICle s.'.
oft the explosive Witli quantities associated xvith tihe sy stem or nicdi ur whereby flthe stiiiiiltts is Itransinitted to thec explosive. For I his reatsont, even thioughli nititatiton iniay be thermal fit thle last analysis. sensitivity must he considered iai Icrn ntit' lifte nature of the initiating tinliiulus atsWell as its tti ago ittode -
7, ']lw ve loci ty tit uropatta ion oht actual detonation is det~Ieiini nd by ('hiati'ila ii.3ougcte t coitfidions atl thle VCciii' of thle
charge. Thus, it is possible, under sonice circuniistanics. fo r at port ion of thle explosive charge, to dc.to ilalhe t near idi al velocity yet fiol surrontildingr in at erial in thli outeir streamlImes to) react only partially,
Two linii ing tlitrc!shold condiit ions or wh tia titig apply to almost every syst em I1 that tit whic i flit:lee is del ive red in a lttlue so short that the losses atev negligible durinig this litime. and (2) that in which the powe I is just sufficienit Ito evenitually cause initiation. hoi the first c:ondition, thle enlergy re'quired is att its ns1il iiti mu while in the sCconld. tile pt 'wer is ;it its ttiniontui. Thecse two condt-
N. Nonidleal detoniation dots not niecessarihy imply itwonleite: reaction. Manly Valuable military i tentis include explosive chitrges that detonate at very low velocities cittiparetd 'AiIhi tile ideal Velocity for Ktie explosives used.
tions
9. The, relatitonship between denisitt and nonideal detonation is coitiptex. Observable plienonenta canl be explained and predicted on [the basis thal. Withi ins:rcasiog porosity, thle decreasing homogeneity of denssity is ieflected fin decreasing liotnoge.ieity of tenmperature distribution and consequtently increasing intitial reaction rate. while the iecrease its pressure reSUlts in Slower propagationi Of thle grain burning reacticti and consequetntly io1g v ri: ct0 111 7111esý Thus- incm-a~sing porosity resutlts tin greater di-smneter efl'e,_t5 Upons detonettotil velocity bill sometimes in smaller failure diatneters, patrtieUlarly unider intermediate conditions of confitteicunct.
heat~hema anddcto
Ir
aretil h
the arius titraciojiofhysi~d
by
xl-
roprtis
the
Jashed
Both expteriment and theory demionstrate the 110111i141i1t role played by conilinemnent ilt thte initiation, growth. and propagation of i'xplosive reactions, partictularly whetn the diminnsions are as small as those of explosive traits ts
~
The properties of a container which contribtute most to confinement depend tupon which of the several dissipative mechlanismss is ~most important. This, its tlun, depends upon ~~s hc hase taeaof theinitiation pr~wessis nlost
sl theredominanttin
f ha
necesar nitatea torectin a chmcladtemlpoetiso
x~
rept esvited
Initiation occuirs whetn the rate atKwhich heat is evolved in at reactive itucletis excceds that at which it is dissipated. Thse impedanice afforded by Ktie surrounidings to this dissipation is comitiloly referred to atsconfinement.
:-3 INITIATIONcopn 2-3.1 ESTABLISHING A SEIF-PROPAGATING REACTION * The hc~~ h~ nrg ~ ~ fa~
arc
aisymuptotes its Fig. 24. Vle relation between tl.:cictF enryTequired for infitiation and tile rate at "'hicli it is applied may be represetited by the hypetibolas. In- its general terms, thle -elationship illustrated applies ito almost all inlitiators-
hetitansfer cnanr
meecianism.
of explosive
In general, the
charges
are much
sevesso hata thin outer layer oftexplosive is
2-15
Sit
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AMCP 706-179
"- 40-:hI
*
A A_
CURVE FITS DATAFOR GRAPHITE FILM BRIDGE ELECTRIC INITIATORS
-6-
A HQT
--
5-
IDEIRE
ELECTR;C INITIATORS
0 CONOUCTIVE MIX ELECTPIC INITIATORS -
X STAB INITIATORS
2 POWER
3 (v
4 5
/vw
S
6
e 9IO
far eictric initnotors,
20
40
80
u/4, for &too initiators)
Figure2-4. Energy-power Relationship for Various Initiators a better insulation than the container. At this stage, except in rare instances, the properties
the material which has been reached by the shock wave induced by the detonation is
of the container have negligible effect upon the initiation process.
affected, the affected mass is proportional to the density of the material times the shock "velocityin the material. This product, known as the shock acoustic impedance, is a good measure of the effectiveness of a material as a confining medium for stable detonation|4
The pressure of detonation of solid explosives is sufficient to burst or permanently deform any container that can be made. However, the time involved in detonation processes is of the same order of magnitude as the expansion times of the containers. The rate at which the container expands is determined by momentum considerations and 's inversely related to the mass of container material which is moved. For a thin-walled container this mass is essentially that of the wall; foT thick-walled container, since only 2-16
Initiation is complicated by such a variety of factors that the most carefully designed expeniments yield data that are difficult to interpret in general terms. Practical situations are usually even more complicated. The questions that arise concern-.ng initiation or explosion are best answered in terms of direct experiments with military materiel under
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AMCP 706-171
possible to generate electrical pulses and currents of accurately known characteristics, these can be combined with the bridgewire characteristics to obtain accurate estimates of power, energy, and temperature.
oo
A large number of experiments have been
carried out in which the interrelationships of
*00-
the variables that affect the operation of bridgewire initiators have been investigated'e. These irvestigations have verified following principles:
woo /the
0
,-/1. •0o
"-
]the
The energy required to fire a hot wire electric initiator is roughly proportional to volume of the bridgewire, if the energy is
delivered in a short enough time (see Fig. 2-5a).
-00
2. Closer analyais shows that the threshold temperature increases with reduced wire diameter. This trend is less marked when the explosive has a high activation energy (like lead styphnate).
.,too
,0
-_3.
0
The energy required per unit volume also increases somewhat with decreasing bridgpwire length, End lo.ses probably account for this.
I
r
Figure2-5. Typical Effect of Bridgewire Volume on Input Characteristics
S~increases
service conditions or experiments with models and conditions that simulate service items and situations as closely as possible. For specific applications to initiator design, see par. 5-2; for testing, par. 12-2.2.
4. For a specific initiator design the energy requirement approaches a minimum as voltage, current, or power is increased and indefinitely as power is reduced to a minimum. 5. The relationship stated in 4 refers to the average power of a firing pulse. Pui:e %hape has a secondary effect that is not easily measured.
2-3.2 INITIATION BY HEAT HOT WIRE ELECTRIC INITIATORS Hot bridgewire electric initiators are the
6. The current requirement varies approximately as the 312 power of the wire diameter and inversely as the i sistivity of the bridgewire metal.
simplest and most direct illustrations of initiation by heat. Since a bridgewire can be measured, its volume, heat capacity, and resistance can be calculated. Since it is further
The behavior of hot wire electric initiators has been described by an equation that agrees well with experimental data
2-3.2.1
*
2-07
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AMCP 706-179
CdT/dt it yT = 12R, W
(2-20)
where C = heat capacity of the thermal mass (ineluding bridgewire and surrounding layer of explosive), W-se4./°C T = temperature,'C t = time, sec -y = cooling rate cuefficient, W/*C = current, A R = resistance, ohm Although the assumption of a constant ignition temperature yields remarkably accurate predictions of the behavior of specific hot wire initiators, it is an approximation. The generality mentioned as 2 is evidence of the limitations of this approximation. Eq. 2-20 and others are based on the assumption of a homogeneous solid charge of explosive. As applied to hot wire initiators, the equations also imply essentially perfect thermal contact between bridgewire and explosive. It has been shown that thc separtiiun between the bridgewire and explosive, which results from some combinations of mechanical design, loading procedure, and aging, can be sufficient to cause failure of hot wire initiators.
-
Another example of a discrepancy between calculations and experiment is worth noting. Based on the usual assumptions, the critical conditions for initiating secondary e-:plosives, such as PETN or RDX, have been computed but attempts to achieve reliable high order detonation in these materials with hot wires have been negative'. The initiation of explosives by means of electrically heated wires is at present more subject to precise quantitative control and theoretical prediction than any other initiation mechanism used by the military. The
r
broad range of available bridgewire materials and sizes makes it possible to vary the energy sensitivity by a factor of nearly 100 without changing either the explosive materials or the external configuration. At the same time, the process is affected by a wide variety of other variables including electrical circuit parameters, state of aggregation of the explosive, and mechanical design of the initiator. For these reasons, a reasonably complete characterization of the hot wire sensitivity ef an explosive would have to be in terms of a series of performance curves. Such data are available for only a few materials. Table 2-6 lists hot wire sensitivities of a number of primary explosives obtained for particular conditions., Extrapolations of these data to other conditions is a reasonable basis for an experimental development program but should not be used to make firm design decisions. The application of the foregoing to the design of hot bridgewire electric initiators is discussed in par. 5-2.4.2. 2-3.2.2 CONDUCTIVE FILM ELECTRIC INITIATORS Both metallic and semiconductor films have been used as bridges in electric initiators. The general principles discussed for wire bridges also apply to metallic film bridges. Irk one system, the large ratio of surface to cross section area of a film is used to greatly increase the steady state power requirement while retaining a desired resistance and energy sensitivity'. In semiconductive films, the negative resis-i tance co.Ticients typical of such materials can produce a channeling of the current in a restricted path between the electrodes and therefore can result in extremely localized heating. This effect can be used to produce extremely sensitive initiators when such items are desired. $etniconductive bridges used by the military are made of graphite. These bridges
"2-18
V
L
.
.Im
-,'..
,
.
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AMCP 706-179
for contact resistance to decrease with current
TABLE 24
flow results in a similar concentration in the preferred path. Along the path, the heat tends to concentrate at the contact points. The degree of concentration, and consequently relationship between temperature and electrical input, is determined by a statistical interaction of particle size, uniformity of
SENSITIVITY OF VARIOUS EXPLOSIVES IN WIRE BRIDGE INITIATORS
SEnergy°e Explosive I.
Ei.ithe 0.00020-in, 0.00014In. diarnrter diamer
mixture, particle shape, composition, loading density, and electrode configuration and spac-
ODNP/KCIOo 75/25 Lead Azide
260 340
1050 1340
Basic Lead Styphnate LDNR
126 138
700 930
ing.
Tetracene
115
460
The formulation of a logical process for the design of a conductive mix system of specified electrical and firing characteristics is a
Tur,gsten wire 0.030 in. long fired at 14-20 V
task of such formidable proportions that it has not been undertaken. However, remarkable results have been attained by enlightened cut-and-try procedures"'.6 A mathematical model also has been attempted in the U.K. The design and fabrication of conluctive mix initiators is discusse, in par. 5-2.4.5.
normally break down forming a very hot, localized arc when their voltage threshold is exceeded. Because of this behavior, it is difficult to design the bridges for specific conditions. However, the sensitivity levels can be determined experimentally with comparative ease.
2-3.2.4 TRANSMISSION OF HOT GAS Present graphite bridge initiators have essentially similar firing characteristics. Their resistance is on the order of 1000 to 10,000 ohms. The design and fabrication of film b •idg-initiatorsa discuseed in pars. 5-2.4.2 and 5-4.4. 2-3.2.3 CONDUCTIVE EXPLOSIVE ELECTRIC INITIATORS
The initiation of reactions of solids by means of hot gases depends upon a highly complex heat transfer situation. The heat transfer between a ias and a solid is proportional to pressure and temFrrature of the gas but is also affected greatly by the movement of the gas relative to the surface and by surface porosity, roughrL-ss, and configuration. Since the heat conductivity of the solid is almost invariably much greater than that of the gas, the temperature attained by the surface is much lower than that of the body of the gas unless the duration of exposure is sufficiant for the solid to reach the gas temperature. In most situations encountered in military materiel, the total heat capacity of the gas is so much less than that of surround-
MIX
The usual conductive mix consists of an explosive to which is added a relatively small percentage of conductivc powder. Such mixes S.re loaded so as to contact a pair of electrodes. Current flowing between the electrodes flows from one conductive particle to another through a series of contact points. In general, many such paths form a complex
X 3cient,
ing solids that the equilibrium temperature approached by the gas-solid system is practically the initial temperature of the solids.
parallel-series network but one such path usually has a lower resistance than others so that the current tends to concentrate. Where the conductor has a negative resistivity coeffilike carbon, the resistive heating tends to reduce the resistance of the preferred path Sand further concentrate the current. Even where the conductor is a metal, the tendency
Initiation by hot gases has not been computed but has been measured in a number of experimental apparatus'". A shock tube is an interesting tool for the exposure of explosives 2-19
' *°
"..
........-
-"
-
.
.:
-
----
-*.'..)
-
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AMCP 706179
TEMPERATURE,
I\
'K
200
___
~~2000_
_
__
_
_
NT NMI NO,
-T
ot~
Tio
N17RATENO i-ROY
.•
•
-
/
LEAD
STYPHNATE
DRIVERTO M~VEN5An PRESSURRATIO
(
Figure2-6. Threshold Conditions for Initiationof Various
t
Sheat t
to high temperture gases. It has the advantage over other devices in that pressure and temperature of the gas in contact with the explosive change virtually instantaneously from initial conditions to those of the reflected sho, k wave. The shock pressures used in such experiments are too low for the shock waves transmitted into the explosive zo be significant factors in initiation. Shock pressure, of course, is an important factor in the transfer between the gas and the solid explosive nmaterial. Some of the data for threshold conditions of initiation are shown in Fig. 2 -6 1. The effects of variations in the gas composition are apparently quite signifi, cant but require further interpretation,
the spray of hot, high velocity, solid particles or of droplets of liquid which they emit. Quantitative measurements of factors affecting initiation by such means are difficult to make. The process, however, is essentially the same as that of initiation of suddenly heated bridgewires, discussed itl par. 2-3.2.1. 2-3.2.6 ADIABATIC COMPRESSION
2-3.2.5 TRANSMISSION OF HOT PARTICLES
If a column of air ahead of an initiator could be compressed rapidly enough, its temperature will rise by adiabatic compression. The force of target impact could be used to crush the nose of a simple fuze thus forming an adiabatic compression mechanism. Fig. 2-79 illustrates such a concept. Undoubtedly the crushed hot particles contribute to the initiation process. Adiabatic
There is reason to believe that the most effective part of the output of some primers is
Australians have a mortar fuze using this principle"9.
compreson is used only rarely; however, the
(
2-20
/
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AMCP 706.179
ALUMINUM WASHE(
FUZE BOOY
I
calculated for explosion in 250 compared with impact sensitivity.
/
•
HIQ_ EXPLOSIVE
EorONATO- CcANSt
AIR COLUMNa
are shown in Fig. 2-820. Here the temperature
Figure2-7. Initiationby Adiabatic Compression 2-3.3 INITIATION BY IMPACT 2-3.3.1 IMPACT SENSITIVITY MEASURED WITH LABORATORY MACHINES Impact initiation of explosives is of interest to designers of nulitary materiel for the assessment and elimination of hazards and for the design of stab and percussmon initiators, For the assessment of the relative hazards during handling and use of explosives, several standard impact machines have been devised, Machines and test methods are described in par. 12-2.1.2.1. Essentially, an impact machine consists of an apparatus by means of which a weight can be dropped from various predetermined heights so as to strike an explosive sample. The height from which the explosive is initiated is a measure of impact sensitivity. Impact sensitivity values of common military explosives are shown in Table 4-2. It long has been agreed that impact initiation is usually thermal'. The explosive is heated locally by compression of interstitial gases, intercrystalline friction, and viscous flow. On this basis it is possible to compute the reaction rates that may be expected in "an impact machine. The data of one experiment
pcsc
is
While impact sensitivity data are used as the basis for establishing safe practices and for selecting explosives that may be used in one or another application, there are two problems. First, it is admitted by most investigators that these tests really do not simulate any situation likely to occur in manufacture or use of military materiel. Secondly, different machines rank the same explosives in different orders. Perhaps part of the problem is that the explosive samples are not prepared in the same manner as cast or pressed explosive components. As a result, many have come to doubt the validity of impact test results as a basis for any binding decisions. Doubtlessly. sound anO valid explanations can be found for the inversions in Table 4-2. However. such explanations are not particularly helpful in efforts to employ the impact machines in the selection of explosives. Still, impact test sensitivities are in widespread use. If a newcomer to the field of explosives wonders what to make of this, he is in the company of experts of long experienc,. One basis that has been suggested for the assessment of the relative hazards connected with the use of an explosive is comparison by means of a variety of machines. Another is the design of tests more subject to analysis in physical terms. A third approach is the use of tests, such as those described in par. 12-2.1.2, which are designed to simulate specific conditions of service and use. 2-3.3.2 STAB INITIATION For detonators initiated by stab action, one of the most important functions is that of convening another form of energy into highly conecentrated heat. As in electrical devices, the energy necessary is nearly proportional to the amount of material that is heated. The standard firing pin for stab initiators is a truncated cone (Fig. 2-9). A rather interest2-21
Sr
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AMCP 706-179
IINCLUDED 00,
ANIGLE 294
-0
0
0
.-- ,
•
71ETRYL
B STNEN OINA
DNPT6 NG
PETN TETRYL trialtftl'lmefte
I
ALL OVER
bistrinitroethyl nitraWifl 5iothyindrcmine diritroto di*mwropl ltnotroWyrate nitrcglycerin peintoerythhwto telranitrOt"
r
TN!
trin,trobenzeRS
TNET8 TNT
triMtyl ImnotrobO.tyrfte trinht rotoluene
standard pin (Fig. 2-9) is used for all stab initiators.
Both steel and
I
[_I OT"M. 1IM•T,
Figure2-9. Standard FiringPin for Stab Initiators
c
Figure2-8. Input Sensitivity vs Explosion Temperature
aluminum alloys are in
common use. Aluminum results in a significant but not serious decrease in sensitivity'. Alignment is critical because misalignment will dccrcise sensitivity. In general, the higher the density of the explomive, the more sensitive the stab initiator (see Table 2-7). Because the denser explosive offers .."n reten.e to the penetration ofI the firing pin, the kinetic energy of the moving mass is dissipated over . shorter distance, so thal a smaller quantity of explosive is heated to a higher temperature.
ing relationship has been found to exist between the sensitivity of the explosive used and !he optimum size of the flat on the firino pin. The less sensitive the explosive, the larger the optimum diameter of the flat required. This can be related to the compactness of the affected volume of the explosive. The most compact shape for a cylinder (i.e., the shape having the least surface area for a given volume) is one whose length is equal to its diameter. Thus, as the energy required for initiation is increased, it is advantageous to Sdistribute it over a large enough area to limit the effective length to nearly the diameter. The flat diameter given scrves the priming mixes commonly used.
Since the resistance of solids to deformation does not change very much with moderate changes of deformation rate, the power dissipation by the displacement of explosive by a firing pin is nearly proportional to its velocity, which, in a drop weight system, is proportional to the square root of the drop height. The eaergy, on the other hand, is proportional to the product of the height and the weight. This energy-power relationship is shown in Fig. 2-4.
To achieve greater sensitivity, special initidtion systems have been employed occasionally. Thus the flat diameter of the pin for the M55 family of detonators is 0.0075 in. Since the firing pin is a critical component of the initiation assembly, the correct firing pin must be tested and used with the particular init ator. Unless otherwise specified, the
2-3.3.3 PERCUSSION INITIATION As in stab initiation, the function of the percussion firing pin is to transform energy into highly concentrated heat. However, con-
2-22
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-~.r
,-
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AMCP 70179
l-
TABLE 2-7
EFFECT OF LOADING PRESSURE ON INITIATOR SENSITIVITY Loacdin Prnoure,
Drop Test Hqht.
m100 pel
in.
15 26 40 60 80
1.31 0.91 0.77 0.68 0.57
ac
OS ON PRIMING MIXTUWRE
MRW WD 0 Prefi) (STANDARD
1
S~NOL firing Strary pin does
Priminig Mix in MARK 102 Cups, 2 az ball
to initiation by stab. the
d
_
the pin dents the case and pinches S~Rather, the cxplclivc between r.nvil and case. Energy must be supplied at a rate sufficient to fracture the granular structure of the explosive. Criteria for percussion firing pins have
Is T"
an MIXTUREN S O. 7
F
L
not been refined to the same degree as those for stab pins. It has been established that a hemispherical tip gives greater sensitivity thmn a truncated cone, and that tip radius has little
osa
effect on sensitivity. Typical radius is 0.050 in.
FPTJUc OWT V"OCST. Figure2-10. Energy-.locryRelariosltup
A study on the effect of firing pin alignment showed that there is little effect if the eccentricity is less than 0.02 in. Above 0.04 in. eccentricity, sensitivity decreases rapidiy because of primer construction. Sensitivity also decreases as the rigidity of primer mounting is decreased- In general, a study of the relationship of cup. anvil, explosive charge, and firing pin has shown that sensitivity variations appear to depend on the nature of primer cup collapse rather than on explosion phenomena themselvesa, The effect of firing pin velocity results in the same general hyperbolic energy-velocity relationship as that of other initiators (see Fig. 2-10(). From experimental data it can be inferred that stab and percussion initiations occur by different mechanisms. Kinetic energy appears
0
10
it
to be the determining magnitude for stab initiation, momLntum for percussion. 2-3.4. INITIATION BY OTHER MEANS 2-3.4.1 FRICTION The importance of frictional heating in the initiation of explosives has been demonstrated by several invtstigators2 . The importance of thii types of initiation with respect to handling hazardi is attested by the experience of press loading activities, rnamely, "press blows" are much more frequent during pellet ejection and ram extraction than dtuing the actual presuing phase. However, no quantitative means of measurg this property is in current use. Perhaps the most pertinent data reardlng friction sensitivity inr those shown in Table 2-8' which relate impact sensitivity to
2-23
{J
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AMCP 706-179
TABLE 24 INITIATION OF EXPLOSION BY FRICTION OF PETN IN THE PRESENCE OF ORIT
mobs Nil Ipum PETN) Ammonium nitrte Potindum biulphate Silvw nitrate Sodisum dichromnet Patassium nftra Poassium dichromate Sliwr bromIde Lodichloride SlimvIodide -aMX
Plrirmthinit GlIn Rocu slt Chalcoles Gal"e" C4cit@
1.8 2-3 3 2-3 2-3 2-3 2-3 2-3 2-3 2-3 34 2-2.5 7 2-2.5 3-3.5 2.5-2.7 3
melting point and hardness of the intermixed grit, 2-3.4.2 ELECTRIC SPAR K3S-3.4.3
Frlitign
ImpWct
10011M
o"elncy.
effideny,
141 le 210 212 320 334 396 434 501 580 500 665 800 804 1100 1114 1330
0 0 0
0 0 0 0 50 60 100 100 100 I0n so 100 100 100
2 3 3 2 0 0 0 6 27 30 42 100 6 so an 43
military explosives to static electricity is shown in Table 4-2.,4 XPLOMNG-I
D E.Sm..
The initiation of explosives by electric sparks is of interest with respect to hazards of use. An individual may carry a charge of a few hundredths of a joule on his body, which if
Exploding bridgewire (EBW) devices are a recent development in explosive materiel. Of course, almost any bridgewire may be made to explode if subjected to a sufficiently rapid
discharged could initiate exploslvesI'. It has been found that the energy rquired for initiation is highly dependent upon physical "and electrical characteristics of the discharge system and the form of the explosive (see Table 2-917).
and energetic electrical discharge. However, the feature that classtfies an item as an EBW device is that it will fire only if subjected to such an impulse. Lesser energies or lower rates will burn out the bridge without initiating the explosive. The key feature of exploding hbidgewires is that they can initiate secondary explosives directly and hence result in insensitive initiators.
The military application consists of "high tension" initiators which are ignited by ledctric sparks (see par. 5-2.4.6). A number of experimental detonators are also being studied", ". Lead azide can be initiated with as little as l103 erg at as low as 4 V under specific, critical conditions. The plastic windows in operational shields are quite capable of generating this amount of static electri( ty2 3. The sensitivity of common 2-24
The exploding wire phennmenon as well as that of the initiation of explosives thereby is complex. The rate at which the energy can be delivered is limited by circuit inductance, impedance mismatch between cable and bridgewite, and skin effect in the bridge which raise the effective resistance to several ohms
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AMCP 700-479 TABLE 2-9 THRESHOLD IGNITION ENERGIE8 Rubber/mtreel eod ¶ýdn eerie.essmsJ
Metal/nIstat eleatrode Imo adwselml: veustanas)
Materia
* *cinat.
Load mwide Lead mvplinste Lead dinitroreor-
Conttlat Worksa, NO pF
Gesomm "Weks. 1000 pF
Mnlnhvugi
20 600
¶0,000
2250 206
600
1250
25
-
Mdmu sqapoy.
SW,,
Notes: (1) The energy vielue quoted isthe energy (ertil stored on the capacitor; One enervN disuipated In the gap is about one-tenth of this. 12) The geecous awd contact sperk regilons of sensitiveness we continuous with lead htywpinew.
*crease *this
during the initial stage of the discharge. As the discharge continues, the tzmperature inin the wire maintains its resistance in range. The discharge time is thus increased to about 2psec which is long -nough, even at sonic velocity, for a shock envelope to expand to a few hundred times the volume of thc wire. Thus, the energy density may bes low that it is surprising that explosion is
satisfactory in the laboratory. platinum and gold have been preferred for military items because of their resistance to corrosion. Diameters between 1.5-2 mils appear to be optimum for initiation of such explosives as PETN.
initiated,
ing densities much higleie
Gleaed romman reearc stdie 2 426, Gleaed mnyfom eseach sudie"', the following practical generalities may serve as atguide to applications of EBW devices: 1. Firing units should consist of special high-tite discharge condensers and of switches with mrninium inductance anmdtransient resistance so that the rate of current rise is on~ the order of 10' Aisec. Triggered spark gap switches are most frequently used. 2. Transmission lines should be as short as possible. For more than a few feet of trantsmission line, special "flat" low impedance cable is desirable. All connections must be firm and of negligible resistance3. Bridgewires of pure metals rather than higher resistance alloys are more efficient for EBW purposes. Although silver arnd copper are
4. The state of aggregation of the explosive around the bridgewire is quite critical. Load -
then I glCM 3 greatly increase the einerg requirement for initiation. T'his increase is so great as to make devices loaded at higher densities inoperable foi practical purpose-s. PETIW particles muss be of a epecific crystalline configuration -
needle shaped
-
to achievie the proper pressedI
density. 5. The reac don initiated by an EBW in seconda~y explosives appears to be a low order detonation. Time measurements indicate initial velocities that are definitely supersonic yet well below the stable rates for the explosive.; and loading densities used. The densities and particle sizes used in ESW detonators are iuch that detortation of PETN grows to its stable rate in a few millimeters. For other material, such as RDX, confinement and other measures to augment this tiransmission are desirable2 7
2-25
I
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AMVP 706-179 2-3.4.4 LASER AND LIGHT
2-3.4.5 SPONTANEOUS DETONATION
As a concentrated beam of energy, thie laser a hot spot and thus initiate explosives. The focusing properties of its monochromatic radiation make it capable of producing high temperatures while intensive shock may be produced by the higher-power Q-switched lasers. The explosive initiation ability of the laser has been demonstrated; however, all other initiation mechanisms are smaller, ligh~r, cheaper, and much less complex. Hence, lasers have not been used in the initiation of primary explosives,
Analogous to spontaneous combustion. spontaneous detonation is the self-ignition of detonating materials through chemical action (oxidation) of its constituents or through dissipation of trapped electrostatic charges. Most modern explosives are stable and need some form of external stimulus to cause them to initiate. Hence, spontaneous detonation is extremely rare.
"can provide
On the other hand, military technology would welcome the ability to detonate sec-ondary high explosives directly. This ability would eliminate the need for a primer and perhaps also the sating and arming device. In addition, direct reliable initiation of secondary high explosives by meanis of laser radiation also would be extremely useful in explosive sensitivity tests by permitting the precise measurement of input energy. Present measurement accuracy is limited by the variations of thc in"ator .. used to set off the secondary explosive, An experimental iivestigation has been carried out to establish the feasibility of initiating secondary high explosives by means of a ruby laser (6943 A), both in the free running and Q-switched modes's. Explosive samples of PETN, tetryl, HMX, and RDX were detonated succ ssfully when compressed against a glass platc. Energy inputs were as low as 0.025 J/rm2 . Design of an explosive "train initiatior, system has not yet been attempted. * Explosives can be initiated also by ordinary but high intensity light from such devices as a "flash cube. However, no practical military system exists at present. Efforts also have been conducted on the initiation of silver azide crystals by light. While feasible in the laboratory, it is not practical' . Pyrotechnics also are capable of being initiated by high intensity white light. 2-26
LIN
However, the spontaneous detonation of lead azide has been observed 3 ' 3 ' ; detonators, relays, and leads - all containing lead azide - have fired. While this functioning tends to occur only once in eighty million items, the huge modern production quantities make this incident rate significant and totally unacceptable. The cause of failure is postulated to be a hot spot created from the build-up of an electric charge on the dry lead azidt particles when the particles are moved about during the automatic loading process. (Spontaneous detonation has not been ohserved with manual loading.) In time, the electrical charge is dissipated through the case so thai no d&,tonation has. been observed after three days. The manufactunng process is now being modified to make it safer 3 '. In the interim, all production components containing lead azide are being held in segregat2-d storage for 4 hr. Further, the use of nonpropagating packaging prevents mass detonation (see par. I1-I .2.3). 2-3.4.6 SHOCK THROUGH A BULKHEAD Mentioned here for the sake of completeness, through-bulkhead initiators (TRI) are not true initiators. A true initiator is set off by a nonexplosive stimulus whereas the TBI propagates a detonation front. It is a wellestablished fact that a deto' vave will transmit across a barrier, and such barriers are often inserted ahead of leads and boosters. The TBI makes use of a barrier, the bulkhead, which is an integral part of its housing and remains intact after functioning"2 . This construction results in a sealed unit, having
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AMCP 706-179
several advantageous characteristics such as
C.&Ans
000
W)LKWAD
CCEPIONE--Gt
temperature resistance, that is desirable for initiation of rocket rnotors33. Fig. 2-1 I shows a typical TBi. It consists of a donor charge of secondary high explosive, a steel body containing a bulkhead that passes the shock output of the detonating donor charge without rupturing, an acceptor charge that is initiated by the transmitted shock, and an output charge of secondary high explosive or propellant composition as desired. For design details, see par. 5-2.5.
,
.T
-I
,A.,,,t.
ovu, (.JAe--
Figure2- 11. Schernaticof Typical TOI
REFERENCES a-k Lettered references are listed in ithe General References at the end of this handbook. I. AMCP 706-180. Engineering Design Handbook, Principles of Explosive Be. harior2. F. P. Bowdcn and A. D. Yoffe, Initiation and Growth of Explosives in Liqu~ids and Solids. Cambridge University, Mon.>graphs on Physics. Cambridge Univeristy Press, N.Y. 1952. 3. M A. Cook, 7"te Science uf'Iligh Lxplosives. Reinhold Publishing Corp., N.Y., 1958. 4. S. J. Jacobs, Closed Bomb Burning of High Explosives and Propeflants. OSRD Report 6329, (from Explosive Research Laboratory) Office of Scientific Research and Development, January 22, 1946. SMfetals S. J. W. Taylor, 'The Rapid Burning of Secondary Explosives by a Convective Mechanism", in Third Symposium on Deroiation, Report ACR-52, Office of Naval Research, Navy Dept., Vol. 1, pp. 77-87, September 26-28, 1960. 6. R. H. Strnsau. Low Velocity Detonation of Certain Primary Expiosivei. NAVORD
Report 2460. Naval Ordnance Laboratory, Silver Spring. Md., 28 May 19627. N. Griffiths and J. M, Groocock, The Burning to Detonation of' Solid Explosives, Part I. "Ionization Probe Studies in Confined Channels", ARDE Report (MX) 5159, Ministry of Supply. Armament Research and Development Establishment, Fort tlalstead, Kent, England. March 19598.
roccrultgs o;f . ElP,'trwi Intatotr S.tnposiurn. held at The Franklin n1,titute November 29-30, 1960. Report F-A2446, Papers 14 to 18. 27 (AD-323 117).
9. A. Macek. "Transition From Defllgration to Detonation in Cast Explosives", i. Chem. Phys., 31. I, 162-7 (1959). 10. J. Pearson and J. Rinehart. Behavior of lenp, ?sire Loads, American Society Under for Metals A c954). It. P. J. Hugoniot, de 1'Ecole Polytech, 57,3 (1887). 58. 1 (1888). 12. C. F. Curtiss and J. 0. Ilirsclhfelder, Thermnodynamic Properijes of Air. Report CF-?93. University of Wisconsin Naval Research Laboratory. April 1948. 2-27
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AMCP 708-179
13. Second O'R Si'nlosiu'ri on l),tonarhon. Office of Naval Research, Navy Dept., February 9-1 I, 1955. Papers 15 to 18, pp. 205-85. 14. 11. Eyring, et al.. "The Stability of Detonation" Chemical Reviews, 45, 1, 69-181 (1949). 15. L. D. Hianmplon and R. It. Strcsau, Small Scae 7T'echmique fIr MAiasuremnent of Detonation Veocitics. NAVORD Repoit 2282, Naval Ordnimce Laboratory, Silver Spring, Md.. 27 Dkecember 1951. 16. P. W. Cooper. Low Firing Energy Deto. laiEor Contpaining JVo Primary ExLrdosies. Final Report. Contract DA-1 1-022-501ORD-2892, Armour Research Foundation, 15 June 1960. 17. F. P_ Boiden, el al., "A Discussion of the Initiation and Growth of Explosion in Solids", in Proc. Royal Society, Series A. Mathematical and Physical Sciences, 246, 1245 (1958).
21. J. M. A. de Bruync and J. A. McLean, The initiation of Booster Tr'pc Explrsires b.; Low Enrgv St'ark Discharges, Ame'ical' Cyanamid ('o.. Contract DA-49-18 -502-ORD-537, I April 1957. 22. M. T. Hedges. Development of Exploding Witt, Initiatorv. Report 84, Picatinny Arsenal, Artillery and Rocket Developnmeot Laboratory, Dover, N.J., April 1960. 23. W. G. Clhac, and H. K. Moore, |ds., Exploding Wires, The Plenum Press, N.Y., 1959. 24. Proucecding.s of rite HERO ('ongrt-s.. held at The Frinklin Institute May 24. 25, and 26. 1961. Report F-A2424, Contract NI78-7705, papers 12, 23, 25 (AD-326 263). 25. M. J. Bartarisi and E. G. Kessler, Initialion of Secondari Explosires by heans. of Laser Radiation, Report TR3861, Picatinny Arsenal, Dover, N. J., May 1969.
18. T. A. Liilks-,i. "Suime Asictib of Pure
Shock Sensitivity". R. McGill and P. Hlolt. Eds.. in P~rocceding. of the Gilbert B L. Smith M),enorial Conference on Explosive Sensitiv'ity. NAVORD Report 5746, U. S. Nasia Ordnance LaborAtory, Silver Spring, Md., 2 June 1958. p. XXXV-348.
19. 1. Wenograd, "The Behavior of Explosives at Very Htgn Temperatures", in Third Symposium on Detonation, Report ACR-52, Office of Naval Research, Navy Dept.. Vol. I, pp. (,0-76, September 26-28, 1960. 20. F. W. Brown D. J. Kusler, and F. C. Gibson. Sensiti'iOv of Explosives " to Initiation by Elh'trostatic Discharges. Bureau of Mines, Report of Investigations 5002, September 1953.
2-28
26 R. L. Wagner, Lead Azides for Use in Detonators, Report TR 2662, Picatinny Arsecal, Dover, N. i., January 1960. 27. E. Demberg. "Accidents/lncident,, Encountered in Detonator/Primer/Fuze Production", Minutes of the Second An'nual DCASR. Atlanta Exp;io.•,ives Safety Seminar. held in Allinta, Georgia, 23-25 May 1972. 28. R. L. Wagner, Shock Initiation Through a Barrie-, Report TR 3085. Picatii|ny Arsenal, Dover, N. J.. September 1963. 29. U.S. Patent 3.238,876,. Method for Through-Bulkhead Shock Initiation. (McCotmick Selph Asso,., Inc.) March 1966.
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AMCP 706-179
CHAPTER 3 DE1 ONA fION TRANSFER AND OUTPUT
3.1 EFFECTIVENESS OF ONE CHARGE IN INITIATING ANOTHER
to inrstrumniit real cha~rges for detonation rate nmeasurirentrs. hlence, high order dvtoritioiio is generally considered to be a reaction whose
3-1.1 DETONATION PROP'AGATION
effects are
Piot significantly less than thle
miaxii mutothatI has beeni
observed with :i
far some instances. two charges are in such close contact that thle traaisfr o.- detoniation fronm one Io another is indistiniguishable front the propagation within a !ingle continuous charge More often. however, packaging. structuoral, and fabrication considerations result in thle interposition of gaps and barriers of such nra,,ni tuLde that thle agency oft tansmission is nonreactive shock, blast, flying
charge of the type in question. For main chiarges. high order may be considered in termvs of thle desired effects of' the charge. Booster charges, as iusually used, tend either to detonate high order by' almost ainy criterion or to fail completely.
fragnients, or some conmbinatioii of these. The conditions in-rlced by sucfh ititerruiptioits differ iii imipurtant respccti fromt those of stable detonation. In general. it takes timec and space to re-establish detonation in the receptor charge,
distance for transmission between one explosive cfharge and another s'aric-, witfi the cubc root of' the weight of the donor cftarge3l However, where the intervening space wais filled with air rather than solids, a !rend was noticed toward a relationship of thc 21;3 power of thle ctarge weight"
Fig. 3-I illustrates a detonation front as recorded by a st-cak camera. .-nvestIigatIors agree tflat detonation of' the receptor first occurs at a point within tfre- receptor charge rather thin at a surface exposed to the initiating imrpulse2 . Although this phenomnenon must be ta.lsen into account in the design of intitiation systemis for main charges whose effce:tivenesq is critic~'ly influenced by the form of the detonation wave front, it is geaeradly ignor-.d iii other explosive traini charges. For most practical purposes, transfer of detonation is coinsidered in ternirs of the probability tinat hrigh order detonation will be induced in the receptor. High order detonation is defined as that in whrich thre detonation rate is equal to or jueatei than thle stable detonation velocity' of tile explosive. It is rarely practical. however,
A proposed law of simtili tide f-or sy in pathetic detonation states that tfie critical
3-1.2 DIMENSIONAL INTERACTIONS The effectiveness of one charge in initiating another is detenininr'd by the interaction of tlte properties of the explosive, its loading density, and the dimensions and conf'itnement of the chargec. The interaction is such that it would bý impractical to discuss these factors separately, except in broad generalities. Although, as might be expected. thle effective output of' a donor charge increa-se systematically with its diameter. t're relationshiip between acceptor dianieter arid sensitivity is more conmplex (.-,e Fi.3-'1 Note that the optimum diameter of in acceptor. from the point of view of the air gap acris~i which it cart be irsitioted. is slightly less thtan the diameter of thle donor. This relationship
3-1
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AMCP 706-179
six AIR
SHOCKC
FAOCEAPTORO
Figure 3. 1. Streak Camera Record of Detonation 0.30o-
0300
0.0
150 1iS.ACCIPTOR 0.250
-
.. 0.
.
0..-2000o
o
DONOR
Z 0.050
.OA0 .OO OR
0.20
0.160 DIAIIETE5,
FFigure
l•.
0.060
0.100
ACO C: P OA
0IV6
0.200
DI AM I[ ER, I..
3-2. CriticalGap as a Function of Column Diameteri
II|
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AMCP 706-179
260
ALL CIANAES LOADED AT K0.00 ACCEPTOR ,IAMETER 0 150I•0,I.
240
L LELNGTH OF LEAD AZIDE D•O•, 04 DAVE TEROF DONOR, • IN.
tOO
__
_
PSi
0•0.200
IN.
L/102.5
1
L.6L .
i!o.4.
. sO m
.-
It o
-
. L/ D
.l
Ir
L/04.4 __
-0__
IL020.345
0
.
L02.3
DONORDIAMETER CONSTANT-0.I 10 11D-_NOR nL-OQT ] 4C L/ • *. e
L/0.
00
COLUMNLIENOTIN -.
D*O.OTS.L /DO.. T
DONOR C•ARGE,
-o
Figure3.3. CriticalAxial Air GapsAcros Which Detonation Is Transmitted Between Lead Azide and Tetryl
applis specifically to well confined columns of cxpiosive. As might be expected, beyond a certain minimum height the increase in the weight of a donor charge is more effective in increasing output if it is due to a diameter increase than to a length increase (see Fig- 3 -3'). , Most experimental determination of the relative effectiveness of explosive charges in initiating other charges has been done as part of a study of a specific. system. Hence, the variables are generally so intermingled as to make generalizations from such data difficult. However. the evidence that the volume of devt whichi a charge makes in a steel block is nearly prepo:tional to iis effectiveness as an initiator, combined with relatively broad and interpretable plate-dent data, makes it possible to derive relationships that appear to have relatively broad applicabilitys. Confinement has a significant ef.ect. In rcatively thin-walled containers, confinement
-.
is related to the weight ratio of case to charge. For heavily confined charges (where the wall "thicknem exceeds the charge radius) the shock impedance of the confining material is a good criterion of confinement effectiveness- The object of confinement is to have the greatest mismatch possible between explosive and container material so that as much of the detonation wave as possible is reflected back into the explosive. Shock velocities of various metals are listed in Table 3-1 (see also par. 5-3.2.3.5). 3-2 SENSITIVITY ro INITIATION 3-2.1 SENSITIVITY TESTSd 3-2.1.1 STANDARD TESTS The sensitivity of an explosive charge to initiation by another is the result of the interaction of a number of variables. This ;nteraction has not been reduced to a formula. However, a review of available tests should help the designer to develop an
3-3
I
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AMCP 706-179
One test employed to measure sensitivity
TABLE 3-1
to initiation is the booster sensitivity test in which a gap between donor arid test charge is filled with wax (see par. 12-2.1.2.5 for a
DENSITIES AND SHOCK VELOCITIES IN VARIOUS METALS Density, g/cm'
Metal
Shock Velocity, nintts1c:
descript'on of the test). Typical results are The 507o gaps were shown in Table 3-2. determined by means of Bruceton tests (see
Aluminum Babbitt Brass bronze
2.71 9.13
7.00 3.25
par. 12-1.2.2). Results of several other tests are compared in Table 3-3.
8.50 8.80
4.57 4.82
3-2.1.2 GAP TESTS
Copper Lead Magnesium
8.9
4.6'
11.3 1.76
2.1 * 7 83
The small scale air-gap test has been employed by a number of investigators. In
7.85 6.60
5.30 3.95
this test, donor and acceptor explosives are separated by a variable air gap (see Fig. 3-4').
Steel Zinc AIIo,
die cast)
"Ref. 6
Gap distance is the measure of sensitivilyk.
intuitive grasp of the effects and interactions of the various factors involved, The fact that results obtained by various procedures differ does Pot necessarily imply that one is right aand another wrong or that one is necessarily
In Fig 3-5', results of this test are coinpared with average impact sensitivity results. Impact data for the various explosives were compared with results obtained with the small scale gap test. Thiis test consists of determin-
better. Each. may be completely valid as a measurement of the sensitivity of an explosive under the conditions of the test.
ing the minimum priming charge by loading the explosive into a cup of a blasting cap with a priming charge of DDNP. Both donor and
TABLE 3.2 TYPICAL RESULTS OF BOOSTER SENSITIVITY TEST Explosive Amatol 8WB20 Amatol 50/60 Composition A-3 Composition B Composition C Composition C-3 Cyclonite (RDX) DBX Ednatol 55/4h Exploslva 0 (Ammonium Picrte) Halelte (EDNA) MIr ol,2 Nitrowanidine Pentolite 50650 Pentolite 50/50 Picratoi 52/48 TetryI Tetrytol 76/25 INT TNT Tritona! 80/20
In.
Prepstlo
91cm!
Presed Cast Presad Cat Pressed Pr.ed Preasd Cut Cast Premed
0.83 0.60 1.70 1.40 1.36 1.36 2.33 1.35 1.28 1.27
1.65 1.55 1.62 1.69 1.56 1.62 1.54 1.76 1.62 1.54
Presd Prissed Praswd Premed Ct Cast Premed Cst Prumed Cat Cat
2.00 1.46 G.67 2.36 2.06 1.00 2.01 1.86 1.68 0.8O 0.58
1.42 1.74 1.41 1.61 1.66 1.63 1.58 1.66 1.55 1.60 1.75
3-4
. .
.
. . . ..-
., S.. .
• •=•i.•=z• Ie- l
•'m°"
I 'lP'[•T'r
:'Pl~,•.
12
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AMCP.76
17
"
TABLE 3-3
EVERAL TESTS
BY INITIAT1ON SENSITIVITY MEASURED impet,' Tests Min. •rn.*Bu. PAID. Chg.. •ExglOSIVO - ca.
Explosive Composition B (Oosens.) Cocqonitt (R-XI
owl. Air
.pd
0.2 EROe No. 12
Minot. can
Q19
14(171
5
82
_
8i1 8 )
32
-
Cyclonite/WoX 99/1 W8/2 9W1
-
0.318
95/5 9119 (Comp- A-3) Cyc-lonite/Calqium Stearate 99.3/0-7 96.6/1.4 98.0(2.0 97.2t2.8 1 Pentolite, 50 10 190 PETN Tt0.17 Tatryl Iti. 70ese TNT,. Pro/3 C ost
0.21
16(17)
34
--
-
35 43 47
-
>100
-
-
0 -D
0- 9 0.09
12 (0b) C W1 140816
S115)
11(18) 14(171 -
2 > 96 -
0.266
55.76
0.470
3.28
4.07 4.79 5.04
-
0.47
"-
-
0.184
0.434
M d,
_
6.25
---
8(18 0.19 0.25
_ 0.144
23 37 32 38
304 65 11
OS•
0.32 0.332 0.313 O.2W9
-. -
In.
-
-
-
0%
in. 0401t.. in.
34OX
Cylnt
Clit. L.uci G0ap
3.63 6.62
0.281 est
0.021
f14g
16.7
m
of 1.4 gJ~unl. Grwn$ of DUNP to inititei material pressd lodeasity e ilbren M. m" amaa •iwhts are a bRef, d- Figures in parend cr' if 1011. . SdRef. - ROX I in long 0.2 in. diameter. Pressed in Iteel at 10 kw-i. , hnw d
-0no
-RD,
i-
0"gQ|i Doan
AIR GOA
FXPLMI.
Small Figure3-4.
Gao Teat Scale Air
V
0
~
i t's . 1 0 1
S
MS
.04S
I
-
-
Charge and Figure 3-5. Minimum Priming Propz9tion Criticl for Gap
"3.5
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AMCP 706-179 acceptor were loaded at 10,000 psi. Bruceton te,.ts of from fifteen to fifty trials formed the
donor, the transformation function will show the stimulus to be an inverse function of
basis of the estimates of the gap. For these tests, the logarithm of the gap length was assumed to be a normalizing function.
barrier thickness. The transformation function is (3-1)
X = A + 10B log(G,/G,)
A refinement of the small scale gap test is illustrated in Fig. 3-0' 2. Here, a steel dent block is added and the gap filled with Lucite. Further, data are analyzed by th, gap deibang method. The gap decibang DB, is analogc)us to the decibel in that it expresses not an absolute energy or stimulus but rather a comparison with some arbitrarily established reference level. This method of expressing explosive sensitivity is based on a function that transforms .ensitivity data into a normal distribution in which the explosive response increases with increased initiation intensity. Because the initiation intensity is increased by reducing the attenuation of the output of a standard
where X
= stimulus. DB, (gap decibang)
AB = arbitrary constants G,
- reference gap. in.
G,
= observed test gap. in.
The reference gap has been selected to be 1.0 in. using a high-intensity RDX-loaded donor. Conesponding values of decibang intensity and gap thickness are shown in Table 3-4. Table 3-5' 2 lists sensitivities of so:.ie exp~osives in gap decibangs as determind by the the small Lucite gap test. It is possible that
method of gap dec.ibang analysis may have a broader appfication than that of an atbibsary
DONORintensity
/.,
"/
EXPLOSIVE - OR~ MCSEUAGS fEX lSXSE A' *Doow
measure. It may serve- for example, as a unit of effective initiating output of detonator, lead, or booster. The relationship
between the dent produced by a donor acting through a barricr or gap and the gap decibang level of the combination appears to be linear. IVT
tUkI~ntESPWAR)
77 7 7
3-2.2 VARIABLES AFFECTING SENSITIVITY
ACCEPtYO CXPWMtE
3-2.2.1 LOADING DENSITY The voids that are present in most explosive charges affect the initiation sensitivity by
3.4
STEELOtNTTABLE
RELATION OF DECIBANGS TO GAP THICKNESS Intensity,
Figure 3-6. Small Scale Lucite Gap Test
ThIcknen,
0
Il000
3 501
6
9
10
13
16
26• 126 100 50.1 26.?
19
20
12.6 10.0
mil
3-6
U-
Downloaded from http://www.everyspec.com
lI AMCP 71179
material with less than one percent voids, failures were observed with no barrier at all. Results with sns; scale gap tests were similar.
TABLE 3-5 SENSITIVITIES OF SOME EXPLOSIVES ACCORDING TO THE SMALL SCALE
Some data are included in Table 3-5'
LUCITE GAP TEST
3-8"
4
. Fig.
shows the results of a test with RDX,
tetryl, and TNT.
Cydonit. (RDX? Cyclonite IRDX)
"TNT TNT
TNT Tvito•jil
,
I/cm 3 .
Exploulve 10.0 38.2 Cost
1.5654 1.7373 1.5746
3.293 6.069 16.5
6.2
1.4078
4.635
19.0 Cost
1.5,35 2.0567
6.114 17.5
providing reaction nuclei and by redud.ing the effects, pressure in the reaction zone. These of course, interact with those of charge size, confinement, and the nature of the transmitting medium. Results obtained with pressed, gantilar explosives in the wax gap sensitivity test are plotted in Fig. 3-7' ". For
3-2.2.2 LOT-TO-LOT VARIATIONS The variable with the largest effect on lot-to-lot uniformity is loading density. While there are other differences in explosives. which cannot
be explained
in terms of density
effects alone, these are difficult to pinpoint and even morte difficult to control9',". Particle size and its distribution are variables that have been shown to have an appreciable
3-2.2.3 ADDITIVES The addition of a few percent of a waxy substance, such as calcium stearate, reduces
YTEPYL
Oft A-3
No40 -
to
'VOWS,%
40
Figure 3-7. Effect of Voids on BoostrSensrivity (Wax Gap TeOti
3-7
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AMCP 706-179
15
--5 .0-, 1
is
20
25
2
.3
30
460
Figure 3-8. Efect of Voids on Booster Sensitivity (Lucj(ite Gap Test) the sensitivity of RDX by a factor of two or three. as indicat-d by the ia . This effect may be noted in Table 3-3. although on closer consideration, it is apparent that a large meastirc of this desensitization is attributable to the higher density attainable at the samne loading presure when a lubricant is added. In Table 3-6, the effects of added wax on
the sensitivity of a number of cast explosives are given as measured by the wax gap booster test. sensitivity 3-2..4
•
CNFINMENTVARIOUS
in Fig- 3-10"'. Almiost %he identical pies' resilts If ". Dnnei hardncis is iepiace with a dimensionless sti-ength. All of the data were obtained with tetryl acceptor charges. Thc effect of confinemen; upon sensitivity varies considerdbly from one explosive to another'. For small columns the differences become more marked. TABLE 3t
TAIos h i EFFECT OF 5 PERCENT s La2 WAX ON TilE BOOSTER SENSITIVITY OF CAST EXPLOSIVES
Critical air gaps as detearine I by the ar test o ined erla int inn upun butle efe o illustrated in Fig. 3-4 are related to confining media of the acceptors used as shown in Fig. Baronal 0.86 3-9. However, as inay be seen in -able at hs Comp. B 1.32 the agreement is somewhat less than perfect-. PFrtose 2.08 d The sum of a dimensionless density with a Picratol 52/48 1.00 dimensionless Brinell hardness has been promarx-k 1.87 posed to relate the effect of theby.. confining TNT 0.82 Critical air gaps.............t tet--xI.Ofn• 0.50 Tritonal 80020 medium to sensitivity. This relation is shwn .h
3-8
O
t
llsraedi r rlae
Fg.34 t cninngEC~~e
n.
o
in. Ins
0.64 1.16 -6 0.88 1\.6 1.03 104
Wxoli.
in. in.
-0.22 -0.16 -e0.12 -0.-12 -0.24 40.21 40.48
n
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ANY' 706-179 400 -- - -- - -
4$0 IN60CPOR~AC~t9.
k
' 9
900 !s..A CCff ar - \
-0
150 IN,. ACcEPTON
00
-J
d
or.,,
40-'
*2 S--
*s
fTABLE
Figue Efectof 3.. Aeepo~ron iring 4fateriai upon Se;nsitivit1,. in an Air Gap Test
*
3-7
3-2Z5. GAPS ANt, SARRlIERS
AIR GAP £ENSITIVITy RELATIED yo In one %way o nte.gp~I.riro ACOUSTIC IFJAV1 f-~(ftmtrasumi:ompf~en~ t~rrero ACCEPTOR CONFINING; MEDIUIW systlins. in some instwnces, these !'ealui .-s ame Shoe& IMgpwbncv e.qe into atrain to achieve confining of /6meptor a desired effe, t. fIn A.dlm cases, they aTe inhertent t., C fifn~m-~ rlijqaAi~con,tructionother just as is confirnement. Bottoms 0 o f Ag_ _p _t _~q 9Po fI c ups a t art ie vs- e n ma rla a ct u ri ii g to iei - Locite wftccec. introiduce 0-7 Saps. In some iflstanceis, V'ie o ~~ combination~ Magnesium of gaps and barriers are btent-11.4 0.Wa" Zinc (dis cost) ficial. For examuple, barrier 2.6 0.110t Babbitt transpi~tted detonation over fragments htave 3.2 a gal) that wasj~ 0.148 sor-lelirnes forty tiwmes that Jrass across whicht the 0 i63Vic Steel ISAE 10201 b las t w ave 0ci-ne co uld can-y it0.2e0 * Lead acide to teiyl, 06.)in. 4.2diumew columni Avaijat~ie exlnmet data relating the
3-9
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AMCP 7M 179
Po
S(L
401
O.TOSE
on~i ItC !00 UAOJESAI.
04( CAST
CAST
'onf
ensity
0, z i~%
naw
kA)
0so
12
Figure 3-10 Gap Sensitivity Related to Density and Hardness of Accep tor Con fini.:,g Medium i~tv tii
compiere. Fig. /-4 collpircs
and R!)DX
ti-as'uiSviuh o,.Jj.iud whentitle~
performance under service conditions for seveiral gap and barrier combination, both unconfried and confined. In Table 3-8' the effect of chai.ging the spacer material ir, 'lhe wax-gap booster test is given for rout explosives and a number of spacer materials. Attention is directed to the air gap data. It has been suggested that the niczhanism of transmission 3cross anl air gap to the more sensitive materials must involve factors tviher thaai sho..k pressure.
charges were displaced sonicvhia beyond the point of tangcncy. It was also observed t114t these explo-*ves sometimeb deton.itted from an apparent central initiationi point. Out-of-line safety should always be tested to make certaiiu that the u-sin does not propagate in the safe polsition (see par. 12-2.4).
3-2.3 MISALIGNED CHARGES
The mechanism whereby useful output is derived from an explosion is essentially that ef a hcet engine. H-eat is tranisformied into neechanical energy by the adiabatic expansion of hot, compressed gas. As a heat engine, the detonation of a military high explosive is remarkably efficient. Over seventy percent of the theoretic~al heat of explosion usually appeans as measurable rnechanizal output.
Out-of-line safety is a general requircment j. fuzes. The usual situation is that of two well-confined columns of explosives, one or which is displatced laterally with respect to the other 3i, in Fig. 3-11l'. Propagation occurs near the point wher: the txpanded hole of thie donor bec~omes tangen: to the original acceptor charge. 'In an experir.::ent with PEfN 3-10
3-3 OUTPUT
3-3.1 NATURE OF EXPLOSIVE OUTPUT
However, tile effectiveness- of an explosive
P_
Downloaded from http://www.everyspec.com 7_-
-
AMCP 706-179 *1~TABLE
3-8
For thesc reasons, charactcrizartion of the output of al expslosive charge in terms of the phecno~neria involved in its intended applicatoistile miost valid hasis for comjparisont with cinarg~s of other designs and loading%. E xamples of such pi'henonicna are blast and
SENSITIVITY FOR VARIOUS SPACER MATERIALS (Wax Gap Tust) 50 F cn Pohi
t
~~Mawwa
SP.Ct Tatiryl
i.
fragmenutation.
--
B
HOX
1 21 7.0 1. 7 1.43 1.46 1.51 1 50
0.9? 0.93 0.86 1.19 1.28 1.33 1.28
Paritciteofdt't
---
4ýAi
*Stanolind
Wood (oak) Copper Pclystyrene Acreawe' B Aluminum Wax
5.04 1.39 1.69 11.65 1.89 1.90 2.07
5.01 1.47 1.92 1.90 2.08 2.05 7.06
charge in ally particular application is riot necessarily directly relited to its total mechanical en'-rgy output. Only a %mail flac
tion or 1l-c energy usually reaches tile target and, wt this, most is usulally cithct reflected Orf S
I
absorbed without danu~nge to the t.:rg1et. I-Hence, effectiveness is chtaracterized in terms of ahe various phenomena that are used to transmit the output to the target. These phenomena include %Ibock waves, gross movemrnts of such intervening media as a;ir. water h oir tar~lh, an! !th, rniem inn of n,,'l-,I * risa~erals that arc inert comp~onents oftexplosive items. All of these ph-nroanena accom-
pany most explosion%, but thle partition of eneigy between
themn
vanes greatly with
variation of design and composition, a%do other quantities associated with cachi phenornenon which may be more itmportant thtan energy in determiniinn; relative: cfftCtivceness.
iwv The theory Ofd..Ltll w avs i s~.ribed in par. 2-2.3. Tie calculations (It%clss-cd are based onl a number oRassrillptionN that iniclude ideal detonation (Chapinan.JougIetIC CO:.ditiunlS) arid a certain reation chemistry. Aathotgig iii many investigationis agreemncrt has beean attained bectwecii expcrnment and theory. many ci the most interestill arid 111i po 0`1311 al! p1'Ct% Of' tilie OLIt illt be'raviur Of- r~al chanrges stenis [m~ill t!Kie: nonideality or from deviations~ in their chemnicail ia- theriaodynamnic behavior front those
conlnmonlN as..lumeui h-or these neasons, miorc quantitative predcictions of performanace ale made by use of th-e unpirical rcialionstripls bised oin meiasuV-cmacnts of output phcnomenea. Ani introdu~ction to xctual detonations. those which arc rheoretically isonideal, is cont incd in par. 2-21.3.3.
3-3.2 EFFECT OF CHARGE CONFiGURATION
3-3.2.1 THE DETOJA'riON FRONT As a first approximarion. detonation may be consider,!d to prorragmei in all directions wirifin a homogeneous charge at tile same velocity. Thus, if a charge is initiated by a relatively concentrated source, thle detonation, front assumles a divergent sphericAl form. This curvature (convex in thle direction of propagationl is accentuated at the boundaries of thle charge (see par. 2-Z.3)
DOOMSuIchcur'attire,
Figure 3 11. Arrangement for Propsaution of Misaligned Cnarqes
if its radtuis is small cnrio'lr to be conmparable with the reaction 70one length, resilti ill a reduý -on of dctoniitioi, velocity and pressure from that asso':ated
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AMCP 706-179 with ideal detonation. The explobive% used in applications where detoruition prcsstur:- is at pfrime consideration (i,cetolite. Compositions A-3 and B and cyclotols) have rcaction zone lengths of the order 3f a millimeter or less so that this effect is not usuially important. However, with siniail charges of such nmaterials as TNT. Explosive II, or tritonal, they can assume importance. In addition, thLiprvssawe and its gradient vary raidially. For sonic applications, most notably the controlled tiropulsion of solids. wave front profiles, and pressure distributions other titan those resulting front the action of l-ydrodynansii laws in simple charge configuratiors art: desirable. For suich purposes, spi-cial configurations h~ave evc Wved. One of the resulti of pressure variation behind the detoilation front is the variation in miomenitum w~hich the detonatiota wave imparts to solid objects. Where it is desired to propel an jbject of uniform thickness which has a relatively large area in contact with a charge, thcs-.- variations it) ino0ntenturn resuilt in corresponding velocity variations that may result in distortion or even rupture of thie object. This ptoblern may be alleviated by either of two mneanjs alttinýuh thecy are ge-nerally combined: 1. Distributing the expl!osivc charge so as to reduce the variation in mornenturn trans fer, or 2. Adding mass at powints where monwntuni is greatest
tionts has been the subject of mnuch research"~. All techlniques arc eswentially appliicat ions of I Iuyften%' principle that forms the basis of itconetnc optics. For ultimate refiniement, account miust be taken of the fact that detonation vvlucitics are not precisely conistant, but satisfactory control lot mnany purposes is possible by designs that ignore tile relatively small variations. 'fie following four means of controlling the sequence of arrival of' detonation waves at various points iv. a charge have been used' 8. 1. Wave interrupters thiat requnire the wavi. to go around the interrupter. 2. Two explosives of appreciably different ratrs of detonation. 3. Denisity and ckiimpcsition variations in the explosive. 4. Air, inert filters, or both of such thickness as to delay the wave but not destrcy it. Perhaps the simnplest devices tor the control Of' Wave fi-Ont Profile', a7w line wave generators. Those of the mainifold type tF-ig. 3-12) haii~ twoii miaulc by loaina`a . n*. channels machiined. molded, or cast into meital or otlier inert components and by constructing arrays of detonating cord. The detonating cmsd arrays Were, of course i.mited. to relative~y large systems by thle spaciny, needed to prevent initiation or dainage duc to radial blast effects of -idjacent cords.
The hydrodynamic relationshiips the: deter-
mine moenittumn distribution
in
finite explo-
.
~
05%
sive charges are too comnplex to be solved analytiv.ally. However, they have Lven programnmed for solution by comnputer' 7. Intuitive reasoning and cut-asnd-vy develop-
mc~it have yie'ded satisfactory designs in thepast-.A,
-
.--
.*.
*
-
FRIT
FOT
3-3.2.2 WAVE SHAPING The control of the profile of detonation 3-! 2
Figure 3-12. Line Wave Generator' of mhe Manifold Type
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AMCP 706- 79
Thie advect ofl rld detonating cord (MX') opens new p,)ssiiihltics in manifold type wave ,sec par,. 9-2.2.1). II stWeh shai-ig ,CIS ie applw~at:.on%.. .'rticu'lar atlý!nlioln should be 1,/ given the Iroblen. of' t(ansinissioil of detonation from tite very !;ma!l column diameter of MIX' to the Iarger charges in which it is hoped-. to control the wave front profit. Even tiough reliable transmissi,..n is assured, th/ build-tap may introduce enouh !ime scatter to nullify the wave shaping effccts. Step e.oittiSctioti or a tapered lead should result in a satisflctory system. An-ther line wav¢ generator of the manifold type consists of perf,,orated sheet explosive (see Fig. 3-13). addition to such generator%, warped sur laces may be used to produce line waves of lite circular front any desired cirvature. generated by the point i:nitiated detonation of be modified by a plane chargc, may also warping the plan': anti by tianinission to oWiwir explosive surlaces. One exmniple, illustrated I Fig. 3-14, is the generation of a straight line wave by means of"warped sheet explosive. In
I..
.1
,
,
.
/
••""•/t
!
-'
F .
.-
-
,"
" ///
01
/
-
ii
i..os.n
,
Figure 3.14. Line Wave Generatorof Waiped Sheet of Explosive
presiiur- drup below ambient. aM) finally A4) a re'turn to ambient pressure. Fig. 3-I 5 b shows this pressure-time relatioFship resuling from utinder reactions of explosive charges. The area carled impulse. exabove The blast wave is produced by a process that may involve several steps. It always it may be eninvolves ar initial explosioi. lanced by the afterburning or rca ;ing of the explosive products with themselves and with thc oxygci in tic ait. It miay also bc einhanced
3-3.3 BLAST Blast is the brief and rapid movement of air or other fluid away from a center of outward :inan explosion, O it is the ressure, pressure accompanying this movement. Physical manifestations ol blast include ( I ) a shock front that is created by the rapidly expanding gases being opposed by the medium around the explosive, (2) a time period in which the pressure drops to anmbient, (3) a continued
by shock reflection fronm surfaces such as ground. water, or walls.
Blast dec:reases in magnitude at e ratio equivalent to the cube ioot of the distance from the charge. Mlast pressure, P are plotted 1 on graphs as P vs nW' ' where r is the oncerfromathe chrrge an ere" is the
,
root of the charge weight. Variols design equations and graphs have been evolved for predicting the output from explosive charges. most of which are the results of empirical studies. The parameters that affect blast include
~a-~~C 04-
. type of explosive 2. confinenent
Figure3-13. Line Wave Generatorof Sheet Explosive
material used thickness of material 3. configuration of explosive charge
3-13
-.--
~-
i
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AMCP 106 179
kIN-)E 1.R~lVt FORl DURATION r`F POSIIIVE PrkSSURE
4ARIA
PRASEkQUAI,.~ IMI'ULNI, --- URAI ON Of NILGATIVEPRESSURE~ PHASE
PRESSURF PIAIME
TIME
Fiyirv 3- 15, Pressirt lirime
fklationship
4. ef Icts ,t cxIvrnioriwklia ;it iosplivic pssacCxuI IONc 11
i mr b121515 tfr fron pround orctitTOI iVC sttac It the ctiargi is cxpl iticd Close it, s1'nI2Icv, the sliock wave tha~t rcLaclivs this
S.t ebst lcclon 101 sirtacsskirt.c Cxtcirior liasl
will lit I,.rtially rdtkctcd. 'The rc-
1KcEclJ wawc may suhsk. leilely ca~cI1 up with tiw unrt'ia~l %hock wa1ve mid recnlortcc itTh
last.
rctl21500 tr
The
SIIIlkfic% Cimiltlcud Witli ex iomcs suwCO Ow ll~ictVIIICXiAIN a gcllcrdIIId iIda-
I io nhip ,bet wcn Ithc output In termis
omut~e
Aut i eitialcrea
ctharge 10in
tha
Thued Aconl
Oil,!iog Vx llc1i21
voty ([-ll~
slPedI to leadicivll tOi hat appear% *S to lC prdut
N011 I~bics il pa~llý SIod i es of i IC ci elets 01. Altitit Lie O blast shiowed that1 the~re is a. coltstan decreaise ill hlhisi ot1 itlki will ult 1ode". I-or pracical .1 pirIposis. there is .1 V', kOcrtCasC nt1 excess pressueloir eves-ry 100041t 2Illilttdc. 3-14
withou
ie tcIitv
r.ninsufC% r The r111terilr in
I~explodiiiiong i'lsiit
2:
ha
Iup s 11t the civc
travlCs tutoogh the 11ot rases of tile CXIISpinVC NhIIIC itN VnbOcits i%grC.ItCr. If IlunlV rellic t is' so r* I. cs a- 35 2iIab~c. thec resii Iting9 Namt daimi :an .tn ic iconidcrably greatecr than11
tor c~inamý kI1Cs the
sel ht c ni 1112e c iag thicat l pso ilticle ner.iict; argmrokupt por oltpith Williincreai sinoln. cki% rt 1i 111Ic.ls
its catchi
wai
o)I 111Cc spi Nil al id of peak pVcsmlle an~d
s~ch tat o~ihe~ncit ipwarsto poduc
101t
)Im ol~lyl ,IIIJIc% NvcfkC :()IjCrIjlck %ith
The
water
jlrOI ineo
of Explos~vt Blast
is
ile
d
s
cotieatl
look fortid tht Iat.Le%-, hglstbs erqied may ltr compiiii talii1w'1
3.34
JIlleinsideio
thati2'.' iV
Own that
rodullcxes the
*i givenvou batI
Will r e ll ergior xtd faics2 I:n
FRAGMENTATION
eIh
IIil
kill A
CAATR
ISTICS As aI 1121111 ltSt.At i00 Of VXI xpOSiVq 011111it. flagnlentalicin is dwtr~ictcrized by velocity and size distribution of fragments. For sorrif
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AMCP 706-179 plrp he ic. izc and shape of liagnicrits aw pircdctetiiiii.ed cithcr by prefoviiflny or by iioditicawmi s 11 tlw vea-ý or chiarge desin. which predi'joses it to b~reak a, desircd. Mail) stadies hiave bccit carrickd out both f-or fragantd hrC Sieliatlitcd 11l0i1iaitlol pl0JeCitileCs
GURNEY CONSTANTS FOR COMMON EXPLOSIVES
2 fragmtentat~tioni Waliclads
_____ Explosive
'(ABLE 3-9
-,f2oiv Eso
.
Composition R
Velocilty oft fagimenlts is quit..
The fiiiti.1l
orulsPeiiroiite acuitlyliclitCIbylieGunc .tt.tit~ypr.wtdlv h (UII)toiitlsTNT
8800 8400 7600
fer cylinders i"
w / Wthe 105 15'/W
"~ i~sc.
~
(3
for sphe'res iu,, (
TT vi + 0.6 It' ut
ltSCL
3
(33
where =
initial fragmient velo.city. filsec Gurney Constant, it/se,,c clurg weithtlb chrge lbimportant
=eigo.
I
,
weigtgi
oftfragi 01'it itg mtetal, Ilb
The einpiri..ai conistant E is determtined fr jw tota ol cxp. osiv it) per nmergy oft lie qutailtity as t It is expressed un it inass of" explosivye mhiiichi is available as .inIlp~e genieral. kinetic energy of thle this is somtewhait imore dital, half of tile unergy of d101n3tion. IVather than rcducing tite qtuanltti-es to thecoretical termns. Gurney cotislants a.re usually gilver, w-,VelocitIes. Talble 3-9 includes Gurney ,:on-;tits for somic explosivet: of liltiary interest. lititial fragnient velocities have beeit :umputed antd are avail2 able in tabular forim" . a tarti I dial ;-llu
Tile h1tttalitY of a fragmieiit is a funjctioni of its velocity, weight, and( presented area 'I le problems of' assessmtg lethality and vulnetability are qtmnte difficult becauise tile serioutsiicss of the damtage inflicted depends first on
ilat ure 01.t ilc I arge and ickit oil thle pooi of winpact anmd di rectioni of* tile flight of1 the triguin .ii Is withi resjk, it) Ilte ta:rg..' ai wellt as its size,. veloc.ity. shapec. alt Iilide. and niaterial~s. Ref' 33 providecs a quaintitative treatliee n t o f trig i'l tt a tim i .
Tile determuina~tion of tlie oiptintmuii fr;igineml size, til aidditiont to. Ili lcthajlity' cons-derati i~rs. reti. irs an) cstimat- of tile ptoha it e !ocat ion of tile tragmue ntinhg clhtrge with rcspc~ct to lt..' target at Jthe lttle of' bu 'rst and a knowledge of the azimutluti distribution of' the fragmetits. In some instances re~ltive ilovetuiliut of the ettargE. alid target is all faCtOr. Thle positiont of the charge withl respec-t to the target is somletimres ai designt v.Ariable th(at is cornbi ned wi ith othle r factors to muaxim~ize effecuiveness. F-or air-burst antipersonnel in an tjwrtv,ne n sizt% and bti-rm high.tn azimulhai distribution arc combined to maximlie t lte lethality. When a projectile or otlier :omtaimer is burst by tile explosto'i of the eApiosive contoincdi. thle sites ot thle fragilenrts produced vary according to a statistical distribuO cour-se. thia size is also affected by 0i1' tile cha~rgi to-Case maiss ratio and by the physical pruper-ties of [tie ease mi..teniai. Where Al1aspects of I;ie desigit of a !fragiitenitaliorn round or head may be v;;ned to optimize a design. tile choice o.f explosive is simnplified by this general1 tenidency for explosives that produce die fastest fragments to also proatuce tile finmest fragtncr~ts. Tile explosive with lthe highest Cuitiy constant ;ioay thtus be exwected to be capable of producing the example. weal '001.
3-15
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AMCP 706-179
largcst nuimber of lethadl fragmen tts. Where a case originally designed for artipersonnel use is to be s-daipted tot use aigMInS1 miore resistant targets. high perfor-nian~ce explosives may break it into fragment,; too small for effectiveniess. InI such situatoins a less brnsaat explosive may improve effectiveniess. GetieralI, in projectiles suchi considera3tions as strucua srnttoeitstbc
mov~emfent under the action oh tite explosive will riot be Impeded significantly- 'ihis container, completed Witht Suitable end ptales arid usually with aiiiillhýi !fliin liners, is loaded 'vith the explosive.
A continuous rod v~arliead differs front a discrete rod warhead iii that the rods 4r,strongly ioined to one another at alternate ndi a pattern similar to that of a folded
arid spin accelerationis dictate the rise of a ease that forms coarser f'ragnients than is desirable even with the most brisant explosmvc2'.
carpenters' rule. This hoop breaks when its circumference iLquals the sum of the rod leugths. if excess eniergy is imparted by the explosive.
ýS-i4 2 CONTROLLED FP.AGMENTATION
The value of a discrete rod fragment depiends uponl maintenance of its shape (as a relatively straieght rod) and its a~i~ude sueb, that its long axis is at right angles to itspath The value of a continuous rccd dopendI& upor its retzaining its integrity as such. Each of these requirements, in turn., rests on a basic requirement tima. the velocity imparted to eacti element of the length of thu rod is the same as that for eachi oher iernent. This is the miost important tjmpliceatin of the monientumn distribudion co-itrol diseissed in par. 3-3.2.1. The losses of pressure at the ends cause the pairts c., the rnd-z near the ends of
Since the br~akup of chu~gi' eases under explosive attack is mnainly two dimensninal. thie average size of frag;ncnts may be reduced anid their number incrLiased by the use: of multiple walled cases. A wide vareiey of ot~icr methlods have been uzied to produce fr,,grnents that ire almost all of the optimum si-o and shsape. Methods witiih suavebe,!r. usýed Include" 1. preformed fragments (with or without matrix)
2. notche:d or grooved rings -)ed o iremidsection. 3. t: ntchd r( vdwr 3. noce 4. notched or giooved . asings
the warhead to lag behind those nea.- the Distcree rods are bent and wisted, and continnious rods are broken as a result of the diiterences in velocity.
fl. le'd liners. Onec form of' preformed fragment is a rod. y t,,rolled experimenits. a rod has been to be more offeetiv, against aircraft ic same weight of metal broken into pieces. It can sever important strueCtural members rather than merety perfoi.-,e them. ksdiscrete rod varhead consists of a numbet of rods (usually of steel., arranged %ke tlte staves of a bairrel to form a cylindrical container. 1 .ey are joined together with su~fficient strength to provide the needed structural, strength for handling. launching. anid flight hut in such e manner that ther
3-16
3-3.5 OTHER OUTPUT EFFECTS 3-3.5.1 UNDERWATER Tfh- effects of an unde-rwater e..piorion are separabu- into two distinct phenomena, the shock wav'e and the pulsation of the bubble. It is of interest t- note that seventy to eighty percent of the heat ot detonation can be accounted for in the sum o' the energy of the shock wave and that of the movement of the bubble. The shock wave is kharacterized In termis of its peak presosure, energy, impulse. and time constant. These quantities may be computed from existing noniographs2 8 as functlons of distance and charge weight.
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AMCP 706-179
Tith pulsation and otlhr mo0vements of the bubble impart large quantities of mlomentum to surrounding water. Under some circuntstances, the migration of the bubble due to hydrodynahiic and gravitational clleets can result in highly concentrated transfer of this nitlentufin to ships or other structures so that the bubble action can outweigh that of the shock wave in its damaging effects. Bubble parameters may also be calculated conveniently with a nomogram. Tle behavior and actions of bubbles resulting from tinderwater explosions has been the subject of several studies' 9. 3-3.5.2 UNDERGROUND The effects of underground explosion aie more difficult to characterize quantitatively than are those in air or water because soil, and rocks are so much more variable in character and becassc disturbances are transmitted through them as stress waves with components of shear and sometimes tension in additon to the pressure that characterizes waves produced by explosions in fluids. The initial wave transmitted from an explosive chargc to almost any solid medium is a true shock wave, and the pressaies are far beyond file elastic limit. However. such shocks ati-1 Wad, 11, iatit.S L11,111Idlb IenUaWe nmuch because a large fraction of the energy is expended in shattering the medium. As the pressure approaches the compressive strength of the material, the shock is modified to a -tress wave. It loses the sharp rise eharacteris.i, of a shock and may separate into several vaves, elastic compression wave, plastic wave, surface wave, and a shear wave all propagated at different velocities. Meanwhile. since soil and rock are usually variable in structure and density, waves are refracted and reflected in paths of various lengths. In addition. sehere the explosion occurs close enough to the surface to produce an air blast wave, this induces another surface wave. As a result of this wave, at a distance of a mile, the ground disturbance from a single explosion might continue for thirty seconds.
At large distances, the disturbances induced by underground explosions have essentially the same characteristics as seismic waves produced by earthquakes. However. at shorter distances, the..'positive durations of stress waves are simi~lr in magnitude to the exionential decay constants for underwater explosions of charges of similar size'. In addition to inducing shock. stres:s, and seismic waves, underground explosions displace the surrounoing media. When close to tie surface, they produce craters. Expllosions too deep to burst through the surface produce spherical cavities known as camouflets. The products of the volume of a camouflet and the strength of the surrounding ineditim has been related to the heat of explosion of the charge which produces it.
3-3.5.3 SHAPED CHARGE The lined shaped charge is one of tlhc i ost effective means for the defeat of armor in terms of the ratio of thickness penetrated to diameter of round- Much in~formation is avail2 able oa the design of shaped charges 4,3' Action of the shaped charge is sotnetimes referred to .s the-. Mnrmo, effeat Oneration is as follows. At the detonation front, tile met;,l liner is deflected inward. Converging symmetrically toward the centerline, the metal is deflected along this line. The slug of metal which accumul:ates at thle center is squeezed by the continuing convergence to such high pressures that part of it emerges in a jet, like toothpaste from a tube. Because the theory of shaped charges is based on a number of simplifying assumptions and because of unavoidable variations introduced during manufacture and Ioa4..- a, large Imped part of design and developmt .ing charges has been empirical. -I ,iaped rules of thumb on the design charges, are consistent with tile theory although they might not be quantitatively predictable4 3-17
,,
..
. ..
.
.Aaf,
•1
•
"a"'
';"gAt'• '";•'-"•
j
L
N,-,-.-,
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-.
AMCP 101 179 i. Tho optimuri cone (included) anije, for most purposes, is about 42 deg.
counter-balanced, at least to some extent, by use of fluted and trumpet shaped liners.
2. Maiumum penetraticon is obtained with a stand-off d&stance between charge and target of 2 to 6 cal.
7. As the cone angle becomes larger, the velocity of the jet decreases and that of the slug increases. Shallow shaped charges in
3. have soft hum
The cone liner mraterial that seems to the best combination of properties is copper, although mild steel and alumihave been used to advantage.
which the slug is the effective output are referred to as Misznay-Schard'n charges. They arc used extensively in land mines.
5. Detonation pressure seems to be the most important property of an explosive affecting shaped charge performance.
8. As the cone angle becomes smaller the velocity of the jet becomes higher and its mass becomes smaller until, for a tube, they approach infinity and zero, respectively. 9. Although penetrations by shaped charges in armor plate as nigh as 11 cal have been observed in the laboratory, the limit for practical animunition is closer to four or five cone diameters.
6. In spin-stabiliaed projectiles, the centrifugal forces are sufficient to impair shaped charge performance significantly. This may b.
For information on shaped charge scaling, see Ref. 32.
4. Optimum cone liner thickness is about 0.03 cal for copper.
V
REFEREi.NCES u-k Lettered references are listed in the General References at the end of this handbook. I. AMCP 706-180, Engineering Design Handbook, Principles of Explosive Behavior.
4. J. S-vi•t, Investigation of Sympathetic Detur-'tion anre Evaluation of Structures for Ammunition Manufacture. Final Report, Armour Research Foundation, Chicago, IlI. Contract DA-I 1-173ORD-416, October 20, 1955. S. W. M. Shie. A Study of Output of Deto-
3. N. A. Tolch, Law of Similitude for Sympathetic Detonations. BRL Report
tern nal Design Factors Dt iater Ve LReirited External Dimensions, NAVORD Report 3593, Naval Ordnance Labora10 December Silver Sp15ng, tory,3d., 1953. 6. Ultrasonic Inspection, Nondestructive Testing Inspection Handbook. Quality Assurance Pamphlet AMCR 715-501.
385, Aberdeen Proving Ground, Md., 17 July 1943.
Watertown Arsenal, Watertown, Mass., 17 October 1960. (OLSOLETE)
2. M. A. Cook, D. H. Pack, and W. A. Gey, "Deflagration to Detonation Transition in Solid and Liquid Explosives," Proc. Royal Society, Stries A, 246, 1245, 81 (1958).
3-18
~.
.....-. . . . . .. ... .-'"q,, .
..
••,
'•rli•VI
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AMCP 700179 7- E. 11. Eyster, L, C. Smith. and S. R. Walton- The Sensitivity o•. tIgh Expjln5ives to Purer Si•ockv, Memo 10336, Naval Ordnance Laboratory, Silver Spring. Md., 14 July 1949.
l6. J. Savitt, Study oj Parautni.rsAfJ'ctiig
8. Sensitivrencss of Iligh Explosiics. Report OSRD 6629, (lrom Herculcs Powder Co.) Office of Scientific Research and Devclopmcnt, March 1946.
17. T. Orlow, E. Piacesi, ind H. M. Sternbert. "A Computer Program for the Analysis of Transient Axially Symmetric Explosion and Shock Dynamics Problems",
9. L. D. Hampton, Sensitivity and Pelleting C(harau teristics of Certain Desensitized RDX Mixtures. NAVORD Report 4320, Naval Ordnance Laboratory. Silver Spring, Md., 25 Jun2 1956. 10. S. Duck, G. W. Reynolds, and L. E. Starr, Sensaivrtit of Explositcs to Impact. NAVORD Report 4212, Naval Ordnance SLaboratory. Silver Spring, Md., I May 1955 to I November 1955. II. G. Svadeba, Sen.sitii,it of Explosives to impect, NAVORD Report 2940. Natal Ordnance Laboratory, Silver Spring, Md., 1 May 1953 to I July 1953. 12.
. N. Ayies. el al., Varicomp. A Merlaod for Determining Deronation-Traiix4cr Probabilities, NAVWEPS Report 7411, Silver Ordnance Laboratory, Naval Spring. Md., July 1961.
13. W. E. Dimmock, L. D. Hampton. and L. E. Starr, Investigation of the Propagation of Detonation Between Small Confined Charges. NAVORD Report 2385, Naval Ordnance Laboratory. Silver Spring, Md., I April 1952. 14. J. Smith, Some Observations of the Growth of Detonation. NAVORD Report 3753, Naval Ordnance Laboratory. Silver Spring. Md.. August 25, 1954.
Fraze Explosive Train Performance. Report 8. Armour Resecrch Foundation, Chicago, Ill.. Contract DA-1 1-022-501ORD-2219, February 1957.
Third Syvmposiou on Detonation, Report ACR-52, Office of Naval Research, Navy Dept., Vol. 1, September 26-28, 1959. pp. 226.40. 18. Proceedings of Detonation Wave Shaping Conference. Picatinny Arsenal, California Institute of Technology, Pasadena. Califonfia, 5-7 June 1956 19. M. A. Cook, Fundamental Principles of Wave Shaping, Report TR 52. Utah Utiversity, Salt Lake City, Utah, Contract N7-ONR-45107, August 1, 1956. 20. Robert W. Evans and D. K. Parks, The Dcrelopment of Equations for the Prcdiction of Explosur-e Effectiveness. Report 8. Denver Research Institute, Contract DAI-23-072-501-ORD(P)-35, 15 March 19,61 (AD-323 207, 21. S. D. Stein, Effect of Confinement on Blast Performance of Explosives, Report TR 2555, Picatinny Arsenal, Dover, N. J., November 1958. 22. R. W. HeinCirTann, R. W. Snook, and S. D. Stein. The Effect of Casing Materials and Explosive Compositions on Blast. Report DR-TR-I-60, Picatinny Arsenal, Ammunition Group. Dover, N.J_, February 1961.
15. J. Savitt, Effect of Acceptor ConfineUpon Acceptor Se•nsitivity. ment
23. Detonation of Cased Explosive Charges Inside F-47 Aircraft Aft Structures at a
NAVORD Report 2938, Naval Ordnance Laboratory, Silver Spring, Md., 13 November 1953.
Simulated Altitude of 100.000 Fet. Firing Record P-62416, Aberdeen Proving Ground, Md-, September 1956. 3-19
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AMCP 706-170
24. AMCP 706-245 (C), Engineering Design Handbook, Ammairzion Series, Design for Terminal Effects (U).
Report 2986, Naval Ordnance Laboratory, Silver Spring, Md., 4 June 1955. 29. R. H. Cole, Underwater Explosions, Princcton University Press, N.J., 1948.
25. AMCP 706-290 (C) Engineeriing Design Handbook, Warheads - General (U).
26. Table of Initial Fragment Velocities Cal-nhl
30. M A. Cook, The Science of High Explo-
ubihngCr..N
p. 1958,
culared from Sperui Formulas For Various Ratios and Explosive Energie.;. NAV*EPS Report 7592, Naval Ordnance Test Station, China Lake, Calif., December 22, 1960.
.
83.
31. Transactions of Symposium on Shaped Charges. BRL Report 985, Aberdeen Proving Ground, Md., May 22-24. 1956.
27. R. Webster, D. Nathan, and G. Gaydos, A Systems Effectiveness Analysis of the 105 mm MI Shell Loaded with Five Explosnves (U), WASP Laboratory Report No. 53, Picatinny Arenal, Dover, N. J. October 1970 (Confidential report).
32. 0. A. Klamer, Shaped Charge Scaling. Report TM 1383, Picatinny Arsen'al, Dover, N. J., March 1964. 33. AMCP 706-160 ,S), Engineering Design Handbook, Elements of Terminal Ballistics. Part One. Kill Mechanisms and Vulnerability (U).
28. E. A. Christian and E. M. Fisher. Ed-. Explosion Effects Data Sheets. NAVORL)
r2
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-
"
..
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AMCP 70& 179
C14APTER 4 ENVIROJNMENTAL RESPONSE
4-1 MILITARY REQUIREMENTS A military item must perform as intended afttr years of storage under conditions that may vary from tropical to arc-tic and from
jungle to desert'. In the case of *'xpiosive miateriel. the situation is aggrivated first by the fact that explosives are of neces.sity metastable materials, and second by the irreversibility of their operation. While all miii-
tarv items are not
In the course of their use, some explosive materiel is exposed to temperatures substantially higher than 1610'F. Three common sources of such high temperatures are hot guns. heat transferred through metal parts from-, rackut motors, and aerodynamic heating- The hnt gun problem, for the present, is soniewhat simplified for thle explosive charge designer because it is not difficult to find nigh explosives tha, are more temperature resistant
to the sanme
thaii the propellants usud in guns. Rocket
envaoromental conditions, the more comnmon ones have been standardized and are listed in Table 4-1 ~.so
propellants have flame temnperatures far beyond !hat whic7h any explosive can sustain that the designer of rocket warheads must consider the heat transfer situation- .As missiles are projected at higher velocities for longer times, the aerodynamic heating problem becomes trore severe. At these higher temperatures, al.' effects are exaggerated and accelerated to 3 point where the deteriora-
.ubjWc
Thus, explosive material must endure operating temperatures of --50' to !25'F and storage temperatures of -7O* to 160'F arnd remain operative. The Temperature and Humidit) Test) tests over th.-se temperatures. llt~I
illUS
ii1:01-11113
UL UZDW
L111AUMV IL
JI
h14)
storage tests are conducted at 1600 F. "Ac-
celerated aging" te-sts are conducted Pt higher temperatures although interpretation of results is subject to question. Both bulk explosives and loaded items are subjected to hot storage, surveillance, or accelerated aging tests. After aging, materials mzy be weighed aind analyzed to detect chemical decomposi-
SiUI IS.
W.1 II. IL
Ily
W1kC JIWýII~LtS
Ofi
YC.4I
ill
storage, may occur in minutes or seconds and the thermns1 decomposition of the explosive may become self-sustaining and run away to z thermal explosion. Such explosions are referred to as cocv-of) In addition, the higher temperatures may cause damage of types which would never occur at lower temperatures.
tion or tested to determine changes in per-
formance characteristics. Loaded items are sometimes dissected and their various compo*sents examined and analyzed. More often, they are tested functionally- Changes in funic-
In additon to temiperature, explosives ateI subjected to other environments. One of these is the proximity with metals aind other cxploosivcs ths.1 mn;4y be chemically incompatible.
tional charactcristics nsay result from chemi-
cal dleterioration of explos~vt or inert compo-
In the course of military transportation.
nents, changes in state of aggregation (such as fusion and reconsolidation. sintering or redis-
handling, and use, explosives and explosiv#e charges air necessarily subjected to rather
itsibution of components of mixtures), or dimensional distortion.
violent mechanical disturbances. From the viewpoint of analytical mechanics, the mani-
4-1
k,
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AMCP 7OC-11"
TABLE 4-1 ENVIRONMENTAL REQUIREMENTS FOR MILITARY MATERIEL Condition
The Item Must Withstand:
Operatin%, teinwr&lure
Temperatures ranging from an air temperature of 125 0 1'(ground temperature of 1450 F) in hot dry :limates to an air temperature of - 50OF (ground temperature of - 65'F) in cold climates. Temperatures can drog to - 80'F in borne bays of high flying aircraft, and aerodynamic heating can raise the temperature of missiks launched from high speed planes above 145*F.
Storaje temperature
Storage temperatures fromn
Fumidity
Relative humidities up to 100%.
Rain
A rain storm and function as intended.
Water
In certain instances, water penetration, be waterproof. showing no leakage, and be safe and operable after immersion in water at 700 ±:10F under a gage pressure of 15t± prsi for 1 hr.
Rough treatment
The rigors of transportsticn (including perhaps parachute dalivery), anvd rough handling.
Fungus
rungus growth.
Sur'!eillance
Starage in a seale..:cain for 10 yr (20 yr are desired) and remain safe arndOperable.
- 700
to 16001 and be operable atter removal from sto-age.
festations of these disturbances are comprestensioni, and shear of the explosive which must be specified in time-dependent terms. However, problems assocsated with such distur~iances are not usually considered in such term.. Tne usual approach is that of atte~mpting to simulate conditions that may be experienced hy explosive charges in service under quantitatively controlled conditions and in circumstances where behavior can be observed. Considered in these terms, the disturbances to which explosives may be subjected can be categorized as impact, acceltratior., vibration, and friction.
4-2 TEMPERATURE
Thn! relative sensitivities of common military explosives according to standard laborator) tests are given in Table 4 -2 4 while sensitivities to hiazards of use are tabulated in Table 4 3- d. For details of test procedumes, see par. 1212. 1.
Samples of TNT and tetr-yl, analyzed after storage for twenty years, showed no detectable chemical deterioration 7 . Assume. an activation energy of 33,000 cal/mo) and 1.0 cm 3 gas evolved in 40 hr at 120 0 C as the vacuum stability of tetryl; Eq. 2-2 extrap-
slOts,
4-2,
4-2~I
111cm
YIiEMPEATURE S71 OsiGE.
4-2.1.1 CHEMICAL DECOMPOSITION As indicated by the Arrhenius equation (Eq. 2-2). explosives are decomposing all the time. An important basis for the selection of umilitary high explosives is the slow rate of this decomposith n at storage temrperatures. The Vacuum Stability TestJ is the criterion of thermal stability which is used mosl frequently to predict storage life on ar explosive.
Downloaded from http://www.everyspec.com AMCP 70&-17M
TABLE 4-2 RELATIVE SENSITIVITIES•F OEXPLOSIVES ACCORDING 10 SIANDARID LAORATORY TESIS OF GROUND .SAMAPLES
Impa.t IE'U
*
in.
Explosive
Samitivity..
$VatitElec.
100-i Tetryl
Tesut
Booste
Friooon Tests
Joulo
-
-
-
AIT'UtOI, 5015W
16(071
95
U
BarStol black Powler
11(24)
3! 32
. S
--
. >12.5
-
U U U
38 -
-
16(lin
Comrposition A-3 Composition i *Co"-ition C3
16(17) 14(19) 11133)
*-
CoIPomtston C-4
19(27)
--
Cyvconitc (RUX) Cyclotol, 70/30 Cyclotol, 0W40 Explosvw D (Ammonlum Piorate) Islueita (EDNA) bet "HMX Load Azde (pure) Lsa2W pbynate
8(18) 14(20) 14(19)
100' 75 100*
17(18) 14(17) 9(23) 3(30) 8171)
32 00 75 -
Mlnol.2' Nib'oguA.idini Octo4, 7512b
13 23( 7) 17,26)
PenlolIte, 5W60B PTN Picratol, 52i/48 Piic Acid
12(15) 60(16) 17119) 13(07,
100÷
Tetryl Tttv". 7W30
silo) 11(18)
26 28
C U
14-16(17) 9(15) 13(10)
95v 42 86
U
bTIT Torpex
Tronal, 0/20
*l~igures tn pmeiithiss
-
-
.
-
26
-
-
-
U
-
-
L
--
0.0,,
U E E E
27
35 48 -
U
-..
"A 17
U C U
U
g/cm
ý,•1
-
2 60 d
1.65 2.55
1.0
0.20
0.60
385' A.8 427i
0.20
0.32
-
-..
.
d 278" 2 Wd
0.25 0.20 1.20
1.70 1.40 1.36
ý.6, 1.69 1.62
0.6 0.9 1.21'
290
A.20
.
0.06 0.20 0.20
-
-
0.9 0.81. 0.n
0.20 0.13 0.30
1.27 2.09
1.54 1.42
--
-
2 50
-
2
60'
2 65 d
2pa1
0.0 600+ -
3 18 d
. ... -.
19 11
0.06 ...
26
0.(,V7
14 .
0.06
ate sample v%%*Vhtu in ,ot~ligiaran
bE Explodes; C Cra~ckles,
in.
kI9-d -. 327 0.007 0.007 340 000%9 0.0009 2E2
..
-
g
-
-
.
U
'C
-
U
-
Joule
.
-
E
.
6Q¶% Oat.
Klu Mines
SSnapn. U .kiaffected
.
--
.
0.4 1.,0.45 -0.3
-
0.001
-
435 27?d `... 350
0.20 0.30
0.67 -
..41 --
0.44
-2, 0.21 225" . 28. 321J
01' 0.03 0.20 0.24
2.0' 39 1.00 2 g
1.S5 1.6 1.63 1.7
3.0V G.fit 0.6W 0.5
0.44 2557' 320
0.10 0.2?
2.01 1.66
1.1A 1.66
1.0 3.
0.44
0.27
0.82
1.0
02:4
-
-
1.0
.-
-
0.2
..
..
..
...
.
4 76 0
.-
470f
0.20
2.1 0.39
V
*AtI W00C. value at 1200 C if > I11 'Ref 4
Ref. 3 d[)G€°rnp°•&
iglnites
4.-3
r
-.
(q,-
.
.
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AMEXP 7.6-179
TABLE 43 SENSITIVITY OF EXPLOSIVES 10 HAZARDS OF USE 100 kg Drop Testr 10% Firlng
Cast
T7 Bomb Setbackb
Against
&x Seafe CritkPl
Heiht, Density, It W/cm,
Erplolive
Coniosition A-3
Prurne. k pil
E
P
B
U
0 13 40
0 4
100 80
0
0
20
60 80
-
-
-
-
-
-
-
100
-
-
-
-
-
-
30
0 25 30
40 15 70 30 8
-
-
-
-
87.6
Rifle Bull• t Test
(Apprn. pecnta)
0 3 0 0
.
('lOX)
Drop. ft
209
1.65 -..
-
Cvcozaol 70/30 Cyclotol, 60/40 Expvc~sive D (Ammoniun Picratel
Armor, ft/mc
1.64P
3.1 3.1
Ccmnpas'tion B Conmosition C-3 Composition C CyCloreits
80rn.m Proj.
76.6 .
5 .
82.0 -
70 72
-
-
20
-
100
-
-
-
40
60
64
10 0
23 45 60
..
.
..
Octal, 76/25 Pentolite, 5/60 P.TN Picratol, 52/48
1.5
1.81 1.59
170
-
-
-
-
7.1
1.6•0
-
10,000
-
-
Te-zyl Tet.ylol. 70(30 TNT T04pax Tritornl, 8020
2.8 ..6.5
1.57p
-
-
-
13 0 40 20 60
389
'Ref. 5 bref. 6
E P 8 U
nlummuil~n tiJivessed, 10.000 ps
-
-
1.54
1100 -
-
1.67
6,000
86.0 -
-
509c
-
-
30 65 .
87.0
55 -
80 -
-
-
-
40
Explloded Partially Fxploded Burned Uaffectid
olates to predict less than one percent decom-
580'F). Both have good stability when placed
years a: 160'F. Most
in a vacuum at 500°F for extended periods of
position in twenty
m;litary explosives Ih:ve vacuum stabilities at least as good as tetryl. The storage clihta, teristics of PETN. although worse than those of most mniliutay high eApIOMsis, are not so bad as to outwrigh its desieable properties for certain applications.
"Avery effectise means for achieving longterm chemical stability is to develop new, ligh-Iernpertuve explosives. For some app'ications, such as the space program, it i%the only choice. Recent efforts in this direction have ,-roducet' hexnitrosEtilbene, HNS. ('melting point of 600'F) and diaminohexanitrobiphenyl, DIPAM, (meiting point of
time8 4-2.1.2 DIMENSIONAL CHANGE b
Explosives, in general, have larger therCM. coeffici,'nsi of expansion than the metals in which they are usually !oaded. This results in the exp.msion of 'he explosive charge and the exerti•n of a force of significant magnitude on the explosive container when stored for long periods at high temperatures- Under some circunstances. the pressu-e developed by this expansion is enough to bulge bulkheads or covers.
4-4
V.
-.- . . ....
.
"-
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AMCP 706-179 Some wave shaping ,ysleinls (%ec pai . 3-3.2) involve tile uwc 01 ail spacvs within oi adjacent to explosive charges. At elevated temperatuires, thle Zravi!ational forces arc suintwciert to indiice crcep at a rate such that the configuration, which is so :titical in such applicalions, is modified within days to a point whCIC the w11VC shapingS effects are lost
during World War I contained large eniouigh fractions of such components that theN exuded from the surfaces of crgsThe
exudate, whi.-l was an explosive and which could appear in unintended places. presented a hazard. TNT miade in accoidant-e with present specifications (set point 80.2'C) does
distortion because the high storage temperaturcs are ;o close to their melting points. Tem-perature cycling causes such materials to ..grow". The growing is a perimanent Vxiall,sion wihicusdby tile opening of.
exude at 1 6 3 0p"'. Pentolite. which has ail eutectic of 170'F and tetrytol, cutectic 153'F, have greater tendencius to exudc. Tetrytol exudes at 149'F. Composition B1. which has an CLuteCtic: at 174'F exuides slight-
"microscopic cracks due to thermal gradient
ly at 160'F.
In Renerdl. plastic bonded cxplosives have better d-mensional stability at high temperatures; than caustable materials. The dimensional stahilities of the resin binders of such mnaterials provide reasonable clues regarding those vf the m.ixtumres.
pexudation
Usually TNT coirtains a group of impuritics formn vcrN low mltMing muliple11 component eutectics. Much of the TNT tised (hat canl
Mlaterials, like Composition B, cyctotol. and Minor-.' which contain Ilarge percentages o^. TNT, are p~trticautarly susceptible to such
stre~sses and the bridging of these- cracks by fuimon and refree.nirg of multiple comporent eutecties.
>/associated
A42.1.4 EXUDATION
During a study designed to prevent exudation, it w'as found that tile addition of a bimall amount of calcium silicate* to charges containing TNT will keel, exudation under satisfactory control".~ While the exud~ition is controlled, thle addition of the calcium silicate rende-N thme explosive charge more brittle and prone to the development of cracks. The degree of increased hazard thmakthis addition may cause has not yet been deternimmied.
4-2.1.3 EXPLOSIVE PROPERTY CHANGE
A-2.1.5 EFFECTS IN INITIATORS
Some explosiye properties, espeeaallb those with initiation and growth of detonation (see pars. 2-2 and 2-3), are detennined by the state of aggregation -if an explesive as much as by it: composition. Prelonged storage- of an explosive .-t temperatures near its mel*ing point can. result in changes of structure and, in the case of mixtures, segregation of components.
The performance of initiators is determined as much by spatial configuration and thle properties of inert components as by those of' the explosive materials.
Similarly, a bare tetryl booster in anl unlined cavity in Comp)osition B. or other TNT base material, may be desensitized by of the TNT9. The fuzing system may not be adequate for the initiation of a desensitized tetryl booster pellet. A similar pr-oblemn wouki exist if bare RDX and IIMX boosters had been used.
r4-j
Bridgewites of electric initiators mnay be broken by the tension resulting from the thermal expansion of the plastic plugs that are often used in such items. Such faiiures have been observed' '. In a test of a wirebriJge initiator, substantially increased fining times after hot storage and temperature-humidity cycling were noted. fince the basic lead styphnate charge used is one of tire most stable explosives known and is certainly well *Fo exmpe Mictomll E. repstwed Kr~4e narne of John%Mzvij
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AMCP 706-179
tenlipcrature
to whinh a psv~l ka llu iiat of hetic, t~vcdto oh ta an it-, ignition. As a condition that cook-otT occuy in ;.aiy smiall volume element III tile cxplosavv. thernial energy ,upplieid front anl outsidec sour"e and from chem~licil reaction Must exceed eneryty losses by conidumctioni and radiatiOhi. IgmIitioll Occurs a soi te11atiperJ)atuirc depemndent upon thei hecating late Of all t~xllo~~c
F I-Ee
-GA
Figure 4- 1. Postulated C'onditioni for Initia for Failure Caused by Wire-explosive Separation
SI,
11ist
ex plosive processes ot pmactk~al interest. cook-ot f is tile mos.t necatly ideal Ilnanifest~ation of the thermal explosion de-ncribed in pa-,. 2-1 1. When anl cxplosive ctharge is exposed to a
high temnferaturc environmient, its temperature rises eventually above that of the stirroundings. The tenmperature attained in the interior of the charge is enough hiighevr than
below any softening Or phase tiansition point at 160 0 F. these changes in functioning time must be attributed to mechanical distortions. Oasc sucth disortion, which may be visualized, the compression of the explosive as a result of the difference inI expansion coefficienits of
that of thle surroundings so that the heat liberated by tile reaction is carried oft. Sine thle reaction rate is anl exponential function of temperaturv. Eq. 2-2. a given increase in the temperature of the su rrou ndings causes a larger thtan proportional increase of the
mietal ease and
temperature
its plastic
and explosive
contcnts. Whent the initiator is returned to normal room tempercature. the plastic and the explosive c~ontract and a separation of bridgewire and explosive may result as shown in Fig. 4-1. No s istenatic basin. exists tor tile lirediction or preventiop of' such deterioration of initiators. thence, thorough testing in high temperature surveillance and cycling tests arc i ndicated.
4-2.2 COOK-OFF
Of
the
illteror.
A Point
is
reached where equilibri-man cannot be maintaimied This temperature. referred to a, tile cook-off temperature. is not a constant property of anl explosive but a property of a sys.temr that varies with charge size, thermal prnii'rtie%'of surroundin~s- and time of exposure. For any givein v.-vironmentil temperatu-e. thle interior equilibrium itensperature increases uith the size of the charge becauseL lwat flow depends upon :I temperature gradientt anti
even the sitne vxadicnt over aIlonger distance should gave a higher temperature (bot more
4-2.2.1 THRESHOLD CONDITIONS
KCook-off
is the deklagr ition or detonation of explosive material by the absorption of heat from its environment. Usually it consists of the accidental and spontaneous discharge of anmmunition or explosion in a gun or fircansa caused by anl overheated chaimber or barrel igniting a fu'm-, propellant charge, or bursting
3
Fcharge. The
cook-oft tempeiature is that
4-6
P
a
,
heat is liberated per unit are-a in a large charge so that the giadient is steeper). Thus, the surface temperature thit will result in a Jbermnal expleosion, the cook -off temnperature. dencredses as the si7ze of a chsarge is increased. As a general rule of thumnb. cook-off temperature is decreased About 1000F for ea~la ten-fold increase. in charge diamenter. The use of thermal insulation, of course,
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AMCP 706-11?1
ý01` XPLOIVE __0_
__
-
____0-
EA.INGSRAI1L USEDON ' COPPER SLEEVE INCONTACT WITH BOOiTER END CUiP P HE^TING PAYEOF 00f:%TE9 WELL ATAPeqaXiMArE POINT OF WOOSTER-SOOSltRl WELL CONTACT 3 HEATINGRATE. OF OUTER EXPLDilVE SURFACE AT THE PQIm7 of BOOSTER-90O5TEH ASSIMiUt.AYED *FLL CONTACT
200-
100__
_____
ALUMINUM UOOSTtfi CUVP
OFF EXPLOSIVE COOI(ED A WVTIME
.Mn;
Figure 4-2. Test ofot Booster in Simulated Mistile FWg: reiards the peLehation of heal into an. explisive charge and thus may forestall cook*,ff where the time of i'xpcriure is limited. H-owever, since it also rvtards the dissipation of the heat esoived ir. the reaction, it teric's 10 reduce the lemo~craiuir uhat .W:...........in eventual cook-off, Decisions rcgardiing the use cof insulation must be based on the type of exposuse anticipated. Thie probabilit) .4 cook-utf is teduct-o by insu.'ation of charges that are to be exposed for relatively short times to temnperatures welt above the cook-off temperatures. Charpes to be exposed to miarginal temperatures for time%, long enougit to apprq'ic! thermal equilibrium are morea stbject to cook-off if insulwdtId than if not, Under usua! coiditions. exposure to Or-vated temiperbture is foc relatively short periods. Frequently a charge is detonated purposely after expo!sure to higf temperatures for a few miunutes. '-Inder such Circumstances. the environiieut to whicr. the packaged explosive charg is expospil may be well above the cook-off tenperatuwe of the chjirgr, L~ut the explosive may be detonaited beore it
F
reaches a dangefous tcmper;ýture Fig. 4-2i . ar plot of experimental data. illustrate%a %ease where the explosive reaches the :.ook off temperature after the crnd Of eXPeLted lifeSuch situaiions may be predicted using conventional heat transfer analysis techniques, %-e is neccan:nficaioon although sary. Cook-oft temperature'. of commork miiitary explosive%are listed in Tsible 4-2. 4-22.2 COOK-OFF EXPERIMENTS The COMplic~itio'i~i of heat flow, phase changes, and reaction kinetic. a!; applied to mititary explosive charges in service situations have driven many to the conclusion that the. proibability of cook-off can b-: assessed otily by direcýt experiment. Tests using complete amn.,uution under serviteL conditions is UsualIy loo expensive. Unless a~ charge is instrumenited, such expet.ments Lan yield ao more thar, a yes or no answer as to whether aid whien cook-off occun-ed undet the particul~ar Londitiofli. Instrutitertation 0f a missile or projectide -Involves telemetering, adding to the expense.. The r-ompromisi. that has been
4-7
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X1-MCP 701,1_179
71t
I %citcwr obtainecd iiin; sc1 : a Woodl /nctal bath. and in ceiic;llly heated ti1hi1g.5 01Oi Cler Il~i shoWAta the kLkkf threshold (if iiilt:iiy cxjlosisc ispi the i.ilgr
RE/
of 350" ti 4501j:1 7.18
r
I
HEATING rOP--
it-p ni" ratuzc ant: otlier tactoI ' ti.i..tera d -" 2.1 -- .2. II sonc 1 111 1issilh applicationii, the
1-'-'+
Obtutated delays arc either perctissiot Or electrically ittilateit. l ife prinicipal use at pcrv ussisn prianeis in splasise lIaaitis i, for the tinitiationi of detliy celenients. lIt tisl' ap phica Iii ', Itie ir taiant advanit age over si ab printers is thear adaptability it) obturaicd systerms A typical percussion initiated obtitarated tIlely %ysacia' is shJown ITT I-) I)-I'. Note the heavy cconstruction, to Contaiin the pressure, and the expansion chanmber. Sorte delays contain baffles beyond tile prnter to prevent erratic delay times%causitc~ by) tinetration of the tlelay Column by hot printer particles, erosion by thfe iaction of' the gas streani, (-r elaekintg by thle shock wave. "Itic obturated delay eleitents tmat Lire electrically miniiated are of two types. Sante are essenitially thle sante as pecrCission ituitiatt'd
Downloaded from http://www.everyspec.com
AMCP 7W61 79
Jill
1111 NON- FLANGE TYPE
PELLET RETAINER
RELAY DETONATOR
MAIN DETONATOR
ALL DtIMENS IONS
Figure 6l. Obturated Delay Elornent of Bomb Fuze, ANM ?00A2
K
itemis with electixc initiators in place of the peicussion primers. Others are military adaptations of commercial delay blasting caps. The MARK( 35 Detonator (Fig. 6 -2 ') is an example of such an adaptation. The delay powder is loaded, at bulk density. into a lead tubc of larger than the inmended finished diameter. The tube is then drawn to size, consolidating the explosive, In the Electric Delay Detonator T65 (Fig. 6-3' ) advantage is taken of the small size of spotting charges of recently developed electric initiators and of the modern gasless delay z;~~~~~:comosit~?iontoeiminate baffle anid air spc.Teemay be some question as to whterteT65 ritnsobturated throughoutelaypero ts presasre. th ccasiponale is eoug t~h tocaus pesstre.Occsionl
F[ ir
which gases may escape. As delays become longer, the amou0Lnt of gas the), produce and consequently the internal volume needed in an obturated delay element increases to a point where the units become too bulky. In n "t-~~jebeor th ccvn -nir deiays are used. These designs are usually more reproducible in fur'ctioniiig tim;e than obturated dk'ays because the tollerances An internal volume, size of priming charge, an(, gaseous impurities in the delay element have a cumulative effect of varying pressure and. heflct, burning rate of the delay columns of obturated items. motueadotramspridVents must be kept closed until the devices are fired to protect primer and delay column eI.oion.moigtr and sthows atwosmeans for t~iavent. (A)- c-'so wsin thmwit diasksor
TAS Detonators indicate that those which have satisfactory delay times do so only because they leak. However, the advantage of a sealed unit in storage is reaiiied.
and 111) providing a soft plug to blow owit under the action of the primer.
6-1.2.2 VENTED DELAYS Ven'ed delays have openings through
The ring-type delay is a spetlal type of vented delay and is the.-fore discussed sepa-
6-2
6-1.2.3 RING-TYPE DELAY
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CX
--
_____ -
AMCP 706&179 GASLESS SlARtl'MI AX
KA
ITW
ISARIW CROX10
Figue Elctri 6 Dea
is Figur Te rin-2.Eetype Delay
fuzecavty (i.
f
KLEtoaoMARM5MD
tonaof
MARK mec. TepIncpeivle
ai
genera~lly so laige as to comprise a largc part of1 a f'je. The delay time of thc M154 Fuze can be set at any desired value from 0.4 to 25 see by rotating the calibrat-ýd ring, thus varying the length of the delay train which must be traversed by the. flame between the primer and the oiwput charge-
build-up i! pressure vrnd terminates in the rup t ure of a disk. Designs based on this principle card be vented or obturated. Fig. W.6 shows a delay based on this principle. using a vented type with baffle.
6-1.2.4 DELAYS ACHIEVED BY METHODS OTHER THAN CONTROLLED RATE BURNING
6-2.1 GAS-PRODUCING DELAY CHARGES
Ignition of one charge by another nmay be delayed by control of' the heat transfer process. An experimental design ia which primer -and Output Celay were s.-parated by a baffle with relatively small ports, to delay initiation of the relay until suf,-cient gas has passed through the ports, was iiot successful'.
Since the burning of gas producing matcrials depends upon the transfer of heat between the gaseous reictioii products and the solid, the burning rate is a direct function o( pressure. Thus, the delay tuones of such delays are greatly influenced by all factors that affect the gas pressure at the burning surface. The burning sujr.'.ee, of' course, is all of the surface exposed to the gas, including that of
KAMAU
CHAW.E-
LEA
6-2 DELAY COMPOSITIONS
6-2.1.1 LOADING PRESSURE
MCAY CRARGE
IT
Figure 6-3. Electric Delay L'e:ona tar, T65
ahf
Figure 6-4. Sealing Methodfs for Vented Delays 0-3
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AMCP 706 179
* ,*,1-* .,,-,.
WA Figre6-. I
-,•.
Figure 6-5. Fuze M54
pores and cracks that the gas may penetrate. The largest class of' gas producing delays are "blackpowder elcnaentsd. behavior of any delay it:quires that it burn as a continuous homogeneous substance. P'orosity can result in a *discontinuous relationship between interface pressure and burninqg rate. Black powder therefore are ioaded at 60,000 psi or more. When a long coulur is required, it is pressed in increreiits, each pellet being no longer than its dianLter (soc par, 10-3-1.2). 6-2.1.2 PELLET SUPPORT
121c"E
break~lt freadiiit
nese
IT resoe 0.291.11/•l
yp
Dla
CItITI
terlywudb
determined by such random considerations as surface roughness. The time of breakthrough is made mnore definite buy picbsing an acceleraiofl cavity in the output end of the pellet. The pellet is supported by a washer or the relay detonator cup (Fig. 6 -7 ). 6-2.1.3 EFFECTS OF MOISTURE AND FReproducible TEMPERATURE The effect of moisture on the burning rate. of black rowder is quite complex. For this reason, black powder delay elements must be ddelays kept dry. Effects of temperature extremes on perferonance of black powder deoay elements vary appreciably from one delay to another. The sprcad of data almost invariably increases at extreme temperatures. It may be suspected that tpd variations are related to subtle design details.
As a gas producing delayvburns, the surface in frictional contact with tIe walls diminishome.
Ie addition, for obturated (seated) delays, the pressure increases asr burning lo i g mAe t ( ae ~progresses. t 1 - . . )The .texree
o-4
&2.1.4 OBTURATED DELAYS an obturated hIn sp9d o a a system, a m s i the v rpressure a l n in r athee emertue.
I
my
e
usece
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r
T AMCP 706-179
Wu.E= weight of delay composition, mg
-B7D
-V PELLET
6-2.1.5 VENTED DELAYS
PELLET
The burning rate of a gas producing material is, in general, nearly proportional to
ACCELERATION CAVITY DETONATOR (AZ'E)
RELAY
Figure6.7. Support of Dolay Pellet
* /
= enclosed free volume, in?
enclosed frec volume is increased, quickly at first, by the primer or flash charge and then progressively by the gas liberated by the burning of the delay column. The result is that the burning rate (which usually is nearly proportional to pressure) accelerates continuously. The burning rate does not increase directly with the column length unless the free volume is also increased This requirement for a volume more or less proportional to the delay time limits obturated gas producing delays to about 0-4 sec with the common diameter columns of 0.1 to 0.125 in. The delay time of an obturated delay element, in addition to its direct relationship to the free volume, is inversely related to the gas volume and heat of explosion of the primer (Fig. 6-8a ). If the pressure rise in an obturated system is sufficient to cause bursting or significant leakage, the overall burning time will be greatly increased or the delay charge may not sustain its burning. The pressure may be calcilated from thermodynamic consideration of heat and gas volume liberated by the primer and delay column and the enclosed free volume iti which the gases are confined. For design test purposes, the following emperical equation gives a teasonable estimate
pressure. At atmospheric pressure, a vented black powder delay column 0.125 in. in diameter, pressed at 65,000 psi, burns at an inverse rate of about 5.5 sec/in. When mounted in fuzes, vented delays must be located so as to vent to the outside or to a relatively large volume. If other components of he fuze also occupy the volume, account must be taken of the effects of gaseous combustion products on these components.* Since the behavior of black powder is adversely affected by moisture, vents must be sealed until the delay is initiated. 'Iwo methods of sealing are shown in Fig. 64. 6-2.2 GASLLESS DELAY CHARGES 6-2.2.1
DELAY COMPOSITIONS
The limitations of gas producing delay compositions and the inhereiit problems associated with their design have led to the development of gasless delay mixes. It is possible to write stoichiometric equations for many highly exothermal reactions that produce no gaseous products. A larger number of these have been considered and many subjected to experimental investigations 6". However, most of them have been discarded for one or another of the following reasons: 1. Erratic burning rates
SP
=-30(W~+ Wd)/V, psi S2.
(6-1)I
where
rW
Too large column diameter nece~sary for reliable propagation
pressure, psi
3. Large temperature coefficient of burn4rerutlwtprtring rate
weight of priming composition, mg
4. Falure at low temperatures 6-5
J
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AMCP 7MI711
AA
z
0.6
001
S>-J taa
CD_____
0011
ASIIEARY UNITS
M 14
0.2____ J____
Figur 6-8.CNAAGE WEIGHT,
0009
maV
Fuv8Characteristicsof an Obturated Blak Pow v'Jr LDelaj Elempent sitions. are too insensitive to be initiat~d directly by the agent used in the particular application. T7hese ignition powders also cotn
5. Hygroscopicity 6. Rapid deterioration
U$C4
7. Unavailability of reproducible supply of raw materials 8. Large pressure coefficient of burning rate *
9. Failure at
low~
pressure
10. Reaction products liquid or otherwise subject to movement frcm acceleration dUring burning. Table 64- lits M.e g"Isess delay zombinations in current use. The range of coznpWstions giveni for somne of the combinations allows for adjustment of the burning rutes over wide ranges. 6-2.2.2 IGNITION POWDERS A columnu of gasless delay comaposition izý usually prece:ded by a charge of ignicte mix. are necessary when the delay compo-
rigniters
6-6r
US5;s~iounh 're-
J4UJlihzt
v.,.y
te
(microsecond or millisecond) delay3 Tat~le 6-2 gives thr compositions of igniter mixes used in gasless, delay elements. Note that these are all gasless mihtures that also have application as gaskess delay mtxtures. TheY differ fromt tlhe mixtures or Table 6-1 in that they burm faster and are readijy ignitibie. 6-2.2.3 PROPERTIES OF D)ELAY AND INTO
ODR
6-22.23.1 PROPERTIES OF INTEREST in addition to burning rates, properties of delay powders of interest include variability of burning rate, temperature coefficient of bwuiing rate, pressure coefficient of burning9 rate, effects of storage (both wet and dry), effects of column diameter, and obturation and mechanical properties. Other special problems njy be asscited with the use of
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AMCP 706-1iB
t
4
TABLE 6-1 GASLESS DELAY COMPOSITIONS IN CURRENT USE
Chromic oxide
Barium chromate 0 to 40 70 to 40
Lead chromate 15 to 70 10
Berlum -chromate 70 to 60
Potalunt perchlooFte 10
Barium
Potrelure
Alloy
chromate
perchlorate
so
14
Ni-Zr Mix
Barium chr )mate 22 70
Poste1junm pwchlorate 42 6
4to 11 13to 15 Manganese 45 to 3 20 to 50 Molyb denum
S20
to 30
SNi-Zr
5/31 L.117
-
41 to46 None
None
None
None.
Selenium
83rF.m Peroxide
-
Tekc (01l~ad#ir
Selenium 2C
84O2 80
-
Tin/lead alloy powder 015/135)
SSilnon
Red Lead 80
i20 B
TUhiyenatd
28
27 to 39 39 to 87 cZir 28
elatim
qn
be
stressed that !hey are affected by such vari-
e
t
bsr v
willbtom 5 to 12 3 to 10
-orate
eLOb dioxide 72
these properties, it sh•uld
Ceeit i mox. 8 partssm vy weight
P roptui brth h echlorsante 9.6 4.6S
isum chromab 72to 41,t 59 46 to5
one or another type of composition. Before
discussing
None
Barium chromate 89 to06 40 to
Boron
d
Inert
Oxidant
Fuel
"I
quent treatment of the ignition, and delay
powders. .ot It should similar
properties
will
be
be assumed that observed
in all
ables as particle size. particle size distribution,
mixtur.- of the same nominal cheinical comn-
intimacy and uniformity of mixture, relative distribution of components of a mixture. and impurities that are not readily detectable. To control these variables, relatively elaborate procedutres have been established for the
position. "Thedescription of the compounding of delay compositions is beyond the scope of this handbook.
procurement, characterization, and treatment of raw materials, and the mixing and subse-
Table 6-3,o gives the ranges of burning rates of current gasless delay compositions.
6-2.2.3.2 BURNING RATES
/
K6-7 (1~
--
v~wV'~!
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AMCP 706-179
ith
'I ABLE 6-2
TABLE 6.3
IGNtITION POWDERS FOR GASLESS OE?.AY ELEMEN'TS
BURNING RATES OF GASLd'SS DELAY COMPOSITIONý
.1"1
Oidnt
Boron (30)
Lead peroxiiii (70)
Beron (10)
Harium
Zirconijim (41)
chromaei W)J Ferric oxide (49)
Zirconium (65)
FerriC
oxi4e (1r,)
Inertlrxh~t C opetc~
4-6-85
44/41116
4.5
Oiatomnaceous
44/42114
6.5
Diatomaceous
eo
(10) earth
amrhu)0.5 I crtotaiianxl 96/fi 90/10
3.5 9.12.6 1.5 0.6
WarO,,/KCIO*/W 40/1 GfO
125
ilie variation of hur.irig tinie within a lot of delay elem-rents is expressed as a cipefficient of maratiofl. th, standard deviation of the burning time exprvsscd as a percentage of the total burning !irrie. Unde; controlled laboratory conditions. the c~ctc~icints of variation of irost o( 2he niaterial- listed are three Pcircent or im bL
eiunIing Rate, ____
acr,oir,c,,oe
-
Zirconium (3,1? Ferri.; oxide 1501 Titeniium 0I?)
Lot-to-Ict vairiabhility rn-
Oaiorgna
*'pnst~
by idjusting the length of the delay column for eaica n-w ioi of delay compositlion or by odaing appropriate ingredients and remixing to speed up or slow down the mnixtureVariatio., may be greatly reduced by c~areful control of raw materials and preparation prcdrs
procedures Cocfficictits of variation as small as three perceat. buiwevur. cannot be expected in practical delay elements. Variations in other i.omponeaats :han the delay column contribute to the. viriability. In general. these other variatior~s affect the shorter delays most senous~y.
-~l
701/041 8aO/~I~l-da~yi311
W01419170 3D)1I7i30 70) SDI I4I3)1O.30ir2t3DIJ701
Type 11
T'p III
6 It
ffjC,O/PbC,O,/Mn 0/4565W
0-16
2.5i12.6 2.17
0/s3
1.5
1Re.O, fb~aa I-i
. added Red L~eadIS/Cahte
841
-4.11
801Wt7ade W ~ 87
~
88%; Ni/Zr, 801,'ý-90%; ltorton, 50i%-90%.
Radial losses of heat can retard cr extinguish the burning of a delay column. Such losses, of course, become more serivus as the column dinmeter, turning rate, and ambient temperature are reduced, and these effects
6-9
IA
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AMCP 700-179
TABLE 64 EFFECT OF LOADING PRESSURE ON BaCrO4 -8 COMPOSITIONS Loading Pr~asure, 10' *
-si
36
18
9
3.6
1.3
0.15
1.69
1.00
1.49
1.39
1.29
1.21
9.648 1.2
0.655 0.6
0.645 0.7
0.642 0.7
0.640 0.8
0.693 0.8
Mean burning rate, wc/in.
0.67C
0.853
0.619
0.586
0.558
Mean burning rate. sec/g
0.272
0.276
0.280
0.287
0.297
% Coefficient of Variation
1.5
0.9
1.1
1.6
2.0
0.544 0.309 1.8
961MBaCrO 4 -B Mean burning rate,
nc/in.
Mean burning rate. nc/g % Coefficient of Variation
90/10 BCr.04 -8
combine to r--sult in a failure diameter assoeiated with delay mix and temperature (see Table 6 5). For pracdical manganese delay mixtures at .-65 0 F, the quarter-inch diameter usually used is well above the failure diamcte:.
TABLE 6-5 FAILURE DIAMETER VAR:ATION OF MANGANESE COMPOSITIONS AT -- F Invn" Burning Rata, secin.
Failure Dintetw, in.
3 10 10. 16-.1
sO.109 0.125-0.156 0. 12-0. 153
0-2.2.4.3 WALL THICKNESS The body into which a delay is loaded Serves zis a Iheat sink. Metals in general arc much .better conductors of heat than is the delay composition. Delay columns close to their low temperature failure diameters tend to have larger thermal coefficients as the surrounding wall thickness is increased. For materials well above their failure diameters, the effect of wall thickness becomes less importan. It has been suggested that a body with very thin walls of a good thermal 6 6-1
conductor might accelerate burning by preheating the column ahead of the burning front'. 1The strength of the delay body can be important. Yielding under the loading pressure has been found to result in erratic delay times'• 2 . Stress analysis of the body as a tube stressed hydraulically is a conservative means of assuring adequate strength. However, experience indicates that delay bodies will usually give satisfactory results under conditions such that %aiculatd tfieyond the yield point.
ib well he-
6.3 DESIGN PRINCIPLES 087URATED VS VENTED DESIGN The harmful effects oi moisture and other", atmospheric gases make scaled delay elements desirable in all cases and mandatory for situations where an element that must be exposed ditions humid herenily
te normal storage and handling concontains materials that fail after surveillance. Obturated delays inare sealed.
Delay powders are divided into two categories, those whose reaction products are largely gaseous, and those known as gasless. All current design effort has been applied to
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AMCP 706-1" the latter that lend thenmsclvcs to obturated design.
2. Use obturated or internally vented construction where practical.
The term gaslcss must not be taken literally. Gasless delay compositions produce some gas. chiefly as a result of impumitics. Gas quantity is much less predictable than that of gaseous delays. For this reason, it is the best practice to use an internal volume large enough so that the effect of pressure build-up on the delay time is negligible. This is quite practical in relatively short delays. However, length, and as as the thelangt, ade 0okIscquently onsequntlythethe amountt aeounted fre6. of delay powder increases, the required free volume also incruases, so a delay clement can get quite bulky. Such considerations often drive the designer to the use of a vented system.
3. Where obturated constraction is impractical, usC a seal that opens at ignition. 4. if a scalud unit is not practical, ue delay compositions of denmonstra~cd resistance to conditions of high humidity. 5. Calculate the effect of cumulative toler ances upon such pertinent factors as internal free volume. Provide for adequate free volume iu otrtduis obturated units. 7. Analyze stresses induced by both internal and external forces which may be anticipated during loading, shipping, launching, and operation.
6-3.2 DESIGN RULES OF THUMB Because delay compositions are metastable materials containing all ingredients n~cessary for self-propagating reaction, their burning is metasta-le. The effect of any factor which tends to cause an increase or decrease in burning rate is exaggerated. For this reason, satisfactory performance requires accurate control of alt such factors. Control must be maintained from the procurement of raw suaiterials until the munition, of which the delay is a component, reaches its target. The following rules should govern the designer: I. Use delay compositions prepared by a well established procedure front ingredients of known and controlled characteristics.
8. Make sure that all components will survive these stresses taking into account the elevated temperatures that result from burning of the delay column. 9. Specify adequate loading pressur.s (at least 60,000 psi for gas producing compositions and at least 30,000 psi for gasless delay powders) and short enough increments (onehalf diameter). 10. Provide for proper support of dciay olumn• I I• Use diameters well above failure diameter at -65'F. (Usual practice is 0 ' or 0.25 in. for gasless mixtures; 0.1 or 0.125 in. foi black powder.)
REFERENCES a-k Lettered rejerences are listed in the General References at the end of this handbook.
2. H. S. Lebpold and E. E. Kilmer. An In'estlgaslon of Internal Venting for Delay Actuators. NAVORD Report 5724, Naval Ordnance Laboratory, Silver Spring, Md., 10 September 1957.
I A Compendium of Pyrotechnic Delay Devices. Journal Article 3 1.0 of the JANAF Fuze Committee, 23 October 1963, AD-474 833.
3. D. E. Seeger and R. E. Trezona, Development of the 50 dillisecond-Delay T65 6-11
&l\
(q
- -
-
----
~
-
Downloaded from http://www.everyspec.com
AMCP 706-179 leh'ctric l)c'onator. Report TR 2594. PIc'atimiy
Arsenal,
Dover,
N.J.,
April
1959. 4. "I'l9-1300-2113, Artillery AmmunitiOn for gims, howitzer-i1 recoilless rifler. anj nortirs, DA, 6 April 1967. 5. Sqtier and L. 7ernow, Short Dela' J_ Baffle Detonators for Antiaircraft Contact Fuzcs. BRL Rc'port 690. Aberdeen Proving Ground, Md., February 1949. 6. David hlart, Long-Ranige Dc'relophnent oJ Delay Powders Jor Ammunition Fiuze Application, Report TR 1733, Picatinny Arsenal, Dover, N.J., 7 June 1949. 7. Burton Werbel, L)erelopment ci" Delay Powders, Report TR 2249, Picatinny Arsenal, Dover, N.J., September 1955. 8. R. Comyn and R. Dwiggins, SurreWillance Characteristics of Gasless Igniters, NAVORD Report 1774, Naval Ordnance
6-12
Labor:atory, Silver Spring. Md., 14 March 1951.
9. Efj~c't of Loading Varialh's on the Biurmlng OharaCt'ristlCS oJ Delay Powdery, NAVORD Report 2202. Naval Ordnancc Laboratory. Silver Spring. Md.. December 1951. 10. M. F. Murphy. A ('omnparatihc Studi" of Fic Prrchnic Dclay(Conlposieaes. NAVORD Report 5671. Naval Ordnance Laboratory, Silver Spring. Md., 2 April 1958 11. B. A. Breslow and R. K. Blanche, Sr., )elrclopment of a Short-Time Pinicrt-al Fuze Delay Elemennt for 2. 75-inch Folding kin Aircraft Rocket. NAVORD Report 3333, Naval Ordnance Test Station, China Lake, Calif., May 1954. 12. E. E. Kilmer. The Dei'elopment of the XE-S 78 Delav Prnmerfor the Picket Boat Depth (harge Pistol. NAVORD Report 60O2, Naval Ordnance Laboratory. Silver Spring, Md., 13 October 1958.
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AMP'.ý 7Ott 179
CHAPTER 7 LEADS AND BOOSTERS
Lcad% and btousoss arkctho li eomiponent iiiS of tile explosive trinil whose ILliictioitaiine (1) tile I ranstniisi on of tiw detfoliat ion es ablishedt by thle liciona.1 r. and (2) its augmuenitat ion to a level such that thle mlain c~harge is initijat ed yvlably- They are tile ,lost flexibite tools oh, explosive trajin designer and they atie thle comiponents most inftlu~enced in operation by decision regarding thle design of inert
ti tok III theaiisiliary arming d evice: mak upth o auxiliary arilling device.t it)di prevent jiultiation ofl tile booster in 11w event oftit premahlTr Ito i ttOning 0411 ]th lue de toatof. Wiwin armled by setbac k Ind CentIriungal lot ceN of' firmnt' tile boostcr dictonatcr moves int o linte withb thle totec de ton at oi The ex plosive train is then kiomlplete so lii at thle dci oiiatr ill tlit- tite mlit i'es t lic booslte (te Ionatrir wh ich 1. tot ui l ses otil lead anid booster chiarge. This is all cxamtple ofi complePIX booster. Usu~ally the booterII CotI~ItSl only of at booster charge and a 111oLsmlg. Tueli
parts. They arc relativly simple iii functiont and fabrication.
sifing and itrilling device niornially is part )t thle Iuic explosive train.
7-1 DESCRIPTIONrpake 7.1 DESCRIPTION'c 7-1.1 GENERAL
* *the *his
-fouictiotlirg
'ihe explosive contained in~ a booster is called aIbooster charge. InI common usagc, the terml b5os,,r.r , harge is bb citcto~ bo:ty Actually, a booster consist% of* a housing and other metal parts, the booster cltarg_2 and, as a spe cial feature, ant auxiliary arming device. We are c'incerued here only with booster Ohaiges-
Fig. 7 -2 ' illoIStrates the UiseOf* b0osturh Inl spit-hack systemns. 'Iwo booster charges are requnired tor this application, the doito! (auxIhlary Ilooster) at thec cnd of fihe fouzc csploasec train And thle receiver (booster) At thle bottom o. the Projectile caIvity. Operation of tlits lure is discussed tin par. 7-2.5
Figs. 7o7-3 aesectional views oW' typical military itemns that illustrate thle use of lead, and boosters- Fig. 7-1I' shows at coinplete booster, thle M2 IA4, that Is tiiployed with point -de tona ting fuzes to effect thle of' Projectiles. Thbe e(terinal threads screw into the projectile so that thle booster rests in the lure A01, IThe internal thrvads hold tile nose fuze, one of tile M48 family.
Finally. Fig. 7-3' AhowN a typical small caliber fuze with booster charge. Because of' lith, compactness oi- thle 2( nun 1 tote, nto load is required. When thle lirze is armned, thle firing pin\ initiates tilt detonaitor that svts oil thle boo~kir diteetly. This figure illustrates that boastvr design is not hard andt last. liere thle booster Acts as anl auxiliary boolter while thle top-off ch.orgc loaded into the projectile acts as a booster ýscc also Fig. 1-2).
The booster --onsists of" two marts that thread together, (1) the booster chaige &'(a tetryl pellet) held in thle aluminum booster cop M and (2) the brass housing A4 that
7-1.2 FUNCTIONS'
rcontains detonator E, lead L, aftd a rotor as; t well as a variety of phins arnd springs wyhich
7-1.2.1 LEADS InI sonw constructions, the separation between 'Jvtotlator and the next charge: may be
I
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AMCF 706 119 7-1 2.2 BOOSTERS xi losivVute liafr'nt mam in drgcs of higg atsin:.errsil ivc as it is praklcical ito liii kc
ir
*
0
~
n
flý
ic'.filt
~
AV.,.Augmen
L(Generally.
Figiire7-7. Boosrer. M2A4
short, while ill othters. the defliat~n or is niomiired remotely from the booster. A lead is tised to transmitflte detonation froml detonator to booster wheat the gapl is tooxlarge. fof direct transmission, Leads are also usted whenl ld! csrrnplexi ty or safety Of tile ["ain demara0: thtem. 11asv various circuimstances have: fcStilted ;ri tire eVOILliktl ion of aWide Viricty Of leads. Somle are simple cyliridrical charges of relatively small leght-imtrratius and1 others are quiite long. Some transmnit dctotlaii tiol ;around cornersi or anigles arnd others are flexible.
-
0are
I
Ir
-
While the ftunctionl of a lead is inertly the transmnissionr of' a detonation, ill practice leads are Oftern used to atigment: ftile O~itpirt Of, deto~nators. Th:is is done because. for reasons disctussed iii par. 3-1, boosters are genterally harde-r ito initiate than leads and because leads otiell called ipoin to initiate sulbsequeitnt charges across large gajps or throtiglr heavy barriers. Onl the other hrand. it is possible to design detonator- with Output adequalte for the direct initiation of boostcrs. even where gaps are appreciable. In, fuzes for s5all arrirs. leads usually are not necessary (see Fig. 7-3).
7-2
thein' IDet onator-, arid I .d s ac its -smail it s is consist eo with iclijability In k-lietera I l,neither deflia1.1tors nor leads aret ini iiccll-selvcs %illilt mal i charrge explosics' ficitn I1 to 111I rt.iubly. Hoosieis, are eCInCHi~tS Of stiffilC11ir 001oUt ttor J Cto ii;te mami chiarge., reIi ailly wheni uiitiatcui by dcttlnators or leads. fiencc, 11illo hi net on of1 (ine booster is to Wave:. 1I fili et Al CI,1u1 boosters are loadcd with tile sawrlc ')l similar tVxplosjvtes to those used ill the bImse charges of' detoniators ;arid irn leads. Thecrefore, their inni~ as chiarae-ttrized hy velocity of' propagation, pressure, temiperaWVR' and part icle velocity is not distinguished froml that of dotitrators ;arid leads. lloweitcr. since the booster charge is larger its output is corrtspondringly greater. 7-1.3 EXPLOSIVES For mnany years teiry; was tilt starndard lead and booster e~xplosive- It is still used ill 1iIMil scm VICCa1110111111111t0il. M,11,i' 0 the por it I-j pal rules of turimnb, practices, arid prlocedumes that serve as guides ill the design arnd loading of explosive cormponernts and systemis derive ifl Pitt frontiftle properties oftretryl. For this trasotl, tietryl hals served Lis a starlda'd of comparison for booster explosives, It has given rise it) such design guidaritce as "nro lead or booster shall be more sensitive thanr tetryl-, at least in the U.S. Navy. Qurantitative ..ritcria for the acceptability ofr explosives below the train intz'rrupter have not yet been established". Hiowever, Ref. 4 is the rtsultI Of efforts by the services, under the leadership ot the Navy, in this direction. There are a 11irumer of objectioins to tetryl. It is expensive to 11iatiufactiiiv, causes air polluationi, aind has undiesirable dye clnaracteristics. For these reasons, tire iranufacture/ of tetlyl is being teriminated. Hlowever, a universally accepted substitute has not yet
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AMCt' 706 179
Ahl AUXIItt
-60051111 (lJAnI rULYSIIREHL StdaED AQS PU.LEIJ
jU1 k M122
P.1
Figu~re 7 2. 2.75 ma.flEA I R7ocket Will, SpIit bacA Explosive Systemil
been agrued u )ta
-
RIA coill ainiag .1 111a\ i-
mu tatl ua 2,/, vax (aIcti'tg as%a hiaie r-l aba icati 1) ks use~I ili many ciiinreilt A aity di sig~ns. 1NIX and Other explosives have 1, en toutid to be at0 So tile .a PicI atioatS_ Mi It ads,'$tat sgeols
%,Il9- I?1614
list-, IINS, DIPAM, antd ('i It. A)
W) A thicse .are -ipenasive m.na. ill :'dthiition. (ti jadoes not work wrcit 'a1 tratos - *xrccitaly. lo ('Coaipo.itioaa A-3, A-4 m.0i A. -3 h~avr bren reCo 11Itlacaded as iniL tertim cir. As .
Ait cssealtial teat inc katains iailitlarv xat .aiv'y pioksaisial of thec ft.Table ilais teitore would l~eits ptirl~osc it the -w'tsitltity (If* fla leads anid boost a were ala! mc aast otier iatad. [the baoits Mime td. Oatl liltselasitiv elcaitigta to detolitealr etably when.1 iuitiiated by anroats of a ictiiaa!taror risxplasive lead. 11'li .. 1tt.0,1xlalaaill aild at1i1Itit1t11111 allowalble' hia atas Of seisi lvi ty tatlast tie closer together it). ICad Or haOC lostet e spisive titian forF Othter cx plasivrs. Coti~sideraIititts Of desigit eCoit0101y antd alt safel v anad el tabi lit>' deleratimiaa atson tend t oit) ' e:i!Iiss tlarse tintits stall liar! Ian.
State (11' ggFt ga ho a Ofi'III, VplOias ive. a till' h di mcI ma as ait thle explosive eletcite ts. TIt'l t'e cci
Of fihcsr
3-3 a5 ai list tit titeseaaiilsu
sist' atetta is tile
*.be
a
Thte exploiOSve tt'aiteaial ttSCit ill tilte booster maolttltt seats itive ttta I rtelt thaila i t carge, anld is ctharge, is smiatller thitar filie tarn11 less sestih tan tile previous esplatsive cttiaii oaitts. It shtotuld tte a nii't~alcredl that ittit iaIitittt SCasit li ty is a fL1c ht Iioti alt aI alt'tither at' variables of 'lhr eikperimtietkit system ittcltadiay Ittle agenacy tif elie'ly tralttslr, tlea ralttfticilelttet of tiat expllosive eleancats. ttle
~~~~s %k~l wlit
vaiiabksý interact to imo k
qtaatuillativr p~redictioii dafficult amnlrcss tilc espe amien! is a reasonabily arc taraic si itiala11oi1 Oftthle Coiiditions of, use. Fortian..elv. tire tsigtn aid loading pradctiCcs 11)1 leads and1. boosters are Well enou01gh stalliJidailzd that a rcatively tmodest test schetdule call biedevised to include conaditionis re presctiitativ/ oft all buat luhaily i.l-cialiltei ~app[iatioais.
by eltqtc.tr -co~t coniparisoni, a few ty pi eat matinit harge r sl~osives have bieen inrluinald. Note that thle uireseace ait' oane ort two pereenI oCatlcikumt stra rate Or waxl isa,; jail adverse e'ffect uplora the sensitivity o f Rn)X to Varimits
booaster *:xplosivt' as ancwasared
in it iat ion.
Soate
designers
have
contsid ered
these matenrals atnly as bitt ter-I autrieaati s for thle mittpovetinthit of loadintg piripert ics, toverlUOkiI tgIthei' effects Iapott se I~taiv it>'. I"Or ithis re'asaoni, natl atara a ppwa r tin diavaltigs or specifieattolls Intdic~ating tltal 'lap Ito I perI-cittt at tttese ataterials anti bie addetl. iThe Variatioat atlowedi by sucht rnotatiorns call restult iai ~a changte inl gap) senasit ivit y by a tarto orfa three or fIat1.. T'his is suifficiecnt to make thec differeatce between a highaly reliablte systemn and onte that is,altmost cotuple telI> iinaperaIbtv. In llcoosin~g ant explosive itaterial for a boaster, baths thle desig o f inert parts atnd 7-3
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AMCP 706-179
FIRING PIN
ROTOR
DETONATOR
SOOSTER
particularly when plastic markedly supe-ior to tetryl.
bonded',
are
Most boosters are pressed as pellets. Pure RDX forms low density, crumbly, pellets when pressed at 5,000-15.000 psi, and, at high pressures, the pellets are so brittle that they often break as they are pushed from the die. RDX Class C was developed to alleviate
this difficulty that may be further reduced by the addition of one or two percent of a binder-lubricant.
special environmental conditions associated with the application must be considered. Sensitivity and output of explosives may be
Polystyrene bonded RDX 9/91 (PB-RDX) was origninally intended as a compound for hot molding as a plastic. However, it can be press loaded at ordinary :room temperatures like otk-er powdered e.plosives. When so loaded, its physical properties, although not ,as good as those of hot nziolded PB-RDX, are definitely superior to those of almost aliy other pressed powderei4 explosive usually 98/2 RDX/binder. Tshe seissitivity of PB-RDX, when pressed at similar; pressures, is almost identical with that of other booster cxplosives, while its output closely resembles that of tetryl. Improved physical properties and output can he obtained by hot pressing under
adiusted varying their loadinp densities.is Thus, in by some applications, substitution
ccum-hot pressing can produce pellets that pop open -lone like muffins when"
possible, without adverse effects upon established safety or reliability levels if the designer is free to specify the loading densily of the substituted explosive. However, the loading pressure needed to attain the necessary density may exceed the strength of the container. On the other hand, if the necessaiy density is too low, the explosive may be subject to breakage, crumbling, or to other nmechanical failure.
ejected from the die-hither loading pressures, or both, but at the expense of somewhat reduced initiation sensitivity.
Figure7-3. 20 mm Fuze, M505
-
The need to consider cook-off and thermal decomposition at high temperatures is obvious. In the case of leads and boosters, the effects of temperature extremes upon explosive properties, in particular upon sensitivity, may be more serious than in other explosive charg, As is shown in pars. 4-2.2 and 4-2.3 these 'ects can be quite large. In these respeL ,, RDX and many of its mixtures,
7-2 DESIGN CONSIDI RATIONS 7-2.1 RELATION TO PUZE DESIGN As fuze componentS, dimensions of leads and boosters are largely determined by the necessities of fuze fiesign. Similarly, the mechanical design of the fuze in which it is used is one of the imp,ýrtant governing factors in the confinement afforded an item of this type. The fact of the inatter is that the design of leads and booaters interacts with the mechanical design of fuzes to such an extent that the most practical arrangement is usually that in which these items are designed by the fuze designer.
7-4
.1
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AMCP 700-179
rh. design of leads and boosters in not as complex as that of initiators. For this reason, many past designs have bcen evolved by copying a previous design that served its purpose satisf,'torily. There is aothing wrong with such an approach provided improvements are added when possible, care i, taken not to perpetuate errors, and due consideration is given to safety and reliability. Since lead and booster layout and material, affect other fuze design features to a large extent, it is best to give them careful consideration in early design stages before major dimensions are frozen. In the case of leads, standards have been established for dimensions and cupsh.
"7-2.2 LEADS 7-2.2.1 LENGTH
*
Sdetonating
I
,
U
-.
-
'
When a lead is initiated by a detonator or another lead it is best to have no gaps or barrier at all. When there must be a gap, it is best to have the donor component end covered by a metallic disk on the order of 0.005-0.010 in. thick. When the lead has a closure at the output end, a small gap at the end may also inciease the reliability with which it L61. initiate nhe nucceeding element. Althou'.i a number of investigators have noted that detonation is more effectively transmitted by moving fragments than by shock, flame, or even by the direct contact of explosive, the permatations of variables are so numerous as to have discouraged a quantitative study of their interactions to affect reliability. Where a lead is used to augment the output of a relatively mild detonator or where it is initiated for use under adverse conditions such as across a large gap or through a heavy harrier, it may be necessary to make leads longer than they would be just for transmission. It has been found that the output of a lead that detonates high order for most of its length reaches a point of diminishing returns when the length is about four or five diameters or more.. The growth of detonation in marginally initiated leads iias been observed
to take place over as many as fifteen diametcrs but the reproducibility of this process is not well enough established to be relied upon, even if systems involving such gradual growth in leads had attractive design possibilities. At the present state of the art, the only valid reason for use of a lead more than four diameters long is the necessity arising from the mechanical separation of the components that it connects. 7-2.2.2 DIAMETER
AND CONFINEMENT
The most usual combination of lead diameter and confinement in military usage is an explosive column between 0.150 and 0.160 in. diameter heavily confined in brass or steel. Fig. 7-1 is an example of such a desiga. Failure diameters are listed in Table 7-1. .t must be renlemnhered, however, that failure diameters are highly dependent on particle size, density, and confinement. As is indicated in par. 3-1.1, the most reliable transmission of detonation between a detonator and a confined lead occurs when the lead is close to the same diameter or slightly smaller in diameter than the detontor. Sincra ,rmrncn diameter ofCeAtn nators in military use in 0.192 in. OD and about 0.172 in. ID, the prevalent lead diameter is well chosen from this point of view. The effect of lead diameter upon lead sensitivity is not usually of practical significance in the design of military maieriel. Were it is, present practices are close to ideal. The importance of diameter and gap to sensitivity is illustrated for ideafized acceptors similar to leads in Fig. 3-2. Effect of gap and confinement for actual service leads on initiation by detonators is shown in Fig. 7-4. The effect of the wall thickness of a confining tube upon the initiation sensitivity of leads or similar small columns, has not been quantitatively evaluated. In one experiment with 0.169-in. diameter leads, there 7-5
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AMCP 706-179
TABLE 7-1 FAILURE DIAMETERS OF LEAD AND BOOSTER EXPLOSIVES Confinement, in.
Explolive PETN RDX RDX/Calcium Stearate 98/2 Tetryl TN! (Granular) TNT 125W)
Bare, in. -
any specified reliability or sal'i'fy level is n I2.3/-y-l
I
tila; Iota'iii %hiold"bec ltlC geii It slitul 11id 01 otibe 1
1k iitt
Alma! Life assurance call iikvrrtbe givec t-i unlessi all of the an iis aire tested - A quan titalive tiieastire. however, c:;,a be obt~iaril, in Probability that cala hi' itaI ifiel ~~ttrnis of a
P
~imm'i
miiiidt its prtopetrt ics ctiilt lbe ace llj.iI ely tdeseribetk! by mimiesigii onie ol type. Slinck:
type. The sirlplest, lulost tlirtct, and least quiestionriblte way tot dcuiilst~i~ ate the sa it or reiaibilitWy of 3n iexi)losive tchargt is t') test Cil1tiugh ate his tinder act iia Siii ''ICC coitIMi ins. 11his will enable one to tietet'rin fit' itli rability or saf~ety oft he charge miti nd acit Ia
. fil d 10SI-rICis.1 tis
C~lgitlIce lng 1ti acI CC It is stioi gly itCO-co inc atiile Iha, file readl I stilifilecinlie ii hisIiitk % giomiih by studyrig thie let, rctiieid tcxt%'-. A uth ni aold l, reve ofu
'asi
!iiI
anli'tilisin-I
I elize oil.t'e oliii u Ii;iit1i th-it cor rct'cites igil of cxp' ici ut'iif and pei ice: ri ski I '-Ii tv i lWielal!tst is suet-laity
flu:
cills for thlC
i te Whenacoptlin ltlg
stlist iiac Ie fie
gli
of
Neitice'.
saifely andi re i al i lit> lIn'
kdau
Iralalatioils oft seinsvilt>)
citi
i
e v
on%-'
fol w n
.1
itreabittecinilin-
ar I
tvs safet
A'lanld
'ilt tlie>' lt dvi
Itmatl 11 ai itt
ai pitll ,t'l by assessiiillc ts of (li id cit elcy Conifidnceit levels,.
2.
~Safets'
ap
antd rell hifity dtteiiciiiafoiis bpecoifitalIi>t)i thli conatttills lIs. whichl
they
w~ re
deternined.
plet ely as possi fit' Thus, to cstiiblisti 99.9;, reliabilify at 954-,ý confidence, it is ne'-essary to test 2300 itemis, without a failhre', allil tia estab~lsh3a safety Of'
pat ic:
IS jill pa)rtIalit
where anuI-,r of trials
iiiiia.Jli
lrla.
eitwiite t
U ni
f reom
iccogri ;c (lit' sagr'itiactjarlixaniietels aml
ictccly
~clih
tthis
Iii e'. :it aI ilillit'ii CNjh''i11ltS. beictdck. Ii af' wouildtlc
(lit'
It
as part
aig
0I of'
it
tlie
i liti Ol%
e seetul to plrevail ill McRacc which iiay ti he and to issure hiiiiself of safely, aididrelaility over- the whiile tange.c 12-1
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AMCP 700 179 3..1lie siiiest W.1) to establishl ,.atet a'Id Ivl-aluility Is to test a1laiige enough iqiriirtit :iurder the eskati coridititr:is iusc. 1ite iZ)Iliiitiis lIcccCNwii tfii suh tets Cll cE, how (sci. iuioliriitt. f'ii h llitilyll In thii di sign and deve lopmen' tt phase.
W1isilitit inialily)
of fiii')i tl'
sll
c~lt'oNi~e
atiiiis
III
sii'fi
ti.,igcs 1%dric tjli~lailtllC'
as
dwirsinirs%. dlcmirsi. a~id o'i-tincilic-1i I ins. tlt'e staindaiid tltiidtioll ti! the smshi'. it) :.Ill tstialhlit.i still silirilt.y1 Icilduted by) tirlrrn'stl rout il'I 4)1 tilse%% %jimlaiir de.
4. All tjt.- po'ints are, not what thenr na~nie
iiiiphlie. The oily) way it) ti sticl tit t all eliairgcN of a k6ind %dil fili' ondtic any giveni set of toirdithrlrs is to fire themI all il!Iiit' these ~ilidtilolls. Wife[) this us donec, ironic will be left toii .iill iknniuirtg.io. It- al fire datai art fl.:cohililahlitle by a 5U." Point tiit a )I Jut point. and thle numtibeus of trial, invokcd Ill all! finc and no fi'e- deltcrTiinfatiloii art' spcctifcd, they mta) be' utsedf with a statistical leveli techlnique: to coluptiti' saiety and ieh:''nlity leves. 5. All extrapolations are: based o~naistlmilwtions. dr'peci'i iug on [the rat Liii of thit unIi eirlying dust n buition I clieni. predicted % e should be accompanied by a clear statenicirt of t il ..viu ntl ions madui arid, whi'lese~r pusutile, a justification for ith-ir LI~c-
12-1.1.2 FREQUINCY DISIMHIUTIONSa Ohscra!ionis %%! If mai~ll) take lthe toinin a vaiiables )Ii attribuies IVita cositng Iniiasiirid chl.i0clistk all: s;nld to) be cN iuinsscd by tiri.iblch Aiti d'uties :Iucwt i qii..htics f''s.Jby llW cItei such .is olor. cliaked-. fiied, lit not tiie,! ftcrite. Inl geiic.IA. thei iteml ).. imilled ellther touittiiiiis iii ibi 11iM C0olitoin to $,)filet'iililty . staiirdliid. oi niis fii lilt' tomij of );., aiij six cification Altitmi nio-go diii. siic t i as% tired and not tired. arc at t.iti' olteni retci'cd to as qua~ntal repuzi tue) t cit lici occuLiis f does not oc, tii1onr fie app11lcatlion of a st im tituIs It is oftenci thci advantageous t.) eXpies~s tile Later' as ape cenitage: of Oct ;ri lýc)til itia gise t'iiIi'li uiiii Ill reffc. this is a Inrean of trdnstin~ijiing qrianiltal
data to aI vai iat-c formi .Tire znsitavity of a charge is &cteinincd by its design and that of its suirrounidings. as W ii asY (Ill thei-ios.tec ilatlcidis of Which ii Is coniposed 'Ifius. safety and reliability muns: be ri'-cvaltiated wihen the designi of cattier esplonove charges or mnelt parts is altered. Stceni rigly suial! changes are soinetinizs importat 7. Bith safety and reliability .:rt reI;,[ed to ra t.o of thle difference between tile Cipecetei servie condition alid thle meain antsitivity to the standard deviaition of the Peiisitivity. Etither may be iniptviose by in creasing thus diffetrnce or by reducuing tillstandarid deviation. tile
V
p
S
8. Although, as shown in par. 2-3.1. the initiatioin process often depends upon the nonhomogeneity of explosiv'es. so that sensitivity is pewrluap.- miore inherently statistical in nature (hail nmost qiiatititativi' lroroietien. ii has been. found that fire variability of the
ir
0.e oft It:,Inemtilods thiat canl br usid to piesent 0ie iesiil r. of at sci ics il b'r1 lm is a gIpt111L&alPlot of the tmCq LItincy Of c:achi occutirirnce wito irespeckt to the w~depoicideit variable. Tiil, plot i' a visual display ill tinWith1 pal Icii of s .riafioni bit the ot-Seis6APit 'i roil is. Uistia1) Ml 8a gralithiejtccbi L'It COI*:vIciierI 10 Plot tlue curiutlatre ir.'qijerrc) as a fuiiction of the urrdeperrderrt variable Ani esarirfI1c of t'LinriI :ive :ivt~tieiicy' jItslbtii lion, tIre priumbsility of fuLnict ioining of an elc rueri mInitiator, is showni finFig 12-It A). So ihiary typi's A cui'rileinwiral data 'lit a p.-lumi of thus type taL I kirrwn as a normA- dii itrihu ti')i [ftlat a special gitapir paper tpuobut')litY ~papt rj is tuad' Oiii which1 this functiorn will plot as, a strawigh lure (Fi: I -14h) When1 a distributionl of obscrvatlorrs fits such a pattern, it can lit described by it5, irws'm'l1rm averaset Or 50` 1value) and a standard Jesia tion i Iiic root nirair Nuamre of the di-vration frorii the meaon)
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AMCP 706-179
ST*AND~f NVIATIOft
I I--
_
_
__
-, o ...
i-i 3AJTT
______
______l[O
41
+
V
.5-
,,
-
---
iAPsZO OSVSSLIOT
____
mc
4
•,,•
W0TP'LMTCOM CiW-S'ABIIY MO PAPERf
0.
fljjin 72-1. Cumu~atise Frequency Distribut.,on for a Norrnall4'
K
) Sdetonators
€, o.,.
o uf-lO$T.,
50L
•
DistributedPopulation
icurve
S~has
is
L'
*There are cases when the data will yield a on probahility paper as shown in Figi. 12-2(A). l; is wise in cases of this type to find a suitable mathernatical transform for the
Figure 12-2. Skewed Frequency Distribution Typical of lmpact Sensitivity Data
!ine to take advantage of the properties of the
the energy required for functioning. The
normal distribution which are well defined, The transform (or normalizing function) that been successfully applied to input scsitivity is the logarithm of firing stimulus, Fig.
analogy applies as well to initiation by another explosive charge, the probability of which is related to the logarithm of gap length. The logarithw•.;c relationship has also
12-2KB). Th'• probability that mechanical wijI fie has been found to be nearly &ormnjlly distributed with respect to
been found to be 'aseful for wirebridge electric initiators wit'a respeut to such energyI parameters as current ,nrvoltage. 12"3
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AMCP 706-179
The assumption that statistical quan-tics are normally distributed, or may be made that way by the choice of a normalizing function of the physical variable, has formed the basis for most statistical methods and treatments. Mos; quantitative statements of the variability of experimtentally deternmned quantities are in these terms. For this reason, we discuss the variables in terms of this assumption even though recent experiments have cast some doubt on its applicability to safety and reliability problems. Probability paper may be used to extrapolate from experimental data to predictions of safety and reliability. Consider, for example, that 23 of 25 electric detonators of a given design fire when subjected to the discharge of a l-,iF capacitor charged to 50 V and only one in 25 fires when the potential is reduced to 25 V. Suppose that the firing circuit to be used in service uses a I-1pF capacitor that will he charged to at least 65 V. Assuming that the firing probabiht ,y of the initiator is normally distributed with respect to the logarithm of thi firing voltage, the noted frequencies (92 and 4%) are plotted on log-probability paper versus the voltages at which they occurred (50 and 25 V). A straight line plotted through these points gives the most probable relationship between firing voltage and reliability. When extrapolatlng this line to 65 V, the most probable reliability is found to 'be 99.4%. 12-1.1.3 CONFIDENCE LEVELS Although the most probable reliability, as indicated by constructions such as in Fig. 12-2, is a valid estimate of the performance that may be anticipated, the true reliability has as roach chance of being lower as it has of being higher. For purposes of system evaluation or operations analysis, it is necessary to quote reliabilities with confidence levels. Confidence levels are quantitative statements of the reliance that may be placed upon the statement of a statistical quantity. In the foregoing example, it is certainly true that the 23 out of 25 that fired at 50 V is exactly 92% 12-4
of that group of 25. It is also o!,vious that, if this group were drawn from a lot of 1000, the fact that 92% of the sample fired does not estabii-h 92% as the reliability of the whole lot at this level. There is a possibility that by a remote coincidence of selection, either the only 23 in the lot which would have fired or the only two ?hat would hive failed were those used in the test. Thus, the only statement that can be made with absolute certainty (100% confidence level) is that somewhere between 2.3 and 99.8% of the lot fired at this level. To assess the effec. of reliability of the initiator upon that of the system, the reliability must be quoted as a confidence level somewhere between the 50% level (which Ftates tM~at 92%, more or less) will fire and the 100% level, which gives limits so broad as to be useless- Statisticians generally settle for 95% contfidence level (1911 odds tb.it the statement is correct). 12-1.1.4 RELIABILITY DETERMINATION FROM MEAN AND DEVIATION The standard statistical techniqL ; used n the conduct and analysis of many sensitivity yield --ata eypressed in terms of a mean and standard deviation. The mean is the point at' which 50% explosions are observed or anticipated. The deviation(s) of the sensitivity of an individual charge is the difference between the magnitude of the initiating impulse that is just sufficient to initiate it and the mean for the population from which it is drawn. The standard deviation of the population is the root of the mean square of the tests
deviations of the whole population. Where the correct normalizing function and the true standard deviation of the sensitivity of a charge, as well as the magnitude of the initiating impulse to be expected in use, are known, safety or reliability calculations are quite simple. A graphical method, as shown in Figs. 12-1 and 12-2, can be used but is not usually needed. It is only necessary to divide the difference between mean and anticipated operating condition to obtain the deviation is standard deviation units and interpolate on a
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AMCP 706-179
firing impulse from the mean sensitivity is 6
TABLE 12-1
in.-oz.
SAFETY AND RELIABILITY RELATED TO DEVIATIONS FROM THE &.,ZAN
DNvi.tion From Man
Probability of NaI. $md. of Occurrenc, % For PoSiid. Fcr i Deviation
Deviation
This is three standard deviations above
the mean and the 99.87%.
predicted reliability is
It is well to note that the statement of this example starts with the qualifying phrase if it is known. Many reported sensitivity data are obtained by the use of experimental and analyticai techniques whose validity rests upon that of a series of assumptions which may or may not apply to the situation under consideration. In some cases, careful invcstigations have been made to validate these assumptions. Usually not. The fact that the standard deviation is quoted in inch-ounces implies that the probability of firing is normally distributed with respect to the energy
0.253 0.524 0.842 1.000
60 70 80 84.13
40 30 20 15.87
1.282 1.500 1.645 2.000
90.0 93.32 95.0 97.73
10.0 6.68 5.0 2.27
S2.054
2.327 2.500 2.575
98.0 99.0 99.38 99.5
2.0 1.0 0.62 0.5
2.875 3.000 3.09
99.8 99.87 99.9
0.2 0.13 0.1
of impact. Suppose that the true distribution is normal with respect to the logarithm of the energy. The log of the mean sensitivity is 0.903 with a standard deviation of about 0. log units, while the log of the expected firing energy is 1.146, or 0.243 log units above the mean. The expected firirg condition, assuming the log-normal distribution, is 2.43
3.29
99.96
0.06
t-f.-_r.idi
3.50 3.73 4.00 5.00
6.00 7.00 8.00 9.00 10.00
99.98 99.99 99.997
0.02 0.01 0.00317 2.87.X0 t0 1.0 X 1.3 X 6.4X 1.2X
10"' 10"0 110"4 10."7
8.0 X 10"23
Positive and negative are meant to imply deviations roward aind away from more Iprobeble oaurram•,
dp.v•tions
above 4he mcan. inter-
polating on Table 12-1, the predicted reliability is only 99.23%. This one change in assumptions changes the expected failure rate significantly. Further, it is not correct to assume that a 14 in.-oz energy obtained by 7 dropping a -oz ball 2 in. is equivalent to the examp~e.
The determination of the statistical distribution function of the sensitivity of a given type of charge to a given type of initiating impulse obviously requires the test firing of large numbers of charges, each under closely controlled conditions. For some relatively inexpensive and easily tested items, such programs have been carried out.
*
table (see Table 12-16) to find the reliability. For example, if it is known that the mean sensitivity of a stab initiator is 4 in. when dropping a 2-oz ball (in this example, 8 in.-oz) with a standard deviation of I in. (2 in.-oz) < and if the expected firing impulse is at least 7 in. (14 in.-oz) the deviation of the expected
-
In view of the high costs of many items and the relatively low rate at which they can be tested, it is too mucl, to hope that all aspects of the sensitivity of all types of charge will ever by characterized in this reMpect. Where the designer is faced with the necessity of
12-5
I. \-."
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AMCP 706-179
predicting safety or reliability of an item for which the distribution function is not known, the most prudent approach is to assume the function that gives the most pessimistic prediction (in the case of the last mentioned example, the log-normal distribuuion). 12-1,1.5 OPTIMIZATION Optimization theory encompasses the quantitative study of optima and methods for finding them. Although many phases of optimization theory have bcen known to mathematicians since ancient times, the tedious and voluminous computations required prevented their practical application. The recent development of high-speed computers not only has made older methodIs attractive but also resulted in new advances in optimization methods. Since optimization involves finding the best way to do things, it has obvious applications in military design where sometimes small changes in efficiency spell the difference between success and failure. The application of optimization theory involves three distinct steps7: 1. Complete, . ccurate, and quanlitative understanding of how the system variables imteract. ',his step is most important because there is obviously little point in optimizing a model that does not truly represent the system. 2. Selection of the single measure of system effectiveness that can be expressed in terms of system variables. This step involves value judgmeti and can be most difficult to accomplish. A goal of minimum total cost, for example, can bc ciearly defined to include the costs of production, packing, shipping, storage, maintenance, and delivery to the target. However, some goals can be conflicting and some, such as reliability, require a great deal of judgment to pinpoint their precise meaning in a particular application, 3. Selection of those values of the system
12-6
variables that yield optimum effectiveness. In this step, optimization theory is applied to rational decision making. A comprehension of optimization theory in idealized, quantitative situations not only will determine optima but also furnish insight into the underlying structure of rational decisions. This understanding helps in those instances where problems are not entirety mathematically describable. While optimization plays a definite role in the design of explosive trains, a description of the mathematics is beyond the scope of this handbook. See Ref. 7 for the basic mathematics or, for more information, a bibliography". 12-1.2 STATISTICAL TEST METHODS 12-1.2.1 GENERAL CONSIDERATIONS The sensitivity of an explosive charge is the magnitude of the minimum stimulus which will -esult in its initiation. Stimuli too weak to initiate charges can still alter them, sometimes quite obviously, at other times in ways that can only be detected ir, terms of chan.ed sensitivity. Hence, subjecting each charge to gradually increasing stimuli until it fit,.s is not a satisfactory means for determining sensitivity. In recognition of this variability, a number of statistical plans have beer, devised for sensitivity studies. Some of these plans are designed to characterize the entire distribution, others to characterize it in terms of an assumed normal distribution, and still others to determine some point in the distribution which was felt to be of particular interest. Before these plans may be applied, sampling procedure and critcr.a of acceptance must be established. It is a basic assumption regarding any test of a lirnittd sample that the sample is representative of the population from which it is drawn. Unless some effort is made at randomization, this may not be the zase. Many of the variables that affect sensitivity
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ArACP 706-179
may vary progressively or periodically as production. proceeds. Selection of a sample for test by any systematic means might conceivably produce a biased sample, one in which all items arc more similar in some respect than is the whole batch or lot. A positive plan of randonuzation should be adopted, such as use of a table of random numbers. While most explosive charges used by the military function with nearly maximum vigor, some vary appreciably in output as the vigor of initiation is varied. Even within groups of items for which output is usually independent ot input, an occasional individual.item, when initiated marginally, will explode with significantly less than its maximum vigor. Fot these reasons, it is necessary to prescribe in advance the criterion of fire. Both the quantity associated with output and its magnitude should be specified. A shitt of criterion part way through a test reduces the data to uselessness, Sometimes such shifts are inadvertent. For example, when plate dent output is used As a criterion, the supply of plates may be exhaustSed hbeforn ýnnn.!etn Tho enlenthnih4 supply may come from a ditterent heat of metal with a different response in terms of the dent it sustains, The criterion of fire generally will depend upon the purpose of the test. If it is a reliability test. the charge should be considered to have fired only if it detonated high order in the sense that its output cannot be distinguished from the maximum of which a charge of its type is capable (due allowance having been made for statistical flu.;."tions in this quantity). For safety tests, on the other hand, any evidence of burning, scorchmg. oL" melting of the explosive should be considered to 1ýe the criterion of fire. 12-1.2.2 STAIRCASE METHOD, THE BRUCETON TEST A staircase testing technique is one in which a predetermined set of steps in the magnitude of. the iniliating stimulus is estab-
fished before starting and in which the magnitude used for each trial is deltermincd by results of previous trials. A number of staircase techniques have been proposed. Of these, the simplest and most used is the Bruceton test 9 . In the Bruceton test, the magnitude of stimulus ustd in each trial is detern,ined by the result obtained in the immediately preceding trial. If the preceding trial result,.d in a misfire, the stimulus to be used in the present trial is one step higher than that in the previous trial. If it fired, the stimulus of the presnt trial should be of a magnitude one step lower. The test is continued in this manner for a predetermined number of trials. For maximum likelihood equation; and FORTRAN program, see Ref. 10. The validity of the results of this procedure depends on whether the assumption is valid that the steps are of uniform size in a system in which the frequency of explosions is normally distributed. The Bruceton test is most applicable to systems for which extensive tests have establishea the nature of a generic normalizing function. Unfortunately, it is often applied to .vstems frr which it is not economically feasible to carry on such a program. The logarithm of the initiating stimulus has frequently been assumed as a normaliziLg function (giving a geometric progression of step sizes) on the logical basis that this distribution predicts zevo probability of functioning at zero input and that a positive stimulus is required for any finite probability of firing. This choice has becn supported by such observations as the relative constancy of standard deviations oa similar systems over large ranges of sensitivity. In some cases, rundown tests have also supported this choice. It should be noted that the analytical technique for brucelon data was originally devised with much larger tests in mind t000 trials or more) than those which have been used in most safety and reliability investigations. It seems to have been grasped as a straw by evaluators drowning in the impossible problem of predicting zeliabiliti.i to the 12-7
----
r &S5.,,
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AMCP 106-179 99.9+% level from samples as small as twenty-five samples. It is probable that those who have so little apprcciation of the impossibility as to assign sitch a problem %ill accept solutions that depend on so many untenable assumptions. The Bruceton experimental technique is often used as a convenient means for the collection of data in si:*xtions where the assumption of no,'mality is known to be false znd where it is intended to use other methods of analysis. An objection which has been raised to this practice is that the strong tendency of the Bruceton technique to concentrate testing near the 50 percent point reduces the value of the data in estimating tha nature and deviation of the distribution. In answer, it may be pointed out that the sample sizes available when this technique is used are usually so small that a reasonable estinate of the mean and a rough guess of the deviation is the most that catl be expected.
12-1.2.3 FRANKFORD RUN-DOWN METHOD A run-down method has becen developed at Frankford Arsenal, which, at the expenditure of a much larger sample, makes possible a much better assessment of the distribution of the underlying population'. Beginning at any convenient level of the independent variable (drop height, voltage, barrier thickness or the like) between 0% and 100% of the expected functioning level, a minimum of 25 trials is made atCeach of seeral levels above and below the starting level, using increments equal to or less than the expected. standard deviation. The test is continued in both directions in 1his manner until the 0% and 100% functioning levels are reached as indicated by 0% and 100% functioning in 25 consecutive trials. A cumulative probability plot is then drawn from the results of the tes, which is considered to be the frequency distribution of the parent population.
12-1.2.4 PROBIT, NORMIT, AND LOGIT PROCEDURES These procedures are not data collecting schemes but rather analytical procedures for the estimation of distribution. They can use data colected by any of a number of schemes. They may be used with data collected by the Bruceton experimental techniqut using nonuniform steps or with incomplete or abbreviated versions of the run-down method' ;. Each of these procedures is based upon the transformation of the observed frequency of fire or misfire into a number relhcd to the deviation in terms of an assumed distribution function. In the probit, -for example, the mean is assigned a rrobit value of five, the !5.17% level (the mean minus one standard deviation) a value of four, the 84.13% point a value of six, Rnd so forth' . The normit differs from the probit procedure only in that a value of zero is assigned to the mean. This necessitates the use of negative values but frequently simplifies both thinking and arithmetic. The logit system is similar but assumes the logit distribution function"'. In addition to fitting certain data better thun the normal curve, this function has the advantages of being somewhat more conservative in its predictions and of being simple enough to apply without special tables. 12-2 TESTING TECHNIQUES 12-2.'.1
3EMERAL
Expbsiv: compounds or mixtures are evaluated for acceptance as standard materials on the basis of programs in which their explosive properties are determined. Many tests have been standardhzu.d to describe these explosive properties. In addition, special tests have been developed to take care of unusual conditions or to simulate &particular use.
i2-8
*,/ *
-.. %-
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AMCP 706 179 This paragraph desoirstes the puirpose, nature. and key features of the tests on explosive materials. For a c~ctailed discussion of the tests, the explosive charge designer should consult one of the handbooks on explosivesb .d.3 .3n The tests covered herc are included partly for gecnral informiation and pairtly because somec of the trsts have beecn applied to explosive chargcs. It is important to realize, however, that the pcrf~rinance of a loose explosive sample may differ greatly fron that of the same explosive when pressed or cast into its end itemi.
Tests of cxplosive materials are- convenieniily placed into four groups. Descriptions of tests pertaining to sensitivity, output, and stability follow. Te:st scquence sometimes is specified' '. The fourth group is made tip of' chemical tests designe-d primarily to verify composition and state of aggregation. As such, these tests are not included in this volume but can be found in handbooks on exlsvs. Icue nthis group are such tests as flammability. hygroscopicity. volatility.
moleccular
weight,
end oxygen
balance.h The ~tcsts grouped under sensitivity measure how easily explosive materials are initiatedThey simulate the various stimuli that are
LIcappb!.-
6
ac
AMy TESNT~e E~ XPLOSIVE
70AWvIL
EE Figure 12-3. Picatinny Arsenal impact Test Apparatus
of setting of' the explosive. The
subjected to the actir-n of a falling weight,
stimnulus used most widly is that of impact sensitivity. In addition to the tests that follow, tb-. sand bomb test, listed under brisance output, is also a measuri; of sensi-
usually 2 kg. A 20-mg sampl-c is always used in the BM apparatu'e while the PA sample weight is stated for each cas-. The nminirnum height at which at least one of 10 trials results
vtivity r
2KILOGRAM Vd"QT
to initiation,
12-2.1.2.1 IMPAC7 TEST
ihe impact test consists of dropping a
weight on a sample of explosive. The two most prevalent impact tests are those. by Picatinny Arsenal (PA) and by the Bureau of Mtines (BM) I' ". The PA apparatus is shown in Fig. I2-3t'.
In the test, a sumple of expiosive is
in explosion is the impact test value, For the
PA apparatus, the unit of height is the inch; for the BM apparatus, it is the centimneter.
In the P1 , -n paratus, the sample is placed in the depression of a small steel die cup. capped by a thin brass cover in the center of wvhich is placed a slot-vented cylindrical s~eel plug, slotted side down. In the BM apparatus, the explosive is held between iwo flat and parallel hardened steel surfaces. In the. PA apparatus the impact is tran'smitted to the sample by the 12-9
j.P
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AMCP 706-179
vented plug, in the BM case by tle upper flat plate. 'The main differences between the two tests are that the PA test (1) involves greater confinement, (2) distributes the tranislational impulse over a smaller area, and (3) involves a frictional component. Hence, PA test values are greatly affected by sample density.
a Bniceton type test. Results thercfore arc quantitative Ps compared with the go/no-go nature of the rifle bullet. 12-2.1.2.4 EXPLOSION TEMPERATURE TEST
Sonic additional impact tests differ primarily in the construction of the sample holder. The tests also have been modified to accommodate cast and liquid explosiVes1 7. A new tester has been developed for small staS detonators in which the firing pin is attached to the falling weight'1 .
A 20-mg sampl,' of secondary explosive or a 10-mg sample of primary explosive, loose loaded in a No. 8 blasting cap cup, is immersed in a Wood's metal bath. The teniperature determined is that which produces explosio.., ignition, or decomposition of the sample in 5 sec"'. The DTA test g:adually is replacing this test. See par. 12-2.1.2.11.
12-2.1.2.2 FRICTION PENDULUM TEST
12-2.1.2.5 GAP TESTS
To measuie the sensitivity to friction, a 7 g samp!e, 50-100 mesh, is exposed to the action of a steel or fiber shoe si' nging as a pendulum at the end of a long steel rod". The behavior of the sample is described qualitatively to indicate its reaction to this experience, i.e., the most energetic reaction is explosion and-in decreasing order of seve -ity-maps,cracks, and unaffected.
The sensitivity .of explosives to initiation by a booster ' characterized in terms of the thickness of a gap introduced into the test set-up, see Fig. 12-4. There ate two gap tests both using standard toinponents' 6 :
,,,,, ..,
,v
,,,.
,,
qu-- -,.tita-
i. Small Scale Gap Trest. The gap consists of an 0.005-in. au space. 2. Large Scaki Gap 'Fest. Lucite sleets are -
--
-
-.-
.'wv.
tively. Additional methods have been used, stich as the disk test 5"' 9 . The rifle bullet impact test (see par. 12-2.1.2.3) is also a measure of sensitivity to frictional impact.
one time the gap was fill.d with wax rather than Lucite.)
12-2.1.2.3 RIFLE BULLET IMPACT TEST
To simulate the conditions experienced by the filler of a projectile during acceleration in a gun, the apparatus shown in Fig. ! 2-5 ' was developed. By the action of the propellant, a pr ;sure pulse is transmitted to an exprosive specimen through the piston system that closely resembles setback. The criterion for each explosive tested is the maximum pressure at which the explosive cannot be initiated, when at an initial temperature of 125°F, in 25 or more trials.
The traditional bullet sensitivity test consists of firing a cal .30 rifle into the side of a 3-in. pipe nipple, loaded with approximately 0.5 lb of the explosive being tested, and capped at both endsk. Because of the curved surface presented as a target, the angle of incidence, end consequently the test results, can be greatly affected by the condition of the weapon and charactzristic& of the ammunition. An improved test with a flat target plate was devised at Picatinny Arsenal'*. Projectile impact could be substituted for the rifle bullet. iHie the velocity of the projectile that is shot out of a small bore gun is varied in
12-2.12.6 SETBACK PRESSURE TL- T
12-2.12.7 IMPACT VULNERABILITY TEST A 2-in. diameter by 0.75-in. thick steel plate is assembled at the bottom of an 8-in.
12-10
./
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AMCP 700-179
NQ
S DETONATOR
-BOOSTER,.IOG 1 9/6 IN. DIAM.,2 IN.NIGH . OAP N
x IN. .TEST
CHARGE
....... T4, PLATE I N•.
-'4IN.$OUARE--q Figure 12-4. Gap Test Set-up long sleeve that i3 fidled with a propelling charge. When the charge is ignited, it driv-.s the plate at a velocity of 400 ft/see across an ]-in. air gap against a sample of explosive that rests on a witness plate. The test is passed when there is no damage to the witness plate. For obvious reasons this test is also called the ,Ihn,1o -tat .6 12-2.1.2.8 BOMB DROP TEST Bomb drops are usually made with bombs assembled in the conventional manner, but containing either inert or simulated fuzes. The target is usually reinforced concre t ek. 12-2.1.2.9 COOK-OFF TEMPERATURE TESTS Cook-off data generally are obtained by one of two methods: (1) the minimum cook-off temperature test or (2) the constant heating rate test. In the minimum cook-off temnperature' test, an explosive sample or component is submerged into a constant temperature environment, and time-to-exploslon. versus enviroiamental temperature is recorded and plotted. At same minimum aitical temperature, the relationship becorms asymptotic. This as)mptotic temperature is
called the minimum cook-off temperature. It has significance because it sets the limits of safety.
In the constant
heating rate
test,
the
explosive sample or component is heated at a constant rate from a sciected initial temperature. The cook-off temperature, in this case, is reported as that environmental temnperatture at which ignition occurs. Cook-otff temperature as defined in this manner depends chiefly on the initial temoerature ievel, and increases as the heating rate increases. While this method is widely used, it has obvious disadvantages. Cook-off temperatures obtained are somewhat higher than the minimumn cook-off
I
Itemperature. Constant heating rate test results are not easily correlatcd with actual conditions, Rate of heating, location of thermocouple, and simulation of heat transfer to other charges and weapon parts all affect the cook-off temperature so that kesults vary with different apparatus. The various means of dctermining cook-off temperatures are dibcussed in Rcf. 22.
12-2.1.2.10 ELECTROSTATIC SENSITIV3TY TEST
To determine the sensitivity to electrostatic discharge, a 15-mg sample of the explosive is placed into a phenolic holder positioned on an electrode. It is subjected to 8 voltage levels up to 750W V discharged from capacitors of four different sizes. These data n.ay he related to nazards by keeping in mind that the human bcdy, on a dry winter day, may store as much as 0.05 J of static electrical enegy' 4,, 12-2.1.2.11 DIFFERENTIAL THERMAL ANALYSIS Differential Thermal Analysis (DTA) is a technique by which the reaction of a material to temperature can be followed by observing the heat absorbed or liberated. While this analytical method has been known for many years, it has been applied only rece.ntly when improved instrumentation his become available. DTA is especially suited to studies of 12-11
1aa
".q qb..mstl
,~
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AMCP 706 179
~LLAOT CKAIKU\
01
poFwLI"T
Figure 12-5. Apparatus Which Simnulates Setbacs% Pressure structiral changes within a solid at elevated temperatures~ where few other methods are available" . Heat effects, associated with cher-ival oi physical changes, are measured irv a func~tion temperature as the material is heated or cooled at a uniform rate. As the sample temperature is varied, it will undergo a variety of changes, each being accompanied by the releurss or absorption of energy. Melting. sublimation, phage changes, dehydration. anti boiling genen.lly producc cnidothernmic effects while crystallization, oxidation, and decomposition produce exothermic reactions,
K UFig.
175TC. The series of exetherms beginnii'g. near 250*C represents derompositiar. of the sianple. Actually, the first stron8; exotherni is cauied by :lecc'mposition of an organic contantinatn in this samiple. Sdmples of pure amrmonium nitrate do not show this exotherm in DTA examinatiors. 12-2.1.2.12 THERMVOGRAVIMETRKc; ANALYSIS
In a typic~al apparatus, one set of thermocouple junctions is inserted into an inert Material that does not change over the teinjerature range to be tested. The other set is plaedhith smpeWith constant heating, anytrnsiio orthrmalyinduced reaction in hesamlewil b rcoredasa change in an thrwsestaihtline. DTA records, called thrmgrms hvebeen collected for primary
Another approach to the study of phase transitions is provided by the instsilment known as a thermobalance that perinits continuous recordine of the weight of a si'mple while it is being hea*.ed in a furnace at a constant, linear rate. The weight chainge vs temperature curve obtained provides informtalion about the thermal stability and composition of the original sample. of intcirmediate compoundfs formned. and of the residue. Like VTA, thennogiavinietric analysis ([GA) recently has been refined with modern instru-
12-6 shows a thermogram of ammomium. n-trate. Peaks A. B, and C are due to tuiinsit~ons in the crystal lattice. Peak A is the transition from Rhombic I to Rhombic 11 form: Peak V. from Rhombic 11 to Tetnagonal; and Peak C, from Tetragonal to Cubic. Peak D represents the Melting of the material at
TGA is extensively used ta determine changes in compllositioln due to dth 'ydration, decomposition, and reaction with the experimental attivosphere. It also has been employed for the determination of reaction kinetics. Records for high explosivcs are collected in. Ref. 25.
121
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I'I
AMCP 706170
EXOTHERMIC
SAMPLE HEATING
SIZE-3mq RATE -
20OC/mnin
CNDOTHERMIC
0
s0
100
ISO
200
TEIMPERATURE,
250
3100
350
'C
Figure 12-6. Thermogram of Ammonium Nitrate 12-2.1.2.13 HOT WIRE IGNITION ThST The explosive charge 6sloaded into a squib aainst r
tung4te'i hrtlgewire and piaced
explosive side down on an aluminum witness plate. Twelve volts are applied from an automotive battery of 45 A-hr capacity. The test is passed when the wire buins out but does not ignite the sample. 12-2.1.2.14 THERMAL DETONABILiTY TEST An explosive sample is loaded into a 2-in black pipe nipple below a thermite charge. The Lst is passed when the burning thermite fails tc detonate the sample''. This is also called the bonfire test. 12-2.1.3 OUTPUT The :Ists grouped under output measure the effect that aa explosive produces. As do the sensitivity tests, output tests measure a particular result that is judged to simulaic performance.
12-2.1.3.1 DETONATION VLOCITY Of the fundamental quantitics associat-d wiih dtcioiaiikni. tIi-,
-i,,siijaio.,
The optical technique iikvolvcs the use of a high speed camera. Streak cameras that have been used in detonation velocity measurements include rotmting mirror cameras, rotating drum cameras, high-speed roll film cameras, and electronic image converteW tubf cameras'I. Fi3. 3-1 is a record obtained by a streak camera. A high speed framing cameia has also been leveloped which will take full
S~12-13
............... \-
vel.t
the most readily and directly measurableL .16 While it is not a complete characteiization of the output properties of an explosive, it is a good criterion of performance in many applications. Since the detonation velocity varies with both density and charge dimensions, results must be accompanied by accurate data regarding these quantities. Detcnation velocity may be measured by optical techniques. by electrical measurements, and by coniparison with the known velocity of detonating cord.
-
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AMCP 706- 119 STEEL WIT"11111PLATE
-WAWPCNT or DETONATING C~OR
DIITIP#CrVtV MIT6 P016610 AT POINT OF 00Velsp"6 OKTOSSATIO49
Figure 72-1. Method of d~Autriche for the Measurement of Cetuna ricO Velocity
iluige lpictLCe at rates hiigher million frumes per scujid.
Owln
four
~improved tile' p~r.cision of' the reu~lts. 1ettinahion velocity is computed by (see 12-7)
r*$-
The material wvithin t: detonation zone is highly ionized and, hence, all CXLceIlkt vlectriprobes, placed in or close to anl explosive churgte, become electrically connected when ai detonation. or file shock emitted by a detozia-
lion. enigulfs them. Time intervals betwceen suchi bignals are mteasured with oscilloscopes anid any of seveial types of interval limers2 7. Another techniquec developed by tile BaretU of Mines! involves a ccritintiimis clectrical rccurding of tile defoi~ation ptogress by use of a resistance wire emnbedded parallel to fhil longitudinal axis of the cxplosivc: charge. As detonation ptocctds, the resistanicý. wire is shorted out, resulitiik. in a dynamic i .-.,istance propoi tional to thle rate of deton~ation.
% where D1.) a detonation velocity of lest specimien.
ft/sec D,
11-14
- detonat ion velocity of recfere lice cord,
ft/sec L,
active length of test specimen,. It
LN
nicasurec: lenigth froin ntidpoimi of cord to Point af Colivermilig detollat1i1n. ft
I
Thec d'At-trichc methiod (Fig. 12-7) depends uponl thle augmentation of radial output at Ole~ point where two waves illi acylindrical charge coniverge. Thle method is attri-ctive in that it uses inexpensive instrumnittation and has thc reliability inherent in its txtrmie simplicity. Tlhe tcent ume of mnild detonating fus, 2` has
(1;-2
L'~ 2 1'.
-tune,
sec
12-2.1.3.2 DETONATION PRESSURE Detonation
prcssuires
arc
too
high
Wo
incastirc directly with any ordinary pressure gages. Th.~ pre~surcb of' sho Aks induced by detonations in moetals may be deterinhiied
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AMCF' 700 IN9 W'romi lii easuremienat s lit t he movnelaailIof Il.Ii' mektalI and of shock ve locit y ill flLit: ic ii Froma such data lund tile laws of %shoCk ialteractimia, it is poss~ibl to deduace delojia
pressure,
Ption
.2, ".
I)c [onat aol)
of 11ash X whiyh.
12-2.1.3.4 BRISANCE
12-2.1.3.6 BALLISTIC MORTAR
pissiv 50
almost
distirnguishled 1'r4)iii Its totai Work G111:iitY, is termled I'risancc. Utisance, is meaui'tlred iq %and, plate dentl, oi fragmnirtalion tests.
eiie Iof' tests coinpai C tile llefective A ii L ness lit cxlplosivts it%propeltautss . Ili general. aire e to plmstcrVe file Imortars used. the chargi-s relatively q totec smnall 0 -or example, 10 g iii a
Ini the sand test, a 0.4-g sapiple of file explosive under test pressed at 3000 ps-i into ai No. 6 cap, is inlitiatedI by !cad aizide inl a sand test bomb containing 200 g of *'onl 30 mesh" Ottawa sand" . Thec sand is resieved and is cunisidered to have been crushed it it passes a No. 30 sieve. The signiticanc: of' qhc swnd test is difficult to sta~te in physical ternms. hlowever, it does correlate, generally, with overall pcforbinianue characteristics.
I 0-in, bore naoitar). Thec quantity of' the explosive being tested whlich gives life -.liie as tile wisis 101 recoil ias !O g of TNIF: used-w exprssnatlg the relative outplut or' the explosive. Although ballistic lmortar test data tend to con eclate with taiabdlc output for many expikisives. there aic enloughi iflvcrsjons to inspire seriou%questioninig of- tlie mleaninig aind va:idify of' this typec )I'data. Ballistic mortars have not beenm used exitcnsiveiy ill recent years.
1711 shint cten g powe r of, all~:.xp~osiVc
Plate denit
*
12-21.1.3.5 BLAST ami iii.pu'iisc 5 re d( t on ed exclusively With paiclc uii iC ales .,and tile liackcssa y sjwecia limidclectIlcal Vir Ciffis. Re so ts are obt ai ned by anl an aly-sis of-
also be dctermiaicd fio deoatollast tile density wi hintl dcloiia11011rmi, w ichmay tic measured by neans
velocity and
a
tile Ia.ag
ptrssili c
niay
*
prCselilly- IPi14 tdlo ch a.t~i acle un 1wof at,,.lilIy oMaii c xph'sivce
its
tcsti, a%5Li%4Ill hIrmllncc t!!)s'L-
sui-enlents are auadc with charges ie-ng enough compared with their dianileten that the detonation hlead canl reach a stobic conflir,]iat iot. T~ho. standard specimen is 1-5/8 in. in diameter by 5 in- long. The depth of derit produced in tile steel plate is compared witl) that pro duced by TNT. Plate denit brisince 1for balre charges correlate rather well witlh detoliatioan pressure. T~meframenatio tet i themos dieer The ragenttiontes istilemos diect racasuare of tile brisancc of explosives. It consists of loading a projectile with the sample explosive, detonating tile charge, and recovecring the faagmnints. Thle projectile is r-laced in a wooden box that is buried in san'd and fired electrically. Recovery of fragaments and their classification inuto weight graups perrnit evaluation of the chargea" . A new test titled the "expandring cylinder test" is
112-27.1.3.7 TRAUZL TEST Ini a Tratitl block test, a sall'ple of explosoxc (oil thle order of 10 g) is eXplcmded inl a cavity inl a ILJd 11ock The inICreaJSIL ill VoIlume of" the hole is the criterion or output' s. it usually is related to TN r. The Trajazl test is a direct nicasurec of the mechanical work per. fonrmed by the explosive. It tends to corielate with the lieat or explosion, although the samall sample size is rather small1 for complete reaetioal of TNT'. More sensitive mnaterials, which react more completely, tend to have larger rratizi block values than zinight be exPected. 12-2.1.3.8 UNDERWATE4I SHOCK Underwater explomcv effeets are more complicated thin those in air. The enlergy rulcascd by detormaticn is partitioned into that 12-15
-
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AMCP 700179 ill the: shtAucW-ive. that d:sipAtcd ill tile wlitti Iik)III tile cage to thle gage.* anid Iha( i crilain lap in thle oscillaitintg bubble tul-Iliie by thle detonadtion Inlithct s Sockwavt energy is caltllalted fio m litt e Ilict on of a d iaphraigmi Iagcg placed 3.5 11 away anid Ilaci ng Ilhe sidte oft tIli chargc. RelIaitiv bubhibl ce ie agty is lithe raio jof0 tile period uiiislaii1s Cubted. period cuhistailts. aie dectrmined by nic~asurinq 11w bubble
d~aairm tt.avt-l of the %Ilikwjiseav
pvIiio''' 42-2.1.4 STABI LI TY 1 le vacuumn stability test is tlhe mtosti widclb used stability test for vxplosives. A 5-g saimple
0I
g in the case oh- prinitia)
cxplosives), after twvinig driedl, is heated for 40 fir desired temicprature (100' pRr~tUrV Jand thei volume11 Ciii ) are quoited"'.*I 3
high
int vacuutm at lthe or 120'('). 11cia-
ul- 911' CV0vole
(ill
salisples arc heated for 4) ht and fict eh~ecis noted. Actually, stability of explosivecs under otoldit ioiis of service is too) Complex to tic chaisactcrjicd coniiictly otI (lie ba-is of standardized lah, .ry
tests. Tests like that
oondifionts uif us;:, lie vi teli necessary.
12-22
IPUTapplied
12-2.2.1 MECHANICAL INITIATORS Most mecchanical sensitivity ttsts, whether percussion itemus, consist of dropping weights fruni various heights onto thle tippropriate t iring pins. The tmost coaauinm rrcaris to Sliis end is to release a weight front a augatet. The weights used Ill thle testing of stab and perLuNS~r onmitiators art; usually steirl balls that are dropped free fromi the paints of' contical niagrietN. Impact mnachintes include conivenient amamts of adjusting the hei~ht of Ithe aitngaiet between drops and ailans for rapid and prveesc detcratuination (if (lit trce fall distancer (Fig. 12.3). Ilii sonte machines. the hciglt adjustment includecs inidexing stops for stab or
A *
r
12-16
of a-1 InIch
Mr
Lck11tiMIC1t
).
tl.m t~In
Il i~r
; dial.
icr0,01 scUtICv~ provided lo Ni r apid IC~i-t of tile diaip height. 111t Iattc'r ha-c Cic advatilage, Iit hiiai~cloi tylic testin., thal lit, sp jute Ival-k ii y Ile 1atlk~d (k -. Ii th 14111ot'pi ahe of iiia ioi ag :1ImiL lml VOiLi
fichedopl [cmi I" -lliitld -,It a lilalilicii simitlarto 1u tla used tui cxpulo-% ha.elal (jot. 12-2.1 2.1 Z.I. A gi vlit weight I(j'ehiaps 2 (-)) is dio upped fiiyli vatr k 's heightts '11 fihe lii111 tug pu I wid tile reslts11 noted. Heigh t stepss art v~iriest by the llruckto.i (cclintitivic(po
Z1>..) 12-2.2.2 ELECTRIC INITIATORS
becrs thoaouglly
tests are tile heict tests inl which
bOther
for cvvii intc~val, of Ihicglt tiisiaiill
1)ependilig upon file aplplication. thle sells'.fivity oi electric initiators is chasrticocrime; it terriit
ot
ilic
1-Okr~wer. cniergý.
thireshold current. voltage. or somie
cu-inoinalion
of-
the-scil' . A slCi cmiclioii iii termts oh* only olec cf' them il uay be iiiisleidirg. flow;:ver. in mlanly applicationls, onec or another of' theseI quantities is so vittieli allre signitican I thani lthe others thait it is khpiropri~a:c tu chiaractetile tile sensitivity of tlie initigator I-
its
tcrvii. ilic scisistivity response canl b,- defvied the timie ai weli as (tic magnitude of lthe stimuluis 12-2.2.2.1 CONDENSER DISCHARGE TEST Tile sources uisod to tare lctrcam initiators iii miany mlilitary applicationts emit ptulses in
which both currenit arid vo~ltae exceed, I y man 'v tintes, Ific threshould conditions tot faring thie inititaor bilt for it veiy shot I duration. Ili many instances. (lit quanatity that expresses lintitattiui of' outpiut i%(lie available entergy. F~or this reasonI, it is a somflhttoatl paaclice to express ft-. senisitivity of ailt clectric initiator Iintermis ot its eniersy rexquit.mrCIt. Thc eaterg%) that is sta''ed in .i charfeal capacitr can be coaenmilaity exLpressed by at simple eilrvatioai that works onily wvith the particular units givcin
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AMCP 706-179
w = 5CL'
E = voltage, V
compared with that of the initiator but not so low as to overtax the battery. Aside from this, the circuit should provide for switching and connecting with a minimum of resistance. Contact potentials and inductive surges have beep misleading in such circuits. As for capacitor discharge, a test set is also available lot both constant voltage and constant cur rent tests.
This total energy stored cn a capacitor is
12-2.2.2.3 STEADY CURRENT
,erg
(12-3)
where w = energy, erg C = capacitance, uF 1
frequently used to charact.rize me sensitivity
of initiators. -owever, only in very specific instances would all of this energy be required to produce initiation. On thie other hand. wany initiators are fired fGom a charged capacitor in actual systems- In these instances, capacitor discharge data can be applied directly. it is not a valid procedure to use known sensitivity data at one voltage and. capacitance and extiapolate to a different combination of voltage anJ caplcitance on the basis of equal stored energy. The energy sensitivities of most of the electric init'ators now in military use were determined by using circuits similar to that shown ir Fig. 12-8. Either voltage or capacit.•ne .n•v he varied to vary the energy. in many cases, convenience has been the basis for the choice. However, where a particular application ts under consideration, the choice might be made on the basis of the limitations of the firing circuit in the fuze. 12-?.2.2.2 VOLTAGE SENSITIVITY WI'ere the firing circuit is a very low voltage source, the impedance of which is low compared with that of the initiator (as for example in some types of battery), the threshold voltage for firing way be the most
-'
]
important criterion of sensitivity. Test firing circuits for the determination of threshold firing voltage, similarly, should l-e very low impedance circuits. t_ type of variable source that has proven useful in this respect is a high capacity storage battery shunted by a relative ly low resistance potentiometer. The resistUnce of the potentiometer shovid be low
FUNCTIUjNING
Where the firing source is of high impedance and limited current capacity, such as the high voltage supply of an electronic device, the firing current may ,be the most significant aspect of the sensitivity of an electric initiator. A test circuit for the determination of threshold fi:ing current of an electric initiator should have an impedance that is high compared with the maximum resistance of the initiator at least up to the time of initiation. A high voltage supply with a dropping resistor (a ratio of 10 to I des ible) meets these requirements. The cu-rent r y be varied from trial to trial by vatrying either the voltage or the resistance. In such circuits, if the switch ik in series with the dropping resistance and the initiator in the wrong order, the distributed capacitance of the circuit can get charged to the supply voltage and discharged with an initial surge sufficient to fire the initiator. One means of insuring against such spurious effects is that of shunting the initiator with a switch that is opened to fife the initiator. 12-2.2.3 GAPS AND BARRIERS The relative sensitivity of various explosives to initiation by detonation of nearby charges can be determined from the resalts of trials with varying gaps or barriers interposed' 2 . In such evaluations, determinations a.e made of the mean and deviation of the gap or barrier using data collection schemes and statistical procedures similar to those described in par. 12-1.2. The result is a threshold value of gap or barrier which will result in detonation.
12-11
L
,'L
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AMCP 76-179
DETONATOR
FIRING
ISOV
AC
CYCLE 60
SWITCH
....
i
CHARS& SWITCH
MENCURY CONTACT
SWITCH
Figure 12-8. Typical Condenser DischargeFiring Circuit for Testing Electric Initiarors It must be remembered, however, that the
12-2.3 OUTPUT
use of gap or barrier tests to evaluate the
seliability of systems in which gaps or barriers are not part of the intended design is dubious at besl. As pointed out in pars. 3-2.2.5 and 7-2.2. I Sps and barriers, particularly when combined, may actually improve a system. The Varicomp technique has been devised for this reason"3 . Here, construction, materials, and spatial configuration of a system under investigation are as nearly identica; with those of the intended design as it is practical to make them. The probability of transmission between two consecutive components is reduced by the substitution of a less selnsitive materia! in the acceptor element in the transfer under investigation. By the use of a series of explosives of graded sensitivity, using the sensitivity or composition as the independent variable in a date gathering sys'em like the Bruceton technique, data may be obtained from which it is possible to determine the sensitivity or composidion for 50% functioning and its standard deviation, P!rfoimance of explosives subjected to large scale gap tests has been compiled 3 4 . Explosives of varying sensitivity also have been used to estimate the reliability with which main charges may be expe.;ted t* be initiated by means of boosters (see par. 12-2.1.2.5). 12-18
12-2.3.1 DETONATION The output of detonators, leads, and boosters consists of a shock wave and high velocity hot particles. A number of indirect output tests are. in use which are designed to give a quantitative measure of the ability of the test component to propagate the detonation in the next component. In addition to the tests listed, gaps and hamer tests (par. 12-2.2.3) may be used for this purpose. 12-2.3.1.1 SAND TEST "The sand test, in which the output is characterized in terms of the amount of uand which is crushed by a detonatof, gives a quantitative result for each trial. Early investigators" found good correlation betweer sand test results for blasting caps and their effectiveness in initiating dynamite. More recently, it has been founo that detonators that give good sand test results may fail to initiate booster charges. The trend is away from sand tests for evaluation of explosive components. 12-2.3.12 LEAD DISK TEST This test consists of firing a detonator in direct end-on contact with a lead disk, in
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AMCP 706-179
accordance with test 302 of MIL-STD-331j. The size of the hole produced in the disk is a measure of the output. Hole sizes are measured by means of taper gages. In general, the lead disk test is a reasonably useful quality control test that correlates with the
effectiveness of detonators. Significance in terms of physical quantities is difficult to assess. At least one situation has been experienced in which modifications in loading pro-. cedure which increased output according to the lead disk test decreased effectiveness in
12-2.3.1.4 ALUMINUM'DENT TEST The output test using an aluminum block is performed in accordance with Test 303 of MIL-STD-33l1i This test is identical in all respects with the steel dent test except that
the dent block is made of -aluminum. Substitution of the softer metal allows testing of components whose output is insufficient to dent steel. 12-2.3.1.6 HOPKINSON BAR TEST
initiating subsequent charges. In this test, the output of a detonator is
"The steel dent test consists of firing a detonator in direct end-on contact with a steel block in accordance with Test 301.1 of MIL-STD-331j. The depth of dent, deter-
characterized in terms of the velocity imparted to a steel time piece that is in intimate contact with one end of a steel bar wh:.n the detonator is fired at the other end (see Fig. 12-9). The velocity of the time piece is a measure of the average pressure over the time it takes for the shock to traverse its length
mined by a dial indicator, is a measure of output. Explosive components may be either
and the tension wave to return's. For steel, this time in microseconds is almost exactly
unconfined or confined in polystyrene, brass, aluminum, or steel. The depth of dent correlates well with initiating effectiveness. The
equal, numerically, to the length of the time piece in. centimeters (since both shock and tension waves propagate at 0.5 cm/fsec).
much sand as high order detonation, means no dent whatever in a steel plate. It has been shown that the depth of dent is proportional to the excess of pressure over the yield
Aithough the velocity of the time piece is a precise and rigorous measure of the momenturn of the shock in the bar, the relationship between this shock and the output of the
strength of the steel of the dent block, integrated over the volume of the detonation head.
explosive charge which induced it is less clear. The coupling between the output of the detonator and the input end of the bar is necessarily quite poor. Direct exposure of the bar to the action of the detonator results in damage with each shot and progressively changing characteristics. The effect of attenuators (to protect the bar) on output has net been established. Hence, the test is only in experimental use. However, it is usedextensively in the U.K.
12-2.3.1.3 STEEL DENT TEST
low rate detonation, which crushes nearly as
It has been found that a detonator of 0.190-in. diameter or larger, which produces a dent 00 10 in. deep in a mild steel block, will initiate a lead of tetryl or RDX under favorable conditions. Specification dent requirements for detonators to be used in fuzes are usually at least 0.015 to 0.020-in. deep and many produce dents up to 0.060 in. deep.
12-2.3.1.6 VELOCITY OF THE AIR SHOCK Dent tests also are used to measure the
output of !eads and boosters, and to determine whether token main charges have been caused to detonate high order. Plates used for this purpose are sometimes referred to as witness plates.
Since the velocity of an air shock is a direct measure of its strength, measurements of air shock velocity may seem to be an attractive means of measuring detonator output. However, at the short range over which the blast 12-19
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AMCP 706-179
ATTE"TOR•
STEE I
STTVt ml[R
WAV , rTIA *AVC TEN
[
A
•/
/7
techniques from those of detonating charges. On the one hand, detonating output is more
difficult to measure but on the other hand
nmore work has been done with detonators and rmore tests have been standardized. Non-
o -o"o OR ,,
F•T.T
detonating output
includes the output of
flames and other parameters (primers, squibs,
Figuie 12-9. Principle of Hopkinson Bar Measurement of Detonator Output output of a detonator is effective, a larger part of the effectiveness is attributable to the kinetic energy of the reaction products which support the shock than to the shock itself. In this respect, an inversion results from the nonideality of the reaction product gases. Hence, velocity of the air shock is not a suitable output measure. 12-2.3.1.7 DETONATION PRESSURE MEASURED BY MEANS OF SHOCK TRANSDUCERS The output of detonators may be determined by measuring detonation pressure waves" 6 . Two types of solid state transducers ae used to record the intense stress waves involved. One, based upon changes in electria conducivityuestion sidered as insulators, provides not only a
delay columns: and mechanical output (explosive actuators). 12-2.3&2.1 PRIMER OUTPUT An experimental setup used for the testing of primer output is a manometer connected to a closed chamber into which the primer fires. The output pulse of the primer imparts momentum to the liquid (Hg) in the manometer, causing it to displace to a maximum and recede. The maximum displacement is proportional to the momentum and is referred to as the impulse of the primer. The volume of gas emitted may, of course, be measured after the manometer reaches equilibrium.
some measure of temperature although the may be raised as to whether it ever reaches equilibrium. Perhaps, in many applica-
reading of the peak intensity of the wave but also a record of pressure variation with time. The second transducer utilizes the polarizatohproie 3ladevice tion of molecular solids ulid tos provide deie randr ofsmlecn more capable of resolving the very steep shock -frontsoften produced by explosives of
tions, the temperature reached by such t a thermocouple, which is proportional to the quantity of heat transferred to a solid by the flame, tmrau.1is more pertinent than the actual flame temperature. Light output, as measured by a photocell,
high brisance.
has also been used as a measure of primer output. If the light is mainly biackbody radiation, it may be quite significant. Ho% ever, the presence of some elements such as sodium, which have strong spectral output,
The explosive item to be tested is placed with its output end on the transducer ald initiated in the normal manner. When the detonation gave passes through the transducer, a signal proportional to the magnitude of the presure is produced which is recorded on an oscilloscope or other electronic device thus indicating the output of the explosive. 12-2.3.2 NONDETONATING ITEMS The output of nondetonating explosive charges requites entirely different measuring
might bias such results unduly. The lead disk test, employed for detonating output has be-n used for primers: Primer output does not puncture the disk; rather the volume of the dent be,.omes the measure of output. Softer materials, such as styrofoam, also have bedn used experimentally for this purpose to achieve a larger volume.
12-20
.--
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AMCD 706-179
12-2.3.2.2 SPECIAL PRIMER OUTPUT PARAMETERS The pressure-time output of primers provides a quantitative measure of total er.ergy A test fixture has been designed which has the ability to integrate this output' 7 . A series of experimental primer output measurements included a unique test to determine the effect of primer output on an inert propellant (acrylic polymer) in a cased round. A noticeable weight loss occurred after firing the primer that was associated with "unzippering" of the inert polymer iwto a gasous manometer. The amount of polymer gasified was considered to be a function of such parameters as available chemical energy and rate of gas production3s. Primer times have been measured in attempts to characterize primer lots and assess deviations of individual primer samp'es from other members of a lot, Primer time has been defined as the interval between primer initialion (as recorded by impacting of a firing pin or delivety of the required input energy pulse) and the occurience of soine measurable event (such as the ionization of primer reaction products or the severing of electrically conductive pencil lead). Photographic measurements of the extent (length, width, and height) of the primer flame have also been employed in attempts to assess ignition capabilities of primers. However, no direct correlations have been reported to date. 12.2.3.2.3 MECHANICAL OUTPUT The series of mechanical actuators includes dimple motors, bellows motors, piston motors, and switches. The output of these devices is usually specified in terms of pushing a given weight through a given distance. Use of a test fixture employing dcad weights is therefore best.
r
Output tests have often been performed by
having thc actuator push against a spring. Since th'r spring force is not constant, it is important to specify in tis case whether the givvr. force is measured at t',e start or end of the ,troke. In the case of switches, it has been suggested that the initial hump in the load cirve of a switch can be simulated by having a pin rupure a metal foil. 12-2.4 ENVIRONMENT Explosive charges must not only perform as intended; they also mu,.t be safe and operable in the environment in which they arc cxpected to perform. Encompassing deep water to outer space, the range of military environsments is indeed formidable. A series of tests has been d&veloped to simulate the various conditions to which ammunition may be subjected. Most of the test3 have been standardized to assure uniform conditions. The balk of the tests of interest uo the explosive ch:.rgtl designer are contained in M1L-STD-3?lI. A convenient summary of descriptions anu use of these tests has been compiled for fn,7e componeatsO. The explosive charge designer faces more severe testing problems than the fuze designer because of the relative smallness of his components in the system. For some of the components, the MIL-STD tests arc frankly meaningless. There is no reason, for example, to subject a booster charge pellet to the jumble test. On the other hand, it is dangerous to introduce an untested component, particularly a new concept, into the military environment. In some instances, other system components may help (confinement, structural strength, seating, cushioning); in other instances, they may hinder (incompatible materials, unplanned electric pAths, stress concentrations). This problem must be resolved by sound engineering judgment. If, for example, detonators are to be scbjected to a drop test, they can be placed within ajig that permits positioning and introduces confinement3 9. 12-21
I
I
I I
I
I
I
I
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k
AMCP 706-179 ,*TO-m" Pa .
of tests that apply only tC special conditions, such as the jettison tests.
mnumber "
.-.
,
"Four
a.
st,,trwR Fi4-ure 12-10. Arra.genent for Detonator Safety Test The chief purpose of environment testý; is to insure safety during rough handling and surve;,lance. The safety tests are of two types, destructive and nondestructive. Operability is not required after destructive tests, sihch as jolt; while operability is required after nondestructive tests, such as transportation-vibration. All surveillance tests are nondestructive.
tetts n MIL-STD-331 appiy specifically to explosive components. The Static Detonator Safety test (Test 115) detelmines whether the r-st of the train will be set off when the detonator is initiated in the unarmed position. The fuze or test fixture must be modified so that the detonator may be initiated in the sofe position. A typical modification is shown in Fig. 12-10. The Cest is successful if no explo.ive chzrge beyond the anning device functions, chars, or deforms. The detonator output tests by lead disk, steel dent, and aluminnm dent are discussed in par. 12-2.3.1. As in performance tests, programming is important in the environmental series. It may be desirable to cOmbine several tests sequentinily or to rdd tests to introduce such special
It is important to. understand that MILSTD tests are never specified unless they serve a ucfinriic purpose. The seIeetion of tests for application in a particular case rcq.,ires Lilgi-
conditions as acceleration that can be performed in air gun or centrifuge. Sufficient ,ampl,,s must be tested to assure significant results. As a rule of thumb, no fewer than five samples should ever be tested. The qnnntity depends on the critera for test acceptance, the destructive test (criterion: did this item
rleerng judgment. Tests must not be applied indiscraninately. On the other hand, once a standard test is prescrib,•d, it is mandatory that it be performed precisely as specified without deviation. MIL-STD-331 includes a
explode?) requiring fewer samples than the nondestructive test (criterion: is performance affected?). For electric initiators, specific guidance for test selection is given in MLSTD-3221 and MIL-1-23650 1 .
IN
REFERENCES a-k Lettered references are listed i, the General References at the end of this handbook. 1. G. W. Snedecor and William G. Cochrum, Statistical Methods, Iowa State University Press, Ames, 1967.
3. AMCP 706-111, Engineering Design Har'dbook, Experimental Statistics. Section 2. Analysis of Enumeratle and ClassificatoryData. 4. AMCP 706-112, Engineering Design Handbook, Experimental Statistics. Seetion 3. Planning and Analysis of Corn-
2. AMCP 706-110, Engineering Design Handbook, Experimental Statistics, Seetlon'il. Basic Concepts and Analysis of Mdeaurement Data.
5. AMCP 706-113, Engineering Design Handbook, Experimental Statistics. Seclion 4, Special Topics.
12-22
parativeExperiments.
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(D27189). tion ofOptmizaion Prntic Hal, w:., Englewood Cliffs, N.J., 1967.
t
8. A. Leon, "A Classified Bibliography on Optimization-, in A. Lavi and T. Vogl, Eds.. Recent Advances in Optimization Techniques, John Wilcy & Sons, Inc., New York, 1966, pp. 599-6499. Sttistial Anli' 9.Sentstivhv Ara isis for a New Procedure in Sesrv:'vExperimert, AMP Report 101.IR SRG-P No. 40, St~atistical Research Group, Princeton University, Princeton, N.J., July 1944 (ATI034-558). 10. L. Shainhicit,
stbisaiangthe 1cllanand
11. C. W. Churchman, Statistical Manual, Methods of Making Experimnental hrfrrences. Pitman-Dunn Laboratories, Frankford Araena1, Phi' ade lphia, Pa., 195 1. 12. D. E. Hartvigsen and J. P. Vanderbeck. Sensitvityrs Tests for Fuzes. NAVORD Re~port 3496, Naval Weapons Center, China Lake, Calif., March 1955. 13. D. J. Finney Probit Analysis, A Statistical Treatment of the Si~gmoid Response Wave, Cambridge University Press, Mass., 1952.
j14.
J. Berkson "A Statistically Precise and Relatively Simple Method Estimating the Bio-Assay with Quantal Response", J. Am. Statistical Assoc., 48, 263, 565-99 (1953). 15. Basil T. Fedoroff, et al., Encyclopedia of Explosives and Related Items, Vol. 1,
10.S(4cnand Perft rmance Tisti; for Qualifiration of Explosives. Report NAVORD OD 44811, Vol. 1, Naval Weaponis Center, China Like, Calif.. I January 19)72. 17
A. J. Clear, Standard Laboratory'i Pn'cedisres fo r Determnining Sensitivit-I. ri sance. and Stabiliti' of Explosives. Report TR 3278 Rev. 1, Picatinny Arsenal, Dover, N.J., ApnI !970.
18. V. E. Voreck and E. W. Dalrymnple, Development of an Improved Stab Sensitivity Test and Factors Affecting Stab Sensitii'iet of M-5.5 Detonators, Report TR 4263, Picatinny Arsenal, Dover,
20. S. D. Stein. Quantitativ'e Study of Faramefers Affecting Bt Ilei Sensitivity of Explosives, Report TR 2636, Picatinny Arsenal, Dover, N.J., September 1959. 21. Louis Jablansky, Laboratory Sca.e Test Device to Determine Sensitivitv of Explosives to Initiation b' Setback Pressure, Report TR 2235, Picatinny Arsenal, Dover, N.J.. September 1955. 22. Determnination of Cook-Off Temperatures, Journal Article 43.0 of the JANAF Ftize C'ommittee, 3 May 1967 (AD-816 238). 23. W. W. Wendlandt, Thzermnal Methods of Analysis, Vol. 19, Chemical Analysis Series, Interscienme Pubslisers, New York, N.Y. 1964. 24. E. E. Mason and D. H. Zchner, 7The 12-23
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AMCP 706-179 Development of Techniqucs to Detect and Determine the Effects of Heat on
Institute, Philadelphia, Pa., September 11-12, 1957. papers XXIII and XXXIII
Selected Primary Explosit..s, R&D Repori 81, Naval Weapons Statior., Yorktown, Va., 22 January 1962.
(AD-I53 579) (Confidential ieport).
25. E. E. Mason and HI.A. Davis, Application of Differential Thermal and Thcrtnogravitnetrlc Analyses to Military High Explosives. NAVORD Report 5802, Naval Weapons Station, Yorktown, Va., 22 January 1962 (AD-232 625). 26. Second ONR Symposium on Detonation. Office of Naval Rtsearch, Navy Dept., February 9-11, 1955, papers 15-17, pp. 209-64. 27. L. D. Hampton and R. H. Stresau, Small Scale Technique for Measurement of Detonation Velocities, NAVORD Report 2282, Naval Ordnance Laboratory, Silver Spring, Md., 27 December 1951. 28. U.S. Patent -3,528,280, T. Q. Cicco•ze and J. F. Kowalick, Apparatus and Method for Measurlne Detonation Ve.oril, in
33. J. N. Ayers, et al., Varicomp, A Method for Determining Detonatlon-Transfer Probabilities. NAVWEPS Report 7411, Naval Ordnance Laboratory, Silver Spring, Md., July 1961. 34. 1. Jaffe, ct al., The NOL Large Scale Gap Test, Compilationof Datafor Propellants and Explosives, H1 (U), Report NOLTR 65-177, Naval Ordnance Laboratory, Silver Spring, Md., 15 November, 1965 (Confidential report). 35. C. G. Storm and W. C. Cope, The Sand Test for Determining the Strength bf Detonators,Technical Paper 125, Bureau of Mines, Dept. of Interior, 1916. 36. R. J. Eichelberger and G. E. Hauver, "Solid State Transducers for Recording of Intenqe Pressure Pulsce", L.es Ondes de Detonation, Editions du Centre National de,!.hIccherhc ScicatI.qu., ari-s, 1.--
Explosives. 15 Septerr' er 1970. 29. Donna Price, 1. '.u? ct of Damage Effects Upon l,#!tcr...,; -n P.rameters or Organic High Expl, ;ives", Chemical Reviews, 59, 801-25 ( F'59).
37. M. L. Schimmel and V. W. Drexelius, "Measuremcrt of Explosive Output", in Proceedings of the Fifth Symposium on Electroexplosive Series, held at The Frmaklin Institute, Philadelphia, Pa., June 13-14, 1967, pp. 1-5.1-.20 (AD-720 454).
30. H. T Simmons, St., The Varuumn Thertnial Stability Test for Explosives, Report
NOLTR 70-142, Naval Ordnance LaboraSilver Spring, Md., 28 October tory. 1970. 31. MIL-1-23659 (WEP), Initiators. Electric. Design and Evaluation of. Dept. of Defense, 18 March 1963. 32. Proceedings of the Electric Initiator Symposium (U), held at The Franklin
12-24
38. M. P. Devine, et al., A Comparison of Several Types of 5.56mm and 7.62min Primers. Report R1932, Arsenal, Philadelphia, Pa., July Frankford 1969. 39. R. E. Trezona and E. L Miller, FortyFoot Drop Test for Detonctors (U), Report 28, Explosives Dcvelopmert Seetion, Picatinny Arsenal, Dover. N.J., May 1958 (Confidential report).
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AMCP 706-179
GLOSSARY This Glossary is an excerpt from Nomenclature and Definltions iji the Ap'inu'iution Area, MIL-STD-444, 9 July 1964. Definitions are often abbreviated and only terms pcrtainiing to. explosive charge design arc included. Actuator. An explosive device that produces gas at high pressure in sbort periods of time into a confined volume for the purpose of doing work. Dimple motors, bellows motors, and switches are examples of actuators, Booster, An assembly of metal parts and explosive charge provided to augment the explosiv.e components of a fuze to cause detonation of the main explosive ,haige of the ammunition. It may be an integral part of the fuze. (This term is often uxed as an i,.•tireviotion for booster charge). Booster OCarge. 1. Thc explosive charge contained in a booster, It must be sufficiently sensitive to be actuated by the small explosive elements in the fuze and powerful enough to caue detonation of the =-in explosive tilling. 2. The amount or type of explosive used to reliably detonate the bursting charge of ammunition. Bi'iiance. The ability of an explosive to shatter the medium which confines it; the shattering effect shown by an explosive, Combustion. The continuous rapid combination of a substance with various elements such as oxygen or chlorine or with various oxygen bearing compounds, accompanied by the Wneration of light and heat. Cook-Off The deflagration or detonation of ammunition by the absorption of heat from its environment. Usually it consists of the accidental and spontaneous discharge of, or explosion in, a gun or firearm caused by an overheated chamber or barrel igniting a fuze, propellant charge, or bursting charge.
Defilagration. A very rapid combustion some. times accompanied by flame, sparks, or spattering of burning particles A deflagration, although classed as an explosk, , genera~ly implies the buining of a substance with self-contained oxygen so that the reaction zone advances into the inreacted material at less than the velocity of suund in the unreacted materials. Delay. An expl-sive train component that introduces a controlled time delay in the func :oning piocess. Deronation. Ant exothermic chemical reaction that propagates with such rapidity that the rate of adiance of the reaction zone into the unreacted materi.l e,,(%.ceds the. sound in the unreacted material. The rate of advance of the reaction zone is termed detonation velocity. When this rate of advance attains such a value that it will continue without diminution through the unreacted material, it is termed the stable detonation velocity. When the detonation velocity is equal to or greater than the stable detonation velocity of the explosive, the reaction is termed a high order detonation. When it is lower, the reaction is termed a low order detonation. Detonator. An explosive train component which can be activated by either a nonexplosive impulse or the action of a primer and is capable of reliably initiating high order detonation in a subsequent high explosive component of train. When activated by a nonexplosive impulse, a detonator includes the fun.tion of a primer. In general detonators are classified in accordance with the method of
G-1
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II II
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S70G-17g initiation; such as pcrcussion, stab, elcctric, flash. etc.
contains a small quantity of a sensitive explosive.
Explosion. A chemical reaction or c~hange of
Lead. (Rhymes with "feedl") An explosive
state which is effected in an exceedingly short time with the generation of a high temperatuni and generally a large quantity ofgas. An explosion produces n shock wave in the surrounding medium. The term includes both detonation and deflagration.
train component which consists of a column of high explosive, usually small in diameter, used to transmit detonation from a detonator to booster charge.
Explosive. A substance oi mixture of substancs which may be made to undergo a rapid chemical change, without an outside supply of oxygen, with the liberation of large quantities of energy gentrally accompanied by the evolution of hot gases. Explosive Train. A. train of combustible and explosive elempnts arranged in an order of decreasing sensitivity Its function is to accomplish the controlled augmentation of a rmall impulse into one of suitabl* energy to cause the main charge of the munition to function. It may consist of primer, detonator, delay, relay, lead, and booster charge, one or more of which may be either omitted or co04b1-i.ed. Firing Pin. An item in a firing mechanism of a fuze which strikes and detonates a sensitive explosive to initiate an explosive train. High Explosive (HE). An explosive which when used in its normal manner detonates rather than deflagratc-s or burns; i.e., the ra;e of advance of the reaction zone into the unreacted material exceeds the velocity of sound in the unreacted material,
\
Igniter. A device containing a specially arranged chaige of a ready burning composition. usually black powder, used to amplify the initiation of a primer. initiator. A device used as the first element of an explosive train, such as a detonator or squib, which upon receipt of the proper mechanical or electrical impulse produces a burning or detonating action. It generally
Low Explosiv'e (UE)_ An explosive which, when used in its normal mznncr &dflagrates or burns rather than detonates; i.e., the rate of advance of the reaction zone into the unreacted material is less than the velocity of sound in the untracted material. Low explosives include propellants, certain primer mixtures, black powder, and dclay compositions. Primnary High Explosive. An explosive that is extremely sensitive to heat and shock and is normally used to initiate a secondary high explosive. A primary explosive is capable of building up from a deflagration to detonation in an extiemely short distance and time; it can also propagate a detonration wave in an extremely small diameter column. Primer A relatively small and senuative inital explosive train component which on being act'iated initiates func " ing of the explosive train and will not reliably initiate high explosive charges. In general, primers are clasified in accordance with the methods of initiation; such as percussion or stab. Relay. An explosive train component that provides the required explosive energy to cause the next element in the train to function reliably. It is especially epplied to small charges :hat are initiated by a delay element and, in turn, cause the functioning of a dttonator. Secondary High Explosive. A high explosive which Is relatively insensitive to heat ,id shock and is usually initiated by a primary high explosive. It requires a relatively long distance and tinic to build up from a deflagration to detonation and will net propagate in extremely small diameter columns.
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AMCP 708-179
Sccondary .high explosives arc used tot boosters and bursting charges. Somectimes calied noninitiating high explosives. &Suib.A small explosive device, similar in
apcarmatice to a detonator, but loaded with low ,:xplosive so that its output is primarily heat (ihsh). UJsually cocctricahly initiated, it is provided to initiate action of pyrotechnic devices.
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AMCP 706 179
GENERAL REFERENCES *
P-1 INTRODUCTION A number of general refcrenccs on the subject of explosive trains are here combined for the convenience of handbook uscis. Specifica;ly listed are (I) gcncral references consisting if handbooks, manuals, and ,o'mpilations, (2) JANAI Journal arlicl.c, and (3) Military SpeCifications. The general references are identified by letter to make multirle referral simple:. Note that specific referrences usd fut the material discussed in this handbook anc listed at the end of each ch~apterb
Much of the information for this handbook was obtained from an earlier handbook, Ref. a, par. R-2.
Ordnancc Labmratory. White Oak, Md., Aplid 1.52 (AD4j)O 15 1)A handbook of resceuch results, data, and tests on explosives and explosive components. b. TM 9-1300-214, Alititur) Explosves, D)ept. of Anny. November 1967. A manual about the common military cxplosivc., covering descriptions, prop ertics, trsts, and handling methods. c. AM.CP 706-106, Engineeringd-
book, Elebents ol,4rnapent Engineeringn Fart One Sourtes (ifErnerg '. A handbook on fundamental facts about chemical energy including theory of explosivs. reactions and properties of explosives.
It is an underlying assumption that the readFr has some knowledge of militaryexplosimes. For this reatn details of explosive d. AMCP 706-1i7, Engineering Design oHandmaterials are not treated in this handbook.nxplo-ive book, Series, Pro acrties of ExSuch da -rc thamost u!-t:-atefb, colltind Listhch of phy.,cal d properties. Refs. and f contain of over 100 explosive compounds and design data for specific components, explosiv iixtures. and e ef. g treats the dcsign of fuzes of which enplosive components are a part. Ref. h e. Electricullnitltorlandbool(U),3rd Ed.. vers dimensioning while Rafs. i and j s.E The Franklin Institute, April 1960 cs procedures. Ref. k is the encyclopedia (AD-319 980)(Confidential report). tesut dealing with detonations and detoHas performance charofcteristics of 25 nators. electric initiators, with curves of input sensitivitiy and functiontng time. series a wrote The JANAF Fuze Committe, of 53 Journ3l articles of which a dozen f. MIL-HDBK-137, -'uzr Catalog. Volume 3. pertain to explosivc components. These arc Explosihe Components (U). Dept. of Dclisted in par. R-3. Finally, in par. R-4 there fensc, 20 February 1970 (Confidential are listed the Military Specifications covering report). explosives and explosive compositions. A compilation of military and technical date on all standard ad developmnetal R-2 GENERAL RIEFERENCES fuze explosive components. a. Ordnance Explosive Train Designers'llandS. AMCP 706-2 10, Engineering Design HandbooA, Report NOLR II 1 I, U.S. Naval book, Amm'unition Series, i-uzcs.
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AMCP 700 179 A IM10db0t)k filni
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anld flic;t L-1lmlts(lLlt*.
(esigllel of" Itlur'S
h. NMII*-SII) 320. 7Trmimjh~g'. and 11 ,ltrig
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i. MIl.-STI)-322, Basic Latuluation Test for 1ý w f- aDe in re 'o en t (if L hi'cttu ill initiated "xplosll've (C'pop•ne.% for Use In wcs, D)ept. of D)efense, ! 5 October 1962. Provides it uniform evaluation of iniilt,
of t/e I)€.,ifr, of BfIooTvars,
Stre.aia and Milton Lipnick,
(1wow U .S . A rm y Il arry D ia no n d l .a *ofatorics), Wiasiiggton.
D.C., 20 JLuIn.
196 1 AD-270 27'
and clovirolnlalllital respv-rim of
to
22.0 Some Asipe't) of(if Prro(ct/ni Ik'lys. 5 December i19 I. AD-2 70 444.
J-u:'e Jid luwe ('6niporients, LIsiTrromVnplal am! Performnt ce Te:ts Ior. D)ept. of L•lfacn., I June 1971. and producSpecifics the developnment lion of fuzes anld (tize component¢IIs.
0.0 Exploding Bridgriwir, Surevj'.. :'xplosivcs C'-mponent Suhbconmmittee, 23 Ocuber 33t. 1Q63, AI)-831
initiated explesivc elements priom their use in military items.
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4J) U(S III lFu-zes. I)ept. of' Il~•im', Ju 19(,2. lFstablishcs terminology. dimensions. and preferred ILhatitral nalerials for exploslve •Lot1lo ftl~lllS.
outputi,
'iij P'h('
ontid Inert Matehrial% hli'o.w, Ph I si( at J'iopwrl'.s R.'.tr'e.'h' 7"h.m ol /.,s''I. I Matcl I '0j, AD 4(8070.
MIL-STI)-331.
k. BT. Fcdcroff and O.E. Sheffield, l'.'clope'dia oJ"rfExplosivs l and Related d ca tcri Vol 4 Ik;',ua/imo to Ve,. nators. Rclo;! TR 2270. Picatinny Arsenal, Dover, N.J. 1909 (AD-795 472). Contains more than 1000 pages of detailed entries pertaining to all aspects of delonations alad detonators.
S44.0
R-3 JOURNAl. ARTICLES OF THE JANAF FUZE COMMITTEE PERTAINING TO EXPLOSIVE TRAINS
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Thet' Sensitiriq c'i,)'L.xpjiok" Ittiaf,
13 February 19'R, AD-208 252. 14.0 A Discussion of the/ Nre-d for Study of the (G2iscsof Uninlentional Initiations of Explosive Derlces Such as Are Used In Ewze r.'xplosive Trains, 13 February 1958, AD-210 743.
31.0 A
Combl'cdium, oej lyrotcchnic Del,').
1re'ices. Explosives Conapotnuits Sub-olnllCmittee, 23 October 1903, AD-474
43.0 li.etermination of (`ooA-Off T7emnperatures, Explosive Components Subeommintce, 3 May 1967, A D-8! 6 238. Mild Detonating Cord, Explosive Coamponents Subcommittee, 3 May 1961, AD-816 229. 46.0 R"
Afe';uation oflnirlitors. Explosive
Committee, 3 May 1967, AD-828 308. 48.0 The Is e of ('onductilc Alle's in Electro-E.pisla'i TDeailes. H.S. L.eopold, Naval Ordna.'ice Laboratory, White Oak, Md., Explosive ,-ornponetits Subcs..namitt .e, 3 May 1967. AD-829 73!.
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AMCP 706-17V
RA4 MILITARY SPECIFICATIONS ON EXPLOSIVES AND EXPLOSIVE COMPOSITIONS 7/i'LE
MIL SJ'Lc'O. A- 159('
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Aut iuuuiy Silfl de
B-I O21)
Barium Nitrale
!)-204A
I)iitrtolioucn I" xploives
P 223B (MLI)
Powdet.
N-244A (Mu)
Nitrocelluflose
N-246
Nitroglycerin
"-248A (MuI)
"YN F
T-3394
Tetryl
P-339B
PI:-N
R-3,
RDXaud
('-4 I V
Ceposition B
C-427A
Compositon C-3
C-440B
Compositions A-3 and
for Use in
k Blacokition
11IIL SillC ,NO.
7711lE
M-14745 (Mu)
Miil-2 ('Compolion
E--149 7OA (Mu)
IExplosive ('on,position A-5
P- 149')9
Powder. Molding Con pound Exllosive (PBX)
L-1055,"C
Icad Styphnatc. Basic
R-21723
RI)X
u-)...7A
Explosive Compositions., 1IBX type
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C4
('45010AAComposition '-451 1,3A (Mu) -43413A
Composition B-3 )
. Militur
11-45444A tOed)
IIMX
0-45445A (Ord)
Oc
P,1 447 0O,1)
Po;;'dcr, Molding. PB•X
Pwr.Mln.VB I
9010 P-4548(oA (Mki)
Pellets, RDX
L-46225C (Mu)
Lead Azide, RD-1333
P--6464A (Mu)
Pellets. Tetryl
Flaked. Graded, Atomized
E-4b495
Explo.ive Composition, IlTA-3
L-757A
Lead Styphnate, Normal
L 46496 (Ord)
LMNR
L-3055A
Lead Azide
C46652 (Mu)
Composition B4
C-i3477B (Mu)
Cyclotol
T-40938 (Mu)
Tetricenc
T-13723
Tetranitr-ocarbazole
E-81i I1
P!3XN-5
:
A-4 N-494
Nitrogoanadine (Picritc)
A-512A (Mu)
Aluminum Powdet,
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AMCP 706-179
INDEN Bureau of Mines impact test, 12-9 Burning, 2 1, 2--5, 4 -0, 6- 7 Burning rate, 2--6, 6 7
Acte'eration, I - 9, 4-- 2, 4 - 14, 6 -9 Acoustic wave. 2 -10 Activation energy, 2-2 Actuator, 9-i, 12-21 Additive effect on sensitivity. 3-6 Adiabatic compression, 2 --20, 4 -15 Aerodynamic heating, 1- 7, 4-F A~r gap test, 3--4, 3 -8 shock velod ity, 12-19 transport, I l-6 Aluminum dent test, 12-19 Ammunition, 8-1, 11-3 Arming, 1--12, I -!5 Arrhenius equation. 2-2 7 Atxiiiary booster, 8 --Availability, 10 - 13
Carbon bridge, 2 -19, 5 -14, 5 -25 Casting. 10- 1 Cavity, 4- 15 Cementing, 10 13 Centrifligal casting, 10-4 Chapman-Jouguet condition, 2- 12 Characteristics of explosives, 10 - 15 Charge configuration effect, 3 -10 Chemical ammunition, 8 -1 decomposition, 4-- 2 intteraction, 4-11, 10-15 Cluster ammunition, 8-2 Colum.i diameter, 3-1 Compatibility, 4-1I, 10- 15 Condenser discharge test, 12 -16 Conductive explosive mix electric initiator, 2-19, 5-15 Conductive film electric initiator, 2- 18, 5-- 15, j --26 Confidence level, 12-4 Confinement, 1 - 11, 3 -3, 3-6, 5 -21, 6-10, 7 -5, 7-11,8-.7 Considerations in design, 1 - 13 Construction. See: specific explosive charge Continuity equation. 2 -9 Controlled fragmentation, 3-16 Cook-off, 4-6, 12--I I Cost effectiveness, I - 15 Cost factor, i 0-13 Cup. 5-6, 5--22, 6--10
Ballistic mortar, 12--15 Barrier, 3-4, 3-6, 7-6, 12-17 Base char);e, 5-20 Bases for ;xplosive charge selection, i -4, 5-4,6.- 10 Bellows mnotoi, 9--I, 12 -21 Blast, 3--13, 12 --15 Blasting cap, 9-6 Bolt, 9-2 Bomb, 8 - I Bomb drop test, 4-13, 12-11 Bonfire test. 12- 13 Boosted surround, 8--7 Booster auxiliary, 8 - 7 charge, 7--I construction, 7--I1 description, 7- I design, 7-6 explosive, 7-2
d'Autriche method, 12-14 Decibang test, 3 -5
Decomposition of explosive, 2-1! Definitions, I --1, 0,- 1
fu nction. 7 -- I1 lcadiag, 7-9
Deflagration, 2-1, 2-5,4-6, 6-7
output, 7--8 positi')n, 8-7 sensitivity test, 3--3, 12-tO Bridgewire, 2-17, 4-5.5-10, 5-14, 5- 25,
Delay charge composition, 6- 3 description, 6-1
5-26. Seealso: EBW Brisance, 12-0 Bruceton technique, 12--7 Bullet impact test, 4-4, 4 -12, 12-10
design, 6 -I0 loading, 6-9 output, 6-3 Demolition block, 9- 6
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AMCP 70C-179
INDEX (Con't.) Delcaoflt •n device, 9 - 4 Density, 10- -15, 10 i 7. See also. iLoading
Envionment electrical, 1--13
density Design considerations 1 -- , I -- 13, 5-1, 5-16,6--1, 7-4, 7-6,8 -1,9--l Destruc:or, 9 -4 Detcnating cord, 3-12, 9-5 Detonaion actual, 2-13, 3:--10 detonator output, 5- 18 front, 3-1,3-.10' growth, 2-7 ideal, 2--5. 3 -9 pressure, 2-9, 5 -21, 10- 13, 12--14 spontaneous, 2-26 transfer to another charge, 3-- 1, 1 -'- 18 transition from deflagration, 2- i, 2-6 velocity,2-7,2 9,2-12,2-14,3-10, 10-15, 12-13 wave, 2- 11, 7-8, 12- 18 De~onatic construction and fabrication, 5- 1, 5-22 design problem, 5 -- ! 2 function, 5--I oitput, 5- i8, 12--13 packing. 11 -2 selection. 5-4 Dextrinated lead aznde, 2-7 Differential thermal analysis, 12 -- I Dimensional -hange, 4-4 Dimensional interaction, 3- 1 Dimple motor, 9--1, 12--21 Disk thickness, 5 -6 Driver, 9 -1 Drcp test, 2-21,4-4 Dual arming safety, I 12, 1-14
military requirements. 12-21 response, 4.-- I, 12 --21 Equation of state, 2- 1I Evaluation procedure, 3-3. 4- 12, 12-1 Exploding bridgewire, 2-24, 5 -13, 5-.26 Explosion temperatu-e, 2-2, 2-21,4--2, 12-10 Explosive belt, 9-2 characteristics, 10-- 15 .cord. 9- 5 material, 1-4, 2-7, 2-13, 2-24, 3-6, 4 -2,4 -115, -14 5-19,6-3,7-2, 8-6, 12-8 nut. 9-4 sheet, 9 -6 train, I-I Explosive charge. See also: specific explosive charge (actuator, booster, delay, detonator, lead, main bursting charge, primer, relay, squib) bases for selection. 1 -4, 5 -4, 6- 10 design considerations, -- 1, 1--13, 5-1 fabrication, 10- 1 general description, I --1, 5 - 1, 6 1, 7 --1, 8 --I, 9--1 location with respect to target, I - 12 packing, 1I -3 purpose, I -shipping, 1 -5 storing. II -3 system approach aspects, - 7 testing, 12-8 Extrusion, 10 -4 Exudation, 4-5, 10-16
EBW, 2-24, 5-13, 5 -26 Economics, I - 15 Electric aspects, 1--13.4--16, 12-It initiation, 1-13, 2- 17, 5-2, 6 -1 initiator, 5-.2, 5 -9, 12-16. See also: specific explosive charge spark initiation, 2-24, 4-16 Electrostatic sensitivity, 1 - 13, 12-Il Energy-power rc;ationship of initiators, 2- 10
Fp'brication, 10--A. Seealso: specific explosive charge Failure diameter, 6- 10, 7-6, 10-15 Failure rate, 12-! Filnm bridge e!,ctric initiator, 2 -18, -- 14, 5-26 Finishing operatioa, 10- 12 Firing energy and power. 5- 10 Firing pin, 2 --2 1. 2-23, 5 -7 Firing time, 5-12
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A' CP 706-179
INDEX (Con't.)
-
Flane output, 5-16, 12--20 Flash charge, 5 -9. 5 -26 Flash detonator, 5 -2, 5 --8, 5 - 24, 12 -16 Flexible linear shaped charge, 9-6 Flying plate tzst, 12- 10 Fragmentati-n, I- Il, 3-14, 12-15 Frankford run-down method, 12-8 Freqjiency distribution, 12-2 Friction, initiation, 2- 23, 4-3. 4 -16, 12-- 10 Functioning, I - 11, 5 - 1. 6 -I Functioning time of initiators, 5 II Fundamental principles, I - I Gamma radiation, 4 - 18 Gap and oarrier, 3--4, 3-6, 7-5, 12--10, 12-17 Gas law, 2-12 transmission, 2 -19 volume, 1O-15 Gasless delay compositions, 6-5 Glosary, G- I Graphite film t-ridge. 2-18, 5-15, 5-26 Grouping o." initiator types, 5- 3 Growth of detonation, 2-7 Gurney constant, 3-!4
... ... ''-'a -- 2.1'aa- 5~ HIEAT avmunitio. 8_--2 Heat initiation, 2-3. 2-15, 2-17 of combustion. 10--15 of explosion, 5 -21, 10-I5 transfer, 2-5 !HEFammunition, 8-2 High explosive ammunition, 8-1 material, 1 -4, 2-7. 2 -13. 2-24, 3-6, 4-2, 4-1I, 5-14, 5-19, 7--2, 8 -6, 9--2, 12 3, 12-20 train, 1-2 High order detonaiiu.-.i, 2-6 High temperature effect, 4-2 High temperature xuoiosive, 4-4 Hopkinson bar tezt, 12 -19 Hot gas transmission, .-19 Hot particle transmission, 2-20 Hot prebging. 10-10 Hot spot theory of initiation, 2-3
Hot wire lectric initiator, 2 -17, 5 -- 2, 5 -9 Hot wire ignition test, 12-13 -lugoniol curve, 2-10 humian factor.; engineering, I - 16 Humidity environment, 4-2 Hydrostaitic pressing, 10-11 Ignition. See also: Initiation eneray, 1--24 powder, 6-b temperature, 2--2, 2-18 Illustration., list, xiii Impact ir~itiation, 2-21,4-12 sensitivity, 2-211, 3--4, 4-3, 4-9 simulation. 4 -1 .4 -12, 12- 9 values of explosives, 4 -3 vulnerability test, 12-10 liert simulant, 8-6 Initiation by cook-off, 4-6 by heat, 2-1 2-17, 5-8 by impact, 2-21, 4- 12 by other means, 2-23 by stray eneigy, I - 13 efftctiveness, 3 -1 eiec ric. 2-i7 general, 2- 5, 3-1 propagation. 3-I sensitivity, 2-18. 2-22, 3-3, 4-3,4-9, 5-6, 6-4, 7-4, 8-6. 10--14, )2-9 threshold conditions, 2-15 Initiator. See: specific explosive charge Input chbracteristics, 2 -3, 5-6, 12-16 Irradiation. 4- 17 Isostatic pressing, 10- 11 Journal articles of the JANAF Fuze Committee, R-.2 Laser initiation, 2-26 Large-scale gap test, 3-4, 12-10 Lead construction, 7 -10 description, 7--I design, 7-4 explosive, 7 -2 function, 7-1 1-3
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AMCP 706-179
INDEX (Con't.) Lead (continued) loading, 7 9 output, 7 -8
!Lead azide, 2-7, 2-26,4 -11, 5 -19, 5-21, 10 -15 Lead disk test, 12- 18 Lead styphnatc, 2 --7 Lethality of fragments, 3 15 Lightning, I -13 Line wave generator. 3-12 Liquid explosive, 10-4 Loading density, 2-8, 2--14, 2-22, 3--5, 5-7, "5-23, 6--3, 6 -9, 7-7, 10 -7 operation. 5--23, 6 -9, 7--9, 8--5, 10-1 process selection, 10- 1 Location of explosive with respect to target. 1 -1i Logit procedure, 12-8 Lot-to-lot variation, 3-5 Low explosive ammunition, 8-1 material, 1-4, 6-3, 9 -2, 12 -20 order detonation, 2--6 train, 1-2 Low temperature effect, 4-1 0 Lucite gap test, 3 -8 F'Machining,.10--
Mach number, 1-8 12 Main bursting charge, 1-13, 8-I MDC, 3-12, 9-5 Mechanical aspects, I - I I Mechanical output, 12- 21 Mechanical initiator. See: specific expiosive charge
Melting, 4-8 Melting, point, 10- 15 Mild detonating Lord, 3-12, 9 -5 Military environment, 4-2 requirements, 4-I SpecificAtions, R-3 Standard tests, 12-21 Mine, 8- I Mini-detonator, 5-3, 5-22. Misaligned charge, 3--7, 7- 10 Moisture effect, 6-4, 6-10
Munroe effect, 3 -17 Normit procedure, 12-8
Obturated delay, 0 - 1, 6 -- 0 Optimization, 12-6 Out-of-line safety. I - 12. 1 -14 Output, 3 -8,5.- 16,6-3.7 -8, 8 -4. 9-2, 10 -14, 12-13, 12--18 Packing, I I - I Particle size, 2-7, 6-9 transmission, 2-20 velocity, 2-13 Pellet casting, 10--3 Pelletizing, 10 -9 Percussion initiation, 2- 22, 5-7, 6-1 Percussion primer, 5-2. 5-7, 5-24, 12-16 Picatinny Arsenal imrlct test, 12-9 Piston motor, 9 -1,12-21 Plastic-bonded explcsive, 7-.2, 8-5 Plate dent test, 12-15 Plug for electric initiator, 5-25 Porosity of cast charge, 10-2 Press blow, 5-- 23 Pressing, 5 -23, i0-4 Pressure, 2--6, 6 -5. See also: Detonation pressure Primary high explosive, 1-4, 2-7, 4-5,4-12 Primer construction and fabrication. 5 -1,5-22 design problem, 5-12 function, 5-1 output, 5-16, 12-20 packing, I 1-22 pellet, 4.-I 6 selection, 5 -4 7 Priming composition, 5.Principles, 1- I Probit procedufe, 12-8 Projectile, 8-1 Projectile preparation, 10-.1 Propagation of detonation, 3-1 Punching and trimming of cups, 5-22 Purpose, 1-I Pyroswitch 9-1 Pyrotechnic ammunition, 8-2
1-4
L ,
-
!
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AMCP 706-179
4
INDEX (Con't.) Quality assurance, 10-- 16 Quantity-distance table, II --4 Rail transport. I1 -6 Ramming, 4. 14 Reaction establishing self-prop.-gating rate, 2 15 kinetics. 2-2 rate, 2-2 Reconsolidatioa, 10 -10 References, I-1S, 2--.27, 3 -18, 4-17, 5 -27, 6 11,7 -13,8 -8. 9-- 7, 10-18,1t-6. 12-22, R.-I Relay. 5 - 2 Reliability. 1-14. 1.-, I,12-4 Resistivity of wire bridge, 5 -10 Response time, 5-11 RF energy, I - 13.4-16.5 -25 Rifle bullet test, 4-4, 4- 12 Ring delay. 6--2 Rocket propellant, 2-6, 4 -1 Safety, 1-- 12, 1-14, 11-2, 12 - 1 Safing and arming device, 1- 12 Sand test, 12- 18 Sealing disk, 5- 6 Secondary high explosive, 1-4, 2-7, 2-13, 2--24, 3-6, 4-2,4--I, 5l--14, 5-19, 7 --2, 8-4, 9-2, 12-20 Seismic wave, 3-17 Sensitivity test, 2-21, 3-3, 10--14, 12-9 Sensitivity to initiation, 2-18, 2- 22, 3-3, 4-3, 4-9, 5-6, 6-4, 7-4, 8-6, 10-14, 1,-9 Sensitization, 4-9 Setback acceleration, 1-9,4-4,4-14, 12-10 Setforward acceleration, 4-14 Shaped charge, 3- ,7.7 --8 Sheet explosive, 9-6 Shippin3, 11-5, 1 1--6 Shock temperature, 2-!0 through a bulkhead, 2-26 :rai•ducer. 12-20 tube, 2-19 velocity, 3 -4, 3-11I wave, 2-9, 3-12
Sideways acceleration, 4- 14 Simulation of aerodynamic heating, 4 -8 Simulation of impact, 4- 12 Slurry. 8 .5. 10 -4 Small-scale gap test, 3 -4, 12 - 10 Smoke mixture. 8 -4 Sound velocity. 2-10 Spark gap electric initiator, 5 - 15, 5 26 Spit-back ;ystem, 7 -9 Spontaneous detonation, 2- 26 Spotting charge. 5 -26 Spurious electrical signal, I 13,4--16 Squib. 5-3. 5-15 Stab initiation, 2-21, 5 6.6-1 Stab initiator, 4-8, 5- 2, 5-6, 5.-.24, 12-16 Stability. 12-16 Stagnation temperature, I -8, 2-10 Staircase technique, 12-7 Standardization, I-.15 Static detonator safety test, 12-22 J Static electricity, 1-13, 2-24,4-3,4--16 Statistical test method, 12- 1, 12-6 Steel dent test, 12-19 Stop and pressure loading, 10-6 Storage ai high temperatur:, 4 -2 Streak camera record, 3 - I Strength of explosive, I - 10 Structural aspects, 1-10 Suitabili:y, 10-13 Surveillance environment, 4 -2 Switch, 9-1 Symbols, list, xviii Sys;tems approach lo ammunition, 1-7 Tables, list, xvi TBI, 2-26, 5-16 Temperature adiabatic cempression, 2-20,4-15 cook-off, 4-6, 12-1I decomposition, 2-2 effect, 1 -7, 4-2, 4-9, 6-4, 6-8 explosion, 2-2, 2-21, 4-3, 12-10 high, 4-2 ignition, 2-2. 2-18 low, 4-10 milit.ry requirement, 4 -1 reaction rate effect, 2-2 1-5
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AMCP 706-179 INDEX (Con't.)
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Temperature (continued) sensitization, 4-9 shock, 2-10 stagnation. 1-8, 2- 10 storage, 4-2 Test environmeni, 12-21 evaluation considerations, 12-I explosive materials, 12-8 input, 12-16 output, 12-18 fafety and reliability procedures, 12--I statistical test methods, 12-6 Thermal decomposition. 2-I Thermal detonability test, 12-13 Thermodynamic heat transtcr, 2-5 Thermogravimetric analysis, 12--I 2 Throuah-bulkhead initiation, 2- 26, 5.-10 Transfer of detonation from one charge to another, 3-1, 12- 18 Transition from deflagration to detonation, 2-1,2-6 Transmission of hot gas, 2-!9 Tiansmission of hot particles, 2--20 Trauzl test. 12-15 Truck transport, 11--6
Kpj' r
1-6
Underground output effect, 3-17 Lnderwater output effect, 3-16, 12-15
Vacuum casting. 10-3 pressing, 10-10 stability, 4-3, 12-16 Varicomp technique, 12-18 Vehicular aspects, 1-7 Vented uelay, 6--2, 6-10 Vibration, 4-16 Voltage .;ensitivity, 12- 7
Warheed fragmentation, 3-16 Water detonation, 3-16 Wtter environmert, 4-2 Wave shaping. 3-12, 4-5, 4-9 Wax gap test, 3-12, 4-3 Wire bridge bridging, 5-25 EBW, 2-24, 5-13, 5- 26 initiation, 2-17 material, 5-10, 5 -14 4 separation, --5
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AMCP 706-179
(AMCRD-TV)
FOR THE COMMANDER:
JOSEPH W. PEZOIRTZ
OFFICIAL:
Major General, USA Chief of Staff
JOHN LYCAS Colonel, GS Chief, HQ Admin Mgt Ofc
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DISTRIBUTION: Special
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ENGINEERING DESIGN HANDBOOKS
Avooishleto A'( ac-tivities, DOD0 agencies.end Government agenciesfroei Lettarkesiny Ar.y Depot, ChmetrSburg. PA17201. r and n riefTa dniva Isale to contractors of Coira, Department fo ii4tiV&Sltdnhni§ 1 Informatiovt Service(PilS). (NC~kgI~1~ Sprigfied. V
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No. ANl' 706-
*116
Title
Nie. Title WEtP708PartOne. Protliminuary, Engineering. M.elicopter 201 Design 202 flielicoipter Engineering, Part Two. DetailDesign 203 Helicopter Engineering, Part Three.Qealificetion Assurance 204 *Helicopter Perforouciice Tooting 205 *TiningSystems and Ct6pceaets M1 Fuies 71I(C) Fuzes. Proaieity, fiectrical. Part One (U) 21?(S) Poles, Prvmlmity. Electricel. Part Two (U) 213(S Foxes.Proxielty. Electrical. Part Three(11) 214(S9 Foles,Proolmity. Electrical, Part four (U) 215(C) Fozes.Proximity. Elactric-i, Part five MII 235, Hardetning WeaponSystemsAgolestAF Eeg 238 -Recoilless RifleWeaponSystem 239 -SmallAnusWeaponSystmems 240(S) Greaeda%(U) Flight Designfur Controlof Projectile 242 Characteristics (BEPLACES -246) 244 Aawssnition. Section 1. Artillery Aemiunition-Geinerel. with Table of Contenrts, Glossery. and Index for Series 245(C) Aminunition. Section 2. Design for Terminal Effects MU 246 tArminition. Section3, Design for Controlof Fiii'haatritc (REPLACED BY -242)
Uesigv W.idancefor Producibility, lOll 104 Value toigivieering 106 [tenents of Arehanment Engineering. Part Jone, Sources of Energy 107 Elnimnets of ArmamentEngineering. PertTwo, Balilistics 108 (1lnemots of ArmeionntEngineering. Part Three, WeaponSytteir and Co~opovots 109 %llisof to! Cuonlaot iv lBnooielProbatilities .10 Lopertimnetal Statistics. Section1. BasicCooceytsand Analysisof M-asuremeiot Dtte tI Eperlwintal Statistics. Section2, AtialysIs of Evnuerative and Classificatory beto 112 ixperimrntal Statistics. Section 3. Planning and Analysisof Co" srativoExperrimnnts 113 Eaoeriemental Statistics, Tecciun4, Special lopics SectionS. Tebles Scitistics. (voeriarstal 11 4 115 **A Environmnental Series.Part One. BasicEnoiron-enotol Concepts -Eooironinentel Series,PartTeo.Nistural Environmental FaCtoxa 120 Criteria for rrnoironrnavtal Control of Mobile Syse, 2I Packagingand Pock Engineering ,,3 iydraulic fluids ,21 lierctncl aIrf and Cab'e 127 ** Inrar itiltory Systems.Part One 128I) I(.-rdMiliarySysems. Pat To 30 Design for hir Transportend Airdropof Materiel 133 'aioal icytginetin"gD Theoryand Prectice 134 . ýt oJe~ýes DA Ign 13.5 Inecos Patnt. c4 elted katters 30 Seo..ecaoiis Theoy 137 * enorcAass Section 2. Mceasuremenot cod Signal tbnoerters 138 * A Seronn, ha n S. ection2. Amvliflcetito 139 Sroo ycsanss hn Sectin 8, PowerElementsend SysteinDesign 140 Trajectories, fifferestiell Effects,cindData
241 248 249 210 251 252 251 235 260 270 20
Guns--General, rtin DoniriCen J, Gun Tubes -BreachPiechesise Desg Spectral Choracterlustics of MuozleFlashI Automiatic We-Pont "Propellant Actuet'dDenices Designof Aerodynsamically Slebilixed Free Rockets 2B1'StD) Weapon SystemEffectineness (5U) afrns-ilsion and Propellents (REPLACED BY -28S)
Oar *281 . sc El,) 1enmntsof --1nullsss Part One. kill (01 O1,inerobilitt~y :1ainsad t 161(s) Eleinens Termina BI eistlis, Part Two, Collectionerg Analysisof Data Concerning Targets (U! l62:SBO) tlirmmots of Tenninal Velliscics. Part Three. yp~licattno Missileand SpaceTargets(A) losili-iled Projectilbesin ?OS rmor ens Its Applications (ul 176(C) Solid PopelIents PrtI Tin It) 1177 Properties oifEnPlosinos go Militaryinterest IWOC oProperties of Explosiors of MilitaryInterest. *Section Z (U) (REPLACED BY -171) 19 tuolo Sice Trains lAG Pinci'ples of faPlosIor Behavior 10 i.o i.son In Air:par n 68215) 'Explosions in Air Part Tn 185 MilitaryPpry -cs Pa Treoryand AppoInk Milli, itaechincs. .r letIw, Safety, Proceduret arI Glossary IA? HilitaryPyrotechnics. Part Three.Properties *of Materials Usen in Pyrol,chnicCompositionss 1tO 'Military Pyrotechnics. Part Four.Design of Armeunitiorn fur Pyrotechnic Effects 109 MilitaryPyrotecninics. Part Fine,Bibliography 190 'Arv~WeaponSystemAnalysts IV: Syste.. Analysisand Cost-Effnctloeness 199 -Development Ewed for Beliahil .-.. et One. Introduction. Background, ,nf9fr *Army Mater-AŽ1 Bmuiremevi I~ 'bPoxeelopitent Guidefor Belie ilitg,Pert Tao, Ons'uo for Reliability Is? 'Developmlent Guide'or Beliability, Part Three. *Reliubility PredictionI5 'Ocerlotnnent Guidefor Beliability. Fart Four. * elsabllity Measuremenot 199) -0frnlopmnet Guidefor Beliability. Pert Five. Contractingufor Be liasillity "cit Urrlom nt de for Beliaki lity-, Part Sin, Mathemtatical Agpe-ndia and Glossary *UNDER PREPARATION--not available
of
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**UEVISION UNDER PREPARATION -oBsoLEIE--Oout of stock
mo in Section 4, Design for Projeztioc *Areesxnitioc. Section5. Inspection Aspectsof CocAtionletsy ArtilleryionmDniti Amnte.S on .N rtu of Mietallit
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284(c) 289 286 290(C) 291 292
Trajectories (t) tlementsof Aircraftand MissilePropulsion (BtPLtCt$ -282) Structures hiarheasi--General (II) Surface-to-Air Missiles. Pcrt One, System Integratioin Missiles.PartTen, Weapon' Suirface-ti-Aim,
Control Surface-to-Air Missiles. Pars foue, Missile Armament(U) 29S(S) Surface-to-Air Missiles. Part Five.Coniterneesuroas (U) 246 Surface-to-Air Missiles. Pert Sin, Structares and PowerSources Z9715) Surfacet-fUl-Ar Missiles. Part Sevne,Stmple Prblm U 327 FireControlSystems--General 3219 FireControlComputing Systems 331 Conceiesating Elerneimts 335(SVD)*DesignEngineers' MoclearSofectiMarcel. and Weapons Systems(11) 0 folurm1. tienitions ?33C~50) Design tngineers' MaclearEffe-cts Maceel, Volsme11. Electronic Systemoand Logisticala systems(U) 337(940)'DesrIgnfEngseers NuclearEffectsMuhasclI Vol Ill . NuclearEnnironmentWU 33e1553) nino'NclearEfetMaul Aps n .sIrVninf.vla Effects MaUca 4 arae and Mouists--general 381 creeams 342 RecoilSystems 183 Top Carriages 3it BottomCrrriages 345 Esuillibators 346 Elevating Mechenisms 347 TraversinS Mechanisms 350 Whitceled Amphisbians 355 the Aattimtinis Assembly 356 Autmoatlne Suspensions 357 Automotive Bodies a91d Mulls 360 -Military Vehicle Electrical Systemt 845 Scoot Technology Engineering 294(S)
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No. AMCP 706117 118 119 124 126(S) 129 192 300 361
Title *Environmental Series, Part Three, Induced Environmental Factors *Environmental Series, Part Your, Life Cycle Pnvironments *Environmental Series, Part Five. Glossary of Environmental Terms kReliable Military Electronics *Vulnerability of Communication-Electronic (C-E) Systems to Electronic Countermeasures (except Guided Missiles) (U) *Electromagnetic Compatibility (EMC) Computer Aided Design of Mechanical Systems Fabric Design *Military Vehicle Power Plaf.t Cooling
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