R-2800: Pratt and Whitney's Dependable Masterpiece (Premiere Series Books) 0768002729, 9780768002720

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Pratt & Whitney's Dependable Masterpiece

Graham White

This book is on what was arguably I the finest aircraft piston engine ever produced - the Pratt & Whitney R-2800. It was an engine that was put together with the invaluable help of those who were actually there at the drawing boards, in the test cells and at the test flights . An aircraft engine, however, does not stand alone. R-2800: Pratt & Whitn ey s Dependable Masterpiece provides a background of Pratt & Whitney, and delves into the design challenges faced by its engineers when building the R-2800; answering questions like, "How did the airframe designers mount the engine?"; or "How was the intercooler supplied with cooling air?" In addition, this comprehensive book covers propellers, carburetors, and the many famous and not so famous aircraft the R-2800 powered.

From the Preface ... As the heyday of the R-2800 is rapidly becoming a fond memory, the younger generation needs to realize how commercial and military aviation gained prominence in this country thanks to the R-2800. Today 's generation, raised on the pungent stink of kerosene and the high pitched whine of a gas turbine's compressor, can take solace in knowing that at one time the wonderful aroma of burned oil and high performance fuel used to waft through airports along with that wonderful, loping idle of the R-2800, or its ferocious roar at takeoff power. That they dripped oil, and always looked messy with exhaust stains and oil leaks only added to th~ir charisma.

R-2800: Pratt & Whitney's Dependable Masterpiece examines the piston powered engine that helped lead a nation to victory in war, and the men and women whose hard work and dedication made it possible. Topics covered in this book include: • Why Radials? • Pratt & Whitney History and Background • R-2800 Development • Model Types & Specifications • Carburetors • Propellers • Installations • Military Applications • Commercial Applications • Helicopters • Operating, Service Difficulties and Overhaul • Racing • The Future

About the Author... Graham White was born in 1945 and spent his formative years in England where he got his start in aviation by racing U control model airplanes. Since then, he has spent much of his time researching and learning about the various piston powered aircraft engines that he adores so much. In addition to owning and restoring an R-2800, Graham's collection also includes an ultra-rare Continental IV-1430 Hyper engine; a Packard built Rolls-Royce Merlin, and two Pratt & Whitney R-4360s. Graham is also author of the SAE Bestseller Allied Aircraft Piston Engines of World War II (R-154).

R-2800 Pratt & Whitney's Dependable Masterpiece

Other SAE books

Allied Aircraft Piston Engines of World War II By Graham White (Order No. R-154) German Aircraft Industry and Production, 1933-1945 By Ferenc A. Vajda and Peter Dancey (Order No. R-236) The World's Most Significant and Magnificent Aircraft Evolution of the Modern Airplane By David B. Thurston (Order No. R-285)

For more information or to order this book, contact SAE at 400 Commonwealth Drive, Warrendale, PA 15096-0001; (724)776-4970 ; fax (724)776-0790; e-mail: publications @sae.org; web site: www.sae.org/BOOKSTORE.

R-2800 Pratt & Whitney's Dependable Masterpiece

Graham White

Library of Congress Cataloging-in-Publication Data White, Graham, 1945R-2800 : Pratt & Whitney 's dependable masterpiece I Graham White. p. cm. Includes bibliographical references and index. ISBN 0-7680-0272-9 1. Airplanes-Motors-Design and construction-History. 2. Air cooled enginesDesign and construction-History. 3. Pratt & Whitney Aircraft Group-History. I. Title. TL703 .P7 W45 2001 629.134'35'0973-dc21 2001020429

Copyright © 2001

Society of Automotive Engineers, Inc. 400 Commonwealth Drive Warrendale, PA 15096-0001 U.S.A. Phone: (724)776-4841 Fax: (724)776-5760 E-mail: [email protected] http://www.sae.org

ISBN 0-7680-0272-9 All rights reserved. Printed in Canada Permission to photocopy for internal or personal use, or the internal or personal use of specific clients, is granted by SAE for libraries and other users registered with the Copyright Clearance Center (CCC), provided that the base fee of $.50 per page is paid directly to CCC, 222 Rosewood Dr. , Danvers, MA 01923. Special requests should be addressed to tl1e SAE Publications Group. 0-7680-0272-9/01-$ .50. SAE Order No. R-241

Dedicated to my wonderful wife Diane who has always supported me in my various endeavors

Contents

Foreword .............. ........ ..... ... .... .... ... ..... ..... ........ .. .... ............ .......... .................. ..... ....... ............ ........... ix Preface .... .............. ........ .... ... .... ........ .... ..... ... .............. ... ... ..................... .. .............................. ...... .... .. xi Acknowledgments ...... ............ ...... ....... .......... ..... ...... .. ...... ..... .. ...... .. .... .. ... ....... .. .... .. ... ....... ...... .... .... . xv Introduction ... ............. .... ......... ............... ...... ..... .... .. ..... ......... .... ... .... ..... ....... ..... .... .... .... ...... .......... ... xix Chapter 1 Why Radials ? ......... .... ........... ....... ........ ........... ...... ... ......... .. ...... .... .... ..... ...... ... .... ... .. ... .. ... 1 Chapter 2 Pratt & Whitney History and Background ..... ... ................ .. .... .... .... ... ...................... .. ... ... 9 Chapter 3 R-2800 Development ........................ .... .... ..... ..... .... .... .. ..... .... .. .. ...... ... ....... ..... ...... ......... . 21 Chapter 4 Variations .......... ..... ..... ... ........ ............... ..... ....... ... .. ... ... .... ......... ..... ...... .... .. ............ .. ..... 125 Chapter 5 Model Types & Specifications .... ........................ .... ...... ............... ..... ..... ... .. ................ . 225 Chapter 6 Carburetors ....... ................ .......... .. ......... .. ... .. ... ... ... .. ... .... ... ....... ... .... .. ...... ..... .... ..... ....... 299 Chapter 7 Propellers ........ ..... ........ .... .......... ...... ............. .... .. .... ... ... ....... ... ..... .. .... .. ...... .... ... ..... ....... 317 Chapter 8 Installations ................... .............. .. ... ................. ... .. .. .... .... .... ... ...... ... ... ..... .............. ..... .. 365 Chapter 9 Military Applications ...... ............ .. .. ....................... ..... .. ... ... ............... ..... .... .. ... ... ....... ... . 375 Chapter 10 Commercial Applications ...... ..... ... ...... .. .......... ..... .......... .... .. ........ .... ...... .. .. .... ... ....... ... 563 Chapter 11 Helicopters ...... .... ...... .................. ........ .. .. .................. ........................... .. ..................... 601 Chapter 12 Operating, Service Difficulties and Overhaul ....... ...... ....... .... ... .... ... ... .... ....... ............. 617 Chapter 13 Racing ................. .... .................. ........ ...... .. ..... ... .. .... ..... ...... ..... .. ........ ...... ......... ... .... .... 655 Chapter 14 The Future ....... ... .. ..... .. ... ... ......... .. ...... .. .... .. ... ... .... ..... ... ..... .. ..... ... .... .. .... .... .... .. ... ..... ... 663 Color Section ...... ..... ............... ............... ...... .... .................. ........... ... .. ... ....... ... ... .... ....... .. .... ....... ... ... C 1 Index ............ ... ......... .. ............ ....................... .. ...... ... .... ........ .. .. .... .. ............. .. ... ..... ..... .... ... .. ..... .. ..... 669 About the Author ..... ......... ... .... ....... .................. .... ...... .. ..... .. ... ........ .. .. ..... .. ... ... .. .... .. ........ ....... ... ..... 717

vii

Foreword

It has been a pleasure for me to know that Graham White 's first book-Allied Aircraft Piston Engines of World War II-has sold a solid 9000 copies to date . It's comforting for each of us who have read this book to know that there are nine thousand others out there with similar interests. Because the book had none of the usual "units and markings" flavor of so many WWII equipment histories, we can be sure that most of those nine thousand are others to whom historic engines and their design are important. The value of writing a book such as this is threefold. First, for many of us these engines stand on their own as engineering, art, or theater. Second, preservation of the details of human technologies is always valuable. And third, and perhaps of the greatest interest to the publishers, SAE, is the lesson herein that engineering is detailed analytical thought about physical problems . It is not just a simple of process of plugging values into some $30,000 engineering software and then hitting "run." Many persons, and this too often includes management, imagine that "engineering is solved now. " This view holds, for example, that successful auto engines can be designed from electronic cookbooks, sent for brief testing at Prototype, and will then be ready for production- almost entirely bypassing all processes of human analysis and thought. To the degree that what we are designing is of routine specification, this may be possible. The plan fails when anything difficult is attempted. Consider the cam drives of auto or motorcycle racing engines, which almost invariably display some kind of destructive instability as first drawn. These problems must then be, in the language of Pratt & Whitney engineers, "trampled to death." This means that such a variety of possible solutions must be tried in rapid succession, that an answer is shortly found and development can proceed to the next difficulty. The higher you reach in technology, the more true this becomes . The development history of the Space Shuttle Main Engines is a prime example. No doubt computer analysis using every kind of boilerplate and custom computer software was attempted in the initial design, but many years were necessary to achieve reliability. Each tin1e there was a failure in an oxygen turbopump, nearly all evidence was destroyed by hot reaction with the escaping fluid. The engineering team then had to propose all conceivable failure modes, eliminate those made impossible by surviving evidence, and

ix

Foreword

quickly implement whatever remained for the next test. This is the essence of engineering-to extend physical understanding of what is happening in the equipment, and then to make and test the hardware implied by that understanding. This is the great lesson of the R-2800 radial aircraft engine; that each difficulty must be solved by reasoned physical thinking, guided by recourse to testing . This places great importance on understanding what goes on in devices and processes. It makes experience and reflection important. It reveals that analytical tools are valuable, but can take us only so far. These tools by themselves understand nothing . That is up to us. At a pleasant dinner with three professors from RPI, I was told that every entering class of students is better prepared in math and keyboard skills- and less experienced in dealing with practical physical matters. This is a result of the present emphasis on formal preparation and credentials as the unique pathway to a good job. This emphasis leaves much less time for the former youthful pastimes of Erector Set, hot-rodding engines, and soldering electronic kits. The armed forces of the world observe the same trend-new recruits in the 1930s could be relied upon to have some physical intuition, based upon experience with farm vehicles or personal projects. Today, it is a rare soldier who knows that there are 25.4 millimeters in an inch. Without traditional childhood play as a source of physical intuition, today's formally educated engineer must complete his childhood on the job, making the foolish mistakes that old-timers love to joke about. The R-2800 is a valuable example of thoughtful engineering. It is an antidote to the temptation to become just another chair-warming ProE jockey, keeping physical reality at a distance with electronic menus.

Kevin Cameron

x

Preface

On a beautiful fall day in November, 1998, eight elderly gentlemen met with the author in one of Pratt & Whitney's plush conference rooms, in the company's training center located at corporate headquarters in East Hartford, Connecticut. They came from all walks of life. Some were in better health than others, but they all had one thing in common: each was a WWII veteran, not in the trenches but in the test cells and design offices. Their primary interest was aviation, specifically a passionate belief that preserving the history of the Pratt & Whitney R-2800 was essential. Even though their bodies were showing signs of wear and tear, there was no doubt that their minds remained as sharp as tacks. The other thing they had in common was that when this engine was in its infancy they were there. These fine gentlemen made a contribution to WWII well beyond even their wildest dreams. As the author of this book, I am simply the historian, but these men made it happen with their fertile minds and engineering ingenuity. They were part of that great generation that won WWII, and the freedom that we all too often take for granted these days. Even though they were not in the trenches, they made similar sacrifices: 70- to 80-hour work weeks, no time off, and intense stress and pressure to squeeze every last horsepower out of the engine yet maintaining some modicum of reliability and maintainability. They also shouldered the additional responsibility of ensuring that the brave young fighter pilots, bomber pilots, and transport pilots could assume their engine would not let them down. Allow me to introduce them to you in alphabetical order: C.G. Beckwith Larry Carlson Jack Connors Jesse Hendershot Phil Hopper Bill Martens George Meloy Elton Sceggel Frank Walker Dana Waring

xi

Preface

A group shot of some of the pioneers responsible for the R-2800. This p hoto of the R-2800 test engineers was taken around 1944. Front Row: Frank Walker, Grady McRae, John Kojfel, Al Swansson, Bob Teneyck, Art Krill, Armin Rabel, and unknown. Second Row: Elaine Anderson, June Davis, unknown, Ralph Page, Elton Sceggel, Jim Roets, Bob Rickner, Bev Pierce, and Bob Meyer. Third Row: Jim Nassau, Charles Malcolm, Fred Hendy, Jack McDermott, Larry Carlson, unknown, Gordon Beckwith, Norm Briggs, Hilton Hamm, and Jack Esgar. Not available for this historic photo were: Roland Ely, Bob Davisson, Bill Isfdeld, Clay Osborne, Clarence Bird, Harold Archer, Bill Kennedy, and Wes Khurt.

The photo above shows many of the gentlemen mentioned above during their R-2800 development days along with other members of their team. The focus of this book is on what was arguably the finest aircraft piston engine ever produced. It was put together with the invaluable help of those who were actually there at the drawing boards, in the test cells, test flying, twisting wrenches, troubleshooting, and redesigning . I feel privileged to record the history of this significant artifact and piece of Americana.

xii

Preface

As with many successful mechanical developments, the R-2800 's history is littered with many failures and success stories. The success stories are, by now, quite familiar; however, the failures are hidden in dusty archives . And of course, this is exactly how it should be. Failures, design problems, and the like should never be allowed to escape into the manufacturing environment. In the case of the R-2800, instances of problems getting into production were, thankfully, few and far between. Nevertheless, with an engine as complex and highly stressed as the R-2800 it was almost inevitable that on occasion this did occur. Sometimes it was due to design problems and on other occasions manufacturing problems manifested themselves as field problems and even in-flight failures. Thanks to the valiant efforts of the fine gentlemen listed above, and their co-workers, the R-2800 was constantly updated with design improvements, manufacturing improvements, and ease of maintenance improvements . The desperate days of WWII brought out the best in man and machine. And don 't let us forget the sacrifices made by the legions of women collectively known as "Rosie the Riveter. " During World War II, the R-2800 would never have been manufactured in the huge quantities necessary for successful execution of the war without the women who gave up home life in order to help out on the battlefront. Second best was not good enough, particularly in light of the excellent material being produced by the Third Reich and Japanese industry. The technological see-saw battle ensured that no one got any rest until the monumental conflict of WWII was over. At the end of WWII the respite was brief; after all, Pratt & Whitney was a business with stockholders to take care of and bills to pay. The postwar period was one of developing a reliable power plant for the airlines to power their aircraft, and, hopefully, with which to make a profit. In this environment, the R-2800 succeeded beyond anyone 's expectations. By piston engine standards, the R-2800 delivered as promised and helped the burgeoning post-WWII airline industry into profitability. Obviously, an aircraft engine does not stand alone: How did the airframe designers mount the engine? What kind of exhaust system was employed? How was the intercooler supplied with cooling air? And how was the critical oil system designed so the engine was assured of a copious amount of clean, filtered, and cool oil? These and other these design challenges are covered along with chapters on propellers, carburetors, and the many famous and not so famous aircraft it powered . As time goes by the historian's job becomes increasingly difficult as fiction starts to take over from fact, and the people actually involved with the production of the R-2800 inevitably pass on. My good friend Kevin Cameron once eloquently expressed it as "history passing to the grave." A macabre way of looking at things, possibly-but true nonetheless . The inspiration for this book came from the late Harvey Lippincott. While performing research on my previous book, Allied Aircraft Piston Engines of World War II, I visited with Harvey and his extensive research facility in the basement of his charming home in Connecticut. During our visit I casually asked Harvey ifhe knew of anyone writing a book on the R-2800. It came as a surprise to me to learn that no one had even expressed an interest in tackling the job, even though readership

xiii

Preface

interest was there . The seed was then planted in my head to rectify this oversight, despite the fact that far more qualified people than I could have accomplished the job. Hopefully, I have not let down the thousands of engineers, manufacturing people, pilots, maintenance personnel, and others involved with the R-2800. As the heyday of the R-2800 is rapidly becoming a fond memory, the younger generation needs to realize how commercial* and military aviation gained prominence in the United States thanks to the R-2800. Today's generation, raised on the pungent stink of kerosene and the high pitched whine of a gas turbine's compressor, can take solace in knowing that at one time the wonderful aroma of burned oil and high performance fuel used to waft through airports along with that wonderful, loping idle of the R-2800, or its ferocious roar at takeoff power. That they dripped oil, and always looked messy with exhaust stains and oil leaks only added to their charisma.

*Please note that the words "commercial" and "civilian" have been used interchangeably throughout the text.

xiv

Acknowledgments

When writing a book I am reminded of two Chinese proverbs: "Be careful what you ask for-you may get it"; and "A journey of a thousand miles starts with the first step. " Staring at a blank computer screen with the cursor blinking at you (the first step) and realizing that a book has to be produced (1000-mile journey) is intimidating-to say the least. That's why "Be careful what you ask for" is valid advice, after all, no one twisted my arm to write this book. Without the help of many people, this metaphorical journey of a thousand miles would never have come together. With the foregoing in mind, I'd like to mention some of the folks who have offered their assistance in the production of this book. I met Kim McCutcheon at the 1998 Sun 'n Fun Convention held each year in Lakeland, Florida. Kim immediately took an interest in the R-2800 book project. He asked to accompany me on the Pratt & Whitney archive trip, which I gladly agreed to. The R-2800 crankshaft development was a tortuous one. Kim immediately started to assemble all the SMRs (short memorandum reports) pertaining to crankshaft development. This material was sufficient for a detailed paper to be published by the American Aviation Historical Society. Kim also kept me honest with his thorough reviews of the manuscript. Pratt & Whitney has a long and proud heritage, and like many, but not enough, corporations, they would like to preserve and publicize this history. Fortunately, Pratt & Whitney kept much of its obsolete documentation regarding the R-2800: engineering reports, company memos, and the like. And this is how it should be. Even if it could be argued that this material is no longer relevant in today's environment, regardless of what Henry Ford said ("History is bunk"), those who ignore history are destined to repeat it. Reading through accounts of the trials and tribulations that the brightest and smartest engineers the United States could offer faced over 50 to 60 years ago, many of the lessons learned are still valid today. Without this information, the R-2800 's history would have been far more difficult to document. With this in mind, a posthumous acknowledgment is in order. Harvey Lippincott was the driving force behind the world class Pratt & Whitney archives. Harvey passed away before this project got off the ground; nevertheless, without his diligence in collecting material that, in all likelihood would have been pitched out, the archives would never have come together. In no particular order, I would like to mention some of the folks who contributed to this book.

xv

Acknowledgments

Dick Wellman, manager of Pratt & Whitney's Training Center, was very helpful in greasing the skids on my behalf in order to gain access to the archives. Dick also went out of his way to ensure that everything I needed was at hand including a copier, computer, etc. Without Dick's cooperation, I would never have gleaned as much information from the archives . Additionally, Dick is to be highly commended for his commitment to preserving a piece of Pratt & Whitney's heritage by supporting and ensuring adequate funding of the Pratt & Whitney Museum located on the company's premises. Last but not least, Dick jumped through hoops on my behalf to get permission to use the Flying Eagle logo on the dust jacket. Riding shotgun with Kim and me in the archives was Jesse Hendershot. Jesse pulled together as much R-2800 material as he could find in the archives. Considering its size, a daunting task. Nevertheless, Jesse managed to gather a huge amount of material prior to my visit. For that, I'm extremely grateful. Jack Connors, retired Pratt & Whitney engineer, also greased the skids on my behalf on many occasions . Although retired, Jack still keeps his hands full with respect to aircraft power plants by volunteering his time as engine curator at the New England Air Museum. Larry Carlson, another retired Pratt & Whitney executive, shared many insights with me, particularly in regard to personalities such as Luke Hobbs, George Mead, etc. His experiences with the development of fluid drive superchargers, which he was personally involved in for "E" series R-2800s, was invaluable. Larry also kept me honest, the most unenviable of tasks, reviewing various drafts of the manuscript. Craig McBumey's enthusiasm for the Chance Vought Corsair knows no bounds. Over the years, in his quest to gather parts and information for the F4U-4 he is restoring, Craig has accumulated a significant collection of Corsair material. Information for the manufacture of "C" series cylinder heads came from a paper Craig had acquired. In addition, Craig's encyclopedic knowledge of the Corsair series of aircraft has been of inestimable value. He also reviewed drafts of the manuscript, and his many suggestions and corrections were invaluable. Kevin Cameron, technical editor of Cycle World magazine is always an inspiration and a ready source of technical information. Never one to shy away from a project, Kevin and I purchased several Pratt & Whitney R-4360s for eventual restoration to running condition. Whenever a technical issue arose during this project, Kevin always had a ready answer via e-mail or our alwayslengthy and interesting telephone conversations. Ray Anderson is the owner of Day Air in Stockton, California. Day Air is one of the few R-2800 overhaul facilities left in the world. Despite having to run a business, Ray always graciously accepted my calls in my quest for R-2800 information. Even though Rolls-Royce is a fierce competitor of Pratt & Whitney, I can always rely on them, in particular the Rolls-Royce Heritage Trust, to assist in any project I am involved with. Notwithstanding their competitive relationship with Pratt & Whitney, both companies realize the importance of

wi

Acknowledgments

saving our aviation heritage. In this regard, Richard Haigh of the R-RHT always responded immediately to my requests for photographs. Karl Ludvigsen, fellow committee member on SAE's Historical Committee, has a vast collection of auto and aviation photos and related material. My constant requests for difficult-to-find photographs were always answered with a care package containing the much sought after photos. Warren Bodie and I (he refers to me as "Red Bearing," a play on words for my e-mail handle of "redbaron") have enjoyed many animated discussions related to aircraft or anything else that comes to mind. Warren is a preeminent aviation author with many best-selling books to his credit. His photograph collection is legendary. Whenever I needed a photo, Warren could be relied upon to come through. Often described as "A Prince of a Guy," Al Marcucci richly deserves this accolade. Al has always supported my aviation interests. He is owner of "Savage Magneto Services," based in Oakland, California. In the quest for information on R-2800 ignition systems, Al very kindly loaned me his entire collection of R-2800 ignition related material. Bruce Vandermark is always on the lookout for manuals and other material that he knows I will appreciate. Bruce sent many interesting pieces of historical material that helped out with this R-2800 project. Carlos Arana is the owner of Florida Airline Services, Inc., based in Miami, Florida. Carlos has spent his entire career working on and around large radials. Whenever a technical problem arises, Carlos is always ready to help me out. He also kindly loaned me several photos of "Corrosion Comer" in its heyday. Tim Travis, corporate communications manager at Raytheon Aircraft Company was kind enough to dig into the elusive Beech T-36A for me. Don Jordan is the brilliant engineer responsible for the engine installation designs of the F 4U Corsair series of aircraft. Don kept me honest in describing the Corsairs ' power plant installation details. In addition, he finally solved the mystery of who the "Turbo Engineering Company of New Jersey" was . Willie Walter has always been a good friend. He spent his entire career from WWII to the early 1990s working on P&W radials. David Cummings came to my rescue at the last minute by furnishing information and anecdotes about the Howard 500. David was also responsible for supplying the Howard 500 photo. Andrew Richards kindly offered to put his commercial art skills to use by fixing up a number of very obscure line drawings to make them more understandable. Andrew is now employed by my good friend Al Marcucci.

xvii

Acknowledgments

Carburetor and fuel guru, Pete Law, kindly loaned me a color copy of the Bendix carburetor layout. Dan Whitney, author of Vees for Victory, the definitive work on the Allison V-1710, was always willing to offer his expertise. Dan also came up with a fascinating and unpublished Navy report that gave insight into fuel injection and propellers-among other things . Indexing is a difficult and thankless job. Nevertheless, I'd like to mention Bob Richardson who did a superb job of indexing this book. In addition to the folks mentioned above, a special thanks to the engineers mentioned in the Introduction and the individuals mentioned in the text. Without them, the R-2800 would not have happened and consequently you would not be reading this book. For those who assisted in any way and are not mentioned in these acknowledgments, my sincere apology.

XVUI

Introduction

The magnificent roar of big cubic inch, air-cooled radial engines has almost been silenced. This state of affairs is a result of the reliability, smoothness, and overall economy of Sir Frank Whittle's gas turbine. Almost-but not quite silenced. Due to the efforts of dedicated enthusiasts and collectors, many examples of these aviation masterpieces are still stirring the hearts of even the most hardened aviation enthusiast. During their heyday, radials dominated commercial aviation and played a significant role in military aviation . Their simplicity of design, particularly cooling, held sway over their liquid cooled inline competitor for commercial applications; however, as we shall see, the controversy over these two concepts dominated leading edge aircraft engine technology for the better part of four decades . We tend to assume that all radials are air-cooled, but in fact many examples were developed that featured water or liquid cooling. The first aircraft radial engine developed and built was the Manly 5-cylinder radial, built for Langley's attempt at aircraft design called the "Aerodrome" (Ref. I. l). At 5 3 horsepower, this water-cooled engine was far superior to any other gasoline engine of 1903. Unfortunately it did not receive the accolades it so richly deserved due to the miserable failure of the Aerodrome. Too bad Charles Manly never hooked up with the Wright brothers. Rather surprisingly, despite the undisputed efficiency of Manly's engine, it would be many years before serious development of the radial was undertaken again. One factor that contributed to this concept being sidelined was the introduction of the rotary. Developed in Paris, France, by the Seguin brothers, this rather odd but fascinating engine development dominated aviation power plant thought for several years until the end of World War I, and then, like the mayfly, seemingly disappeared from the aviation scene almost overnight (Ref. I.2). The story of the rotary is out of the bounds of this work. However, a brief description is in order. In a conventional engine the driven member is the crankshaft, which also serves as the power means to supply the power out via gears, clutch, or in the case of a direct drive aircraft engine, the propeller. For the rotary, things were reversed. The crankshaft remained stationary and the rest of the engine rotated. Furthermore, the crankshaft also served as the engine mount via a large round flange at its rear, which was then attached to the airframe. The cylinders, arranged in a radial configuration, attached to the cylindrical crankcase. Fuel/air mixture was introduced through the hollow crankshaft via a primitive carburetor mounted at its end. Upon entering the crankcase, the fuel/air mixture entered the cylinder through a spring-loaded valve located in the crmvn of each piston. As the piston descended on the induction stroke, the valve would open under the influence of low pressure in the cylinder, allowing the fuel/air mixture to enter from inside the crankcase. As rotaries evolved, dedicated intake valves were developed, mounted in the cylinder xix

Introduction

head. A conventional spark plug and magneto supplied ignition. High-tension voltage was transmitted to the plug via a slip ring and wire, under spring tension, from the slip ring to the plug. A single valve in the cylinder head provided egress for the exhaust gases. A cam ring, pushrod, and rocker arm actuated the valve. Lubrication was of the total loss system, i.e. , the oil was not returned to the engine or an oil tank; instead, it was burned in the exhaust. State of the art for lubricating oil in those far off days was castor oil. Of course, castor's medicinal value was well known, even in those days. Much has been written about the effects on the pilot from breathing the castor oil fumes. In reality, it probably was not as bad as has been documented. The reason for this is that the exhaust valves, regardless of which cylinder it belonged to, always opened at the same part of the revolution of the engine. Therefore, rotary engines were always timed to open the exhaust valve towards the bottom of the cowl in an effort to keep the exhaust and its medicinal properties a\vay from the pilot. Interestingly, in a further effo1t to keep exhaust gases away from the pilot, ring cowls were developed, similar to the Townend ring and NACA cowls developed in the late 1920s for improved radial engine cooling and reduced drag. At the time they were developed for the rotary powered aircraft, their aerodynamic advantages were not fully realized. The French Salmson radial was arguably the first successful radial to be developed after Manly's superb effort. Again, the Salmson was developed in France and manufactured in volume during WWI with later ones rated at 250 horsepower (Ref. 1.3). This water-cooled engine was developed in many varieties including a version with a right angle drive for the power output. Interestingly, many of the early radials featured water cooling. The primary factor contributing to this was the difficulty of air cooling or more precisely heat rejection. It took several years before air-cooled cylinder technology was up to the task. In the meantime, aircraft engine development was littered with dismal failures . Undoubtedly the best known was the ABC Dragonfly. Built in England during the latter stages of WWI, the Dragonfly engine was designed by Granville Bradshaw, who later moved into the auto industry where he developed so-called cycle cars, popular in England during the 1920s. This poor excuse for an engine almost crippled the British war effort of WWI. Vibration and its effects were a little understood phenomenon in the early days of aviation and engine development. Bradshaw unintentionally designed the Dragonfly's crankshaft to run at its natural harmonic frequency (Ref. 1.1). In as little as five hours, the crank would fail from metal fatigue. Fatigue failure was another little understood phenomenon at this time, often described as "crystallization. " Aircooled cylinder design, even after the intense development forced by WWI, was still in its infancy. Rotary engines rarely suffered from overheating because the cylinders produced their own powerful forced draft as a result of their rotation with the engine. The Dragonfly's cylinder, on the other hand, was totally deficient from a heat rejection perspective. Inadequate cooling fin area that was incapable of dissipating the heat rejection of combustion from the Dragonfly's 295 horsepower caused serious overheating. At night, the cylinder heads could be seen glowing a dull red! Exacerbating the problem was the fact that it suffered poor mixture distribution resulting in lean and rich running cylinders. Being a skillful entrepreneur, Bradshaw convinced the British government that his radial engines should power the next generation of Royal Air Force (RAF) aircraft. Consequently, British industry retooled for this monstrosity and it was fortunate that WWI ended when it did, otherwise the British would have had to rely on other engines such as the U.S.-built Liberty. The Dragonfly exemplified some of the more serious problems that can beset a radial, i.e ., torsional vibration,

xx

Introduction

overheating due to poor cylinder design, fatigue failure of major components, and poor mixture distribution. Although most radials suffered from these and other types of failure during development, rarely did an engine enter mass production with one of the aforementioned problems. Over the course of the next 20 years, these problems and others would be overcome, making the radial the power plant of choice for commercial and military aviation. Fuels and fuel development would continue apace with development of the engine. As one part of the development envelope was pushed, a weakness in another area would surface . Therefore, as fuel quality increased, via octane rating or performance number, engine developers immediately took advantage of this and increased compression ratio or increased the maximum allowable manifold pressure and ad infinitum. Starting with an octane rating of 50, or even less, fuel development finally reached a high of 150 PN (performance number). However, the most common high performance aviation fuel used at the end of the large displacement piston engine era was 115/145 PN. A brief dissertation on the meaning of performance number and its relationship to octane number is in order. Sam Heron (more about Sam Heron later) came up with the performance number label. The PN scale was introduced in 1943, some years after the British had a crude version of it based on a 100 octane number commercial gasoline (Grade 100/125). The PN scale was introduced after the army and navy specified fuel with a lean rating of 100 octane number and a rich mixture rating equal to isooctane plus one cubic centimeter (1 cc) of tetraethyl lead (Grade 100/125). In simple terms this means pure isooctane is 100 octane and adding one cubic centimeter of tetraethyl lead boosted the performance of the fuel to 125 PN when running on the rich side of stoichiometric (Ref. 1.4and1.5). Army and Navy personnel were confronted with the problem of explaining to military brass that it was not possible to assign an octane number to isooctane plus one cubic centimeter oflead. Operating personnel in the supply and maintenance divisions of the services arbitrarily started to assign octane numbers to the new fuel and consequently mark fuel-servicing trucks. Of course, no specs existed at the time so fuel might have been described as 104 octane at one location and 108 octane at another location. One can imagine the confusion caused by this mislabeling. A pilot landing at a field with fuel designated as 104 octane and needing " 10 8" would, in all likelihood, refuse the 104 fuel as being unsafe. This state of confusion and, at times, chaos needed a fix. The army, navy and British Air Commission representatives decided that fuels of 100 octane number and higher should be described by performance number (PN). The PN scale was based on 100 octane number, i.e., pure isooctane, as permitting 100 percent power in a supercharged engine, and 130 PN fuel permitting 130 percent of the power for the same engine operating on 100 octane fuel. The relation between permissible power (i .e., maximum power before the onset of detonation) and various concentrations of lead in isooctane (which, of course, had been the rating scale previously in use) was derived by averaging a large number of single-cylinder and full-scale engine and laboratory single-cylinder engine data. Bearing materials and bearing technology also advanced. As horsepower ratings increased, existing bearing technology became inadequate for the job at hand with resulting catastrophic failures becoming commonplace. And again, engineers stepped up to the challenge with fatigue resistant hard backed silver and later lead indium silver bearings for the arduous duty of master rod bearings and crankshaft main bearings.

xxi

Introduction

Despite the devastating depression of the 1930s, significant developments continued unabated in the quest for ever more power at lower weights, lower fuel consumption, and greater reliability. It was during this period of feverish development that commercial aviation was at last a viable form of transportation and entrepreneurs could finally make money at running an airline. The air-cooled radial played a significant part in this transportation revolution. Better fuels , lubricants, advanced propeller designs, carburetion, and supercharger design also made their contributions. World War II brought these developments together and, as World War I did, accelerated further development. By the end of World War II, the big cubic inch military piston engine had reached its zeQith. Post-World War II development was reduced to a minimum thanks to the introduction of the gas turbine. However, the piston engine would continue to be the only type of power plant available to commercial aviation for another dozen or so years. Nonetheless, the technology employed was, if anything, less sophisticated than that used during World War II. A couple of notable exceptions stood out from the foregoing, one being the jet powered de Havilland Comet. A brave attempt at introducing jet powered transportation, the Comet suffered from a fatal flaw. Although fatigue failures were better understood by the 1940s, this type of failure mode was not a science for aircraft structures. As a result, the Comet suffered from catastrophic fatigue failure of the fuselage emanating from passenger window openings . After an exhaustive investigation of several Comet crashes, the results were published in a detailed report. Boeing, in particular, was the beneficiary of this report when designing the highly successful 707. Even though the early Comets suffered from this fatal flaw, the British still pioneered gas turbine powered civilian aircraft the most notable being the successful Vickers Viscount powered by four Rolls-Royce Dart turbo-props. The United Stated took a more conservative approach and relied on the, by now, fully developed aircooled radial engine to power their commercial transports. But, piston engine development was sidelined by the big manufacturers such as Pratt & Whitney in favor of gas turbine development. Even so, many military and civilian aircraft were developed, manufactured, and operated through the 1960s by major airlines and the USAF. Of course, the Pratt & Whitney R-2800 played a major role in these activities. Many historic and significant R-2800 powered aircraft are being modified by their well-meaning owners . One of the favorite modifications is the replacement of the correct military R-2800 in warbirds for a civilian CB16. Oftentimes the CB16, or other incorrect R-2800, bears little resemblance to the correct engine. Although these modifications typically do not compromise the safety of the aircraft, historians should be aware of these major changes and not be fooled into thinking that's how the airplane was originally manufactured. If this book only achieves this one objective of making folks aware of what is correct and what is not, I' 11 be happy. Throughout the text various terms have been used interchangeably. For example, water injection and ADI are both used, as they are both standard terminology; likewise with blower and supercharger. The terms single-stage supercharging and two-stage supercharging are often abbreviated to single stage or two stage.

xxii

Introduction

References I.I Gunston, Bill, World Encyclopedia of Aero Engines, Patrick Stephens Limited, 1986. 1.2 Morse, William, Rotary Engines of World War One, Nelson & Saunders, Buckinghamshire, 1987. 1.3 Jane, Fred, Janes Fighting Aircraft of World War I, Military Press, New York, 1990, originally published in 1919. 1.4 Heron, S.D. , The History of the Aircraft Piston Engine, Ethyl Corp. , Detroit, 1961. 1.5 "Development of Aviation Fuels," Aero Digests Aviation Engineering, May 1941.

xxiii

Chapter 1

Why Radials?

Why power an aircraft with a radial engine? After all, we come to expect aircraft to be the personification of streamlining and perfection of form-the ultimate statement of form follows function. The radial engine seems to defy these basic attributes with its air-cooled cylinders radiating out fan style creating what appears to be built-in drag. In fact the radial offers many advantages over its inline, liquid-cooled competitor. And even the perceived installation drag was all but eliminated at the end of the radial engine 's reign putting it in the predominant position for power plant choice. The lowest weight for the most power and the lowest specific fuel consumption are the parameters any aircraft engine is designed to-commensurate, of course, with a reasonable time between overhauls; and, if you are a commercial operator, low cost. Looking at the big picture, the radial actually fills the bill in all the aforementioned areas. However, it took many years and the creative genius of the finest aerospace engineers of the 1920s and 193 Os to achieve these goals. Cooling, structural issues, manufacturing, reducing the installed drag to the level of its inline, liquid-cooled competitor, and other problems were resolved to make the radial supreme in commercial aviation and a worthy power plant for military applications. It was, of course, the Pratt & Whitney R-2800 that personified all the above requirements. Without this engine, World War II would have been a far more difficult war for the Allies to win. Powering many of the significant fighters and medium bombers of this monumental conflict, its reliability, ease of maintenance, and power were of supreme importance. Postwar, the R-2800 continued to distinguish itself in military and c01m11ercial aviation. Although the military soon took advantage of the emerging gas turbine technology, some commercial passenger operators relied on the R-2800 into the 1970s. Cargo hauling operators will use R-2800 powered aircraft well into the 21st century. The R-2800 has also gained a new lease on life with the burgeoning warbird environment. It was the evolutionary development of the cylinder-the heart of the engine-that contributed to the radial engine concept (Ref. 1.1). As horsepower ratings increased, the required heat rejection also increased. Unlike its liquid-cooled sibling, improving the heat rejection of an air-cooled engine required a lot more thought than sin1ply installing a larger radiator and/or a higher output coolant pump . Indeed, it took many years of painful development with many setbacks on the road to success .

1

Chapter 1

Early air-cooled cylinders employed what was known as the poultice head . This simply meant that the cylinder barrel featured a closed end at the combustion chamber end. The valve seats were incorporated into this closed end and the cylinder head butted up against the top of the cylinder. Even under ideal conditions the heat transfer between the cylinder top and the cylinder head was marginal and under typical operating conditions the seal and consequently the heat transfer was almost non existent. This design concept resulted in design disasters like the ABC Dragonfly (Fig. 1.1). Precision casting technology was also in its infancy during these embryonic years. This resulted in cooling fins being spaced too far apart with insufficient depth. An Englishman by the name of Sam Heron (Fig. 1.2) was the knight in shining armor as the savior for the air-cooled concept. His contributions to the science of air-cooled cylinder design have continued on to the present day and can be seen on any Continental or Lycoming general aviation aircraft engine. As an aside, Heron (Ref. 1.4) also made significant contributions to fuel development and other engine-related improvements such as the sodium-cooled valve. Heron was born in New Castle Upon-Tyne in the North East of England on May 18, 1891. While serving an apprenticeship as a mechanic and foundryman at the Thames Iron Works Shipbuilding and Engineering Company, he attended night school for engineering classes. He also gained experience as a draftsman at Sir W.G. Armstrong Whitworth & Company Ltd. Later, this company became a major player in the British aircraft construction business. During World War I he bounced around several employers, but his most significant work was the time he spent at the Royal Aircraft Establishment. While there, he worked with Major F.M. Green, with whom he collaborated on, among other things, air-cooled cylinder design. Green was one of the pioneers of engine development and during his tenure at the RAE he was responsible for the development of several aircraft engines, most of which were based on modified Renault air-cooled V-8s and V-12s.

It was during World War I that aircraft engine development took quantum leaps . With increasing power came liabilities. One of the more significant was the requirement for more heat rejection as the power per cubic inch of engine displacement increased. Water-cooled engines of the time experienced little difficulty in dealing with this problem- not so with the stationary air-cooled engine. Aircooled rotary engines rarely suffered from overheating because of their idiosyncratic mode of operation by spinning on their axis, which induced a forced draft and their relatively low specific power. Heron played a significant part in understanding and developing solutions to these heat rejection issues by employing new (for the time) materials such as aluminum alloys. At the cessation of hostilities, Heron worked for several British aircraft engine companies, but could not find his "niche. " Consequently he sailed for the United States in 1921 and got a job with the Engineering Division, United States Army Air Corps (USAAC), at McCook Field and later Wright Field . He was associated with the military from 1921to1926 and 1928 to 1933, during which time Heron continued to make valuable contributions to air-cooled aircraft engine technology. The in-between years of 192 7 and into 1928 were spent at Wright Aeronautical Corporation, where he helped develop the Wright Whirlwind. This engine was the power plant that got Charles Lindbergh safely across the Atlantic from New York to Paris in 1927, and in doing so forever placed Lindbergh in the annals of aviation history. Heron took personal responsibility to inspect Lindbergh's engine for this epic flight. Every detail of the high performance air-cooled cylinder received Heron 's scrutiny. Exhaust valves were a constant source of problems, particularly with all early internal combustion engines prior to the 2

Tif!hy Radials?

921·~1

Fig. 1.1 ABC Dragonfly, possibly one of the sorriest excuses for an aircraft engine ever produced. If World War I had dragged on for an additional six months, England would have been in serious trouble due to commitments made to have the Dragonfly replace other aircraft engines. This engine exemplified all the possible design problems of a radial engine and therefore represented an excellent example of how not to do it. (Courtesy of "World War I Aero" and Bruce VanderMark.) 3

Chapter 1

Fig. 1.2 Sam Heron, one of the pioneers of air-cooled engine development and fuel development. His engine development work strongly influenced Pratt & Whitney along with all the other major producers of aircooled radials.

advent of high temperature steel alloys . Sodium-cooled valves, which became indispensable when specific powers reached 0.5 horsepower per cubic inch and greater, were developed by Heron (Fig. 1.3). Although solid at ambient temperature, the sodium quickly liquefied in the high temperature environment of the exhaust. Upon melting, the sodium would slosh up and down inside the hollow valve thus transferring heat from the red-hot head of the valve to the much cooler stem, through the valve guide and ultimately to the cylinder head. Spark plug design, metallurgy, lubrication, fuels , and valve seat insert material also contributed to his repertoire of innovation. All of the above were key to the radial engines' domination of piston engine powered aircraft and to the R-2800 's subsequent success. Early radial engine installations simply consisted of hanging the engine on a tubular steel mount with no cowling. This arrangement was adequate for aircraft developed in the 1920s with air speeds ofless than 150 mph, but as horsepower and consequently speed increased the fallacy of this concept became painfully evident. In two parallel developments, cowlings were perfected which overcame these deficiencies . In England, H. Townend developed a cowling ring named after him. Working for the National Physical Laboratory, he wrapped an airfoil shape, made from aluminum, around the cylinders. This made a dramatic difference to installed drag even though it only had a narrow chord and simply covered the cylinder heads (Ref. 1.2). In the United States a similar solution was evolved by NACA, except their solution featured a wider chord (Fig. 1.4). NACA's cowl was somewhat analogous to a ram jet. An efficient diffuser, in the form of the NACA cowl, resides at the front where it recovers much of the flight dynamic pressure and converts it into static pressure in front of the engine. The cooling baffles and cylinder cooling fins restrict air flow to the minimum required to transfer heat to the highest practical cooling air temperature. The exhaust system is often designed to accelerate the used hot cooling air up to the highest possible aft velocity. When this combined exhaust and cooling air velocity is higher than flight speed, the cooling drag can be reduced to zero or a net thrust; just like a ram jet (Ref. 1.3). Of course, some R-2800 installations were better than other in this regard as will be related in more detail in subsequent chapters. As cowling design evolved, cooling flaps were incorporated to control the mass air flow through the cowling and thus control the engine temperatures and maintain them at their optimum (Fig. 1.5). As the radial engine

4

Why Radials?

Fig. 1.3 One of Sam Heron :S more wellknown developments, the sodium-cooled valve. Prior to Heron :S internally cooled valve, engine designers were forced into solutions such as pumping engine oil through the valve stem and exposing valve gear to the elements in an effort to get more cooling to the valves. (Double Wasp B Series Two Stage Engines [R-2800-8, -10, -8W, and -lOW], Second Edition. Author :S collection.)

Section A -A show ing shape

of bC>Hies

5

Fig 1.4 One of the breakthroughs that allowed radial engines to be competitive with liquid-cooled inlines. The NACA cowl was developed at the same time as the British developed Townend ring Both accomplished the same purpose, i.e. , reducing cooling drag; however, the NACA was far superior and consequently ended up being the standard for radial engine cowling. By the end of the radial engine era, cowl design, still based on the NACA development, had advanced to the point where drag, or lack thereof, was on a par with liquidcooled inlines. (Parts Catalog for Martin B-26G, 20 December 1944. Courtesy of the National Air and Space Museum.)

Chapter 1

2 3 4

5 6 7 8 9 10 11

12 13 14 15 16 17 18 19 20 21

Motor - 1003-263 Adopter - (Prototype only) Flexible Shaft - 95017 Engine Mount - 19031 Bracket - 120189L l 20190L Flop Assembly - 116860L Filler Plate - 116847 Flop Assembly - 118281 Flop Assembly - 116859 Deleted Flop Assembly - 11686 l

22 23

Flop Assembly - 116862 Bonding Strip - A-595 Angle Assembly - 117 526L Support Segment - 116872 Support Brocket - 121345L Link - 13762 Support Brock et - 1168 70L Torque Tvbe - 1 16863 Support Brocket - 1l6858L Support Bracket - 118672 R Support Bracket - 116B64L Support Brack et - l l 6864R

Fig. 1.5 After NACA developed the definitive radial engine cowl, the next issue was temperature control. By controlling mass air flow through the cowl via adjustable flaps, an ideal engine temperature could be maintained. This illustration shows the inside of the cowl and its cowl flap operating mechanism. (Fairchild C-82 Erection & Maintenance Manual AN Ol -115CBA -4. Courtesy of the National Air and Space Museum.)

6

Why Radials.?

era came to a close, even more sophisticated methods to reduce installed drag and improve cooling entered into the picture. Exhaust gases were utilized to "pump" cooling air through the cowling and consequently eliminate the need for cowl flaps. These arrangements were known as "augmented exhausts ." Fan cooling and buried installations contributed to this sophistication. In the meantime, the air-cooled radial engine's competitor, the liquid-cooled inline had also enjoyed the fruits of innovative minds working on similar problems such as the most effective way to reject the heat of combustion, reduce cooling drag, radiator development, etc. These challenges were met by the introduction of ethylene glycol mixed with water, more efficiently cowled radiators, and development of radiators with greater heat rejection capability and yet retaining a relatively small frontal area. By the end of the day, however, the installed drag of a radial was lower than its erstwhile liquid-cooled competitor. Furthermore, with one less complex system to maintain, maintenance was considerably easier and cheaper. This was a key selling point for commercial operators who had more of an eye to the bottom line rather than the ultimate in performance and consequently could not afford the sophistication or problems of the highly stressed liquid-cooled inline . And as further proof of the air-cooled engine 's capability, later R-2800 CB series were required to reject up to 10,000 BTUs per minute at takeoff power (Ref 1.4).

References 1.1 Ryder, Earle A, "Recent Developments in the R-4360 Engine," paper presented at the SAE Summer Meeting (French Lick, Ind.), Society of Automotive Engineers, Warrendale, Pa., June 1950. 1.2 Schlaifer, Robert and Heron, S .D ., Development ofAircraft Engines and Fuels , Harvard University, Boston, 1950. 1.3 Letter on this subject from Larry Carlson to the author, dated December 12, 1998. 1.4 Copy of telegram from WJ. Cake to R.H. Frazier, West Coast Office, on heat rejection requirements of CB 17, dated 3-31-65 .

7

Chapter 2

Pratt & Whitney History and Background

What kind of company would enter into the hostile and treacherous world of aircraft engine development and manufacture? As it turns out, those with incredible intestinal fortitude and perseverance, not to mention good luck and business acumen. The very nature of aviation demands nothing but the best; anything else will fail-resulting in crashed airplanes or worse yet, loss of human life . Frederick Rentschler (Fig. 2.1) was well aware of this difficult arena when he proposed the idea of an aircraft engine company to the cash-rich Pratt & Whitney company in 1925. Born in 1887, he enjoyed an Ivy League education at Princeton. He was one of the few men gifted with the ability to operate machine tools, understand engines and yet have the business acumen that is so key to success . With this unique combination of abilities he had very few peers. 191 7 found the United States embroiled in the human slaughter we refer to as World War I. After enlisting in the Army at the outbreak of the war as a first lieutenant, his abilities were quickly recognized and he rose through the ranks to captain in the Air Signal Corps (forerunner to the Army Air Corps, U.S. Army Air Forces and finally the independent U.S. Air Force) (Ref. 2.1). He was stationed in New York where he was

Fig. 2.1 Frederick Rentschler, Pratt & Whitney s visionary founder. (Courtesy of Pratt & Whitney.)

9

Chapter 2

responsible for aviation power plant production and inspection . These responsibilities brought him in contact with the then state of the art Hispano-Suiza water-cooled V-8 aircraft engine (Fig. 2.2) (Ref. 2.2). After the war, Rentschler joined Wright Aeronautical. Wright had evolved into a large corporation via numerous reorganizations, acquisitions, and name changes. The contributions made to aviation by the Wright brothers can never be overestimated. However, by 1910 the brothers' collective inventive genius had waned. In their place a young and aggressive Glenn Curtiss took over. This resulted in rivalry and at times bitter disputes between the Wrights and Curtiss. One of the more well known of these disputes was the patent infringement suit brought by the Wrights, who claimed Curtiss 's ailerons breached the Wright brothers ' patent on wing warping for lateral control. This bitterly contested lawsuit drained the Wrights emotionally and physically. Another key player in the burgeoning aviation business prior to World War I was Glenn Martin. He fanned the Gleim L. Martin Company in 19 12 in California. In the same year, 1912, Orville Wright sold his remaining interests in the Wright Company to a group of eastern capitalists including Frank Manville, president of the Johns Manville company. In the meantime our young and aggressive entrepreneur, Glenn Curtiss, had fanned the Curtiss Aeroplane Company. The Wright Company merged with the Glenn L. Martin Company to fom1 Wright-Martin Aircraft Corporation. Business for the Curtiss Aeroplane Company had skyrocketed thanks to lucrative war-related business building aircraft and engines . This healthy state of affairs caught the attention of a New York syndicate who took control of the company in 1916. Base of operations was moved to Buffalo, New York, and the company was renamed Curtiss Aeroplane and Motor Corporation. In a similar fashion to the Wright Brothers, Glenn Curtiss faded from the aviation scene and ended his days selling real estate in Florida.

Fig. 2.2 Simply known as the "Hisso, " the Hispano-Suiza V-8 of World War I vintage represented the state of the art in 1915 when it was first introduced. Rentschler s involvement with a Wright Martin license built version while serving with Air Signal Corps brought him into contact with sophisticated aircraft engines. (Courtesy of Pratt & Whitney)

10

Pratt & Whitney History and Background

Wright-Martin had also profited from World War I by delivering large numbers of aircraft engines5816 in all. Most of these engines were license built Hispano-Suiza V-8s. In 1919 the WrightMartin Company was dissolved and the Wright Aeronautical Corporation was created in its stead . Rentschler 's World War I experience with the Hispano-Suiza was to prove valuable . Wright Aeronautical Corporation was licensed to build this engine, which proved to be the mainstay for U.S. military aviation in the early postwar years. With his unequaled technical, business, and managerial abilities he was given the position of vice president of Wright Aeronautical Corporation. He then quickly ascended to the presidency. Like many gifted managers, he tired of working for someone else and quit in April 1924. Contributing to his discontent was his relationship with the Wright board of directors. On several occasions the board overruled his business decisions, an example being Wright's acquisition of the Lawrence Corporation on May 15, 1923, of which Rentschler strongly disapproved. Despite family pressure to get out of the aviation business, Rentschler came up with a proposal for the Pratt & Whitney division of Niles-Bement-Pond. Lucrative World War I contracts had put them in this enviable position. The skids were appropriately greased for Rentschler by way of an introductory letter written by James K. Cullen, president of Niles-Bement-Pond. The fact that Rentschler 's father was a friend of Cullen didn ' t hurt. Part of Rentschler 's proposal to Pratt & Whitney was a request for start-up capital. The initial amount invested was $250,000.00. This was considered the amount necessary to finance development of the first engine. If Pratt & Whitney considered this engine to be successful a further one million dollars would be invested to cover the cost of production tooling and further development. As one can imagine, Rentschler was not prone to take undue risks. He felt very confident that business could be drummed up for his initial engine. Clearly, his position as president of Wright had given him the inside track on future requirements for the military, particularly the Navy. Knowing full well that the Navy was looking for a 400 horsepower air-cooled radial that weighed less than 650 pounds, Rentschler realized this was a plum contract ripe for the picking. By this time, the Navy had made its famous decree: no more water-cooled engines, or as one high ranking Navy officer has been often quoted, "A water-cooled aircraft engine makes as much sense as an air-cooled submarine. " This Navy decision was to last throughout the piston engine era. Despite a number of water-cooled and liquid-cooled powered aircraft being evaluated for carrier operations, none were awarded production contracts . In the early days of Naval aviation after World War I, water cooling made good sense. Due to the immature stage of air-cooled cylinder development, air-cooled engines were forced to run a rich fuel/air mixture to facilitate cooling. 1 The additional fuel load was sufficient to offset any weight penalty suffered by a water-cooled installation. Thanks to his relationship with Rear Admiral W.A. Moffett, Rentschler succeeded with his proposal, and in 1925 the Pratt & Whitney Aircraft Company was created. The first facility was located on Capitol Avenue in East Ha1tford. Part of the financing deal with Pratt & Whitney Tool was to utilize

1 Interestingly,

even today 's " modern" air-cooled aircraft engines are forced into the same situation of running a rich mixture for additiona l cooling, particu larly at hi gh power settings such as takeoff.

11

Chapter 2

one of the brick buildings on Capitol Avenue. These facilities had been in disuse since WWI and a major interest on the part of Pratt & Whitney was to utilize this manufacturing space in order to utilize their excess cash. The Capitol Avenue building was a four-story brick machine shop that had been previously used by the Pope-Hartford automobile company. Interestingly, a copy of this unsuccessful auto in on display at the Hartford office of the American Automobile Association (Ref. 2.3) . At the time Rentschler took over, part of the space was being temporarily used for storing tobacco. East Hartford tobacco sheds were large wood sheds with slat siding that could be opened up on sunny days to cure tobacco hanging inside. Nothing but dirt floors. Most folks around East Hartford could not believe anything could be manufactured inside one of these, let alone a precision aircraft engine . After four years of successful work for the Navy and other customers, more space was needed. A large plot was purchased from East Haitford tobacco growers to build a larger manufacturing plant and airport. Rentschler 's wife broke ground for this plant on July 16, 1929, which began operating in 1930 with 400,000 square feet of manufacturing space and 30 engine test houses. New England was a fo1tuitous choice due to the abundance of highly skilled labor. Many machine tool companies were located in this part of the country. Industries such as gun making, and the manufacture of precision instnunents sprung up in New England during the Eighteenth and Nineteenth Centuries. This in tum attracted the kinds of skills that Pratt & Whitney would require : tool & die makers, machinists, pattern makers, fitters, etc. During his tenure at Wright, Rentschler identified key people that he felt would be essential for his new undertaking. Consequently, George Mead, Donald Brown, Andy Willgoos, Charlie Marks, and John Borrop, all from Wright, jumped ship and came aboard with Rentschler. Mead eventually ascended to vice president of Pratt & Whitney and Willgoos became chief engineer. With this talented team in place, design work started on the fledgling new company's first engine . Willgoos was a quiet man, a hard worker, and highly respected. As chief engineer, he was totally engrossed in engine design and function. He would spend hours examining post-test engine parts looking for signs of trouble missed by more junior engineers. Like any "engine" man, he realized that a distressed part is trying to tell the engineer a story (Ref. 2.3). Later on, his contributions to R-2800 development were key to its success. Luke Hobbs (Fig. 2.3) (more about Hobbs later), who joined the company shortly after, relied on Willgoos as his right-hand man . Earle A. Ryder, formerly with Aeromarine Plane & Motor Company joined in July. Ryder was another early employee to enjoy a long and successful career with Pratt & Whitney. His accomplishments included much of the cylinder development for Pratt & Whitney's last piston engine hurrahthe R-4360 (Ref. 1.1) . He was gifted with a sharp mind, professional type personality, well read, and had a solid grasp of mechanics. He had little patience for those whom he judged to be technically incompetent. However, he was always kind enough to explain the facts (Ref. 2.3). This small band of talented individuals was now faced with an enormous task: design a 400 horsepower engine that weighed less than 650 pounds . At 1.625 pounds per horsepower, even modem general aviation engines can barely match this achievement.

12

Pratt & Whitney History and Background

Fig. 2. 3 Key to many Pratt & Whitney piston engines and gas turbines, Luke Hobbs led their engineering efforts through many difficulties and obstacles. (Courtesy of Pratt & Whitney.)

Design work started in August 1925. The displacement was quickly determined to be 1344 cubic inches. This figure was derived from a cylinder bore and stroke of 5.75 inches and nine cylinders. The military designation was R-1 340 derived from the fact it was a radial, which accounted for the "R," and the displacement, rounded out to the nearest 5 cubic inches gave 1340 . Pratt & Whitney bestowed the name "Wasp" onto it's first born. Rentschler 's wife-conjured up this name. Variations on the Wasp name continued on into the gas turbine era: Wasp Jr. (R-985), the follow-on to the R-1340; Twin Wasp (R-1830); Twin Wasp Jr. (R-1535) ; Double Wasp (R-2800), the subject of this book; Wasp Major (R-4360); and Turbo Wasp . The last mentioned engine was Pratt & Whitney's first foray into the totally new world of gas turbines. The Turbo Wasp was a license built RollsRoyce Nene (Fig. 2.4). As an interesting aside, the left-wing Marxist, British Labour government at the time (194 7) authorized Rolls-Royce to sell 16 Nenes to the Russians, who immediately reverse engineered it and installed it in the Mig-15 of Korean war fame (Ref. 2 .4). One thousand three hundred and forty-four cubic inches was more displacement than that used by Pratt & Whitney's closest rival, Rentschler 's former employer, Wright. The Wright Simoon, in competition for the same Navy contract, had a displacement of 1176 cubic inches. The rationale for this disparity was the difficult task of meeting the stringent Navy weight requirement. Pratt & Whitney had a couple of aces up its sleeve to meet the 65 0-pound weight limit. In the early 1920s, Roy Feddon of the Bristol Aeroplane Company had developed the forging process for radial engine crankcases, initially for the Bristol Jupiter (Ref. 2.5) and then all subsequent Bristol piston engines. Willgoos, who was doing the lion's share of design work, utilized this concept for the R-1340. This allowed for a considerable weight saving compared to a cast crankcase. This weight saving was then taken advantage of in the form of greater displacement. The Wright Simoon on the other hand utilized a cast crankcase and its designers were forced into a smaller displacement. Even though the internal combustion engine had been in common use for about 50 years when the R-1340 was designed, numerous difficulties still plagued it, one of the more vexing being valve spring life. Operating at high temperatures, valve springs are subjected to tremendous fatigue loads. Cam profiles had not been perfected to the point of gentle lift-offs from the valve seat and similarly gentle valve closure. The rapid acceleration of the valve from the harsh cam profiles caused numerous valve spring fatigue

13

Chapter 2

Fig. 2. 4 As their first foray into the mamifacture of gas turbines, Pratt & Whitney manufactured the Rolls-Royce Nene under license. Interestingly, the left-wing British socialist government in power at the time of the Nene s development- the mid to late J 940s- also had Rolls-Royce ship a number to Russia. Without benefit of a mamifacturing license, the Russians immediately put Nenes into mass production and used them to power Mig l 5s of Korean War fame . Of course the "Georgian Cockroach, " aka Joseph Stalin, had no respect/or niceties such as manufacturing licenses. (Courtesy of the Rolls-Royce Heritage Trust.)

failures. Exacerbating the problem was a lack of high quality, vacuum refined valve spring wire and inspection techniques such as Magnafluxing for crack detection. These problems resulted in valve trains being exposed to the elements in most, if not all, early internal combustion engines. This exposure gave improved cooling and allowed easy detection of any failed valve springs. Willgoos felt he could design around the requirement of exposed valve springs. As a result, all Pratt & Whitney engines featured enclosed valve gear. Initially, the lubrication requirements were taken care of via grease fittings requiring replenishment after each flight, resulting in the familiar grease splotches on windshields. Another key design decision, which differed from the Simoon, was the use of a onepiece master connecting rod and a built-up crankshaft. Wright went the other route and used a onepiece crank and split master connecting rod (Ref 1.2). Due to its lighter weight compared to a two-piece component, the one-piece master rod allowed Pratt & Whitney to run the R-1340 at higher rpm, 1900, compared to the Wright Simoon's 1650 rpm. This contributed significantly to the performance of the engine by allowing it to reach its power peak and by allowing more radical valve timing, i.e., earlier opening and later closing. Additionally, the lighter one-piece master rod allowed for lighter counterweights contributing to a lower overall weight. Having said that, Pratt & Whitney did employ split master rods and one-piece cranks on its first two-row engines, the R-1535 and R-1830, as a conservative design feature. The R-4360 also featured a split master rod design, in all

14

Pratt & TiVhitney History and Background

probability because of the difficulty in designing and manufacturing a built-up crank for a four-row engine . Aircraft engines of this time period, the mid-l 920s, typically ran at a brake mean effective pressure (BMEP) of 120 pounds per square inch. The R-1340 was designed from the outset to run at a BMEP of 130 pounds per square inch. As Willgoos finished his detail designs, the drawings were immediately dispatched to the machine shop or foundry. Assembly of the new engine occurred on Christmas Eve, 1925 , a Thursday, and the first run occurred on December 28, a Monday. Willgoos obviously did his calculations well: the engine produced 380 horsepower straight from the drawing board. The two subsequent runs produced 410 hp and 425 hp. Although designed for a forged crankcase, the first prototype, in the interest of speedy development, used a cast crankcase (Fig. 2.5) .

Fig. 2. 5 This is how it all began- the first Wasp undergoing a test run. Initially rated at 420 horsepower, later variants were rated at 600 horsepower and up to 900 horsepower for racing applications. (Courtesy of Pratt & Whitney.)

15

Chapter 2

On May 5, 1926, the new Pratt & Whitney R-1340 flew for the first time, ironically, in a Wright Apache (Ref. 2.6). The performance was so superior to that of the Wright Simoon, Wright did not pursue its development any further. Although both engines weighed the same, the R-1340 was rated at 410 horsepower compared to the Simoon's rather anemic 325. So enamored was the Navy with the R-1340, a production order for 200 engines was immediately given. This was the kick-start Rentschler had hoped for-and needed for his new venture . On the heels of the massive Navy order, Pratt & Whitney received a request for 28 engines to power Boeing Model 40 mailplanes. These orders ensured the early success of Pratt & Whitney. Within a few short years an amazing 90 percent of cmmnercial aircraft flew behind Pratt & Whitney power. In another touch of irony, the R-1340 was the first engine to be produced and one of the last piston engines manufactured by Pratt & Whitney. Production ran into 1960. The Wasp powered many military and civilian aircraft, but it is probably the North American T-6 that has given it lasting fame. Although the R-1340 Wasp design was a hard act to follow, Pratt & Whitney managed such a feat. This was accomplished by way of the Hornet, a larger version of the R-1340 displacing 1690 cubic inches. Initially rated at 575 horsepower, developed versions of the R-1690 Hornet were rated at 800 horsepower. Hornets were later manufactured under license by BMW in Germany to power aircraft for the fledgling Luftwaffe. Other variations on the single-row Wasp theme included the Wasp Jr. (Fig. 2.6). Displacing 985 cubic inches, the R-985 was the smaller sibling to the R-1340, even sharing the same bore/stroke ratio of 1: 1. Tens of thousands of 985s would be manufactured before production ended-most being installed in various models and permutations of the ubiquitous Beechcraft model 18. Many Boeing Stearmans were converted to R-985 power, resulting in the so-called 450 (for 450 horsepower) Stearman.

Fig. 2. 6 The Wasps smaller sibling, the Wasp Jr. Sharing the same design features as the R-1340 Wasp, the R-985 Wasp Jr. enjoyed a long and successful production run. Rated at 450 horsepower, its conservative rating contributed to its longevity. (Courtesy of Pratt & Whitney.)

16

Pratt & Wh itney History and Background

Rentschler 's business and management foresight was apparent in many ways. One of his more astute moves was the decision to subcontract out 50 percent of production. With a well developed network of subcontractors, Pratt & Whitney was in good shape to handle the exponential increase in business during the late 1930s and throughout World War II. Furthennore, competition among subcontractors kept costs under control. With the company on a secure financial footing, the restless and ambitious Rentschler made the decision to expand his horizons. This was accomplished in 1928 when Rentschler joined forces with Boeing and Vought. The resulting corporation from this merger was named United Aircraft & Transport Corporation. Later, Hamilton Propellers joined the corporation. This in tum caused other mergers within the new corporation such as Hamilton's merger with Standard Steel Propellers, thus creating Hamilton Standard Propellers. By the mid-193 Os the size of the organization was weighing heavily on Rentschler. Serious problems were on the horizon. Spread too thin with all his responsibilities, Rentschler relinquished the presidency of Pratt & Whitney to Don Brown. Brown's and Rentschler 's relationship went back to the Wright days. He was another ofRentschler's early recruits for Pratt & Whitney. This decision allowed Rentschler to fry larger fish in the form of running United Aircraft and freed him from the day-to-day responsibilities of Pratt & Whitney. This may have planted the seed of discontent that ultimately led to the resignation of George Mead in 1940 (Fig. 2. 7). Always a sickly man, Mead suffered a nervous collapse after the R-1340 type test in 1926. And again in 1928 Mead suffered serious health problems in the form of chronic ear, nose throat, and mouth infections, and a hernia operation. Mead 's ill health as well as his discontent with Pratt & Whitney management became a trend which, in all likelihood, contributed to his decision to resign when he did. As with many successful startup companies, Pratt & Whitney sta1ted to feel its oats in the form of venturing outside the scope of its now established area of expertise and taking on too many projects.

Fig. 2. 7 Being one of the original employees of Pratt & Whitney, George Mead made many significant contributions until he got off on a tangent in the late 19 30s developing liquidcooled sleeve valve projects. The failure of his sleeve valve developments contributed to his resignation Ji-om Pratt & Whitney in 1940. (Courtesy of Pratt & Whitney.)

17

Chapter 2

Fig. 2.8 Not all early Pratt & Whitney engines were a success. The water-cooled, twenty-cylinder R-2060 was beset with problems. Pratt & Whitney wisely chose to drop this project soon after it became apparent it was not going anywhere. (Courtesy of Pratt & Whitney.)

These forays included some less than stellar engine projects such as the ill-starred R-2060 (Fig. 2.8). The most obvious deviation from the tried and true, for Pratt & Whitney, was water cooling. It was a twenty-cylinder engine composed of four inline rows of five cylinders. An overly complex engine considering its displacement and horsepower, it also suffered from excessive frontal area. Fortunately, this project was shelved before it could drain significant resources. However, other projects did drain significant resources and talent when these resources and talents were most needed. In 193 7 Mead took a trip to England. Whilst there, he checked out the British aircraft engine business and came back totally captivated with the sleeve valve concept. Although sleeve valve engines had a lot to justify them, as witnessed by the fact that almost 50 percent of the total horsepower of Royal Air Force aircraft in World War II were sleeve valve engines, they took inordinate amounts of development time and skill to manufacture. Nevertheless, upon his return, Mead ventured into the sleeve valve camp. This caused his undoing. Conceptually based on the Napier Sabre, the X-1800 2 displaced 2240 cubic inches . Built to an Army contract, even though the contract was not signed until May 1939, Mead consumed himself with this engine. Pratt & Whitney also hoped Douglas would use this engine for a medium bomber, despite the fact Douglas had intended for this airplane to be powered by an air-cooled radial. Several variations on this H-24 sleeve valve theme were manufactured. None ever flew. The last of them, H-3740, displaced 3740 cubic inches and produced 3500 horsepower (Fig. 2.9). Mead's health had deteriorated to the point where he was forced into running the liquid-cooled sleeve projects from his home-literally in his sickbed. Luke Hobbs was another brilliant engineer recruited in the early days-1927 in his case. Born in Carbon, Wyoming, in 1896 he died at age eighty in 1977 . In 1916 he graduated from Texas A&M with a bachelor 's degree. Shortly after graduating he did a stint in the Army serving in the famous 42nd (Rainbow) Division in France during World War I. After the war, Hobbs obtained a master 's 2

The X-1 800 de signated "X" for experimental and 1800 for the projected horsepower output.

18

Pratt & Whitney History and Background

Fig 2.9 The result of George Meads hard work on the sleeve valve projects, Pratt & Whitneys H-3740. Configured in a similar way to the British Napier Sabre, it featured 2-1 liquid-cooled cylinders with sleeve valves. The Navy continued to fimd this project into the early 1940s, but to no avail; no H-3 740 ever flew. (Courtesy of Pratt & Whitney.)

degree in science at Kansas State. The years 1920 to 1923 were spent at McCook Field where he worked with luminaries such as George Mead . In 1923 , he moved onto Bendix, who at that time supplied most of the carburetors installed on military aircraft engines . His crowning achievement at Bendix was the development of the superlative Bendix injection carburetor, unsurpassed before-or since-for its ability to accurately meter fuel , resistance to "G" loading, and anti-icing capabilities . By 1938 Hobbs had risen through the ranks to Engineering Manager at Pratt & Whitney (Refs . 2.7 and 2 8). Watching Mead flail away at the liquid-cooled sleeve valve project disturbed Hobbs. To him it was a waste of resources at a critical time when efforts should have been concentrated on Pratt & Whitney's core of knowledge-air-cooled radials. In 1940 Hobbs persuaded General "Hap" Arnold that the X-1800 project should be dropped. Arnold agreed, however, the H-3740 project continued on for several years to satisfy a Navy contract (Ref 1.2). Also, in 1940, Mead resigned from Pratt & Whitney due to increasingly failing health and his dissatisfaction with Pratt & Whitney. In 1953 Hobbs was awarded the prestigious Collier Trophy for his work on the J-57, an engine that powered many of the Air Force's 1950s era aircraft including the B-52, and in civilian guise was known as the JT-3 that powered the Boeing 707. In the mid- l 930s a 2600 cubic inch, two-row, eighteen-cylinder air-cooled radial was designed. This was the company's first engine with this number and configuration of cylinders. Design work was complete and an engineering mock-up started . However, Hobbs decided to up the ante by increasing displacement to 2800 cubic inches. Perhaps a contributing factor to this change of heart was Wright's R-2600. Thus, the famous R-2800 was born.

References 2.1 The Pratt & Whitney Aircraft Story, Pratt & Whitney Div. , United Aircraft Corp. , East Hartford, Conn. , 15 May 1952.

19

Chapter 2

2.2 Frederick Rentschler and His Legacy, notes from a presentation made by Harvey Lippincott. 2.3 Interviews and correspondence with Larry Carlson, 1998-1999 . 1.1 Ryder, Earle A. , "Recent Developments in the R-4360 Engine," paper presented at the SAE Summer Meeting (French Lick, Ind .), Society of Automotive Engineers, Warrendale, Pa., June 1950.

2.4 Banks, Air Commodore FR. (Rod), "I Kept No Diary," Airlife, 1978 . 2.5 Gunston, W.T.,ByJupiter, R.Ae.S. , London, 1978. 1.2 Schlaifer, Robert and Heron, S.D. , Development ofAircraft Engines and Fuels, Harvard University, Boston, 19 5 0. 2.6 Harvey Lippincott, former Pratt & Whitney archivist, correspondence and interviews with author, 1993-1994 . 2.7 Current Biography 1954, Hobbs, Leonard S(inclair), Dec. 20 1896- Business Executive Engineer. 2.8 New York Times , obituary section, Thursday, November 3, 1977 .

20

Chapter 3

R-2800 Development

Designated "Double Wasp" by Pratt & Whitney and the civilian market, and R-2800 by the military, this remarkable engine garnered a special place in aviation history. This v,;as an acknowledgment of the engine's superb reliability, maintainability, power, economy, and low weight. Interestingly, R-2800s did not excel in any one of the above mentioned attributes . But its combination of those key attributes spelled success, both militarily and commercially, for this formidable power plant. Luke Hobbs, the man most responsible for the development of the R-2800, enjoyed a long and successful career with Pratt & Whitney. It could be argued that the R-2800 was his crnwning achievement despite the fact he went on to design many of the early gas turbines to come out of Pratt & Whitney. Chief engineer for the R-2800 project was Andy Willgoos . Unlike Hobbs, Willgoos involved himself with every detail design of the engine. He had a large design board in his office and approved every design layout before parts went to detail design. Willgoos maintained this position right into the gas turbine era. Alas, like this author, his interest in the new-fangled gas turbines did not motivate him to the extent piston engines had . He died of a heart attack in the early development of the PT-2 gas turbine without ever having seen it run. At the time of his death Pratt & Whitney had partly completed the construction of a new gas turbine lab. At its completion, in honor of a great engineer, it was named the Willgoos Gas Turbine Lab. Another key contributor to the R-2800 was Perry Pratt. He was the project engineer from approximately 1939 until war 's end when he was pulled off to establish a gas turbine research and design group. During this period he and his group were responsible for initiating all design, development work, and coordination with the airframers using the R-2800. As project engineer, he was essentially the chief on the project. He was a dynamic and driven engineer involved in everything all hours of the day and night. Everyone involved in the R-2800, including customers regarded him as "Mr. R-2800 ." Praise indeed (Ref. 2.3) ! Design of the company's eighteen-cylinder R-2600 was complete and the engineering mock-up almost complete when events overtook this project. Deciding 2600 cubic inches was insufficient (Ref. 1.2), Hobbs wisely shelved this engine . Instead, he set his sights on bigger fish in the fom1 of 2804 cubic inches . By this time, mid-l 930s, Pratt & Whitney had considerable air-cooled, two-ro'"' radial experience. This experience had been achieved through the following fourteen-cylinder engines: R-1535,

21

Chapter 3

R-1830 and the stillborn R-2180-even though the latter engine was ready for production. The R-2800 would be the first, and as it turned out the only, eighteen-cylinder radial developed and manufactured in quantity by Pratt & Whitney. Starting with a clean slate, many key decisions are required before serious design of a new engine can commence. These include: one-piece master rods with a built-up crankshaft vs. two-piece master rods and one-piece crank, number, and arrangement of cylinders, crankshaft design, cooling method, type of propeller reduction gearing, combustion chamber design, number of valves per cylinder, supercharging method, carburetion, lubrication, accessory drives, etc. Hobbs decided upon eighteen cylinders situated in two rows of nine. Each cylinder would have a bore of 5. 7 5 inches and a stroke of 6.0 inches. Reduction gearing was a must for such a large and powerful engine. In the same vein, supercharging was also a given. During its production life, five design series were developed: "A," "B," "C," "D," and "E" series with many variations and sub-variations on these basic themes. Of the five above-mentioned series, by far the most numerous were the "B"s and "C''s. "A"s and "B"s were very similar. The "C" was a total redesign of the "A"/"B" with two significant subsets: "CA" and "CB. " A subset known as the "CE" was produced in relatively small numbers. The "D" was a one-off dash number variation based on the "B. " The "E" used a modified "CB" power section with hydraulically driven superchargers. Developing a large multi-cylinder, high performance aircraft engine is a painstaking, step-by-step process. Initially, single-cylinder engines are developed for cooling studies, valve timing, combustion chamber design, compression ratio, etc. Once the cylinder design has started to evolve, the next step is the building of a multi-cylinder engine . Authorization of the first R-2800, or Double Wasp as Pratt & Whitney referred to it, was made when an order was sent out on March 21 , 193 7, for the release of crankshaft and crankcase forgings and castings. This first engine, designated X-77, became the first of the "A" series. As a proof of concept engine, a number of concessions were made such as employing direct drive and parts modified from an R-183 0. Interestingly, at this very early stage of development, Pratt & Whitney experimented with the use of eighteen separate intake pipes and compared this configuration to the "forked" or "Y" shaped intake pipes . "Y" pipes won out over the eighteen individual pipes based on improved mixture distribution (Ref. 3 .1). On April 21, 193 7, the early specifications were released as follows: Number of cylinders ...................... 18 Cylinder arrangement ................... Two-row radial Bore and stroke .............. ................ 5:X in. bore, 6.0 in. stroke Displacement .................. ............... 2804 in.3 Estimated weight ......... ..... ... ..... ..... 2100 lbs Rating on 100 octane fuel : Takeoff power ...... ....... ................ . 1650 hp at 2500 rpm Normal power ........ ..... .. ............. .. 1300 hp at 2300 rpm to 10,000 ft Max. crnising ......... ....................... 952 hp Normal cruising .... .. ..................... 850 hp

22

R-2800 Development

Fuel consumption: Max. cruising .... .............. .... ........ .. 0.45 lb/bhp/hr Normal ....... ...... ... ........................... 0.42 lb/bhp/hr Approximate dimensions: Overall length ... .. ................... ........ 69 in. Diameter ............. ...... ... ...... ...... ...... 52Yz in. Looking into the future, Pratt & Whitney configured the engine to incorporate a turbosupercharger or use a two-stage supercharger. Clearly, these latter two requirements were aimed at the military; turbosupercharging for the Army Air Corps and two-stage supercharging for the Navy. Four prototypes were built designated: X-77, X-78, X-79 and X-80. X-80 was a single-row, nine-cylinder engine representative of half an R-2800. This nine-cylinder engine was built and ready for testing in February, 1938 . Over the course of the following year, X-80, along with X-77, X-78, and X-79, took on the role ofa development mule (Ref 3.2) . As is the case in most development efforts, these four engines bore the brunt of much abuse, catastrophic failures , and of course, the necessary learning curve. By March, 1939, X-80 had amassed 695 .92 hours, countless rebuilds and the honor of making a major contribution to the R-2800 program . All major components went through their initial development cycle inside X-80. This included master rods, knuckle pins, bearings, oil pumps, reduction gearing and the crankshaft. In addition, the oil pressure and scavenging systems were optimized with this test engine. This included: ideal oil flows , oil pressure, oil temperature, and oil viscosity. Like many historically significant artifacts, after its useful life was over X-80 was unceremoniously scrapped. Following is a description of the first R-2800 model series manufactured, the "A" series (Fig. 3.1).

Cylinders Cylinders are where the engine's power is generated and the majority of the heat rejection requirements take place. The R-2800 's cylinder design was, by now, well proven and tried on many previous engines. Thanks to Sam Heron 's and the pioneering work, many of the pitfalls could be avoided. S.D . Siddeley of Armstrong Siddeley developed the classic screwed and shrunk cylinder assembly. Heron 's original design called for an integral aluminum head and finned muff shrunk over a steel liner. However, Heron, at Siddeley's instructions, had this design altered to an aluminum head screwed to a steel barrel by a short thread. This type of construction, which became universally used within a decade, had been first tried by Siddeley in his water-cooled Puma. Two major components made up the R-2800 cylinder assembly: the cylinder barrel and the cylinder head . The cylinder barrel, manufactured from an SAE 3140 chromium-molybdenum forging, featured a male screw thread machined on its outer circumference at the top (Fig. 3.2). The cylinder head, manufactured

23

Chapter 3

G EARED A4 DOUBLE W ASP

Fig 3.1 Three views of an "A " series R-2800. Many early f eatures are shown: the two-piece pushrod tubes, stamped steel intake manifolds, and rubber couplings for the front cylinder intake manifolds. These features were soon dropped and replaced with improved designs. (Courtesy of Pratt & Whitney.)

from an aluminum casting, featured a corresponding female screw thread machined on its inner diameter. The aforementioned threads were designed to produce an interference fit. By heating the cylinder head and cooling the cylinder barrel the two could be assembled. To ensure that the cylinder head and barrel assembled in the correct relationship, the threads were "timed," i.e., in the final, tightened position the head was correctly positioned in relationship to the barrel. A hemispherical combustion chamber with two valves was the, by now, accepted design concept, not only for Pratt & Whitney but most air-cooled radials from other manufacturers . The most notable exception to this design philosophy was from the inventive genius of Roy Feddon at Bristol. He initially used a pent

24

R-2800 Development

Fig. 3. 2 Beautifully machined R-2800 cylinder barrel. Manufactured from a chrome-moly forging, it was nitrided for additional durability. Note the lack of holes in the lower flange, these were drilled in after the cylinder head and cooling muff were screwed and shrunk into position. The aluminum cooling muff is shown to the left. (Courtesy of Pratt & Whitney.)

roof, four valves per cylinder design in engines such as the Jupiter, Mercury, and Pegasus . Later, Feddon was smitten by the sleeve valve concept and all his later engines featured this valve system with its own unique combustion chamber shape (Ref 3.3). Valves and valve problems were the cause of many engine failures in the early days . Particularly hard-hit were exhaust valves. With temperatures as high as 1800 degrees Fahrenheit, it is little wonder that exhaust valve life was limited. Although it is taken for granted today, the development of high temperature steel alloys was in its infancy from the tum of the century and into the 1930s. Once again, our old friend Sam Heron came to the rescue with an internally cooled valve (Ref 1.4). Several materials were experimented with, including mercury; however, sodium won out over the coolants tried. As with many "wonder" solutions, some problems are created by internally cooled valves, one of the more severe being "coking" of the oil in the exhaust rocker boxes. Additional heat rejection into the valve stem is transferred into the valve guide and rocker box. Oil coming into contact with temperatures in excess of its coking temp can cause early oil contamination. Overall, however, the advantages of reducing severe valve bum are worth any coking problems created. The R-2800 's 2.75 inch diameter exhaust valve was manufactured with a stellite face and a hardened tip pressed into the end of the stem. The exhaust valve seat, also manufactured from stellite welded onto a parent steel, was a thermal press fit into the hemispherical combustion chamber and finally swaged into position. The 2.975 inch diameter inlet valve was solid, i.e., not internally cooled. It seated on a bronze insert pressed into the combustion chamber. The rocker arms, featured a 1.5: 1 ratio, i.e. , for every 0.100 inches of lift from the cam, the valve would lift 0.150 inches. They were manufactured from steel forgings and pivoted on a two-row ball bearing. It is interesting to note that the R-2800 used plain bearing almost exclusively throughout, a departure from its previous design practice. The only exceptions to the foregoing being the aforementioned rocker pivot bearings and the propeller thrust bearing. Fine adjustment of valve clearance was achieved with a conventional

25

Chapter 3

threaded stud and lock-nut (see below for description of the pushrod). One end of the stud had a screwdriver slot, the other end a ball socket to accommodate the ball end pushrod. A swiveling pad on the valve stem end ensured surface contact between the rocker and valve stem (Ref 3.4). This is in contrast with many designs that do not accommodate the geometry of the rocker and valve stem. This resulted in a concentrated line contact between the end of the rocker arm and the valve stem. Other woes associated with this arrangement included high thrust loading on the valve guide leading to excessive valve guide wear. A steel pipe connected the two rocker boxes for pressure equalization and oil drain. Tubular steel pushrods actuated the rocker arms . Pressed-in ball joints at both ends mated with a corresponding socket on the rocker arm and tappet. Oil holes in both ball joints fed lubricant to the rocker arm pivot and valve stem pad. Copious amounts of leakage contributed to cooling the rocker box and valve components. Of course this was more critical on the exhaust side. The pressed-in ball joints seated on shims. These shin1s gave coarse adjustment for the valve clearance. Fine adjustment, i.e. , 0.010 inches or less, was dialed in with the rocker ann screw adjuster. Telescoping pushrod tubes attached at the cylinder head end and the crankcase via gland nuts sealed the valve gear. As an interesting aside in the R-2800 development story, Thompson Products, manufacturers of many aircraft engine related items in the 1930s and 1940s, developed a "selfadjusting" pushrod for the R-2800 (Ref 3.5) . In a similar manner to hydraulic lifters, it was intended to automatically adjust the valve clearances to the correct value. It never worked . In a similar vein, during the Thompson self adjusting pushrod experiments in 1941 , Pratt & Whitney investigated the use of n;vo position tappets in order to improve the flexibility, fuel economy, and power of the R-2800 . During development of the "B" engine it was found that improved fuel economy in cruise condition was possible by using "A" valve timing and improved power and detonation characteristics were possible with "B" valve timing . After exhaustive tests with various forms of hydraulic tappets, the whole idea of variable valve timing/self adjusting tappets was dropped. However, during these tests, it was found that to optimize the variable valve timing/self adjusting tappets some form of adjustable ignition timing was necessary. These tests may well have prompted the adoption of variable ignition timing for the "C" engine. Ironically, the variable ignition timing feature was disabled on all R-2800s during the 1950s. Cooling, or lack thereof, of a high performance air-cooled radial is key to its success-or dismal failure. In the case of the R-2800 great care was taken to ensure overheating would not be one of its Achilles ' heels. Consequently, the "A" and "B" series R-2800 pushed the envelope of cylinder head casting technology to the limit. By the standards of the late 1930s the R-2800 was a masterpiece. The deep and closely spaced cooling fins handled the heat rejection requirements asked of them. It is in the cylinder head where the majority of the heat is generated and therefore this component received special attention . But it takes more than designing in deep, closely spaced fins-the available cooling air must be taken full advantage of To achieve this goal, aluminum sheet metal baffles were snugly fitted over and around the cylinder (Fig. 3.3). The depth and quantity of cooling fins was optimized to ensure even cooling. Earl Ryder, one of Pratt & Whitney 's early recruits, did much of the research into cylinder design and the assurance of even cooling. Blast tubes formed part of the baffling to cool rear spark plugs . Even so, it was, and still is in some cases, necessary to install plugs with a cooler heat range in the rear position (Ref 3.6) . Among Ryder 's other accomplishments were testing machines for master rod bearings during the panic of 1937 when they suffered a rash of

26

R-2800 Development

INTER-EAR .OEFLECTOR

'--INHR·CYL . DEFLECTORS_j

0EFLECTORS FOR A FRONT CYLIHDER

Fig 3.3 One of the lessons learned in the 1930sfor radial engine cooling was to take full advantage of the available cooling air. Baffles wrapped around the cylinder ensured even cooling and the most efficient use of cooling air. Pratt & Whitney expended huge amounts of resources on cooling studies, particularly as specific power approached one horsepower per cubic inch. (Parts Catalog for Mode ls R-2800 Series -27, -31, -43, -59, -71, -75 and -79 Aircraft Engines. Author :S collection.)

failures. This was the period when Pratt & Whitney desperately searched for the definitive master rod bearing solution as related later in the text. Each cylinder had two spark plugs-one at the front and one at the rear. It has often been assumed that the use of two spark plugs per cylinder was as a safety backup . In fact this is not the case at allat least for highly supercharged, high performance engines . The primary reason for two plugs per cylinder, not only on the R-2800, but all other large displacement, high output aircraft piston engines, is one of performance. Running on one plug at anything above a low cruise power setting could cause serious internal engine damage, the culprit being detonation-uncontrolled burning of the fuel-air mixture. With two sources of ignition, two flame fronts are established, therefore the fuel/air charge is burned in less time. With one source of ignition, the single flame front takes more time to bum the fuel/air charge. This slower bum time allows the unburned mixture ahead of the flame front to heat up to the point where it will ignite uncontrollably, i.e. , detonate (Ref 3.7). Further bolstering the foregoing argument is the fact that many ignition systems, including many for the R-2800, featured only one dual magneto, albeit with two distributors and two sets of points. Therefore if that one magneto failed the entire ignition system was shut down and as a consequence, the engine. However, it should be pointed out that drive failure to the R-2800's dual magneto is almost unheard of Most automobile engines get by with a single ignition source for several reasons: they have much smaller diameter cylinders, therefore the flame front has less distance to travel and secondly, most auto engines run naturally aspirated, i.e., they are not supercharged.

27

Chapter 3

The nitralloy, later chrome-molybdenum, cylinder barrel started life as a forging and was then machined and ground on its outer diameter and honed on its bore . An aluminwn forging with closely pitched cooling fins was shrunk onto the barrel. A mounting flange near the base formed the method of mounting the cylinder to the crankcase. Fifteen holes were drilled into the mounting flange allowing clearance for 3/s inch diameter studs fitted into the crankcase. On top of each mounting nut a "Pal" nut was attached for locking purposes. Cylinders were "choked" (Fig. 3.4) (Ref. 3.8), in other words the inside bore had three diameters. Each diameter would transition to the next dimension over approximately Yi inch, the smallest diameter being at top dead center. The cylinder choking was accomplished via the interference fit of the cylinder head screw thread and the interference fit of the cooling muff That is, the barrel was ground and honed round and parallel. The interference fit of the cooling muff was optimized to shrink the barrel and obtain the desired choke. Choking served several purposes: it more effectively sealed the cylinder towards top dead center where the highest pressure was experienced and conversely reduced piston drag towards the lower part of the cylinder where pressure was considerably lower and consequently sealing concerns were less of a problem. Front and rear cylinders were similar but not interchangeable. Front cylinders had the puslu·ods at the front and intake and exhaust ports at the rear. Rear cylinders had pushrods, and both ports at the rear. Valve covers ensured total enclosure of the valve gear and yet give access to the valve stems for valve clearance checking .

Cooling Baffles Incorporating adequate cooling fin area for the cylinders only represents a small part of the overall cooling requirements of the cylinder and by default the entire engine. If the available cooling air is not utilized to the full then all is for naught. Metal bafiles made from sheet aluminum wrapped around the cylinder barrel and over the cylinder head ensures cooling air is evenly distributed, particularly around hot spots such as the exhaust valve area . The forward speed of the aircraft induces a pressure differential between the front and rear of the cylinders. Additional bafile seals are provided for between the gaps forn1ed by the front and rear cylinders. In this way, all air that enters the cowl is forced through the cylinder cooling fins.

Pistons With the piston 's role of transferring the heat and pressure of combustion from a high performance, supercharged engine, this was not the area to cut costs or incorporate an inadequate design. The highest quality materials and manufacturing were givens. In the case of the R-2800 the piston started life as an aluminum forging. Slightly domed on top with two valve relief cut-outs, it resulted in a compression ratio of 6.65 : 1. This seemingly low compression ratio is typical of a highly supercharged engine. High manifold pressures demand a reduced compression ratio-even when running on high performance fuel. Despite the deceptively low compression ratio, BMEP (brake mean effective pressure) was quite high-typically running at 150 psi. These characteristics conspired to make the piston's life difficult at best. Ribs were machined into the inside ski1t areas for improved heat rejection and rigidity.

28

R-2800 Development

Fig. 3.4 "Chokin g" of cylinders was used in all R-2800 variants. It was accompl ished by the shrink fit of the cylinder head screwed onto the barrel. As the heated cylinder head cooled and assumed the same temperature of the barrel it contract ed enough to choke the barrel's bore. This illustrati on graphica lly shows the contour of the barrel bore dimensio n. It can be seen that a maximum of 0. 006 inches choke was obtained at top dead center. (Double Wasp B Series Two Stage Engines [R-2800 -8, -10, -8W, and -JOW], Second Edition. Authors collectio n.)

Rings It was only in the early 1930s that any semblance of good ring design had evolved. Prior to this, aircraft engines and any other engine for that matter, tended to suffer from excessive oil consump tion. This was a result of the piston ring's steam engine ancestry. The two primary functions of piston rings are (1) to seal the piston against the enonnous gas pressure s generated during the power stroke and (2) to reduce the flow of oil into the combustion chamber to a minimum. Always a difficult design challenge , ring development tended to progress on an empirical basis. The spring tension in a ring is not very important, since the major component of the radial pressure for sealing is provided by gas pressure behind the ring exerting pressure against the cylinder wall. Spring tension, however, does play a more important role in the case of a badly worn cylinder. Side clearance in the piston ring land is a key dimension. Sufficient clearance needs to be provided for to

29

Chapter 3

allow gases to flow over the top face of the ring and pressurize it against the cylinder wall . On the other hand excessive clearance will result in hammering of the ring against the lands, resulting in premature failure. This is especially true of the vulnerable top ring land. Early engine designers failed to realize the importance of sufficient land clearance. This resulted in collapsed rings, i.e. , the gas pressure would tend to force the ring inwards thus destroying the seal. Sir Harry Ricardo (Fig. 3.5) (Ref. 3.7) was one of the pioneers to realize this anomaly with a tank engine he developed during World War I. As a quick expedient he had grooves machined into the top faces of the rings to allow the gas pressure to get to the back of the ring. Ring face width was another area of controversy. The proponents of a wide ring face argued that there was less chance of the oil film being squeezed out, particularly towards the top of the stroke where boundary layer lubrication exists. This, of course, resulted in less cylinder barrel wear. On the other hand, a wider ring carries more inertia, resulting in a greater tendency to ring flutter. Ring flutter is the phenomenon caused at high piston speeds, typically 2500 feet per minute and higher, when the ring will float off the lower ring land consequently destroying the gas seal. This results in violent blow-by and significant loss of power. For many years this phenomena was thought to be caused by radial vibration of the ring . Paul Dykes, for whom his piston ring is named, demonstrated what really occurred. Under normal circumstances, as the piston rises on the compression stroke, the ring is held, at first by inertia, and later by gas pressure, against the lower ring land. In this way, the full clearance above the ring is available for gas pressure to seal the ring against the cylinder wall. And at the same time the lower land is completely sealed. At some critical piston speed, however, the ring 's inertia will exceed both friction and gas pressure during the compression stroke and allow the ring to float off the lower land. Under these running conditions the ring will lose the gas seal and collapse resulting in the classic case of "ring flutter. " The foregoing gives an idea of the idiosyncrasies involved in ring design. Most of it resulted from trial and error. Rolls-Royce ran afoul ofring problems developing the 1931 Schneider trophy "R" racing engine. At one time during this engines development, oil consumption reached an unheard of rate of 112 gallons per houri

Fig 3.5 Sir Harry Ricardo, one of the early engine development pioneers. Ricardo made numerous contributions to engine development during his long and illustrious career (Courtesy of Ricardo Consulting Engineers.)

30

R-2800 Development

For the R-2800, five piston ring grooves were provided for six piston rings (Fig. 3.6). The top three grooves contained compression rings of the "wedge" type. These rings were originally developed for the hyper perfom1ance Napier Sabre in England. Its advantages include less susceptibility to ring sticking from oil coking, and a better seal. Typically, the ideal included angle is 15 degrees. The top ring was manufactured from a chrome faced, gray cast iron material, the lower compression rings were similar in design but did not include the chrome facing. A dual oil control ring resided below the top three grooves. At the bottom of the piston, below the wrist pin, an oil scraper ring resided. A fully floating, hollow steel wrist pin made from a centerless grinding operation was used with aluminum plugs pressed into its ends for cylinder barrel protection.

Cam Rings It would be impracticable for a radial engine to have a conventional camshaft such as those used for inline engines. Therefore a cam ring was employed. It performs the same function as a camshaft but in a slightly different manner. The engine does not care how the valves are opened and closed just as long as these events occur at the correct time with the correct acceleration/deceleration and valve

END GA P

SIDE CLEARANCE

END GAP

SIDE CLEARANCE

.o9e5 - . 1035

.004 - .0 06

.06!!5 -.0735

.002 - .004

. 0985 -.1035

.004 - .006

.0665 - .0735

.002 - .004

. 0665 - .0735

.002 - .004

. 06&5 - .0735

.0 02 - .004

. 0665 -.0735

.0685 - .0735

.004 - .007

.05 6 5 - .0735

.0665 - .0 735

.O!l!l5 - . 0735

. 003 - . 005

.062

-.074

.004 - .007

.003 - .005

LEGEND CC-CHROME PLATED COMPRESSION RING C-PLAIN COMPRESSION RING DUAL OIL CONTROL RING S- SCRAPER RING

IF A PLAIN COMPRESSION RING IS USEO IN THE TOP GROOVE , A RECTANGULAR -SECTIONED COMPRESSION RING MUST BE USEC IN THE BOTTOM GROOVE.

DO-

Fig 3. 6 Cross section showing the R-2800 s piston ring configuration. (Double Wasp B Series Two Stage Engines [R-2800-8, -1 0, -8W, and -1 OW], Second Edition. Authors collection.)

31

Chapter 3

lift. As its name suggests, a cam ring is basically a ring with two tracks precision ground onto its outer diameter with four (in the case of the R-2800) cam profiles on each track (Fig. 3. 7) . One cam track operates the intake valves and the other cam track operates the exhaust valves . For the early series of R-2800 described herein the timing was as follows: Intake opens 20 degrees BTDC Intake closes 76 degree ABDC Exhaust opens 76 degrees BBDC Exhaust closes 20 degrees ATDC A four stroke engine completes a cycle every 720 degrees or two revolutions. That is why the inline engine uses 2: 1 reduction gearing between the camshaft and crankshaft. On the other hand a radial engine designer has a number of options at his disposal. In the case of the R-2800 with its four lobes, 8: 1 reduction gearing is required. Each row of cylinders has a dedicated cam ring . Some n;vo-row

ENGINE LIFTING LINKS MAGNETO INlERMEDIATE ORIVESPURGEAR

UPPER CAM REDUCTION

, \

OISTRIBUTOR DRIVE

IDL£R GEAR

GEAR REAR BUSHING

~

\

UPPER CAM

_,r--- FRONT CAM

REDUCTIOrt GEAR

DISTRIBUTOR DRIVE IDLER GEAR

COUN.ll:RBALANCE INTERMEBIATE DRIVE GEAR SHAFT

CIRCLED NUMBERS REFER TO

POSITION NUMBERS ETCHED ON PARTS

Fig. 3. 7 Front cam ring and support plate. The R-2800 used four cam lobes per cam track and consequently 8: 1 reduction gearing from the crankshaft. Note the roller cam followers . (Double Wasp B Series Two Stage Engines [R-2800-8, -JO, -8W, and -JOW], Second Edition. Authors collection.)

32

R-2800 Development

engines would use one cam ring located in the front. While this obviously helped to reduce the complexity and weight of the engine, it was a compromise at best. For the pushrods to reach the rear row of cylinders, a severe angle was introduced . This was detrimental to valve timing and valve lift because of the different geometry compared to the front row. Furthermore, heavy thrust loads were introduced, particularly at the tappets. The R-2800 's cam ring, running at one-eighth crankshaft speed, was supported in a large diameter, narrow bronze bushing. Due to the necessary clearance of this large diameter bushing, it was essential that the cam ring be centered in this bushing during valve clearance adjustments. This was accomplished by simply depressing the diametrically opposite valve. A compound gear train emanating from the crankshaft drove the cam ring. Final drive was via a pinion gear driving an internal gear machined into the cam ring (Fig. 3.8). Drive arrangements were similar both front and rear. Cam followers were steel with rollers riding on the cam track (Fig. 3.9). The tappets ran in aluminum tappet guides shrunk into the front and rear sections of the main crankcase.

PISTON

PIN

VALVE TA P P ET MASTER ROD BEARING· AND KNUCK L E PIN RETAINING PLATE

VA LV E TA P PET ROLLER

CRAN K SH A FT FR ON T GE AR

COUNTERWEI GHT

COUNTERWEIGHT ROLLER

MASTER

ROOS

Fig. 3.8 With four cam lobes, 8:1 reduction gearing is required. This illustration shows how Pratt & Wh itney achieved this reduction ratio. (Double Wasp B Series Two Stage Engines [R-2800-8, -1 0, -8W, and -lO W}, Second Edition. Authors collection.)

33

Chapter 3

CRANKSHAFT FRONT GEAR

ENGINE LI FTING LINK

VALVE TA PPET ROLLERS

FRONT MAIN CRANKCASE VA LVE TAPPETS

Fig. 3.9 Tappet chest and roller cam fo llowers shown to good advantage in this front view. (Double Wasp B Series Two Stage Engines [R-2800-8, -10, -8W, and -JOW], Second Edition. Authors collection.)

The outer ends of the tappet guides are supported in the outer wall of the crankcase and the inner ends are anchored in bosses forged integral with the crankcase section.

Crankshaft One of the key considerations when designing a crankshaft is vibration, specifically torsional and linear vibrations, the bane of many engine designers. Torsional vibration is induced by a slight twisting and untwisting of the crankshaft along its longitudinal axis. Each time a cylinder fires , a sudden surge of energy is imparted to the crankshaft. Total elimination of torsional vibration is impossible; however, keeping it within reasonable bounds, i.e., less than one degree, will contribute to the crank enjoying a long life. If a crankshaft were infinitely rigid, torsional vibration would not be an issue. Unfortunately, no such ideal material exists, so in the real world of highly stressed, lightweight engines, things bend, stretch, and twist. Linear vibration is the perceived "shaking" of the engine . The final fix for the

34

R-2800 Development

R-2800 's linear vibration problems was the incorporation of two second order counterweights rotating at twice crank speed. The following is a brief discourse on some of the background surrounding crankshaft development and its associated quirks.

Torsional Vibration Background A bitter rivalry between carmakers Frederick Lanchester and Henry (later Sir Henry) Royce (Fig. 3.10) (of Rolls-Royce fame) (Ref. 3.7) evolved in the early part of the century, each claiming to be the inventor of the crankshaft torsional vibration damper. Both men understood the problem and attacked it in similar ways, a torsionally resilient flywheel at the front of the crank . Royce later used a clutch pack on his first aircraft engine, the water cooled V-12 Eagle. It was installed in the nose case as part of the epicyclic reduction gearing. Although it worked well, one disadvantage was that the positional relationship between the crank and propeller was constantly changing, which negated the possibility of using a gun synchronizer. In addition, Royce used a spring drive at the rear similar to the R-2800 's blower drive, i.e. , axially disposed compression springs in a two-piece drive gear, with the hub of the gear being cushioned by the springs. Without these torsional vibration attenuation devices the Eagle could not operate at its optimal speed of 1750 rpm. As engine powers climbed way beyond the Rolls-Royce Eagle's 360 to 400 horsepower something more effective was required. In the United States, Pratt & Whitney, Curtiss-Wright, and Lycoming, all of whom were developing radials, ran into crankshaft torsional vibration problems at about the same time controllable pitch propellers were introduced. It has been argued that the relatively loose mounting of blades in their hubs compared to rigid fixed pitch propellers "detuned" previously stable crankshafts. This resulted in reducing the effective inertia of the propeller resulting in some cases of harmonic torsional vibration periods. Two lieutenants working at Wright Field zeroed in on this phenomenon: Lt. Orval Cook and Lt. Turner A. Sims, both of whom worked in the Wright Field Propeller Branch. A counterargument suggests that rather than the loose mounting of the propeller blades detuning crankshafts, a more

Fig. 3.10 Henry Royce (later Sir Henry Royce), co-founder of Rolls-Royce, was a contemporary of Lanchester :S. Like Lanchester, Royce recognized the destructive forces at play with crankshaft torsional vibration. (Courtesy of the Rolls-Royce Heritage Trust.)

35

Chapter 3

plausible explanation might be that controllable props had considerably greater mass than previously used fixed pitch propellers or test clubs. The severity of the problem peaked in 1934 when Wright suffered serious problems with the R-1820 including broken propeller shafts. During this time frame, E.S. Taylor of the Massachusetts Institute of Technology proposed that a pendulum type damper should be incorporated into the crankshaft webs. His first proposal was the "Salomon" or hockey puck type as used in the "A," "B," and "D" series R-2800. Roland Chilton of Wright used a floating counten¥eight supported on two pins and consequently was called the bifilar-the same type used on the R-2800 "C" and "E" series. Independently of the work taking place at Wright Field, MIT, Wright, etc. , the French also had an understanding of this problem. According to Taylor, " Salomon was the first to understand the principle of the pendulum damper. " Also according to Taylor, another Frenchman, Sarazin, had designed a device almost identical to Chilton's, which influenced Hispano-Suiza and their aircraft engines (Ref. 3. 9). With the incorporation of Salomon type dynamic counteraeights, this took care of the more immediate problem of crankshaft torsional vibration. But it had little effect on the perceived and actual smoothness of the engine. It took the introduction of the second order linear vibration damper to smooth out the engine, rather than crankshaft torsional, vibration. Contributing to second order vibration, as with all engines, was the variation in connecting rod geometry. The master connecting rod was the only one describing a true circular path. The link rods described an elliptical path. For this reason the link rod knuckle pins were tucked in as tightly as possible to the master rod. Even so, the distance between the center of the master rod journal and the center of the link rod knuckle pin created a differing geometry, resulting in a second order vibration being set up due to the "whirling" effect of the link rods. In practice, many variations were used to attenuate this second order vibration resulting from the differing rod geometries. Pratt & Whitney took a fairly simple route. Two disks, approximately one-third the diameter of the engine's crankcase, mounted co-axially to the crankshaft, one at the front and one at the rear was their chosen solution (Fig. 3.11). A lead bronze bearing pressed into the counteraeight runs on an extension to the number one crankshaft main bearing journal for the front counte1weight and number three main journal for the rear counteraeight. To attenuate second order, the counteraeights need to run at twice crank speed. The 2:1 gearing is achieved through a gear attached to the crankshaft and intermediate gears. Driving a massive counten¥eight at up to 6000 rpm-and sometimes greater, takes some thought in the design process . Torsional vibrations emanating from the crankshaft, propeller, and other internal engine parts could excite the counteraeight and its drive gears. In order to attenuate this tendency, compression springs, disposed axially around the crank gear offers the appropriate amount of cushion to ensure the system lives in harmony with its neighbors. This solution was also used for the supercharger drive. With the two aforementioned second order counteraeights installed, things smoothed out considerably (Fig. 3.12). Contributing to second order linear vibration was the fact that the cylinders did not share the same stroke . This is due to link rod knuckle pins not being located at the crankpin center. The first two on either side of the master rod have the same stroke but not the same as the master rod. The next two pistons have the same stroke, but again different from the others. The last pair likewise have the same stroke but different from the others. When analyzing the inertia of all pistons and reciprocating portion of the

36

R-2800 Development

A

5:375 DIA. SILVER

5. 180

5 .7 95 P.O.

4.8755 4.8745

THESE SURFACES MUST BE PARALLEL WITHIN .0 0 1 AND SQUARE WITH THIS DIA WITHIN .002 FULL INDICATOR RE ADING BEFORE ANO AFTER PLATING

STEEL SILVER SECTION A-A

FRONT COUNTERBALANCE ENCLOSED AREA CASE HARDENED 81 TO 84 ROCKWELL "A" SCALE

5180

A

THESE SURFACES MUST BE PARALL EL WIT HIN .OOI FULL INDICATOR READING AND. SQUARE WITH THIS DIA. WITHIN 002 FULL INDICATOR READING BEFORE AND AFTER PLATING

____

STEEL SILVER

SECTION A-A

REAR COUNTERBALANCE Fig 3.11 Second order counterweights rotating at twice crank speed were essential in ensuring the survivability of the R-2800 crankshaft. These second order counterweights attenuated linear vibration. (Double Wasp B Series Two Stage Engines [R-2800-8, -10, -8W, and -lOW}, Second Edition. Author '.s collection.)

37

Chapter 3

Fig. 3.12 Even the second order counterweight gear drive needed protection from torsional vibration. This was accomplished via the compression springs shown in this illustration. A similar cushioning drive was used for the supercharger drive. (Overhaul Manual Double Wasp B Series Two Stage Engines, 1944. Authors collection.)

rods, an inertia force that rotates twice at twice crank speed results in a 2X force. This non-uniform stroking is an incentive to pull the knuckle pins in as close to the crankpin center as possible . As a typical example of the out of balance forces that had to be contended with, the bare R-2800 master connecting rod weighs approximately 15 pounds. Part of this 15 pound mass is reciprocating and part rotating and constantly changing geometry. Even so, Pratt & Whitney went through many variations on twice crank speed second order counterweight design before settling on one that was dependable and yet smoothed things out for the engine. Nevertheless, the second order counterweight and its drive continued to keep Pratt & Whitney 's finest engineers on their toes. At a critical stage of World War II, Eighth Air Force P-47s were grounded because of a manufacturing problem with this key component (Ref 3.10). As mentioned previously, another key design decision for the crankshaft is the choice of one piece with split master rod, or built up with one-piece master rod. Hobbs clearly favored the latter. But it did introduce design challenges which, fortunately, Pratt & Whitney engineers were up to. The most basic of these challenges was how to assemble the crankshaft and ensure it would hold together under punishing loadings . Secondly, how many major components should the crankshaft be made from ? Either design route was littered with compromises and mechanical booby traps for the unwary.

38

R-2800 Development

With a one-piece crank and split master rods, the compromise is the lower BMEP and rpm capability of the rod. A higher structural weight of a two-piece master rod also increases the weight of the counterweight necessary to balance the engine. The one-piece master rod and built up crank introduced problems of integrity of the crankshaft. Subjected to enormous bending, vibratory, and torsional loads, the joints were susceptible to " creeping" and fretting. The design that finally evolved, at least for the "A" and "B" series engine being described here, was as follows : A three-piece, three main bearing crankshaft was developed. The front and rear sections comprised the front and rear main bearings. They also incorporated half the master rod bearing journal for the front and rear rows of cylinders. The center section comprised the center main bearing journal and the remaining halves of the front and rear master rod bearing journal. Each of these major components was machined from a chromium-molybdenum forging. Furthermore, each component was polished all over for fatigue resistance. The bearing journals were micro polished. A pair of massive counterweights took care of static out of balance forces for each crank throw. Additional weights, manufactured from tungsten, were riveted to the pair of crank cheeks for the front master rod journal. The rear master rod journal still had tungsten counterweights riveted to the front crank web. Additionally, the rear crank web featured dynamic Salomon "hockey puck" type weights, again, made of tungsten. The dynan1ic counterweights took the fonn of circular pucks allowed to float on the rear crank cheeks. These hockey puck dynamic weights attenuated 4Yz order vibration modes. Holding a heavily loaded crankshaft together required ingenuity and bolts of the highest precision and strength . The split journals featured a male and female spline for location and transmission of torque. A force fit required the use of a jack to assemble the crankshaft components. A precision bolt then held the splined couplings together. All in all, a tricky design and manufacturing job (Fig. 3.13 and Fig. 3.14). The front of the crankshaft was bored out to accommodate a steel-backed bronze bearing. The tail end of the propeller shaft ran in this bearing. The weight of the propeller, up to 600 pounds, plus gyroscopic loads during aircraft maneuvers conspired to place heavy loads on the front main bearing. Under extreme operating conditions, such as violent combat maneuvers, premature front main bearing failure could result. Although adequate (barely) for the " A" and "B" series R-2800, the master rod journals could distort under heavy load. This deficiency was corrected in the "C" and "E" series engine with their face splines described in the next chapter.

Notches on the Telephone As indicated in the foregoing description, nothing comes easy in life, particularly when it pertains to design of the R-2800 crankshaft. George Meloy, one of Pratt & Whitney's experimental test engineers in charge of crankshaft development testing, probably suffered more through these trying times than any one . Meloy quickly rose through the management ranks at Pratt & Whitney, and even today he is fondly remembered by his co-workers as one of the few people who could spend time in a test cell wearing a crisp white shirt and not get a drop of oil on it! Born in 1916 in Chicago, hi s family moved to New York four years later, eventually settling in Teaneck, New Jersey, ironically Curtiss Wright territory. After graduating high school in Teaneck, Meloy successfully pursued a bachelor of aeronautical engineering degree from New York University. In 1938, even though this

39

Chapter 3

Fig 3. 13 Built up crank for the "A " and "B " series R-2800. Note the "hockey puck" type Salomon dynamic counterweights on the right and male/female splines for holding the sections together. (Overhaul Manual Double Wasp B Series Two Stage Engines, 1944.)

was in the depths of the Great Depression, Meloy found employment with Pratt & Whitney. Starting as a test engineer, his managerial talents were quickly recognized. In an effort to inject some humor in a serious situation, one of George 's co-workers cut a notch in his telephone each time a crankshaft failed. His phone soon ran out of space to add notches! As can be imagined, a crankshaft failure was a devastating blow requiring a root cause analysis and then a redesign (Ref. 3.11). Obviously, many of the crank failures were associated with metallurgy problems. To attack the problem from this angle, Pratt & Whitney employed metallurgists to investigate crank failures and other metal fatigue related design problems. Two names that came to the forefront during interviews for this book were A.W.F. Green, or as he was better known, "Awful Green. " Despite this rather disrespectful moniker, he was key in helping George Meloy overcome the serious crankshaft failures with his innovative metallurgical solutions. Herb Noble was another key metallurgist working diligently on improving materials . The recognized guru of vibration is Den Hartog, who wrote the definitive work on the subject, Mechanical Vibrations. At the time of the R-2800's development, Hartog was a professor at MIT. He consulted with Pratt & Whitney during the development phase of the R-2800 crankshaft. The following table is a synopsis of Short Memorandum Reports (SMRs). They give some idea of the tremendous effort required to get something that would not fail under the abuse of propeller loads, gyroscopic loads, attenuating various orders of vibration, etc. As an example of what can go wrong, Dana Waring witnessed a typical catastrophic failure in the test house. A rear crank cheek failed between the Salomon dampers. At the time of failure, the engine was running at takeoff power. This failure immediately locked the engine solid. Of course the laws of physics take over in situations like this and the engine tore itself off the mount, and rotated in the test cell until the carburetor stopped its rotation. The propeller, in the meantime, tore itself loose and continued to slam itself against the walls of the test house. When everything had settled down, the scene was that of utter destruction!

40

R-2800 Development

TABLE 3-1 CRANKSHAFT DEVELOPMENT

Object/Process

Results/Conclusions/ Recommendations

217138

Determine amplitude and frequency of crankshaft vibration . Wood club, 1500 hp, 700 to 2100 rpm, measurements taken at front of accessory drive shaft (rear of crank) .

Ax amplitude +/- 0.19 de., crank natural frequency - 90 Hz, no marked resonance , test stopped at 2100 rpm due to an unspecified bearing failure

2/16/38

3/11/38

Continuation of SM 393. 2:1 reduction gear, wood club, 1500 hp, 1000 to 2400 rpm, measurements taken at front of accessory drive shaft (rear of crank).

Safe to run. 4.5X resonance at 1200 rpm+/- 0.49 de (ax). Natural frequency not sharply defined , seems about 90 Hz, 2.5X-5.5X vibration throughout the rpm range.

X-79 410 (Ref. 3.14)

3/22/38

3/25/38

Determine resonant speeds of torsional vibration on "Z" dynamometer, 2:1 reduction gear, motoring 500 to 2100 rpm, firing 400 to 2600 rpm, load of 1800 hp at 2600 rpm, lack of torsiograph adapters for starter shaft prevented gathering data on accessory shaft twist.

Accessory drive shaft failure . Unsafe to operate this dynamometer-engine combination below 1500 rpm. Serious resonance at 800 and 1300 rpm .

X-79 415 (Ref. 3.15)

3/30/38

4/12/38

Investigate torsional vibration with direct drive on "Z" dynamometer, concentrating on accessory drive and crank motion . Data taken at front of accessory drive shaft and generator drive 300 to 2000 rpm motoring , 500 to 2200 rpm firing, and load of 1800 hp at 2600 rpm.

Serious 1X at 1000 and 1400 rpm. Unsafe to operate from 800 to 1600 rpm . Suggests installing first order pendulum damper on dynamometer coup ling . Suggests placing master rods near O de, but points out that unbalanced secondary torque would necessitate tear down before and after dynamometer run and the need for special evenfiring mags.

X-79 418 (Ref. 3.16)

4/19/38

4/27/38

Investigate torsional vibration with wood club and single-pinion 2:1 reduction gear, 60-spline prop shaft. 1200 to 2600 rpm , load of 1800 hp at 2600 rpm.

Natural frequency is 5200 rpm. Ax torsional vibration amplitude is 0.32 de . Slight resonance at 2600 rpm. "With the master rods set at 100 de on this engine , the second ary torque harmonic is practically balanced out."

X-79 420 (Ref. 3.17)

4/26/38

4/39/38

Investigate destructive vibration that resulted in carburetor mount, air chute, and exhaust stack failures. Steel and aluminum air chutes were tried unsuccessfully. Metal prop and wood prop were tried , no change . Ax amplitude is 2600 rpm (endurance operating speed).

Whirling motion at twice engine speed with a node at the center main bearing indicates unbalanced second order inertia forces. A 1.5X vibration at higher speed thought to be due to prop interference. Suggests variation in piston weights between cylinders or three master rods spaced at 120 de on each crankpin as possible solutions.

Test Date

Report Date

X-78 393 (Ref. 3.12)

1/31 /38

X-78 408 (Ref. 3.13)

Report Number

Engine Serial #

(continued)

41

Chapter 3

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Report Number

Engine Serial#

Test Date

Report Date

431 X-70 (Ref. 3.18)

4/26/38

5/ 17/38

Torsional vibrati on investigation with 3-blade metal prop. 1200 to 2600 rpm, load of 1830 hp at 2600 prm , 2: 1 reductio n, 1T prop , doublepinion, 60-spline prop shaft.

Safe to operate. Ax tors ional vibration at 2600 rpm at 0.64 de. Natu ral frequency -100 rpm less than with wood club.

432 X-78 (Ref. 3.19)

5/11 /3 8

5/18/38

Investigate the fix proposed in SM 420. Heavier pistons, solid pins, and bronze caps in master cy linder and 3 adjacent on each side. Primary balance maintained by increasing master balance weight.

Found impractical for achieving secondary inertia balance. An incorrect assumption in original ca lcu lations predicting 80% improvement was actually 10% with a 75 lb increase in engine we ight. Suggestion of second order counterbalance method.

442 (Ref. 3.20)

6/17/38 7/1/38 to 6/2 1/38

Test of second order counterbalances front and rear, designed to counterbalance -80% of combined secondary couple and shaking force, load of 1800 bhp at 2600 rpm, wood club.

Inconclusive but promising. Front co unterbalance drive broke. Suggestion of flexible drives for co unterba lances. Suggestion of 180-de master rod orientation.

X-78

Object/Process

Results/Conclusions/ Recommendations

449 X-7 8 (Ref. 3.21)

7/2/38

7/ 15/38

Torsional vibration with 180 de master rods (6 & 15) , single pinion, 2: 1 reduction , 60-spl ine prop shaft, wood club .

Excessive second order tors ional vibration (1 .32 de with 180 de spacing as opposed to 0.30 de with 10 de spacing) , both at 2550 rpm, amplitude of the second order whirling was not red uced . 3.5X resonance attributed to valve inertia was observed.

450 X-78 (Ref. 3.22)

7/1/38 to 7/5/38

7/15/38

Linear vibration with 180 de master rod placement. Investigation of test club role inducing second order vibration investigated by indexing club.

No change in li near vibration. Prop co ntribution to second order linear vibration deemed insign ificant. 3.5X resonance in air chute is deemed destructive.

454 X-78 (Ref. 3.23)

7/15/38 8/5/38 to 7/26/38

Linear vibration with 50-spline prop shaft and Ham Standard Hydromatic prop with 6159-0 blades. 2: 1 reduction , 100 de master rods , 1800- 2600 rpm , wood club then metal prop .

Resonant speed with wood club dropped to 2050 rpm due to less stiff prop shaft. Amplitudes of 0.0 15" to 0.0 17" With Ham Standard Hydromatic prop , resonance at 2550 rpm , amplitude of .013".016". Prop interference resonance at 1800 and 2400 rpm 0.023". No resonance but high amplitude of 3.5X linear vibration.

(continued)

42

R-2800 Development

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Report Number

Engine Serial#

Test Date

Report Date

ObjecUProcess

Results/Conclusions/ Recommendations

X-78 455 (Ref. 3.24)

7/22/38 8/9/38 to 7/26/38

Torsional vibration with 50-spline prop shaft and Ham Standard Hydromatic prop with 6150-0 blades . 2:1 reductio n, 100 de master rods , 1200 to 2700 rpm , load of 1800 hp at 2600 rpm.

Wood club: crank natural frequency reduced from 5200 cpm to 4600 cpm , amplitude went from 0.30 to 1.02 de. Prop: reduced natural frequency to 4400 cpm , ax amplitude of 1.35 de. Second order torsional in resonance at 2200 rpm higher speeds, 1.5X and 1X are outstanding. Suggests determining if the 1X component is torsion of entire engine.

X-78 462 (Ref. 3.25)

8/22/38 8/8/38 to 8/16/38

Test second order counterbalances (designed for 68% excitation reduction) with neoprene rubber drive couplings in counterbalance drive, 50-spline prop shaft, wood club, 1600 to 2600 rpm , load of 1800 bhp at 2600 rpm , Ham Standard Hydromatic 14 · prop (23E50 hub, 6159-0 blades) .

Six and fifteen drive buttons were tried. Counterbalance drive failed in each case (sheared buttons and bearing failure) . Data that was gathered indicated 60% (wood club) and 75% (prop) reduction in 2X vibration (measured at the thrust plate) and similar reduction at the carb flange. 1.5X (prop interference) and 3.5X (valve) vibration remain. Suspect test house influence on 1.5X vibration. Suggests spring counterbalance drive and lead-plated bearings.

X-78 474 (Ref. 3.26)

8/ 15/38

9/ 17/38

Torsional vibration tests with 15button rubber counterbalance drives and Ham Standard Hydromatic prop (23E50 hub, 6159-0 blades), 2:1 reduction , 50-spline prop shaft, 1200 to 2500 rpm , load of 1800 hp at 2600 rpm.

Torsional vibration ax amplitudes: 2.5X of 1.20 de at 1200 rpm; 2X of 0.88 de at 2000 rpm ; and 1X of 0.96 de at 2300 rpm. Crank natural frequency reduced 400 cpm to 4000 cpm. 1X vibration peaks at 2300 rpm. Torsional motion of engine may contribute to 1X vi bration. Overall improvement in torsional vibration except for 1200 rpm resonance.

X-78 475 (Ref. 3.27)

8/31 /38

9/28/38

Linear and torsional vibration test with leaf spring drive counterbalances and wood club. 2:1 reduction, 50-spline prop shaft, linear measurements from 1500 to 2400 rpm, torsional measurements 1050 to 2450 rpm , load of 1800 hp at 2450 rpm .

2X linear vibration down to .0095" at 1600 rpm (60% reduction same as rubber-drive counterbalances). 3.5X resonance is now biggest vibration. A 5.5X resonance is believed due to flexible sensor mounting . Reduction of 2X linear vibration not as good as theoretical due to additional 2X interference from the 4-blade test club.

(continued)

43

Chapter 3

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Report Number

Engine Serial#

Test Date

Report Date

Object/Process

Results/Conclusions/ Recommendations

476 X-78 (Ref. 3.28)

9/2/38 9/28/38 to 9/ 10/38

Torsional vibration with leaf spring counterbalances and Ham Standard Hydromatic prop 2:1 reduction, 50-spline prop shaft. 1200 to 2700 rpm , load of 1800 hp at 2600 rpm. Sensor to determine 1X torsional vibration of entire engine applied , found to be 0.1 O de , also 0.18 de at .5X.

Ax torsional vibration of 1.60 de at 2700 rpm (1.5X and 1X). Variation in torsional vibration attributed to prop interference and interaction with other engines running in the test house. 2X component peaked at 2150 rpm indicating slight reduction in crank natural frequency. Torsional vibration is too high above 2400 rpm , but 1.5X is probably prop/test house interaction and will not be as noticeable on airplane. Since only a small torsional vibration exists for the entire engine, most torsional vibration is in the crank, reduction gearing , and prop shaft. Suggests higher speed tests for 1.5X and 1X to see if it peaks below 3000 rpm .

479 X-78 (Ref. 3.29)

9/2/38 10/7/38 to 9/10/38

Test of linear vibration with springdrive counterbalances. Ham Standard Hydromatic 14 · prop (23E50 hub, 6159-0 blades). 2:1 reduction , 50spl ine prop shaft, 1700 to 2650 rpm , load of 1800 hp at 2600 rpm . Correlation of prop blade stresses at conslant BMEP of 195 and full throttle . 1200 to 2700 rpm.

60% reduction in linear vibration corre lates wel l with 68% theoretical prediction. 2X linear vibration ax of 0.012" in vertical direction at carb flange, resonance of entire engine at 2500 rpm . 1X and 1.5X vibration gave largest amplitude, but the 3.5X that is in resonance at 2400 rpm is the most serious. Carb resonance up to .010" at 2050 , 4.5X and 5.5X vibration exist through the range , but shows no resonance. Blade tip stress peaks of 5X at 1500 rpm, 4X at 1900 rpm , and 3X at 2500 rpm (highest at 11500 psi) . No crank torsion at 3X , 4X or 5X. Prop shank showed peaks of 1X, 1.5X and 3.5X vibration (1900 and 2400 rpm) with amplitude up to 3000 psi. Prop tip stresses exceed limits of 4 to 5000 psi , but excitation source is unknown. Prop shank stress is acceptable.

487 X-79 (Ref. 3.30)

10/31 /38 Find source of high prop tip stresses 9/30/38 by sensing vertica l, transverse , and to 10/5/38 fore-aft linear vibration , and observe 1X torsional vibration from 2600 to 2800 rpm. Ham Standard Hydromatic

Vertical and transverse linear vibralions were nearly identical to SM 479. 2X peak at 2500 rpm , 3.5X peak at 1600 rpm , and 4.5X peak at 2300 rpm were all in resonance . (continued)

44

R-2800 Development

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Report Number

Engine Serial #

Test Date

Report Date

487 (Cont)

488 X-78 (Ref. 3.31)

10/11/38 11 /8/38 to 10/21 /38

Object/Process

Results/Conclusions/ Recommendations

14· prop (23E50 hub, 6159-0 blades), 2:1 reduction , leaf-spring drive counterbalances, 50-spline prop shaft, 100 de master rods , 1200 to 2600 rpm at 196 BMEP, 2600 to 2800 rpm with load of 1800 hp.

5.5X linear vibration was not. Foreaft linear vibration shows resonance of 3X at 2500 rpm (highest blade-tip stress) , and 4.5X at 1500 and 2300 rpm. Torsional vibration of 0.79 de is within spec. 1X torsional vibration component still increasing at 2800 rpm with no indication of peaking below the 4000 cpm crank natural frequency. Subsequent tip stress runs have failed to duplicate 3, 4, and 5X stresses reported in SM 479. All runs show a 4.5X resonance at 2300 rpm and some a 4.5X at 1500 rpm. There is excitation at all the usual harmonic orders, with the 4.5X being the one resonating in this application. While it is destructive to the prop, it probably has no effect on the engine. A 4.5X damper would remove the 4.5X stress, but may introduce worse 3.5, 4, 5, 5.5X stresses. Suggests redesign of cra nk to decrease in natural frequency to 500 to 1000 rpm , combination of torsional flexibility and damping, and centrifugally coup ling . Suggests a 4.5X cra nk damper to reduce prop tip stresses.

Crank torsional vibration characteristics with 1X damper. 2:1 reduction, leaf spring counterbalances, double link 1X crank damper, 50-spline prop shaft, 100 de master rods , wood club and Ham Standard Hydromatic 14· prop (23E50 hub, 6159-0 blades) . 1200 to 2600 rpm, load of 1800 hp at 2600 (wood); 1200 to 2200 rpm at 148 BM EP, 22 to 2800 rpm at 196 BMEP (prop). Note that galling of the damper links caused friction and decreased function. Clearances and oil supply were reworked, but mechanism continued to give trouble.

Linear vibration and 1X torsional vibration unaffected, 1.5X and 2X torsional vibration were higher at 196 BMEP, but at 148 BMEP 1.5X was practically negligible and 2X was below 0.20 de. No clear indication of damper effectiveness due to friction. Increase of 1.5X and 2X torsional vibration probably due to high prop blade angle and amplification of higher orders by 1X damper motion. Again , test house conditions seem to influence 1.5X torsional vibration. There is still a large 4.5X torsional vibration at 2300 rpm. This is the source of high blade tip stresses reported in SM 487. (continued)

45

Chapter 3

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Report Number

Engine Serial #

Results/Conclusions/ Recommendations

Test Date

Report Date

489 X-79 (Ref. 3.32)

10/20/38

11 /8/38

490 X-78 (Ref. 3.33)

10/3 138 11/10/38 Test of 1X damper with needle bearto 11 /3/38 ing links. 2:1 reduction , 50-spline prop shaft, 100 de master rods, spring drive counterbalances, Ham Standard Hydromatic 14 · prop (23E50 hub , 6159-0 blades). 2000 to 2800 rpm at 196 BMEP.

First run 1X tors ional vibration amplitude was 0.96 de compared to 0.48 de without dampers. Second run 1X torsional vibration was 1.12 de, proving 1X damper unsuccessful. Rear counterbalances incorrectly assembled, requiring rework. Front counterbalance drive failed . Some test house effects observedthe more engines running, the less 1.5X vibration. Postulation that 1X damper failed because it was operating far from the resonant frequency of the system, and phase relationships between disturbing force , cran k motion , and damper motion are important, causing more crank motion in the off-resonant condition.

515 X-79 (Ref. 3.34)

11 /23/38 2/ 1/3 9 to 12/5/38

Runs of counterbalances with Wx R of 2.0 are reported previously in SM Rs* 462 and 475. This test explores W*Rs of 2.82 and 2.41. No difference in reduction was noted with the wood club , but with the metal prop and 2.82 counterbalances , 2X vibration dropped below 1.5X prop interference vibration. No metal-prop runs were made with 2.4 1 counte rbalances, since the intent of this test was to check heavier counterbalances for over correction. Indexing of the 4-blade test club , a result of uncontrolled reduction gear assembly variations, induces 2X interference indistinguishable from unbalanced secondary inertial forces. Although

Object/Process Linear vibration characteristics when operated outside the test house. 2:1 reduction, 50-spline prop shaft, 100 de master rod, leaf spring cou nterbalances , Ham Standard Hydromatic 14' prop (23 E50 hub , 6159-0 blades). 1400 to 2800 rpm , load of 1800 hp at 2600 rpm.

Comparison of linear vibration with light, medium , and heavy counterbalances , with wood and metal props . Tests of heavy counterbalances (2.82 lb/in. weight x radius product) were made from 1500 to 2600 rpm , load of 1800 hp at 2550 rpm. Two cranks, P/N 32550, center-split crankpins, and similar crank with splined plug joining th e crankpins. Flexibility of the sensor mounts affected 4.5X and 5.5X resonant peaks with Ham Standard Hydromatic prop (6159-0 bl ades). These are to be made stiffer in the future .

Vibration characteristics are similar to test house co nditions, with the largest vibration at 1.5X, 1800 rpm , .027" transverse , indicating a large propeller interference , particularly in the transverse plane. 2X vibration was higher than the last test and teardown revealed broken leaf springs in both counterba lances .

(continued)

46

R-2800 Development

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Report Number

Engine Serial#

Test Date

Report Date

Object/Process

Results/Conclusions/ Recommendations qualitatively better with heavy counterbalances, quantitative assessment is impossible due to 1.5X (prop) and 2X (club) vibration. A 50% reduction in 1X whirling motion was observed and believed due to better balance of the P/N 32550 crank over P/N 27985.

515 (Cont)

X-83 519 (Ref. 3.35)

12/2 1/38

2/15/39

Torsional vibration, linear vibration, and prop blade tip stress with qu ill shaft drive. 20 de master rods (8 & 9) to reduce 1X torsional vibration. New counterbalances, P/ Ns 33612 & 33698 with spring drives to reduce larger unbalanced secondary inertia forces caused by 20 de master rods , P/N 32550 crank with splined plug , club runs from 1200 to 2600 rpm, load of 1800 hp at 2600 rpm , prop runs at 196 BMEP from 1200 to 2600 rpm.

High blade tip stresses at 4.5X led to this attempt to isolate the prop and crank with a quill shaft. Though successful at this, 4X and 9X stresses combined to produce excessive tip stress. Further, it was determined unsafe to operate the engine below 900 rpm , between 1600 and 1900 rpm , and above 2600 rpm because of torsional resonance. Similar results were obtained with the test club. Additional damping must be installed to make the system safe to operate. A leaf-spring accessory drive is being considered.

X-79 521 (Ref. 3.36)

1/23/39

3/2/39

Torsional vibration with 2 wood clubs, crank assembly P/N 32550-B (3-piece , split crankpin), no dampers, P/N r-27000 counterbalances, 100 de master rods (8 & 13). 1200-2600 rpm with a load of 1800 hp at 2600 rpm , 2000 to 2800 rpm with a load 1840 hp at 2800 rpm .

0.55 de torsional vibration 2500 to 2600 rpm with load of 1800 hp at 2600 rpm. Principal frequency components were 1X and 2X . 2X was resonant at 2250 rpm, 2.5X was resonant at 1950 rpm. 1X increasing toward 2800 rpm. This test was done in preparation for the test in SM 522.

X-79 522 (Ref. 3.37)

3/2/39 1/20/39 to 1/23/39

Measurement of torsional vibration in accordance with Army torsional vibralion spec 95-28184. Ham Standard Hydromatic 14 · prop (23E50 hub, 6159-0 blades). Same engine as SM 521 .

Ax torsional vibration 1 .04 de at 110% rated speed (2640 rpm). Principal component was 1X. Natural frequency of 4200 to 4500 cpm. For a continuous run at 196 BMEP, ax torsional vibration was 1.05 de at 2800 rpm . The 1X resonance is a resonance of the whole engine, and not a result of crank windup.

X-79 530 (Ref. 3.38)

3/14/39 2/24/39 to 2/27/39

Torsional vibration with Ham Standard Ax torsional vibration of 1.08 de at 2700 to 2800 rpm. Natural IreHydromatic 13 '6" prop (23E50 hub, quency of 4100 to 4300 cpm. 6159-6 blades). Same engine as

(continued)

47

Chapter 3

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Report Number

Engine Serial#

Test Date

Report Date

530 (Cont)

Object/Process

Results/Conclusions/ Recommendations

SM 521. 1200 to 2800 rpm , load of 196 BMEP.

Nearly identical to 14' prop. Unacceptable 4.5X tip stress resonance. Discovery that misfiring cylinder induces erroneous torsional vibralion measurement.

531 X-83 (Ref. 3.39)

1/4/39 to 2/ 14/39 2/1/39 and 2/8/39 to 2/24/39

Torsional vibration and linear vibration with independently supported prop shafts (rear of shaft not supported by crank, but case web instead) . Crank P/N 32550-B, 100 de master rods (8 & 13), Ham Standard Hydromatic 14 ' prop (23E50 hub, 6159-0 blades) , 1200 to 2800 rpm , load of 196 BMEP. Test 2 replaced plain bearing on prop shaft tail with ball bearing , held drive gear concentric inside pinions with roller bearing on prop shaft, and used a fi x gear held instead of one floating on the spline . Test 3 replaced prop with Ham Standard Hydromatic 15 , (23F50 hub, 6183-0 blades).

Believing that bearing clearances between crank and prop al lowed excessive prop whirling , these tests sought to isolate prop shaft and crank. Test 1 tors ional vibration at 4.5X was 35% worse, tip stress was much higher, and linear vibration was indeterminate due to sensor mounting. This was believed due to clearances in the plain bearings, so Test 2 sought to eliminate clearances via rolling element bearings. Torsional vibration at 4.5X was 35% lower, with large 1.5X and 2X peaks. Linear vibration was unchanged. Prop tip stress was unchanged and excessive. Test 3, with a 15 , prop , used the same bearing plan as Test 2. Ax torsional vibration of combined 1X and 1 .5X was 1.38 de at 2600 rpm. Natural frequency at 4000 cpm. Linear vibration from 1600 to 2400 rpm reached resonant 1.5X peaks of 0.050 to 0.060 (probably misfire?) . Tip stresses were reduced but still excessive. No benefits from this design.

544 (Ref. 3.40)

12/28/38 3/24/39 to 1/28/39 and 2/2/39 to 2/10/39

Torsional vibration , linear vibration , and tip stress with 4.5X crank dampers . Engine mounted rigidly and on radial rubber engine mounts. 100 de master rods (8 &13). TEST 1-2 ea . 4.5X damper on rear counterweight, light counterbalances, Ham Standard Hydromatic HX-3 prop (6159 to O blad es) , torsional vibration tests from 1200 to 2800 rpm with load of 196 BMEP, linear vibration tests from 1400 to 2800 rpm, load of 196 BMEP, rigid mounting.

TEST 1-4.5X torsional vibration down to -0.07 from -0 .14 de. 4.5X blade tip stress not reduced . TEST 2-4.5X torsional vibration up to -0.1 O de , an increase over Test 1. 4.5X blade tip stress not reduced . TEST 3-4.5X torsional vibration stays at -0 .1O de, no change in prop tip stresses. More evidence that 1.5X torsional vibration is due to misfiring. Suggestion that new 4.5X dampers be designed that are

X to 78

(continued)

48

R-2800 Development

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Report Number

Engine Serial #

Test Date

Report Date

544 (Cont)

Object/Process

Results/Conclusions/ Recommendations

TEST 2-4 ea. 4.5X dampers on front and aft counterweights . Normal counterbalances. Ham Standard Hydromatic prop with dynamically balanced hub and 6159-0 blades, torsional vibration tests from 1200 to 2800 rpm , load of 196 BMEP, rigid mounting . TEST 3- as above except 9 radial rubber mounts and Ham Standard Hydromatic HX-13 prop (6159-0 blades).

symmetrical about the crank centerline , that in the future engines have CHT on all cylinders to detect misfiring , and that the effect of missing cylinders in various locations around the crank be investigated to correlate transient vibration evident in several previous tests .

X-78 547 (Ref. 3.41)

2/27/39 to 3/31 /39 3/8/39 and 2/14/39 to 2/17/39

Torsional vibration of two counterweight crank (center counterweights removed) , P/N 34169-70 MP with and without prop paddle dampers. R-27000 counterbalances, 100 de master rods (8 & 13). 1200 to 2800 rpm , load of 196 BMEP. TEST 1-Ham Standard Hydromatic 14 · prop with balanced hub and 6159-0 blades. TEST 2-Ham Standard Hydromatic HX-16 with paddle dampers and 6159-0 blades.

TEST 1-Ax torsional vibration of 1.0 de , crank natural frequency of 4500 cpm . TEST 2-no change from previous test. Two-counterweight shaft is no different torsionally, but is lighter, has a higher natural frequency, and eliminates the split center case. Paddle dampers have no effect on engine torsional vibration.

X-83 569 (Ref. 3.42)

6/ 12/39 to 6/27/39 6/22/39

Torsional and linear vibration with clamp-type crank LD-3403. 2:1 reduclion, third-design secondary counterbalances LD-3197. Ham Standard Hydromatic HX-17 prop with 6159-0 blades . Torsional runs from 1200 to 2800 rpm with load of 196 BMEP. Linear runs from 1200 to 2800 rpm with load of 196 BMEP.

On first torsional runs , irregular 1.5X, 0.90 de vibration attributed to misfiring . Teardown revealed slipped front counterweight. Second runs produced ax torsional vibration of 0.55 de at 2800 rpm and resonant peaks of: 1.5X, 0.32 de at 2700 rpm ; 2X, 0.31 de at 2300 rpm ; and 2.5X, 0.19 de at 1700 rpm . 1X was a ax of 0.32 at 2800 rpm. 4.5X ax of 0.06 de at 1500 rpm and 0.07 de at 2300 rpm. Blade tip stress of 6000 to 7000 psi was resonant at 4.5X and 2300 rpm . Blade shank stress was resonant at 1.5X and 2400 . Vibration characteristics of the clamp-type crank are not different from the four-counterweight split-pin crank. Blade stress was identical to two-counterweight split-pin crank, and somewhat lower than the fourcou nterweight crank. (continued)

49

Chapter 3

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Report Number

Engine Serial#

Test Date

Report Date

X-79 588 (Ref. 3.43)

3/30/39 to 8/8/39 5/19/39

607 (Ref. 3.44)

10/18/39

X-80

Object/Process

Results/Conclusions/ Recommendations

Overload endurance test to ascertain durability of components at 1850 hp take-off rating . 6.7:1 compression ratio , 7.6:1 impeller drive , 2:1 reduction , and wood test club . Considerable experimentation with cooling arrangements resulted in forced-air cooling for the majority of the testing. Initially, engine was a stock single-stage engine with the following changes : lightened crankcase; different second order counterbalances (LA-3333 and LA-3334); 4.5X damper 34674M/P; special exhaust valves in cylinders 13-18; heavy valve springs on rear bank. At the 43 hour rebuild the following were changed: 34169-70MP, twocounterwe ight crank (no 4.5X dampers); "Aero" thread cylinders in 9 positions; cam oiling changes; heavy and light va lve springs interchanged.

Five failures occurred: #8 inlet push rod at 9.25 hours; #6 inlet push rod at 13 hours; #4 exhaust rocker arm at 29.5 hours; center main crankcase at 43 hours , and twocounterweight crankshaft at 50.75 hours. Inspection at 43 hours revealed a split reduction gear, center crankcase cracked (#12-14 pad broker out) , numerous cracked piston pin bosses, numerous cracks in tappet rollers ; severe gall ing on secondary counterbalance drive gears. Inspection at 50.75 hours revealed crank broken through rear counterwe ight at bottom of rear crankpin fillet. Observations: case failure due to thin wall sections as a result of lightening operations that were discontinued; fixed reduction gear shou ld strengthened; piston pin bosses should be heavier; tappet roller material , processes, and inspection should be carefully controlled ; rocker arm failure was a material defect; failed crank was a reworked unit; valve spring change was to see if light springs played a role in push rod failures-inconclusive; counterbalance drive gear gal ling fixed by lead plating of trouble spots.

10/27/39 Torsional vibration and linear vibration of single-row X-80 . 9-cylinder (Y, R-2800) test engine; 2:1 reduction; wood test club (load of 850 hp at 2600 rpm) ; no dampers or counterbalances. 1200 to 2600 rpm.

Endurance running resulted in several crank failures, but no linear vibration troubles. Ax 2X torsional vibration of 0.64 de at 2600 rpm. Ax linear vibration of 0.006". A 2X damper is required to prevent crank failure at 2600 rpm and to reduce tors ional vibration at lower power. Linear vibration is satisfactory, no counterbalances required.

(continued)

50

R-2800 Development

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Test Date

Report Date

X-83 609 (Ref. 3.45)

5/1/39 to 10/7/39

11/20/39 Investigation of two-counterweight, clamp-type crankshaft, no dampers , 7.6 :1 impeller ratio, 6.7:1 compression ratio , 2:1 reduction.

X-79 611 (Ref. 3.46)

7/17/3 9 to 11 /23/39 Torsional vib ration and linear vibration with Curtiss props. 2: 1 reduction , 8/ 14/39 3-piece crank (32548, 32549, 35076), 4.5X rear co unterweight dampers, load of 196 BMEP. The fo llowing props were tested:

X-78 612 (Ref. 3.47)

8/7/39 to 8/ 14/39

Rep ort Nu mber

Engine Serial#

Object/Process

Results/Conclusions/ Recommendations Torsional vibration and linear vibration characteristics are no different than four-counterweight, split-pin crank. Slight galling of clamp surfaces after each teardown. Special assembly jigs required . Frequent crank rebuilds will necessitate drilling new cotter pin holes in the clamp bolt. Design changes are required to prevent clamp surface galling and crankpin regrinding due to plug insertion. This crank concept was intended to eliminate weakness of the split-pin type crank and a 7.5-lb reduction in weight from the four-counterweight crank. Face-spline type cranks promise a 32-lb reduction.

TEST 1-Ax torsional vibration of 0.67 de at 2500 rpm (1 X and 1.5X), 4200 to 4500 cpm natural fre quency, resonance of 1.5X at 2000 rpm and 1X at 2600 rpm . Ax dive torsional vibration of 0.68 de at (6) 3120 rpm. (6) (5) (4) (1) (2) (3) Dia. Bids. Mat'I Bid. No. Hub No. Mfg. No. Test TEST 2-2X torsional vibration at 2200 rpm exceeds the 0.50 de Steel 722Cc2 C-5325 958 12 3 AN-9504 Torsional Vibration Speci2 Dural 89303-0 C-542D 13 4 fication due to prop interference in 3 1655 Dural 89304-6 14.5 3 the 24· test house. 4 1655 Dural 89316-0 153 TEST 3-torsional vibration and (1) Diameter of test propeller in feet linear vibration assumed to be very (2) Numbe r of propeller blades similar to TEST 4, no measure(3) Prope ller blade material ments other than dive tests taken (4) Building number tests were per0. 78 de at 3000 rpm with 1X and formed in 1.5X components. (5) Curtiss Electric propeller hub TEST 4-Ax torsional vibration of assembly number 0.68 de at 2600 to 2800 rpm with (6) Test number 1X and 1.5X components, 4200 cpm natural frequency. All props tested exceed AN -9504.

11/7/39

Torsional vibration and linear vibration characteristi cs on "Z" dynamo meter of the two-stage R-2800-A2G, 2:1 reduction and direct drive

Serious .5X transverse linear vibra!ion of 0.039" at 1800 rpm, accessory driveshaft fai led . 2:1 reduction gear replaced with direct drive . 1X

(continued)

51

Chapter 3

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Report Number

Engine Serial #

Test Date

Report Date

Object/Process

612 (Co nt)

linear vibration of 0.025-0.035" at -1100 rpm. 1X torsional vibration of 1.20 de resonant at 1100 rpm . Engine must be run on dynamometer with direct drive adapter and above 1400 rpm.

617 X-78 (Ref. 3.48)

4/14/39 to 11 /21/39 See SM 547. Crank P/N 34169-70 5/20/39 MP reworked from P/N 27984-5 with total time of 301.4 hr. Previously used for blade stress, carburetor, calibration , and endurance runs. Rebalanced to 36354-5 MP and installed in X-79 for endurance runs at 1850 hp and 2600 rpm.

X-83

622 X-83 (Ref. 3.50)

Crank broke through rear crankpin at total time of 453.2. Further testing of the design is suggested. Weight of 187.5 versus 221.9 pounds. Trial can not be considered fair since this crank was reworked from a hand forging that had previously failed. Metallurgical reports describe the effect of poor grain flow and structure on the failure.

First Air Corp type test successfully completed.

6/30/39

619 (Ref. 3.49)

Results/Conclusions/ Recommendations

11 /3/39

11 /22/39 Lin ear vibration and torsional vibration using two-counterweight splined crank P/N 37282 MP with loose counterweight plugs in the 18 · Horizontal Intake test house. 2:1 reduction , Ham Standard Hydromatic 14 · HX-2 with 6159-0 blades, 1200 to 2800 rpm, load of 196 BMEP.

Failure of two-counterweight splined crank, attributed to bending vibration , led to design of a twocounterweight crank with reduced rear counterweight effective mass via two cylindrical plugs that were free to slide fore-aft . No difference exists in the crank vibration characteristics . 1.5X linear vibration is reduced 40 to 60% in the new test house. It is recommended that all future flight-prop tests be done there to allow accurate measurement of other vibration components.

11 /15/39

12/5/39

Fore-aft crank resonance : 4.5X at 1700 rpm = 0.0018" ; 9X at 1800 rpm= 0.0014"; 1.5X at 2300 rpm= 0.0014"; 5.5X at 2600 rpm= 0.0011 ". None of the above were present on the engine. Natural bending frequencies are 240 and 270 cps. The loose CW plugs seem to have eliminated serious 4.5X bending vibration. (Is this origin of Solomon dampers?)

Bending vibration of th e twocounterweight P/N 37282 MP crank with loose plugs in rear counterweight; Ham Standard Hydromatic 14 ' HX-2 , 6159-0 prop . Fore-aft motion of both crank and engine measured from 1200 to 2800 rpm, load of 196 BMEP.

(continued)

52

R-2800 Development

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Results/Conclusions/ Recommendations

Test Date

Report Date

X-79 636 (Ref. 3.51)

3/8/40

3/ 19/40

Torsional vibration of R-2800-A6G (reworked for single-speed blower) on X-2 dynamometer (with long tubular shaft). 2:1 reduction , 900 to 2800 rpm, load of 1500 hp at 2400 rpm.

1X resonance of 4.0 de at 1100 rpm. Engine should not be operated between 900 and 1200 rpm on this dynamometer due to excessive torsional vibration .

X-78 651 (Ref. 3.52)

4/8/40 to 5/10/40

5/22/40

Torsional vibration of R-2800-A5 on X-3 dynamometer, two-stage rear section with 7.8:1 primary ratio, 2:1 reduction , instrumentation on accessory shaft and crank.

1X resonance of 2.5 de on crank and 1 .28 de on rear accessory shaft while motoring at 1100 rpm. Ax of 1.43 de at 2200 rpm while firing . rpm restriction on this dynamometer in the 900 to 1400 rpm range . Expect torsional vibration of -1 .5 de on this dynamometer in the 2100 to 2200 rpm range while firing.

X-78 654 (Ref. 3.53)

5/23/40

6/4/40

Determine if crank torsional vibration of R-2800-4 on torque stand can be measured at the rear of the accessory drive shaft (starter dog). 2:1 reduction , 4-blad e Ham Standard Hydromatic HX-28 prop with 6423-0 blades. 1200 to 2500 rpm , with a load of 189 BMEP and 2000 to 2500 rpm with a load of 201 BMEP.

Accessory shaft torsional vibration of 0.40-0 .50 de from 1200 to 2200 rpm. Increases to 0.79 de at 2500 rpm . Largely 2X below 1700 rpm and 1X above . Accessory shaft torsional vibration measurements can theoretically be converted to crank torsional vibration, but not with enough accuracy to meet the AN-9504 spec.

Report Number

Engine Serial#

unknown unknown 686 (Ref. 3.54)

697 (Ref. 3.55)

unknown 915140

Object/Process

10/29/40 Static tests were performed for various types of R-2800 crank joints, and the deflection verses force results plotted.

Joints rank weak to strong as follows: internal spline (0.0035" at 15000 in. lb) ; clamp-type ; facespline , big-bolt with 0.0018 stretch; face-spline with plug; face-spline , big-bolt, no plug (0.002 at 50000 in. lb). Joint bolt preload of 0.0060.007" required to prevent joint opening . The clamp-type constru etion is stiffer than the internal spline, but not as good as the face spline.

11 /19/40 Torsional vibration of R-2800-7 (Army #10) with 6-pinion 16:9 reduction , 6.5:1 blower drive , and 2 ea. 4.5X dampers in the rear counterweights. Curtiss 11 '6" C-542-S 4-blade (#714 Cc2-24) , 1200 to 2600 rpm with load of 196 BMEP.

Resonant peaks: 3.5X at 1400 rpm , 0.09 de; 2.5X at 1900 rpm, 0.13 de ; 2X at 2400 rpm , 0.12 de. Ax of 0.41 de at 2600 rpm . This arrangement has cons iderably less torsional vibration than 2:1, 3-blade arrangement, and is satisfactory.

(continued)

53

Chapter 3

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Report Number

Engine Serial#

Test Date

Report Date

Object/Process

697 (Cont)

Results/Conclusions/ Recommendations Natural frequency is 4400 to 4800 cpm. Improvement due to elimination of 1.5X prop interference excitalion which is resonant at 2600 rpm with 3-blade prop.

790 X-79 (Ref. 3.56)

7/1/41 to 8/25/41

801 X-111 (Ref. 3.57)

11 /4/41 to 12/22/41 Vibration characteristics of R-2800D2G with dual-rotation props and 12/12/41 extension shaft. The engine had crank PIN 52599 with two P&W 4.5X dampers in the rear counterweight. 100 de master rods (8 & 13). Extension shaft to gearbox ran at crank

12/18/41 Effects of different 4.5X dampers on torsiona l vibration of R-2800-2SBG {2-speed, 1-stage), 2:1 reduction, Ham Standard Hydromatic 127" HX-52 (33050 hub , 6257-6 blades) . The damper config urations were: 1) Standard spool-type dampers of P&Wdesign; 2) Roller dampers with gearing to eliminate sl ip and improve tuning accuracy; 3) Same damper configuration as above, but with loose prop blade bushings to see if any reduction in vibration transferred to the blades was achieved; 4) Two "Chilton" dampers, one in the forward counterweight and one in the rear counterweight. Note : Rolland Chi lton of Wright Aeronautical invented "Chilton" dampers. P&W later referred to them as "bifi lar'' dampers.

Test 1: Peaks of 0.042 de at 1400 rpm, 0.056 de at 2400 rpm , 0.40 de at 2800 rpm. 4.5X blade stress peak of 10,000 psi at 2400 rpm . Test 2: Peaks of 0.045 de at 1800 rpm ; 0.054 de at 2400 rpm, ax of 0.044 de at 2800 rpm. 4.5X blade stress peak of 10000 psi. Test 3: 4.5X peak of 0.090 de at 2400 rpm , same blades stress. Test 4: Peak of 0.040 de at 1500 rpm, no 2400 rpm peak. 4.5X blade stress peak of 5400 psi at 2350 rpm, 4X blade stress peak of 7000 psi at 2050 rpm, 5X peak of 5500 psi at 1550 rpm (caused by lateral reaction inducing whirl?). Neither spool nor geared dampers reduce prop stress acceptably. Loose blades increased torsional vibration and did not help prop stress. While Chilton dampers reduce both torsional vibration and blade stress acceptably, they introduce 5X-blade stress at 1550 and 2750. Recommend investigation of 5X stress with independent prop shaft suspension, torsional vibration and blade stress with tuned 4.5X mechanical filter in nose, and torsional vibration and blade stress with one Chilton damper on rear counterweight. The system was rich in both torsional and linear vibration harmonies. The worst condition resulted from flexible mounting of the gearbox. The best condition resulted from rigid mounting of the gearbox and flexible mounting of

(continued)

54

R-2800 Development

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Report Number

Engine Serial#

Test Date

Report Date

speed. Reduction of 26 :15 for both props. Fi xed pitch props used were Curtiss 3-blade (40-spline hub, 512cc1.5 blades , 1o·; 60-spline hub, 551 cc1.5, 9'9" ) and Ham Standard 3-blade (40-spline hub , 43A2-22T-14, 10 '; 60spline hub, 44A2-22T-14, 10 '). A load of 2000 hp at 2700 rpm was used for Curtiss props. Ham Standard props we re set for a load of 1920 hp at 2700 rpm. The engine was restrained torsionally and fore-aft at the blower section and radially at the front accessory section. The gearbox was restrained in all directions . Provisions existed to mount both engine and gearbox either flexibly or rigid ly. Torsional vibration measurements were obtained via an adapter passing through the accessory drive shaft to the crank. Engine linear vibration was measured with a pickup on the vertical centerline of the front accessory section , horizontal transverse pickups on the rear cover case (one above the engine axis , one at the lower edge of the rear cover case). Gearbox linear vibration was measured by two vertical pickups, one on the vertical centerline and one tangential to the bolt circle . No cooling fan was installed.

801 (Cont)

X-79 805 (Ref. 3.58)

Object/Process

1/ 14/42 11 /22/41 to 11 /25/4 1

Results/Conclusions/ Recommendations the engine. In all cases, 1X torsional vibration was most troublesome , and while not strong enough to cause crank problems , would result in accessory drive trouble. It was anticipated that aircraft mount ing would be more fle xible than the test stand, exacerbating 1X vibration. It was expected that when the rubber-coupled coo ling fan was added , natural frequency would rise to around 3000 rpm, possibly proving satisfactory (later tests did not bear out this idea). A 4.5X torsional vibration in the gearbox gave rise to linear vibration that may fatigue fittings and other gearbox protrusions. There was little difference in the vibration characteristics of the Curtiss and Ham Standard props . Blade tip stress of the Ham Standard props was satisfactory. Recommendations: 1) Investigate vibration character istics with the cooling fan installed and 100 de master rods (8 & 13). 2) If 1X vibration is still excessive and within the operating range with the cooling fan installed: A) Try to run the master rods in adjacent cylinders to reduce the 1X excitation (this may require a 2X crankshaft torsional damper) . B) Employ a first-order crankshaft torsional damper and leave the master rods 100 degrees apart. 3) Investigate the apparent 4.5X gearbox vibration.

Investigation of torsional vibration and PROP CS-1: 2X resonance of 0.19 blade stress with tuned 4.5X mechani- de at 1700 rpm; 1X of 0.47 de cal filter. R-2800-BG , 100 de master increasing at 2600 rpm ; 4.5X of

(continued)

55

Chapter 3

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Report Number

Engine Serial#

Test Date

Report Date

805 (Cont)

811 X-111 (Ref. 3.59)

2/42 to 5/42

2/ 16/42

Object/Process

Results/Conclusions/ Recommendations

rods (8 & 13), 4-counterweight crank #38318 with two P&W 4.5X dampers in rear counterweight, 2:1 reduction. Heavy springs in place of oil in the torque cylinders act with the ring gear moment of inertia to prevent transmission of 4.5X torque impulses to the prop. Two props were used: Ham Standard Hydromatic 11 ' CS-1 (3E50 hub , 6105-24 blades); Ham Standard Hydromatic 12 '6" HX-52 (33050 hub , 6457-6 blades) .

0.08 de increasing at 2600 rpm. PROP HX-52: 2X of 0.34 at 1700 rpm; 1X resonance of 0.99 de at 1700 rpm ; 1X of 0.27 de increasing at 2600 rpm; 1.5X resonance of 0.18 de at 2300 rpm ; 4.5X constant at 0.05 de 2200 through 2600 rpm. 4.5X blade stress reduced to insignificant level. The most serious blade stresses is a 4X stress due to 3.5X engine whirl , but this is below the allowable stress limit. Recommendation of continued work on mechanical filter, and further work on 3.5X whirl, radially isolating crank from prop shaft if necessary.

Investigation of crank torsional vibration with the cooling fan attached and of gearbox motion associated with 4.5X torsional resonance. Same engine and mounting as in SM 801. The cooling fan was a 22-blade NACA design driven by a splined adapter from the crank. The fan hub was supported in bearings on the front accessory housing . Natural rubber damper assemblies isolated the fan blades from the inner fan hub.

With rigid gearbox mounting, 1X torsional vibration was 0.68 de and increasing at 2700 rpm. With flexible gearbox mounting, 1X torsional vibration was 1.44 de and increasing at 2700 rpm. 4.5X torsional motion of the gearbox was confirmed at 2400 rpm. While the addition of the cooling fan has moved the torsional resonance upward 150-250 rpm in the speed range, it is still within the takeoff range. 4.5X gearbox vibration produces linear acceleration at the periphery of the gearbox of about 25 g at 180 Hz, and is likely to cause fatigue failure of fittings , vibration in the aircraft structure, and excessive prop blade stress. Suggests changing master rod locations or installing a damper to address the 1X vibration, and investigating Chilton dampers to reduce the 4.5X gearbox resonance. Each combination of engine, prop, and airframe must be carefully checked for harmful vibration.

(continued)

56

R-2800 Development

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Report Number

Engine Serial#

Results/Conclusions/ Recommendations

Test Date

Report Date

812 #1061 (Ref. 3.60)

1/30/42 to 2/1/42

2/25/42

Determine vibration characteristics of the single-speed, single-stage XR-2800-12 Navy Engine #1061 with 26:15 dual rotation nose and Curtiss dual rotation props. Crank was fourcounterweight type with two rearmounted 4.5X dampers . 100 de master rods (8 & 13). Front prop used 3 each 512c1 .5 blades and a 40-spline hub . Rear prop used 3 each 551 c1 .5 blades and a 60-spline hub. A check run was made with Ham Standard 3-blade dual rotation props with 43A2-22T-14 blades in front and 44A2-22T-1 4 blades in back.

A 1X torsional peak of 0.38 de was observed at 2100 rpm. A 15/26X linear peak of 0.022" at 2000 rpm was observed at the starter pad. The large 1X crank torsional vibration usually found at takeoff speeds in single rotation engines was absent in the dual rotation eng ine. The crank natural frequency in this application is about 5250 cpm compared to 4600 cpm single rotation engines with 16:9 reductions. Single rotation engines frequently show a large 1X peak at 1800 rpm. No such peak was found with the dual rotation engine, but a moderate 1X peak was observed at 2100 rpm. Ham Standard prop was not significantly different than Curtiss .

819 #6 (Ref. 3.61)

3/6/42 to 3/14/42

4/7/42

Crank torsional vibration of the simulated R-2800-D2G engine. See SM Rs 801 and 811. Previous 1X torsional vibration proved troublesome. Th is special two-stage , two-speed engine No. 6 was built with springs in the torque meter cylinders to provide torsional similitude to the R-2800D2G. Ham Standard Hydromatic 11 ·5" prop with 23E50 hub and three 6243-42 blades was used. Thi s basic engine was built in three co nfigurations : 1) 100 de master rods (8 & 13) , fourcounterwe ight crank P/N 52599 with two P&W rear-mounted dampers and standard second order counterbalances; 2) 100 de master rods (8 & 9) , same crank as above, special second order counterba lances P/N 52112 and 52113; 3) 20 de master rods (8 & 9), fourcounterweight crank with Chilton 2X dampers on front and rear counterweight, same second order counterbalances as in (2) above.

Test results in the three configurations : 1) 1X tors ional vibration resonant at 2600 rpm with an amplitude of 2.4 de . No large 2X resonance was observed at low speed. 2) 1X tors ional vibration resonant at 2500 rpm with an amplitude of 1.02 de. A second order peak of 1.14 de was observed at 1250 rpm. 2X linear vibration at the starter pad reached 0.005" at 2700 rpm (about the same as engines with 100 de master rods. 3) 1X torsiona l vibration resonant at 2500 rpm with an amplitude of 0.97 de. Second order torsional vibration did not exceed 0.05 de at any rpm. Conclusions: 1X peak at 2500 rpm is not excessive with 20 de master rods , and is small compared to engines with 100 de master rods. 2X torsional peak at 1250 rpm is larger in configuration (2) than (1 ), but is still not excessive . Chilton 2X dampers are

Object/Process

(continued)

57

Chapter 3

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Report Number

Engine Serial#

Test Date

Report Date

Object/Process

819 (Cont)

Results/Conclusions/ Recommendations highly effective. Since 2X dampers are not necessary, space wi ll be available for 4.5X dampers if they are necessary. Special second order counterbalances prevented abnormal linear vibration in configuration (3) that would have otherwise resulted from greater excitation with master rods in adjacent cylinders.

X-1 11 823 (Ref. 3.62)

4/6/42 to 4/7/42

4/21/42

Crank tors ional vibration of an actual R-2800-D2G with 100 de master rods (8 & 9). See SMRs 801 , 811 , and 819 . Engine used four-counterweight crank with two rear-mounted 4.5X P&W dampers. Second order counterbalances we re P/Ns 52112 and 52113. Ham Standard 3-blade dual rotation tractor props were used. Rear was 10 · 40-spline with 43A222T-14 blades. Front was 1O· 60spl ine with 44A2-22T-14 blades. The first test run was with rigid gearbox mounting. The second test run was with fle xible gearbox mounting. The engine was flexibly mounted in both cases.

Test 1: 1X crank torsional vibration of 0.26 de at 2800 rpm was observed . 2X torsional peak of 0.40 de at 2100 rpm was observed. Test 2: 1X crank torsional vibration of 0.66 de at 2800 rpm was observed. Lin ear vibration , measured tangential to the port gearbox side had a 4.5X peak of 0.004" at 2500 rpm . 45/26X peaks of 0.011 " at 2100 rpm and 0.013" at 2700 rpm were also observed. Relocation of the master rods to 8 & 9 reduced 1X torsional vibration to an acceptable level. Aircraft structural rigidity has a fundamental influence on gearbox and crank torsional vibration , particularly in regards to the 4.5X gearbox torsional mode. Coincidence of 4.5X vibration with a natural prop or aircraft structural mode will probably produce objectionable vibration amplitudes.

871 X-88 (Ref. 3.63)

10/29/42

11 /27/42 Torsional vibration and linear vibration Torsional vibration: 2X of 0.76 de at of R-2800-37 (2-speed, 1-stage) with 1900 rpm; 4.5X of 0.21 de at 2900 two-counterweight face-splined crank, rpm with higher peak. Vertical 4.5X bifilar damper on each counter- linear vibration: 1X-1.35X of 0.025" weight, 20 de master rods (8 & 9) . at 1400 rpm ; 2X of 0.0077" at 2900 20 :9 reduction , Ham Standard Hydro- rpm . Horizontal linear vibration: 1X matic 15 · prop (33E60 hub , 6243A-0 to 1.35X of 0.023 at 1400 rpm; 2X blades). 1200 to 2900 rpm . Master of 0.0078" at 2900 rpm . 3500 psi rod locations changed to eliminate prop stress of 2X at 1950 rpm and the excessive 1X torsional vibration 2150 rpm . Inspection of damper with the 100 de master rod showed galling of mating surfaces. This in conjunction with high 4.5X placement. torsional vibration indicates faulty damper operation. Suggests endurance runnin g to see if 2X torsional (continued)

58

R-2800 Development

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Report Number

Engine Serial#

Test Date

Report Date

Object/Process

vibration is destructive and to install 2X damper if so. Suggestion to increase unbalance of rear counterbalance to reduce 2X linear vibration. The large 2X torsional vibration is due to maser rod placement allowing 2X inertia torq ues to add nearly in phase.

871 (Cont)

879 X-78, (Ref. 3.64) X-88 , X-107

Results/Conclusions/ Recommendations

6/11 /42 to 10/29/42

1/ 18/43

Linear Vibration-Peaks Tests of 2 engines with 100 de master rods (8 & 9), #52112 front counterbalance (4.00 in. lb unbalance) , #52113 rear counterbalance (4.20 in . lb unbalance). X-88 R-2800-37 (2-speed, 1-stage) with two-counterweight face-spline crank #72611 having bifilar 4.5X damper on each counterweight, 20:9 reduction . Ham Standard Hydromatic 157.5" HX-35 prop (33E60 hub, 6243A-O blades).

Horizontal transverse at right generator pad-2X, 0.0078" at 2900 rpm. Vertical at starter pad-2X, 0.0077" at 2900 rpm.

X-78 R-2800-B2G (1-stage) with 2-counterweight LR-4866 crank with 2X bifilar damper on each counterweight, front damper locked. 16:9 reduction. Ham Standard Hydromatic 11 · HX-23 (23E50 hub , 6159A-36 blades).

Horizontal transverse at right generator pad-2X , 0.0033" at 2700 rpm. Vertical at starter pad- 2X, 0.0069" at 2700 rpm. Horizontal transverse at thrust plate-2X, 0.021 O at 3000 rpm.

X-78 , same as above but rear bifilar damper locked instead of front.

Horizontal transverse at right generator pad-2X , 0.021 O" at 3000 rpm. Horizontal transverse at right generator pad-3.5X, 0.0075" at 1700 rpm. Vertical at starter pad-2X, 0.0069" at 3000 rpm. Vertical at starter pad-3.5X, 0.0082" at 1700 rpm.

Measurements of second order linear vibration with 100 de master rods and various counterbalances. X-107 R-2800-1 O two-counterweight with two P&W 4.5X dampers . Standard "B" counterbalances having 2.46 in lb of unbalance , #37762 front and #37763 rear. Ham Standard Hydromatic 11 '4 .5" HX-107 (23E50 hub, A-6243-A-42 blades). 2:1 reduction .

Horizontal transverse at right generator pad-2X, 0.0155" at 2710 rpm. Vertical at thrust plate-2X, 0.0026" at 2730 rpm.

(continued)

59

Chapter 3

TABLE 3-1 CRANKSHAFT DEVELOPMENT continued Report Number

Engine Serial#

Test Date

Report Date

Object/Process

Results/Conclusions/ Recommendations

X-107 Same as above but front counterbalance , #54499 MP, with 3.00 in lb of unbalance and rear counterbalance #54496 with 2.97 in lb unbalance .

Horizontal transverse at right generator pad-2 X, 0.0079" at 2710 rpm. Vertical at starter pad-2X , 0.0093" at 2800 rpm. Vertical at thrust plate-2X , 0.0021" at 2740 rpm. Horizontal transverse at thrust plate-2X, 0.0230" at 2640 rpm.

X-107 R-2800-8 Same as above but with reworked counterbalances having 3.20 in lb of unbalance. Ham Standard Hydromatic 12 · HX-108 (23E50 hub, A-6243-36 blades).

Horizontal transverse at right generator pad-2X, 0.0042" at 2750 rpm. Vertical at starter pad-2X, 0.0065" at 2750 rpm. Vertical at thrust plate-2X , 0.0016 at 2750 rpm. Horizontal transverse at thrust plate-2X, 0.0013 at 2800 rpm.

X-107 R-2800-8 Same as above but with reworked counterbalances with 3.35 in . lb of unbalance and 5:2 reduction.

Horizontal transverse at right generator pad-2X, 0.0031" at 2880 rpm. Vertical at starter pad-2X, 0.0028" at 2880 rpm.

X-99 R-2800-8 with "C" type counterbalances #54496 and #54499, 2.57 in. lb unbalance. All other data same as first X-107 above.

Horizontal transverse at right generator pad-2X, 0.0194" at 2650 rpm. Vertical at thrust plate-2X, 0.0022 at 2710 rpm.

X-99 with vibration pickups mounted on (stiffer) "T" brackets. Otherwise same as above.

Horizontal transverse at right generator pad-2 X, 0.0013" at 2700 & 2900 rpm/ Vertical at starter pad 2X, 0.0025 at 2700 rpm. Increasing the counterbalance unbalance to 3.35 in. lb reduced 2X linear vibration successfully in both sing le and two-stage engines with 100 de master rods . An attempt should be made to reduce 2X linear vibration in engines with 20 de master rods by increasing counterbalance unbalance. Some attempt is made to explain why theoretical counterbalance unbalances do not affect maximum vibration reduction. Calculations assumed a completely stiff engine , which is not true.

Notes: 1) Unless otherwise noted, all references to torsional vibration refer to crankshaft torsional modes. All references to linear vibration refer to "shake" or wh irl of the entire engine. 2) * SM or SMR = Short Memorandum Report.

60

R-2800 Development

1·

Fig. 3.14 "A "/"B " series crank shown assembled. Note the two Salomon dynamic counterweights on the left crank cheek. (Overhaul Manual Double Wasp B Series Two Stage Engines, 1944.)

Crankcase (Ref. 3.4) As described in Chapter 2, Pratt & Whitney History and Background, all their piston engine crankcases were manufactured from aluminum forgings. Being exposed to heavy vibratory, and fatigue loads, the crankcase assembly, like the rest of the engine also needed to be sufficiently strong for the formidable loads imposed upon it and yet be lightweight. For the R-2800 "A" and "B'' series, four aluminum forgings bolted together was the chosen solution. By way of comparison to a casting, forged aluminum exhibits an ultimate tensile strength of 65 ,000 pounds per square inch. Compare this number to an aluminum casting which exhibits a tensile strength of 42,000 pounds per square inch. In other words, the forging is 50% stronger than a comparable casting. The crankcase assembly is made up in three main sections; front, rear, and center, all held together by through bolts (Fig. 3.15) . Front and rear sections are one piece and contain the front and rear main bearings. The center section is split along the horizontal diameter in order to accommodate assembly onto the crankshaft center main bearing. The split center section also houses the center main bearing. The parting lines for the three main sections was the center line for the front and rear

61

Chapter 3

WAGNE TO DRIVE BEVE.L GEAR

PARTING LINE

PA!1TIHG LINE £ET WEEN

REDUCT ION GEAR IN G DRIVE COUPLING

CENTER ANO

REAR MAIN CRANKCASE

SECTIONS

SECONDARY COUN TERBALANCE CAM REDUCTION

GEAR SHAFT OIL DRAIN

ro

MAIN SUMP

Fig. 3.15 "A "/ "B " series crankcase made up from three main sections; front, center, and rear. The center section is split to allow assembly of the crank. (Overhaul Manual Double Wasp B Series Two Stage Engines, 1944.)

rows of cylinders. Precision ground, wasted studs screwed into the hole cutouts for the eighteen cylinders, fifteen per cylinder, supplied each cylinder's fastening requirements. A front support plate is fastened to the front face of the main crankcase assembly and a rear support plate is fastened to the rear face of this assembly.

Main Bearings (Ref. 3.4) One-piece steel-backed lead bronze bearings are pressed into place and locked in the front and rear sections of the main crankcase to support the front and rear crankshaft journals. The center main crankshaft journal is supported via a split steel-backed lead/bronze bearing locked into place by the center section of the crankcase.

62

R-2800 Development

Tappet and Cam Ring Support (Ref. 3.4) The front and rear cam ring bearings are supported in integral circular shelves on the front and rear crankcase sections . The tappets and tappet guides are also housed in the front and rear crankcase sections, respectively.

Front and Rear Support Plates (Ref. 3.4) The front and rear sections of the crankcase house and support the front and rear cam reduction gears, cam ring and tappets (Fig. 3.16). The support plates are manufactured from aluminum castings. In addition to supporting the cam rings and their drive trains and tappets, they provide support for the twice crank speed second order counterweights. The front support plate also provides support for the magneto and distributors drive gears.

Master Rod Bearings (Ref. 3.4) As previously noted, the majority of the bearings in the R-2800 were plain. And of course, this included the crankshaft bearings . Unlike an inline engine, which typically has the load of one connecting rod, the master rod bearing, with nine powerful cylinders acting upon it, bore the brunt of some the heaviest loads in the engine. Always a difficult part to design, by the 1930s master rod bearings were being loaded beyond what the existing state of the art technology would tolerate. Babbitt was the bearing material of choice for all engine bearings through the 1920s. Although it had excellent bearing qualities, babbitt was being loaded beyond its capabilities as BMEPs, oil temperatures, and internal pressures increased. One of the early bearing design breakthroughs occurred with the Allison company. They were tasked with improving the overhaul life of the World War I era Liberty aircraft engine. The Liberty was hurriedly designed in 1917 in a Washington hotel room from May 30 to June 4 (Ref 3.65). It was then rushed into production. Even though it made little impact on the outcome of World War I, tens of thousands were manufactured by Packard, Cadillac, Lincoln, and Ford. It also had the honor of being the only U.S. designed and built aircraft engine to see combat during WWI. After WWI Liberty powered aircraft set numerous records including the first to make a transcontinental flight across the U.S. and first crossing of the Atlantic. Surplus engines were also used up by the fledgling U.S. Air Mail Service. Initially, their overhaul life was little more than abysmal, typically 50 hours. An Allison engineer, Norman Gilman, studied the problem and finally came to the conclusion that relatively soft bearing materials such as babbitt would fail in fatigue-it was literally squashed out (Ref 3. 66). Connecting rod bearing failures in particular plagued the Liberty. Gilman revamped the design by heating the rod and casting the bearing material into where the bearing was located. After cooling, the bearing was machined to size. The bearing material wall thickness was now substantially reduced. With the added strength of the steel connecting rod to back it up fatigue failures were now almost eliminated. Due to this breakthrough, Liberty overhaul times now improved to hundreds of hours . This breakthrough developed the cornerstone from which

63

Chapter 3

COUNTERBALANCE INTERMEDIATE DRIVE GEAR COUNTERBALANCE INTERMEOIATE PRESSURE DRIVE GEAR SHAFT Oil TRANSFER PIPE MAIN BLOWER CASE

I

• ,,

/Oil DISTRIBUTING GROOVE REAR COUNTERBALANCE

'--..

L I

"-

REAR SUPPORT PLATE

Fig. 3.16 Rear support plate. 1944.)

~

~

~

PRESSURE Oil PASSAGE TO REAR CAM COMPARTMENT

(Overhaul Manual Double Wasp B Series Two Stage Engines,

modern plain bearing technology was developed. Instead of pouring the molten bearing material into the connecting rod or crankcase, it was poured into a steel shell that was then fitted to its application. Now that the first and biggest hurdle was over, many improvements still lay ahead. Much experimentation was done in these pioneering and fonnative years following World War I. Lubrication was another technology in its infancy. Dynamic lubrication-what happens inside a high speed, heavily loaded bearing running at high temperatures? Where is the ideal location for crankshaft oil holes? Pratt & Whitney devoted vast resources in overcoming bearing failure and increasing bearing life. From the first R-1340 to the introduction of the R-1535 fourteen cylinder two-row engine steel backed babbitt had been the bearing material of choice. Adequate for the lower powered engines and even in the R-1535 it held up well in testing. However, in-flight R-1535 master rod bearing failures became increasingly common. Luke Hobbs was alarmed. With no immediate solution in sight he made it a top priority to find one. Working with bearing companies, a steel-backed copper/lead bearing proved to be far superior to the previously used babbitt. However, failures , especially in high speed dives still occurred at an unacceptable frequency. When under power, the master rod bearing has some degree of protection from the gas loads inside the cylinder. But, when power is reduced and the engine is turning at high rpm and yet producing little or no power, all the reciprocating loads are now transferred to the master rod bearing . These operating conditions could induce failure . And of course, fighter

64

R-2800 Development

pilots love to wring out aircraft to their maximum capabilities. Numerous materials were tried including tin, which is still commonly used in the automotive industry. Complete success still eluded Hobbs' team and the bearing manufacturers. Pure silver was a known candidate for heavily loaded bearing applications. In combination with a lead "flash" for good "embeddability" properties, it seemed to finally solve the master rod bearing problem. But not quite. Failures were still occurring. With all hands on deck to resolve this issue once and for all, many experiments were performed on every known bearing material. Earl Ryder was at the forefront in this desperate battle for a solution. He devised machines for accelerated testing. The result of all this feverish activity was the classic "sandwich" layered bearing consisting of a thin layer of lead on top of a thicker layer of silver. The application of a thin, 0.00 l inch, layer of lead produced a surface which, unlike the fatigue-resistant silver, was wetted by lubricating oil. Every one involved breathed a collective sigh ofrelief But, it was not over. Reports of failure still filtered in. Back to the drawing board to figure out what the failure mode was. Assuming that the lead overlay was failing under fatigue or erosion this v.1as, naturally, the path of investigation . It was not until Val Cronstedt, one of the engineers assigned to work this issue, realized that perhaps it was not erosion or fatigue of the lead but rather another failure mechanism was at play. That other failure mechanism turned out to be corrosion. During the operation of any gasoline engine, the byproducts of combustion include sulfuric acid, some of which escapes past the piston rings and contaminates the oil. Armed with this newfound knowledge it was a fairly simple task to replace the lead overlay with a far more corrosion resistant lead alloyed with 4 percent indium (Ref 2.1 and Ref 3 .67). At last, the master rod bearing problem was resolved. This technology, developed in 1937, and known in the industry as the "Hobbs" bearing, was a key contributor to the success of U.S. aircraft engines in World War II. Pratt & Whitney shared the fruits of their effotis with its competitors. As an interesting aside, when Gennan engineers investigated and studied aircraft shot down during World War II they were impressed by the quality of American bearings-particularly plain bearings. But, they could not understand why the silver bearings were "contaminated" with lead/indium! The above narrative often begs the question, iflead/indium silver bearings are so great why aren't they used in today's plain bearing applications? The answer is simple . Just about every lubricant manufactured today, with the exception of aircraft engine oils, contains zinc compounds. Marvelous stuff as an anti-scuffing compound. Unfortunately, it reacts badly with silver and results in accelerated corrosion. Despite the foregoing recital and its happy conclusion, the master rod could still tum treacherous if not understood and handled accordingly. As an example, master rod bearing longevity could be reduced by "reverse loading ." In other words, cases where the propeller drove the engine. Examples would be when a pilot or flight engineer pulled the power back suddenly, or the airplane was put into a dive and the throttle was closed. Of course, in a fighter application this is common practice but that is one reason why engines installed in fighter aircraft do not enjoy the same longevity as a multiengine transport. The position of the oil holes, approximately 30 degrees before top dead center in the connecting rod journal was configured to supply the maximum amount of oil to the bearing under load. The reverse situation, i.e. , reverse loading, could leave the most heavily loaded part of

65

Chapter 3

the bearing starved of oil. Therefore reverse loading could result in master rod bearing distress and possible premature failure. Good flight engineers always ensure the engine is driving the propeller and consequently under load rather than the opposite where the propeller drives the engine as would be the case in a sudden descent or careless power reduction during landing. The main bearings for the R-2800, or any other radial for that matter, did not present the degree of difficulty experienced by the master rod bearings. Consequently, the R-2800 used steel-backed leadbronze bearings for the three mains.

Connecting Rods (Ref. 3.4) As previously described, Luke Hobbs went with the one-piece master rod/built-up crank design route (Fig. 3.17). Although complicating the crankshaft layout, it made for an easier master rod design . Attached to each master rod were eight link rods to serve the remaining cylinders. Master rod position varied with different series of the R-2800, however, the early ones being described here used cylinder number 8 in the front row and cylinder number 13 in the rear row. Starting out with an SAE 4140 chromium-molybdenum forging, many manufacturing processes would be needed before it would be ready for installation. Typical of high performance aircraft engines, the entire outer surface was machined and polished for greater fatigue resistance. The final polishing operations were performed by hand by legions offemale workers at polishing stations. The design is a classic "I" section with two flanges at the journal end. Eight 1 V4 inch diameter holes are arranged around each flange to accommodate the link rod knuckle pins. A bronze bushing was press fitted into the small end of the rod to accommodate the fully floating wrist pin. The one-piece steel-backed lead/indium silver rod bearing is a light press fit into the rod. Each link rod is retained to the master rod via a solid steel pin fitted to the above-mentioned holes in the master rod . A pair of "spiders, " one on each side of the master rod retain the knuckle pins and also serve to transfer oil to the knuckle pins and the bronze bushing pressed into the link rod. Like the master rod, the link rods are of an "I" section manufactured from a chromium-molybdenum forging, machined and polished all over. It is easy to imagine the devastation caused when a link rod, or worse, a master rod fails. Although rare, when it occurred, a master rod failure had the capability to slice an R-2800 in two. An idiosyncrasy, not only of the R-2800 but most other radial engines, is the order of assembly/ disassembly of cylinders. It is key that the master rod cylinder is the first cylinder installed on assembly and the last to be removed on disassembly. If this convention is not followed serious problems will arise. The master rod controls the geometry of the link rods attached to it. Therefore, for example, ifthe master rod cylinder is removed before any other cylinder, the other cylinder 's link rods are no longer controlled by the master rod . If the master rod is allowed to swing back and forth

66

R-2800 Development

Fig. 3.17 Master rod from raw forging to finished article. Note exquisite finish. Needless to say, a large number of high precision manufacturing operations were required. Final polishing was performed by hand. (Courtesy of Pratt & Whitney.)

within the cylinder opening in the crankcase, this potential movement would then be transferred to the link rods and create a geometry, i.e ., movement, the engine was not designed for. The result will be some lower oil control rings popping out of the bottom of the cylinder barrel. If this condition is not noticed, the oil control ring and/or the bottom ring land is broken. Likewise, on assembly the master rod cylinder is the first installed for the above-mentioned reasons unless a master rod holding tool is temporarily installed (Ref. 3.68).

Nose Section (Ref. 3.4) Numerous key engine functions were housed in the nose section: propeller reduction gearing, magneto and its drive, distributors and their drives, scavenge pumps, propeller governor, and propeller shaft (Fig. 3.18). The nose section housing was manufactured from a magnesium casting. Thirtysix 3/s diameter studs in the front crankcase section attached the nose case housing. The propeller shaft is supported at both ends. At the propeller end, a massive, deep groove ball thrust bearing mounts in the front of the nose section. This bearing, one of the few rolling element bearings in the engine, handled axial and thrust loads. These loads can be considerable, particularly in a fighter plane application . The gyroscopic loads during violent maneuvers were immense. The tail end of the propeller shaft has a precision journal ground on its outer surface that rides inside a pressed-in lead bronze plain bearing located inside the number one crankshaft main bearing.

67

Chapter 3

Propeller Reduction Gearing (Ref. 3.4) Transmitting over 2000 horsepower being generated from a high performance aircraft engine through reduction gearing is a major design challenge. The history of aircraft engine development contains many dismal failures with this key requirement. Numerous attempts were made during World War I to incorporate reduction gearing with mixed results. What designers did not realize or understand at the time was the fact that the engine/propeller combination is a mass/spring arrangement with each reacting with the other component. Gear design, torsional vibration, materials, manufacturing techniques, tooth finish, tooth form, and bearing design all conspired to make the job of developing a successful reduction gear difficult at best. The question is often begged, why go to the trouble of adding the weight, complexity, and maintenance problems of reduction gearing? The answer, of course, is propeller tip speed. When tip speeds exceed the speed of sound the laws of aerodynamics change profoundly. For a standard atmosphere the speed of sound is 1070 feet per second. If the R-2800 did not have reduction gearing the largest prop it could effectively swing without going supersonic at the blade tips would be 7 .3 feet diameter. This would be totally inadequate from an efficiency standpoint. With the typical 13 foot diameter propeller an R-2800 would swing, maximum tip speed would be 919 feet per second at

Fig. 3.18 "A "l"B" series nose case manufactured from a lightweight magnesium casting. (Overhaul Manual Double Wasp B Series Two Stage Engines, 1944.)

68

R-2800 Development

maximum rpm and 2: l reduction gearing. Designers typically try to keep tip speeds below 1OOOfeet per second. Numerous reduction ratios were developed fo r the R-2800 over its life . For each engine series the design followed similar practice. In all cases it was of the planetary type. This makes sense because the propeller shaft is co-axial with the crankshaft. However, there is always an exception to the rule and in the case of radial engine reduction gearing that exception lay with the quintessentially British manufactured Pobjoy. These small horsepower radials built in the 1930s featured spur reduction gearing . Of course, this meant that the propeller shaft was not co-axial with the crankshaft resulting in a rather odd appearance .

5:2 Propeller Reduction Gearing The R-2800 's reduction gear consisted ofa coupling splined to the front of the crankshaft. A driving gear (sun gear) was splined to the coupling . The drive gear meshed with six pinion gears (planet gears) which in turn meshed with a fixed gear. By necessity, the fixed gear had internal teeth and splines on its outer circumference. The splines mated with splines machined in the magnesium nose case to lock it in place . The six pinions were mounted in a cage integral with the propeller shaft. A bevel gear mounted on the cage provided drive to the nose section oil scavenge pump and the intermediate gear for the propeller governor drive.

2:1 Propeller Reduction Gearing Some "A" and ·'B" series engines featured a compound planetary reduction gear, similar to the reduction gear described above, except in 2: 1 ratio only. The six pinion gears were of composite construction. They consisted of a large 30-tooth pinion internally splined to fit over a portion of the 15-tooth pinion. The 15-tooth pinion meshed with the main drive gear and the 30-pinion meshed with the fixed gear. All other features of the 2: 1 reduction gear were the same as the 5: 2 gearing. It is interesting to note that heavily loaded gear train designs normally avoid numeric ratios. In the case of the R-2800 the 2: 1 ratio caused more problems and suffered more failures than any other ratio . The follO\v-on "C," "CB," and "E" series avoided this ratio and stuck with safer, non-numeric ratios (Fig. 3.19).

16:9 Propeller Reduction Gearing Still using a multi-pinion planetary setup, the 16:9 differed in some significant details. The main drive gear (sun gear) had internal gear teeth with its hub splined to the crankshaft. Instead of six planetary gears, this ratio used fifteen pinions mounted on in a cage integral with the propeller shaft and meshing with the drive gear and fixed gear. The fixed gear had external spur teeth with its hub splined to a support ring mounted on the front inside face of the nose case. All other features remained the same (Fig. 3.20).

69

Chapter 3

DISTRIBUTOR ADAPTER

~--IUONET O

MOUNTINO PAD

MA GNETO ORIV[ OEAR OISTRIOUTOA DRIVE GEARS

COMPOUND _ . . . - - - PINION OURS

REDUCTION \._ DRIVE OUR

flX[D ANN ULAR OUR--~

Fig. 3.19 Compounded 2: 1 propeller reduction gearing. This ratio was only used on "A "/"B " engines. (Overhaul Manual Double Wasp B Series Two Stage Engines, 1944.)

Propeller Shaft (Ref. 3.4) An SAE #50 spline drove the propeller. As an aside, it should be noted that the term SAE #50 spline is somewhat of a misnomer. An SAE #50 spline actually has 16 splines and has a diameter of 3% inches. Likewise with an SAE #60 spline used on the "C" series, it actually has 32 splines and has a diameter of 4.68 inches . The propeller shaft was hollow, not only to reduce weight but more importantly to transmit oil to hydraulically operated propellers . In the case of an electrically operated propeller, the end of the shaft was plugged off. As described above, the front of the propeller shaft was supported in a ball thrust bearing. The rear of the propeller shaft was supported in a copper/lead plain bearing fitted inside the front of the crankshaft. Although this made for a convenient location to support the crankshaft, additional loads were transmitted to the front main crankshaft bearing. This was inconsequential for transport aircraft but for fighter aircraft that were thrown into violent maneuvers, the propeller imposed unusually high loads on the rear support bearing and consequently, the front main (Fig. 3.21).

70

R-2800 D evelopment

A:i%a:~ ~~fe/s

- .)"/ "B and" -se79 ·A ire raft .;;,;:,d~;~on3gearing 59, the , - 1, -43, _for _71 , "A

Fi (Pg. 3.20 Sin . g le stage 16 9 arts Cata! fi : R-2800 propell Engines. ectzon.)

7-

71

rzes R-2800 .

Chapter 3

Ignition As with all aircraft engines of this vintage, magneto ignition was used. A single Scintilla (Ref. 3. 69) (Fig. 3.22) or American Bosch magneto (Ref. 3.70) (Fig. 3.23) was mounted on the center drive pad of the nose section. The only purpose of this magneto was to produce high tension voltage. The output was transmitted to two distributors mounted on both sides of the magneto (Fig. 3.24). The left distributor sent high tension to the 18 spark plugs located at the rear position of each cylinder and the right distributor fired the 18 spark plugs located in the front position. Radio shielding was, and still is, critical to military and civilian aircraft fitted with radios. When the ignition points open and send 20,000 volts surging to the spark plug a powerful radio signal is generated. Without shielding, the aircraft's radios would be rendered almost useless. Shielding was accomplished via metal-coated harnesses and shielded plugs (Fig. 3.25).

Fig. 3.21 "A "/"B " series propeller shaft. Note the SAE #50 spline on the left and tail end bearing journal on right. The tail end journal rides in a bearing pressed into the number one main bearing journal of the crank. (Double Wasp B Series Two Stage Engines [R-2800-8, -10, -8W, and-lOW], Second Edition. Author :S collection.)

72

R-2800 Development

Fig. 3.22 Bendix-Scintilla DFl 8LN magneto. It was mounted on the uppermost center drive pad of the nose case. (Bendix-Scintilla Aircraft Magnetos Types DFl 8RN, DFl 8LN Service Instructions, February 1943. Courtesy of Al Marcucci.)

Type DF18LN Magneto

UPPER MAGNETO - -HOUSING

BREAKER ASSEMB LY

HELICAL PINION HELICAL GEAR COIL PROTECTION COVER -

INDU CTOR ROTOR

LOWER MAGN ETO HOUSING

COIL

73

Fig. 3.23 Not used as extensively as the Scintilla, Bosch magnetos were still excellent units. This cutaway shows the inner components of a unit. (American Bosch Service Instructions Aviation Magneto DF18RU- l , issued August 1944. Courtesy of Al Marcucci.)

Chapter 3

Right and left, clockwise and counterclocbvise, upper and lower, and similar directional references apply to the engine as viewed from the rear with the propeller shaft in the horizontal position and with number one cylinder at the top of the engine. In the case of accessory drives, the direction of rotation is specified as it appears to an observer facing the accessory mounting pad. The normal direction of crankshaft and propeller rotation is clockwise. Beginning with the top cylinder in the rear row, the cylinders are numbered consecutively in the direction of crankshaft rotation. The firing order is as follows : 1 - 12 - 5 - 16 - 9 - 2 - 13 - 6 - 17 - 10 - 3 - 14 - 7 - 18 - 11 - 4 - 15 - 8. As can be ascertained for the foregoing firing order, the R-2800 followed radial engine convention, i.e., every other cylinder fires in a row. Or, if the engine is split into two nine-cylinder engines we can see that the front row (even numbers) firing order is: 12 - 16 - 2 - 6 - 10 - 14 - 18 - 4 - 8. And for the rear row (odd numbers) firing order is: 1 - 5 - 9 - 13 - 17 -3 - 7 - 11 - 15. Viewed from the front, reading counterclockwise, the front cylinders were numbered, starting from the top: 2 - 4 - 6 - 8 - 10 - 12 - 14 - 16 - 18. Likewise, reading counterclockwise, the rear cylinders were numbered, starting from the top : 1 - 3 - 5 - 7 - 9 - 11 - 13 - 15 - 17. The Scintilla ignition system was referred to as the DF18RN or in some cases DF18LN. This designation was a code established by the military and known as the magneto type designation (Ref. 3.69).

H10HTENSIONCURRENTTO SPARK PLUG

~

IW.GNElO CURRENT DURING

NORMAL OPERATION, OR TRANSFORM~~~1' . t

\

flOOSTER

r

\

\ \ \

CENTER BOOY

\I I

I

I \_

r

UPPER BODY -·

I:

I

GEAR

BOLTS _ J

Fig 4.41 Front oil scavenge and torquemeter boost pump. (Overhaul Manual Double Wasp C Series Two Stage Engines, Pratt & Whitney Aircraft, July 1945. Author '.S' collection.)

172

Variations

First Branch Oil from the annulus around the rear end of the oil transfer shaft enters the transfer shaft and passes forward through drilled passages in the intermediate rear and supercharger collector cases to the crankcase rear section. The oil passes through a drilled passage in the crankcase rear section. It then passes to the rear valve tappet boss ring and drilled passages in the tappet boss carry oil to each rear row tappet. Pressure oil feeds the valve operating mechanism. Metered oil feeds the tappets which in tum pressurizes the hollow pushrod tubes . The pushrod oil then feeds into the rocker arms to lubricate the rocker pivot bearing, the valve clearance adjusting screw, and the end of the valve stem. The drilled oil passage that furnishes oil to tappet boss ring continues to a well at the front of the lower rear cam reduction gear front bushing. From this well oil enters an annulus around the cam shelf where it passes through drilled holes in the cam bearing to lubricate the bronze cam bearing and cam. The rear cam bearing shelf annulus feeds oil through a drilled passage into a well at the front of the upper cam gear reduction gear front bushing. The hollow shafts of each cam reduction gear lubricates the rear bushing of each gear. A drilled passage, fed by the rear bushing of the upper cam reduction gear, feeds oil to the rear bushing of each gear. Oil that lubricates the upper cam reduction gear also feeds oil to the rear second order, twice-crank-speed, second order counterweight intermediate drive gear and its support shaft.

Second Branch The annulus formed around the rear end of the oil transfer shaft feeds oil through a passage to a second annulus between the two bushings supporting the rear end of the accessory drive shaft. As previously described, the two-speed supercharger is operated by engine oil pressure. This supercharger operating oil comes through a gallery to the selector valve-essentially a directional control valve. Two galleries are provided for, high blower and low blower, which then engage the appropriate blower clutch. The annulus around the rear end of the accessory drive shaft branches off to supply a reading for main engine oil pressure that is registered in the cockpit gage. Some applications, in addition to main engine oil pressure, may monitor nose case oil pressure as well.

Third Branch As can be imagined, the crankshaft, the most heavily loaded part of the engine, also gets the lion's share of available lubricating oil. The crankshaft is fed from the annulus around the rear end of the accessory drive shaft, through the accessory drive shaft and into the rear of the crankshaft, which is co-axial. Oil being fed to the crank also feeds the impeller shaft bearings via holes in the accessory drive shaft. It should not be forgotten that the impeller can be rotating at up to 24,000 rpm and demands several hundred horsepower to drive- a formidable lubrication chore. Oil passes through drilled galleries and a "hat" type jet in the crankshaft rear section. This oil feeds the rear main bearing, the rear second order counterweight and its associated spring drive components, the rear counterweight bushings, and the rear crankpinjoumal. The rear journal feeds oil to the

173

Chapter 4

WITH SELECTOR VALVE PRESSURE 01 L WILL E WHEN MOVED FROM HI APPLIED AS SHOWN Bl 01 L PRESSURE WILL Al OR HIGH RATIO CLUTC

685aj eee

ee1 e10 811

Fig. 4.42 "C" series lubrication diagram. (Overhaul Manual Double Wasp C Series Two Stage Engines, Pratt & Whitney Aircraft, July 1945. Authors collection.)

174

d

Variations

BLOWER AND ACCESSORY SECTIONS DOUBLE WASP ENG I NE

RATIO POSITION AS SHOWN, ) TO THE HIGH CWTCH. >W, OIL PRESSURE WILL BE D CROSS SECTIONING . "THE APl'UED TO EITHER THE LOW r HER BEING OPEN TO DRAIN.

-11112

-1183 -6114

'l\J

SELECTOR

VALVE

"THRU IMPELLER

SEC"TION

(CREEPING

DRIVE CLU"TCHES

DESLUDGER

"TYPE)

694

704 705

SECTION THRU INTER. IMPELLER DRIVE CLUTCHES '-676 '--- 677 '--678

F I GURES CONTAINED ON THIS CHART ARE REFERENCE NUMBERS

ONLY. CLE A RANCE VALU E S WITH THE I R CORRESPONDING REP'EJltENCE NU M BERS A RE CONTAINED IN THE T A BLE OF CLEARANCES FOR THE SUBJECT ENGINE MODEL .

COL.ORS SHOWN ON TH I S CHART INDICAT E THE ENG I NE OIL C I RCUL~T I ON AS FOLLOWS :

-

• PRESSURE OIL

E'::E'.)

• L OW PRESSU R E O I L

-

- RET U R N O IL

175

Chapter 4

CYLINDER HEAD OIL DRAJl'f SUMP

Fig. 4. 42 (Continued)

176

Variations

POWER SECTION DOUBLE WASP ENGINE

SECTION THRU ROCKER SHAFT

374 ----~

37!>·- - - --.!ll>.I 376

SECTION THRU EXHAUST VALYE AND ROCKER \

\~R

CYL. HEAD SHOWN

343 344

3-4!> 347--'d---t:r'llR'-11

349 3!10 SECTION THRU VALVE TAPPET REAR CYL. SHOWN

DRAIN C*... FROM INT. REAR CRANKCASE

SUCTION OIL TO REAR SCNENCE PUMP

SECTION THRU REAR OF MAIN OIL SUMP

FIGURES CONTAINED ON THIS CHART ARE REFERENCE NUMBERS ONLY. CLE A RANCE VALUES WITH THEIR CORRESPONDING REFER· ENCE NU MBE RS A RE CONTAINED IN THE TABLE OF CLEARANCES

FOR THE SUBJECT ENGINE MODELS . COLORS SHOWN ON THIS CHART INDICATE THE ENGINE OIL CIR· CULAT I ON AS FOL LOWS : -

• -

PRESSURE OIL RETURN O I L

177

Chapter 4

SECTION THR\J SIOC AUXILIARY PUMP ORIVE

SECTION THRU SIOC llJJl

SECTION TH RU Gt:NERATOR I. SIDE ANGULAR AUXLIARY DRIVE

SECTION THR\J .COMFEl)_----- --,

E

~r~~~~~~-~

c-)

© >------------ -j H

LETIER

PART NAME

A

Dome Bruther Hole Nut Lock Wire Dome Breather Hole Nut Dome Assembly D;stributor Volvo Auembly Valve Housin9 Oil Transfer Plate Valve Hous;n9 & Sh.ft Guoet Propeller Reta;ning Nut Looi Wire Propeller Reto;ninq Nut Barrel AHembly De-Icing Dev;ce Auembly

B C D E F G H I

J

Fig. 7.18 Hamilton Standard "Hydromatic " propeller assembly. (Hydromatic Propellers Service Manual. Author :S collection.)

337

Chapter 7

"E" series it has an SAE 60 spline. One spline is omitted to match a corresponding missing spline on the engine propeller shaft. The spider is located by a pair of cones: one at the front and one at the rear. From the foregoing description it can be seen that the spider transmits the power of the engine into the propeller blades. Forged integrally with the spider are three arms (for a three-blade propeller) or four arms (for a four-blade propeller). These arms extend into the shank of the blades and locate them in the propeller assembly. The arms incorporate two precision ground bearing journals . The larger of these two journals is located adjacent to the central portion of the spider and the smaller journal is on the outer portion of each arm. The spider is lightened by matching a hole in each arm . Two small holes drilled perpendicular to the lightening holes in each arm feed oil to the blade bushings. Each spider arm supports a blade and transmits the torque from the engine. In addition, the arms also take the propeller thrust loads . On the inboard side of the spider a ledge is provided to support the chevron type neoprene barrelspider packing and the phenolic spider ring. These seals ensure an oil tight assembly between the spider and barrel. A groove machined just outboard of the front cone ledge accommodates the hub snap ring. Upon installation of the propeller on the engine, this snap ring is inserted around the propeller retaining nut near the outboard face of the front cone and dropped into place in the aforementioned groove. As the propeller retaining nut is backed off the propeller shaft during removal, the nut advances along the propeller shaft threads moving the front cone which in turn contacts the snap ring and thereby "jacks" the propeller off the rear cone. Between each spider arm, a flat surface is machined, in line with the central axis. These surfaces serve to seat and locate the barrel supports . The oil seal between the spider and the engine propeller shaft includes the metal spider and shaft seal washer, a neoprene spider and shaft seal, and a metal spider and shaft seal ring. These parts are inserted just inboard of the front cone bearing surface, and fit between the central bore of the spider and the outside periphery of the shaft.

Barrel The barrel (see Fig. 7.19) is a casing that encloses the propeller hub assembly. Moreover, the barrel has to withstand the high centrifugal loading of the blades. For this reason, it is manufactured from a high quality, heat-treated, drop forging of chromium-vanadium steel. Centrifugal loading of the blades is carried by means of shoulders provided at each blade bore. Lips are incorporated outside the shoulders to hold the blade packing. As previously mentioned above, these chevron type neoprene seals ensure oil tightness between the barrel and blades. The barrel assembly is split horizontally. Grooves machined into the parting lines provide accommodation for 0-ring type seals. The outboard barrel half incorporates a shelf just inboard of the dome

338

Propellers

NO.

PART NAME

Fired C•m Loeating Dowel We lch Plug

b

7 8 9 I0 11

1l IJ I~

15 16

17 18 19

20 21

22 23 H 25 26 27 28

Barrel Bolt - Short Barr•I Bolt - Long Barrel - Outboard Half Hub Snop Ring Front Cone Sp id er & Shaft Sul Ring Sp idor & Sha ft Seal Spider & Shaft Seal Wash tr Sp ider Barrel Support Shim Barre l Support A11embly Stop Pin Spid11 Sh im Plate Spider Shim Slade Gear Segment Blade Spring Pock Shim Blade Spr ing Pack Spring Blade Spring Pack Retainer Blade Pocking Spider Ring Sp ider Packing Rear Cone Barrel Half Sul Barrel - Inboard Half Codie Nut Cotter Pin

Fig. 7.19 Hamilton Standard "Hydromatic " barrel assembly. (Hydromatic Propellers Service Manual. Authors collection.)

339

Chapter 7

retaining nut threads . This shelf locates and supports the dome assembly. It also includes a fixed cam locating dowel hole in the center of the arc between each blade (see description of cams). Dowels are pressed into these holes so that the base section of the dowel seats on top of the corresponding barrel supports, and the tip section protrudes through the base of the fixed cam. Barrel halves are held together by massive, precision ground, nuts and bolts. They are fitted through the bolt hole bosses incorporated in each barrel half in the arc between the propeller blades. A hole is drilled along the axis of each bolt to provide for lead wool used in final balancing of the propeller assembly. Each bolt is sealed with a "welch" type plug.

Miscellaneous Hub Parts Barrel Supports-Phenolic supports (item 13 in Fig. 7.19) are used between the barrel and the spider. They provide alignment and support of the hub and blades assembly on the spider. Brass shims between the phenolic supports and the spider allow adjustment of spider/barrel concentricity. The inside face of the phenolic support is flat and matches the flat surface on the spider. The outer face is curved to match the inside curved portion of the inboard barrel half.

Blade Assembly Hydromatic blades are typically made from heat-treated aluminum forgings or from sheet steel (Fig. 7.20). The butt end (i .e. , the end that fits into the barrel) incorporates a shoulder perpendicular to the shank centerline of the blade which rests on steel rings . For lightness and to provide for bushings in which the spider arms locate, a portion of the blades shank section is forged hollow and bored to finished size for the bushing.

Thrust Washers Two hardened steel rings, which form part of the thrust bearing, are slipped over the butt end of the blade (Fig. 7.20). The blade is then "upset" in a forging operation thus retaining the rings. These thrust washers, which are not replaceable once the upset forging operation has taken place, transmit the centrifugal load into the barrel. The inner thrust washer is radiused to match a fillet machined into the butt end of the blade. The other thrust washer is flat on both sides. One side fits against retaining lips on the barrel and the other side forms the race for a rolling element thrust bearing. Centrifugal blade loads are transmitted the shoulders on the blade butt, through a phenolic chafing ring to the inner (radiused) thrust washer. The bearing assembly is completed by adding the split rolling element thrust bearing between the two thrust washers.

Blade Bushings Blade bushings, which ride on the ground journals of the spider arms, are made from aluminum bronze. At blade assembly, the bushings are shrunk into the tapered blade bore and located by two

340

Propellers

" E" SHAN K BLADE ASSEMBl Y NO. l 2 J .4

5 6 7 8 9 10 11 l2 l3 14 15 I6

PART NAME Blade Thru•I Bearing Flat Washor Thrust Bearing ~etainer Thrust B~or i ng 8e-.el•d Wosher

Blade Chafing Ring Slade Plug Blade Plug Stud Balanc ing Wo1htr lock Wosher Nut Blade Bu•hing Thru•t Plato Pin Blade Bu•hing Thrust Plate Flat Head Screw Blade Bushing Drive Pin Shim Plato Drive Pin

@r---------~\

'~~ -

g

1

1

('.V~~~~~~---~

& - - - - - i.

15r-~~~~~~~~--==--

@1---------a Fig. 7.20 Hamilton Standard Hydromatic blade assembly. (Hydromatic Propellers Service Manual. Author~ collection.)

341

Chapter 7

drive pins (which also include the shim plate drive pins) and two screws (item 11 in Fig. 7.20). Each blade bushing incorporates eight approximately half-circle slots which hold one end of the spring packs. Two of these spring pack slots are offset to provide an initial pre-load (in an assembled propeller) between the mating rotating cam gear and blade segment teeth.

Blade Balancing Plug Each blade is fitted with a tapered aluminum plug (item 6 in Fig. 7.20) wedged into the blade bore at a point just beyond the outer end of the blade bushing. Two purposes are served by this plug: (1) it prevents oil from passing into the extreme end of the taper bore of the blade and (2) it incorporates a stud on which washers may be stacked for initial blade balance.

Thrust Plate Close engagement of the blade gear segment and the gear of the rotating cam is essential. If backlash exists serious vibration may be excited. A thrust plate consisting of a small circular segment is pinned to the blade bushing (item 13 in Fig. 7.20).

Chafing Ring Several key functions are performed by the chafing ring: (i) it prevents chafing and fretting of the metal washer (item 4 in Fig. 7.20) and the aluminum blade, (ii) it serves to reduce stress concentrations. Manufactured from phenolic, it is split to allow assembly over the blade and fits between the blade thrust radius and the beveled thrust washer.

Blade Gear Segment Machined from solid steel forgings , the blade gear segments are attached to the blade via eight spring packs (items 17 and 19 in Fig. 7.19). Eight spring pack slots are equally spaced around the inner periphery of the gear segment and correspond to the spring pack slots in the blade bushing (item 11 in Fig. 7.20). The blade gear segment is attached to the blade and is accomplished via these eight spring slots and spring pack assemblies. Each blade gear segment has fifteen bevel gear teeth machined into it which engage with a corresponding bevel gear machined into the rotating cam (item 26 in Fig 7.21).

Blade Packing Retaining high pressure oil in the propeller assemble is a critical function. Sealing oil between the blade and barrel is accomplished via chevron type neoprene blade packing seals. They are fitted between the outer thrust washer and blade packing lip of the barrel blade bore (item 21 in Fig. 7.19) . The packing includes a header ring, two lip rings, and a follower ring .

342

Propellers

r~~~~~~~~---~----0

.

NO . I

2 3 4 5 b

7 8

9 10 II

I2 I3 14

15

16 I7 18 19 20 21

22

2l 24

25 26

27 28

29 30

~

PART NAME Dome Breether Hole WHher Dome Bruther Hole Sul Dome Cotter Pin Dome Rotoirnng Nut Loc k Screw Dome Rthining Nut Bell Wokh Plug Cotter Pin Pi•ton Guket Nut Lock Screw Pi.ton Gosket Nut Pi.ton Gosket Piston Auembly Com Roller Sheft Look Wire Com Boering Nut Cotter Pin Com Seering - Outboerd Fixed Com W eleh Plug Goor Prolooding Shim Dome Sholl Reto ining Screw Com Seering - lnbo"'d Ctm Roller Shtft Com Roller 8u1hin9 Ctm Rollen Rotating Com Stop Lug Low Pitch Stop High Pitch Stop Dome & Sorrel Sul

Fig. 7.21 Hydromatic dome assembly. collection.)

(Hydromatic Propellers Service Manua l. Authors

343

Chapter 7

Spring Pack Assemblies Providing gear pre-load between the blade gear segment and its mating rotating cam gear is accomplished via the spring packs fitted between the blade segment gear and the blade bushing. Each spring pack consists of two horseshoe spring retainers, and a number of spring leaves. To ensure a snug fit, shims may be added in the retainers. Two of the spring pack slots in the blade bushing are offset in respect to the mating gear segment slots. In this way, the axis of the blade gear segment is moved off the blade bushing towards the rotating cam gear. This ensures the necessary pre-load for backlash elimination.

Shim Plates and Shims A solid brass shim and a cast iron shim plate are fitted between the blade bushing face and the spider arm shoulder (items 15 and 16 in Fig. 7.19). They are held in place by two shim plate drive pins (item 16 in Fig. 7.19).

Dome Assembly Housed in the dome assembly are: the rotating cam, fixed cam, piston and distributor valve, and pitch stops. With standard cams installed, our ubiquitous Model 23E50 propeller has a constant speed range of 10 degrees for low pitch to 41 degrees for course pitch and 90 degrees for feathering. With the example just cited, the propeller has a normal operating range of 31 degrees. These angles are measured at the blade reference station. In the event fast acting cams are used, the blade range is from 15 degrees for low pitch to 55 degrees for course or high pitch and 90 degrees for feathering . With straight slope cams the blade angle range is from 10 degrees for low pitch and 54 degrees for course pitch and 90 degrees for feathering. The dome assembly, therefore, effects pitch change and maintains constant speed of the propeller via oil pressure (Fig. 7.21). When the dome assembly is installed on the propeller hub, the outer or fixed cam is securely fixed via the locating dowels provided for this purpose (item 1 in Fig. 7.19). The inner or rotating cam assembly is supported within the fixed cam by means of ball bearings (items 17 and 22 in Fig. 7.21). These bearings serve to accommodate the thrust loads due to gear reactions and piston oil forces. Piston motion is transmitted, via the fixed cam, to the rotating cam by means of four sets of cam rollers (item 25 in Fig. 7.21) carried on shafts (item 23 in Fig. 7.21) supported by the inner and outer walls of the piston (item 13 in Fig. 7.21).

344

Propellers

Cams Two cylindrical, coaxial cams are incorporated into the dome assembly. One cam is fixed and remains stationary with respect to the hub and the other cam rotates inside the fixed cam. Each cam incorporates a helically cut cam track; however, the cam tracks are cut in opposite directions to each other. The cam rollers ride inside the cam tracks and therefore transform the translatory motion of the piston into rotary motion. The opposite helix of the fixed and rotating cams doubles the rotating motion of the rotating cam for a given straight-line motion of the piston . The cam assembly includes the fixed cam, rotating cam, inboard bearing, outboard bearing, cam bearing nut, and cam bearing nut locking cotter. As with all other sub-assemblies, each cam is balanced independently by incorporating lightening holes.

Rotating Cam Made from a high nickel, low carbon steel, the rotating cam is case hardened on the cam tracks and gear teeth. Four helically cut cam tracks are machined in the cylindrical body portion of the cam (item 26 in Fig. 7.21). The cam tracks feature two helix angles; the lesser angle represents the constant speed operating range and the portion with the greater helix angle is used during feathering and unfeathering operations. As with any aircraft component, all excess weight is removed and in the case of the cams this function is achieved via lightening holes between the cam tracks. An unfortunate aspect of these lightening holes is the fact they act as perfect guillotines when operating the cams on the bench during overhaul. Many mechanics have lost fingers due to carelessly allowing fingers into the holes when operating the cams during overhaul. Integral with the rotating cam on its inboard end is the bevel gear that engages the blade gear segment. Two steel stop lugs (item 27 in Fig. 7.21) pressed into the base of the cam gear teeth and spaced 180 degrees apart, contact the stop rings in the base of the fixed cam. These stop lugs and stop rings serve to regulate the angular setting of the propeller.

Fixed Cam Similar to the rotating cam (see item 18 in Fig. 7.21), it is made of nickel steel but unlike the rotating cam, is not case hardened . Again, like the rotating cam, it has four cam tracks identical in design to the rotating cam except the helix is machined in the opposite direction. The inboard end of the fixed cam features a flange with a fine pitch spline on its inner diameter. This spline accommodates the propeller stop rings. The inboard cam bearing is located just outboard of these splines . The outboard cam bearing is located on the inner diameter of the inner diameter of the outboard fixed cam edge.

345

Chapter 7

Cam Styles The three cam styles were manufactured for Hamilton Standard propellers for R-2800s: standard, fast acting, and straight slope.

Standard Cams Standard cams incorporate two slopes or helix angles (Fig. 7.22). A longer slope used for normal constant speed operation and a shorter cam track, which transitions into the longer slope, for feathering operations . A reduction ratio of 5 :4 exists between the rotating cam gear and the blade gear segment. Total cam range is approximately 100 degrees. The constant speed cam range is 39 degrees, which translates into 31 degrees at the propeller blade . Rotating, or indexing, the blade one gear tooth with respect to the rotating cam gear equates to 8 degrees.

Fast Acting Cams Fast acting cams were developed for use where a more rapid blade angle response was needed. It features a more severe helix angle; therefore, for the same piston travel it will change the blade angle more rapidly than standard cams. Due to the lower mechanical advantage compared to a standard cam, higher pressures are required for actuation. This requires 300 psi single capacity or double capacity governors when used in conjunction with fast acting cams. The gear ratio between the rotating cam gear and the blade gear segment is the san1e as the standard cam, i.e., 5:4. The total cam range is approximately 94 degrees and a constant speed range of 57 degrees. Taking into account the built-in gear reduction, this equates to 45 degrees of blade travel for the constant speed range. Again, indexing the blade one gear tooth equates to 8 degrees.

Straight Slope Cams In this type of cam, the constant speed range of the cam helix, which is the same as that of the standard cam, is extended and the feathering range is omitted. Obviously, straight slope cams cannot be feathered ; therefore, they are used principally on single-engined aircraft. As with the two prior styles of cams, the reduction gear ratio between the rotating cam and the blade gear segment is 5 :4. The total rotating cam range is approximately 55 degrees . Again, taking into account the gear reduction between the rotating cam and the blade gear segment, this equates to 44 degrees of blade movement for constant speed operation. As with the two prior styles of cam, indexing the blade one gear tooth equates to 8 degrees of blade movement. An example of a straight slope cam is shown to the right of Fig. 7.22.

Piston The piston is machined from an alumimun forging to close tolerances. As with other sub-assemblies, it is independently balanced by drilling material out of the inboard face of the inner wall . It is a double

346

Propellers

G. 17. 18. 19. 20.

21 .

n.

13. 24. 2S, 26. 27.

28. 19.

30,

v.,,1

l i~

Wolff Stroi~t Dtoin Valve Fire Woll Junction 6o1 (Ref) Moin JunJfR " ~

f>J(LOSU ~E 8 ~NCLOSUltE - !tEAll HfNCtl) 0. ENClOSUR:C - t[Ai JIX.Et> IQ ll4010 OPERATOlfS WINOOWS II. CONE AS5EM!ol Y - OEW NACfu£ UAR l l ElECTQ~A.l GUN TURtEl 13 CREW NACEL LE ruum ASS~MB L '(' CHW NA.(fLLf Afr SECTtON li:ADlO OPERA.roR·s [)()()Q

,",_ 16.

INNER WIHG lANX. PANEL

IT. ENGINf NACft U IOfWAllO LOWU 1ANEt 18 COVtR ASSEMfliLY NOARD C0"1ER - INtiElt WJNG N(l TA.N( 20. srv1 WING IN&O.e.110 n. STlJi!I WING 0V1110M:D

...

n

ENGINE HA: ...:-··:

494

Fig. 9.118 Exploded view of Martin B-26 showing major sub-assemblies. This also gives a good indication of how the aircraft was manufactured. (Erection and Maintenance Instructions for Army Model B-26B-l and -26C Aircraft. Courtesy of the National Air & Space Museum.)

~ ~ ~

~ () I::)

::::>:

Cl ;:;

"'

Chapter 9

Fig. 9.119 The B-26's APU was stored in the waist position when not in use. (Erection and Maintenance Instructions for Army Model B-26C Aircraft. Courtesy of the National Air & Space Museum.)

Fig. 9.120 Martin B-26A. (Courtesy of the National Air & Space Museum, Smithsonian Institution. Photo No. 2A 23783.)

496

Military Applications

TABLE 9-9 MARTIN B-26 SPECIFICATIONS Parameter First Delivery Engine Propeller Winq Span Wing Area Length Gross Weiqht Fuel Cap. - Normal Ranqe Max. Ranqe Service Ceiling Climb Max. Speed Cruisina Speed Landinq Speed Armament

B-26 (Model 179) November 25, 1940 (first flight) February 25, 1941 (first delivery) R-2800-5

28,340 lbs 465 qal

B-26A

(Fi~.

9.120)

R-2800-5 (Fig. 9.121 ), -39 Curtiss Electric 4-blade 65 ft 602 sq ft 58 ft, 3 in. 34,000 lbs 465 qal 1150 mi 23,500 ft 311 mphat14,500ft 130 mph Five .50 cal. machine guns. Normal bomb load: 2000 pounds. Max. bomb load: 5800 pounds. 24-volt electrical system

130 mph

Comments

Fig 9.121 Early "A" series R-2800-5 that powered the B-26, B-26A, and B-26B. Being an "A " series, this engine was rated at only 1850 horsepower. (Courtesy of Pratt & Whitney.)

497

Chapter 9

Fig 9.122 Martin B-26B. Wing span increased from 65 feet to 71 feet during this production run. (Courtesy of the National Air & Space Museum, Smithsonian Institution. Photo No. 1B 18285.)

Fig 9.123 Martin B-26C. Vertical tail surface increased. (Courtesy of the National Air & Space Museum, Smithsonian Institution. Photo No. 1B 18247.)

498

M ilitary Applications

TABLE 9-9 MARTIN B-26 SPECIFICATIONS (Continued) Parameter No. Built Fi rst Delivery Engine Propeller WinQ Span Wina Area LenQth Gross WeiQht Fuel Cap . - Normal Fuel Cao . - Max. RanQe Max. Range Service Ceiling Climb Max. Speed Cruisina Speed LandinQ Speed Armament

Comments

B-268 (Fig. 9.122)

B-26C (Fig. 9.123)

R-2800-39 , -41 * Curtiss Electric 4-blade 65 ft or 71 ft** 602 sq ft 58 ft, 3 in. 34,000 lbs 465 Qal 1150 mi

R-2800-43 (Fig. 9.124) Curtiss Electric 4-blade 65 ft or 71 ft* 658 sq ft 56 ft, 1 in. 38 ,200 lbs 720 Qal 1462 aal 1150 mi

23 ,500 ft

21 ,700 ft

311 mph at 14,500 ft

282 mph at 10,000 ft

One fixed .50 cal. and one flexible .50 cal. in nose, four "package" guns in sides of forward fuselage, two guns in Martin dorsal tu rret, two flexible waist guns, one tunnel gun and two tail guns. Max. bomb load 4000 lbs. Most produced of the B-26s including the identical B-26C. *B-268-2 ** Long wing introduced in B-26-10 & 15. Crew increased to seven .

Same as B-268

Similar to B-268 except for manufacturing site , "B"s being built at Martin's Baltimore facility and "C"s manufactured at a new production facility in Omaha, Nebraska. *Long wing introduced in B-26C-5 & 6. Vertical tail surface increased.

Fig. 9. 124 Single-stage, twospeed R-2800-43 that p owered: B-26B, B-26C, B-26C, XB-26D, B-26E, B-26F, and TB-26H. This Ford built "B " series engine was a big improvement over the early "A " series R-2800-5s. (Courtesy of Pratt & Wh itney.)

499

Chapter 9

TABLE 9-9 MARTIN B-26 SPECIFICATIONS (Continued) Parameter No. Built First Delivery Enaine Propeller Wina Span Wina Area Lenath Gross WeiQht Fuel Cap. - Normal Fuel Cap. - Max. RanQe Max. Ranae Service Ceilina Climb Max. Speed Cruisina Speed Landing Speed Armament

Comments

B-26F and G (Fig. 9.125 and Fig. 9.126)

R-2800-43 Curtiss Electric 4-blade 71 ft 658 sq ft 58 ft , 2-5/8 in . 38,200 lbs 720 aal 1462 aal 1150 mi 21 ,700 ft 282 mph at 10,000 ft

Typically 4000 lb bomb load. Eleven .50 cal. machine guns; one in nose, two waist guns and two tail Quns. Similar to B-26-C except wing incidence was increased by 3-1/2 degrees. Rear bomb bay eliminated and no provision for torpedo .

Fig. 9.125 Martin B-26F Wing incidence increased by 3~ degrees in order to make the handling characteristics more benign. (Courtesy of the National Air & Space Museum, Smithsonian Institution. Photo No . 1B 18344.)

500

Military Applications

TABLE 9-10 8-26 ARMY AIR FORCE SERIAL NUMBERS B-26 Model

Serial Numbers

B-26 Model

Serial Numbers

8 -26MA 8-26A-MA

40-1361 to 40-1561 41-7345 to 41-7365 41-7368 41-7431 41-7477 to 7483 41-7366 41-7367 41-7369 to 41-7430 41-7432 to 41-7476 41-17544 to 41-17624 41 -17626 to 41 -17851 41 -17852 to 41-17946

8-26C-10-MO 8-26C-15-MO

41-34848 to 41-34907 41-34908 to 41-34997

8-26C-20-MO

41-34498 to 41-35172

8-26C-25-MO

8-268-3-MA

41-17625 41-17947 to 41-17973

8-26C-30-MO

8 -26-4-MA 8-268-10-MA 8-268-15-MA 8-268-20-MA 8-268-25-MA 8-268-30-MA

41-17974 to 41-18185 to 41-31573 to 41 -31673 to 41 -31773 to 41 -31873 to

41-18184 41-18334 41 -31672 41 -31772 41-31872 41-31972

8-26C-45-MO 8-26F-1-MA 8-26F-2-MA 8-26F-6-MA 8-26G-1-MA 8-26G-5-MA

8 -268-35-MA 8-268-40-MA

41-31072 42-43357

8-26G-11-MA 8-26G-15-MA

8-26G-15-MA

44-67945 to 44-67954

8-268-45-MA

41 -31973 to 42-43260 to 42-43360 42-43361 42-43459 42-43358 42-43359 42-43362 to 42-95629 to 42-95738 to

41-35173 to 41 -35370 41-35372 41-35371 41-35561 to 41-35872 42-107471to42-107496 42-107831to42-107855 41-35374 to 41-35515 41-35517 to 41-35538 41-35540 41-35548 to 41-35551 41-35553 to 41-35560 42-107497 to 42-107830 42-96229 to 42-96328 42-96329 to 42-96428 42-96429 to 42-96528 43-3411 5 to 43-34214 43-34215 to 43-34464 43-34540 to 43-34614 43-34465 to 43-34539 44-67805 to 44-67944

8-26G-20-MA

8-268-50-MA 8-268-55-MA 8-26C-5-MO

42-95829 to 42-96028 42-96029 to 42-96228 41-34673 to 41-3484 7

44-67970 44-68065 44-67955 44-67990 44-68105 44-68254 44-68222

8-26A-1-MA

8 -268-MA 8 -26 8-2-MA

AT-23A-MA

AT-238-MO

42-43458 42-95737 42-95828

T8-26G-20-MA 8-26G-21-MA 8-26G-25-MA T8-26G-25-MA

501

to to to to to

44-67989 44-68104 44-67969 44-68064 44-68221

to 44-68253

Chapter 9

Fig. 9.126 Martin B-26G. (Courtesy of the National Air & Space Museum, Smithsonian Institution. Photo No. 1B 18240.)

502

Military Applications

Grumman F6F Hellcat (Fig. 9.127) At the request of the Bureau of Aeronautics, Grumman designed a follow-on to the successful F4F Wildcat. Unlike its predecessor, the F4F, which had been an evolutionary design starting in the early 1930s as a bi-plane, the Hellcat was totally new. Having said that, Grumman's heritage was evident in its shape and design. It also carried on the "Grumman Iron Works" reputation for a strong and rugged aircraft. Anything less would fail in the harsh and rough environment of carrier operations. Unlike the F4U Corsair, all production F6Fs were powered by the same engine, the "B" series R-2800-10 or the water injected R-2800-lOW. It was recognized as early as 1940 that single-stage supercharging would be totally inadequate in the near future. This conclusion came from NACA. The Navy chose mechanical gear driven supercharging over turbosupercharging, thus the two-stage R-2800-10 and later -lOW (Fig. 9.128), was born to power the Hellcat. Almost identical to the R-2800-8 that powered the F4U-l , the primary difference was that the -10 used downdraft carburetion and the -8 used updraft carburetion. The two stages of supercharging were referred to as main stage and auxiliary stage. The main stage was driven at all times and had a single speed. The auxiliary stage could operate in three modes: neutral, i.e ., the blower impeller was not driven; low speed; and high speed. For low altitudes, those under 12,000 feet, the engine was aspirated through the single-speed main stage. At altitudes above 12,000 feet, low speed of the auxiliary blower was selected and for operations above 25 ,000 feet high speed for the auxiliary blower was selected. Therefore, at all altitudes below 12,000 feet the R-2800-10 operated solely on the main stage. Rather surprisingly, ram air was not supplied to the main stage blower, only to the auxiliary stage. This anomaly explains why a Corsair handily outperforms a Hellcat at lower latitudes. The Corsair's main stage was fed ram air and thus gained a significant amount of power. At higher altitude, with the auxiliary stage engaged, there was little to choose between a Hellcat and an F4U-l. All intercooler and induction came from the cowl nose bowl. Again, this is in contrast to the F4U-l , which used its wing root intakes for these two requirements. Dual intakes at approximately the five o' clock and

Fig. 9. 127 Grumman F6F-5 Hellcat. (Courtesy of the National Air & Space Museum, Smithsonian Institution. Photo No. 2A 20726.)

503

Chapter 9

Fig. 9.128 Right side view of an R-2800-1 OW, power plant for all production F6Fs. This "B " series engine also powered the Northrop P-61AIB. Its massive two-stage supercharger is evident in this view. (Courtesy of Pratt & Whitney.)

seven o'clock positions provided cooling air for the dual intercoolers and induction system (Fig. 9.129). A single, oval shaped scoop at the bottom of the cowl provided air for the oil cooler (Fig. 9.130). Various models of the F6F were equipped with ADI for additional emergency power. In December 1942, the Bureau of Aeronautics made a request for a float equipped F6F (Fig. 9.131). The XF6F-l wind tunnel model was brought out of retirement and a scale pair ofEdo floats were fitted . Tests were concluded by mid-1943 with no further action being taken. It is possible the reason for dropping this project was that U.S. Marines had captured a number of islands in the South Pacific negating the requirement for a float equipped fighter. In contrast, as the Japanese lost more and more territory, they had an increasingly greater need, as the war progressed, for float equipped fighters and consequently used them operationally (Refs. 9 .3, 9.39, 9.40, 9.41 , 9.42).

Blower Clutch Desludging An undesirable idiosyncrasy of the R-2800-10 blower clutch arrangement was its propensity for sludging. To overcome this tendency the following procedure was written in the F6F pilots handbook: a. Propeller control in low pitch, high rpm b. Engine rpm approximately 1200 c . Shift supercharger controls remaining in each position for approximately 30 seconds The above procedure, although not foolproof, could eliminate blower clutch problems.

504

Vl

0

Vl

Fig. 9.129 Induction and intercooler arrangement for the F6F Hellcat. Three openings in the cowl :S nose bowl supplied air for the various requirements. Two openings at approximately the five o'clock and seven o'clock positions supplied cooling air to the dual air-to-air intercoolers. The bottom opening supplied induction air to the auxiliary stage supercharger and oil cooler. (Erection and Maintenance Instructions for Navy Model F6F-3, F6F-3N, F6F-5, F6F-5N Airplanes. Courtesy of the Naval Aviation Museum, Pensacola, Florida.)

Chapter 9

Fig. 9.130 Oil system for an F6F Hellcat. The cylindrical tank is shown mounted to the firewall and the oil cooler below. Two triangular fittings shown approximately halfivay up the firewall are the oil in (right side) and oil out (left side). They are bolted to the rear of the R-2800. This arrangement of the two triangular fittings was used on the vast majority of R-2800s. (Erection and Maintenance Instructions for Navy Model F6F-3, F6F-3N, F6F-5, F6F-5N Airplanes. Courtesy of the Naval Aviation Museum, Pensacola, Florida.)

506

___aT""_--_""....,.. e:==J -~----,---

.!@-.

LMOMn:Mt' ~~ OEIWITMENT OF AEROIUUTICS

H.4'Y YMO. MS#itH-GTOH. "- C. MARC.14 JI, tiMJ. F-61·, SEAPt..AME M#K'ML ~H3'°"'4

~

0

I

I

OI MODl'L M9 . . . . . . 6.:Hfl: .I .. j

l...........L..1L I

I

I

t

I

I

I

SCAU *"ftQ.#Vll.L $.tU t0 ~14

Fig. 9.131 Float equipped F6F No aircraft was built to this configuration; however, if the island hopping campaign in the Pacific had not been so successful, this aircraft might have come to fruition. (Report No. 666 12 June 1943. Air Force and Moment for F6F-3 Seaplane. Authors collection)

Chapter 9

HEY BUB

I

TURN THAT COCKPIT HEATER OFF.

1~ I .

TABLE 9-11 GRUMMAN F6F HELLCAT SPECIFICATIONS Parameter No. Built First Delivery Engine Propeller Wing Span Wino Area Length Empty Weight Gross Weight Fuel Cap. - Normal Fuel Cap. - Max. Ranae Max. Range Service Ceilinq Climb in 1 min Max. Speed Cruising Speed Landing Speed

Armament Comments

XF6F-1 1 June 26, 1942 Wriqht R-2600* Curtiss Electric 3-blade 42 ft, 10 in . 334 sq ft 33 ft, 10 in. 84801bs 11 ,629 lbs

XF6F-2*

*R-2800-21

1500 mi 35,600 ft 2340 ft 200 mph 84 mph 6 X .50 Mg . Only the prototype was powered by the Wright R-2600; all subsequent F6Fs were powered by the R-2800. Armament not installed on the prototype.

508

Second prototype. Intended to be powered by turbocharged version of Wright R-2600-16 , instead re-engined with R-2800 . *This designation was used twice. The second XF6F-2 was an experimental aircraft to test the Birman (Turbo Engineering mixed flow turbosupercharger). Not successful.

Military Applications

TABLE 9-1 1 GRUMMAN F6F HELLCAT SPECIFICATIONS (Continued) F6F-3, -3E, -3N, -3P 4403* December 4, 1942 R-2800-10/-1 OW Hamilton Standard 3-blade 42 ft, 10 in. 334 sq ft 33 ft, 10 in. 9023 lbs 13,221 lbs 15,487 lbs 235 qal 385 Qal 1090 mi 1850 mi 37 ,300 ft 3100 ft 324 mph at S.L. 376 mph at 20,000 ft 200 moh 84 mph

Parameter No. Built First Delivery EnQine Propeller Winq Span WinQ Area Lenqth Empty Weiqht Gross Weight Max. Takeoff Fuel Cap. - Normal Fuel Cap. - Max. RanQe Max. Ranqe Service CeilinQ Climb in 1 min Max. Speed

XF6F-3 1 March 15, 1943 R-2800-10 Curtiss Electric 3-blade 42 ft, 10 in . 334 sq ft 33ft,10in . 88961bs 12, 179 lbs

Cruisina Soeed Landinq Speed

200 mph

Armament Comments

6 X .50 caliber machine quns XF6F-3 same structure as planned XF6F-2 except for use of R-2800. Armament not installed. -10 engine essentially the same as the -8 installed in the F4U-1 except for downdraft induction.

1350 mi 39 ,900 ft 3200 ft 398 mph at S.L.

509

6 X .50 caliber machine quns * Total production of F6F-3s. First version to be mass-produced. Went into action September 1, 1943. -3E: Designation given to 18 F6F-3 with APS-4 radar under right wing. -3P : Photo recon version. -3N : Similar to -3E with radar under riqht winq.

Chapter 9

TABLE 9-11 GRUMMAN F6F HELLCAT SPECIFICATIONS (Continued) Parameter No. Built First Delivery Enqine Propeller Winq Span Winq Area Length Empty Weiaht Gross Weight Max. Takeoff Fuel Cap. - Normal Fuel Cap. - Max. Ranqe Max. Ranae Service Ceilinq Climb in 1 min Max. Speed

XF6F-4 1 March , 1943 R-2800-27*

F6F-S, -SD, -SE, -SK, -SN, -SP, Hellcat II 7870* April 29, 1944 R-2800-10/-1 OW Hamilton Standard 3-blade 42 ft, 10 in . 334 sq ft 33 ft, 10 in. 9060 to 9421 lbs 12,598 lbs to 13,190 lbs 14,250 lbs to 15,413 lbs 250 aal 408 qal 800 to 945 mi 1260 to 1530 mi 37,300 ft 3100 ft 324 mph at S.L. 380 mph at 23,400 ft 200 mph 88 mph

Armament

4 X 20 mm cannon , 200 rpg

Comments

Single-stage, two-speed engine. Modified from the XF6F-1. This aircraft, after going through four different configurations ended up being converted into an F6F-3.

6 X .50 caliber machine guns or 2 X 20 mm cannon 2000 lbs bombs *Total production of all F6F-5 variants. Similar to -3 variant except for strengthened tail , engine cowl , reinforced ailerons, and flat windshield. Royal Navy designated -5s as "Hellcat II." -SK were modified -5 and -5Ns used as radio controlled flying bombs in Korean conflict.

Cruisinq Speed Landinq Speed

510

Military Applications

TABLE 9-11 GRUMMAN F6F HELLCAT SPECIFICATIONS (Continued) Parameter No. Built First Delivery Engine Propeller Winq Span Winq Area Lenqth Empty Weiqht Gross We ight Max. Takeoff Fuel Cao. - Normal Fuel Cap. - Max. Ranae Max. Ranae Service Ceilinq Climb in 1 min Max. Speed Cruising Speed Landinq Speed Armament

Comments

XF6F-6 2 July 6, 1944 R-2800-18W Hamilton Standard 4-blade 42 ft, 10 in . 334 sq ft 33 ft, 10 in. 9060 to 9421 lbs 12,598 lbs to 13,190 lbs 14,250 lbs to 15,413 lbs 250 qal 408 gal 1170 mi 1730 mi 39,000 ft 3070 ft 417 mph at 21 ,900 ft 200 mph 85 mph 6 X .50 caliber machine guns 2000 lbs bombs Only F6F variant fitted with a "C" series enoine - same as F4U-4. Onlv two built.

511

Chapter 9

Grumman F7F Tigercat Grumman's F7F Tigercat (Fig. 9.132) probably personified the concept of stuffing two of the biggest engines in the smallest possible airframe. It was also the Navy's first twin-engined fighter and first operational Navy aircraft with tricycle landing gear (Fig. 9.133 and 9.134). Like many successful military aircraft that saw evolutionary development, the F7F evolved from two prior Grumman aircraft that never saw series production. Grumman built the XF5F powered by a pair of Wright R-1820s for the Navy. Numerous problems were encountered such as overheating and weak landing gear. A similar aircraft was built for the Army Air Force and designated XP-50. The primary difference between the XP-50 and XF5F was that turbosuperchargers were fitted to the XP-50. This feature turned out to be its downfall. After accumulating less than 20 flight hours, a turbosupercharger let go in a big way. The explosive force of the turbosupercharger failure damaged the hydraulic system and consequently disabled the nose gear. Due to the landing characteristics of the XP-50 it was deemed too dangerous land without the nose gear extended . This forced the test pilot, famous prewar race pilot Bob Hall, to bail out. The loss of the one and only prototype signed the death knell for this project. Undaunted, Grumman learned many lessons on the XF5F and XP-50 programs that were incorporated into the F7F. Both sides of the F7F engine nacelle featured airscoops: one for induction air (Fig. 9.135) and one for oil cooling (Refs. 9.3 , 9.43 , 9.44, 9.45).

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Operating, Service Difficulties and Overhaul

When an engine is as complex and heavily loaded as the R-2800, it goes without saying the oil system is equally complex and circuitous. If the engine were simply hooked up to an oil tank and fuel system and started up, significant damage would result. Even though the mechanic applied copious amounts of oil to all moving parts during re-build, the entire oil system is full of air. If this air is not purged, upon start-up, the entrapped air will be blown across the bearings resulting in metal to metal contact. To ensure the oil system is primed, an electrically driven, positive displacement, pump is connected to one of the pressure take-off ports on the rear case . One of the upper rocker box covers is removed for evidence that the engine is pre-oiled. When oil starts issuing from the rocker shaft pivot bearing, that is a good indication that the rest of the engine is pre-oiled. Hook-ups required for testing include: (i) thermocouple lines to cylinders 1, 4, 12, 16, and 18; (ii) breather lines on intermediate rear case; (iii) throttle control (Fig. 12.17); (iv) mixture control; (v) number 1 inlet port manifold pressure manometer line for registering manifold pressure; (vi) fuel pressure gage line to carburetor; (vii) vapor separator chamber vent line to the opening directly behind the carburetor fuel inlet connection ; (viii) fuel lines to the engine driven fuel pump and carburetor and a fuel pressure relief valve, if the pump does not incorporate one; (ix) high and low clutch pressure gage lines to the front and rear of the selector valve; (x) clutch selector valve control; (xi) main oil pressure gage line at either the upper left or upper right side of the rear case; (xii) low pressure oil gage line just above the low pressure relief valve; (xiii) tachometer generator; (xiv) fuel pump drainline; (xv) oil inlet and scavenge lines; (xvi) exhaust stacks; (xvii) priming system; (xviii) front oil pressure line to governor mount pad cover; (xviv) torquemeter booster oil pressure gage line at the lower right side of the front accessory case; (xx) torquemeter gage line to the pressure transfer cover; (xxi) carburetor air intake duct to the airscoop on the carburetor; (xxii) air intake thermometer line to the air intake duct; (xx iii) cooling cowl; (xxiv) electrical hook-up for starter control and any other electrical hook-ups the starter may require; (xxv) induction vibrator hook-up; and (xxvi) mount test club . Prior to starting, the usual procedures are gone through to ensure the engine is not hydraulic-locked . This entails removing the lower, front plugs and motoring the engine over on the starter. With all the plugs installed, starting can commence. Oil pressure is normally in the range of 80 to 90 psi and this is the focus of attention on initial start-up . Break-in usually takes two hours. Starting with 1400 rpm, the speed is increased by 100 rpm increments over the two hour period finishing up at 70 percent rated power. At each speed increase, the blower clutches are exercised. The engine is run at 89 percent power at 2300 rpm for half an hour. At this point the engine is shut down and checked for leaks . It's then run for another half hour at 89 percent and 2300 rpm. Finally, a one minute run is conducted at takeoff power dry and one minute at takeoff power wet. Throughout the test, all engine parameters are logged, magneto checks made, numerous blower shifts are made.

Torquemeter Checks: The torquemeter is monitored closely throughout the test to ensure there are no fluctuations. A fluctuation is a bad omen indicating internal engine failure or ignition problems . Torquemeter pressure can be converted to BHP by use of the equation: Torque pressure x RPM x torque constant = BHP

651

Chapter 12

PRESSURE STROKE

Fig. 12.17 In order to make lically actuated throttles were throttle arm was located; the Manual for Aircraft Engines,

RETURN STROKE

throttle hook-ups easier in the test cell, Sperry Exactor hydrauused In this way, it was not critical where the carburetor Exactor could accommodate any position. (Engine Test Navy Department Bureau of Aeronautics. Author '.s' collection.)

For example, with a typical CB-16 if the constant of the torque nose 0.00632 and the torquemeter pressure is 61.3 pounds at an engine speed of 2000 rpm the horsepower can be equated to: 61.3 pounds times 2000 rpm times 0.00632, which equals 775 BHP. Even after an R-2800 comes out of test, it still needs more time to break-in. Newly overhauled R-2800s typically need 50 hours before they can be considered fully broken-in. Upon successful completion of testing, the engine is pickled and packed. Pickling takes the form of spraying preservative oil into each cylinder, replacing the spark plugs with a preservative plug, plugging off all openings, spraying the exterior with preservative, wrapping with plastic wrap, and installing in a shipping container. During World War II, shipping engines to all parts of the world in the most inhospitable and corrosive environments forced Pratt & Whitney to development a steel shipping can. Configured like a massive 55-gallon oil drum, they were split on their horizontal center line. Brackets welded inside the can supported the engine and any ancillary tools and accessories such as the carburetor. The two halves were sealed with a gasket, evacuated then charged with

652

Operating, Service Difficulties and Overhaul

nitrogen. The ability to float was another prerequisite. It was not uncommon during the island hopping campaigns of World War II for cans containing their precious R-2800 cargo to be dumped overboard from ships and floated ashore to be retrieved and installed in waiting aircraft (Ref. 12.12).

References 12.1 Airlines Engineering Depaitment Letter Report No. 195, December 31 , 1951 , revised July 18, 1958, Notes on Operation of Pratt & Whitney Aircraft R-2800-CB Series Engine. 12.2 R-2800 Piston Top Land Failure, Internal Pratt & Whitney report dated March 13, 1956. 12.3 Letter from W.G. Anderson (Pratt & Whitney Airlines Engineer) to W.G. Heil, Power Plant Engineering Section, United Airlines. Dated July 12, 1956. 12.4 Internal Pratt & Whitney memo from A. Lewis MacClain to L.H. Gitzinger, R-2800 Piston Dishing or Hydraulicking at National Airlines, Jacksonville . Dated March 23 , 1949. 12.5 Letter from A.E. Hale, Flight Operations Engineer, Pratt & Whitney Aircraft to Mr. Charles Blair, Power Plant Engineer, An1erican Airlines. Dated May 19, 1964. 12.6 Report from F.H. Flynn, Pratt & Whitney Service Manager to Commander, San Antonio Air Material Area, Kelly Air Force Base. Reported Inconsistent Power Versus AMP Indications On R-2800-99W engines at SAMA. Dated 9/23/66. 12.7 Correspondence between Lemcke S.A. Industria E Comercio, Rio De Janeiro and N.H. Bell, Pratt & Whitney Flight Operations Engineer. Subject: Information on P&W R-2800-CBl 7 Engine Operation. Dated February 1965 . 12.8 Report from N .H . Bell, Pratt & Whitney Flight Operations Engineer. Stuck High Blower Operation for CB-16 and CB-17 engines. 9.26 Erection and Maintenance Instructions for Army Models P-61A and B , 30 December 1944. 12.9 R-2800 Engine Reliability, Internal Pratt & Whitney report. Dated 12/21/67. 12.10 Author's interviews with numerous operators and overhaul shops. 5.2 Double Wasp (R-2800) CB Series Overhaul Manual, Pratt & Whitney Aircraft Group, United Technologies, March 1957, revised February 1980. 12.11 Double Wasp (R-2800) CB Series Maintenance Manual, Pratt & Whitney Aircraft Group, United Technologies, March 1957, revised October 1977. 12.12 Engine Test Manual for Aircraft Engines, Navy Department Bureau of Aeronautics.

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Chapter 13

Racing

From the beginning of time humans have raced. No doubt the earliest caveman looking for his neJ1..'t meal, in all probability, raced his neighbor to the hunt. Since then, just about everything that moves has been raced. At the dawn of the 20th century, when aviation was still in its infancy and it was all aviators could do to stay aloft, airplanes were pitted against each other in contests of speed. Over the years, highly prestigious aircraft racing events developed. The 1930s are recognized as the "Golden Age" of racing in the United States . Prestigious trophies such as the Bendix Trophy and the Thompson Trophy v11ere hotly contested during this time. Everything, including air racing, was put on hold during World War II. 1946 saw the recommencement of air racing once again. This time, the Thompson Trophy Race was the preeminent contest. Held in Cleveland, Ohio, and therefore sometimes referred to as the Cleveland Air Races, the postwar races were radically different from the prewar races. Tens of thousands of high performance fighters had been manufactured during the duration of World War II that incorporated the latest in aviation technology. Unlike the home built specials of prewar days, these sophisticated and modem fighters had far superior performance to their prewar racing counterparts. In fact, any late World War II fighter could have walked away with any of the prewar races. The fact that these surplus aircraft were available at bargain basement prices added to the attraction. Cook Cleland 's FG-1 "Lucky Gallon" (Fig. 13.1), the Goodyear-built equivalent to a Vought F4U- l was this famous racers first mount. Cleland eliminated the ram air induction scoop in the wing leading edge and instead fabricated a ram scoop that ran along the bottom of the cowl, somewhat reminiscent of an F4U-4 . Competing as race number 90, he finished in an uninspiring sixth position with a race average of 35 7 mph (Ref. 13 .1). As Frank Walker found out during the war with his ADI work and R-4360 vs. R-2800 contest, there is no replacement for displacement. Cook Cleland came to the same conclusion. For that reason, he campaigned an R-4360 powered Goodyear F2G in 1947, 1948, and 1949. This time, even though it was essentially the same airframe raced in 1946, Cleland was victorious. However, the 1946 effort was not totally wasted. Leaming from the experience of the R-2800 powered FG-1 , Cleland fitted an extended induction ram air scoop that reached to the front of the cowl's nose bowl. The stock

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Chapter 13

Fig 13.1 Coo~ Cleland campaigned this Goodyear FG-1 at the 1946 Cleveland National Air Races. Jn subsequent years, Cleland successfitlly raced a highly modified R-4360 powered Goodyear F2G (Photo by Warren M Bodie.)

configuration had the ram scoop situated just ahead of the carburetor, i.e., some distance from the front of the cowl. It has been theorized that the stock design compromised induction efficiency by picking up the boundary layer air flow and therefore reduced or even eliminated the ram effect. Cleland was not the only one to campaign an FG-1 in the 1946 Thompson: Thomas Call raced FG-1 race number 90 . However, he was not in the running (Fig. 13.2). This same aircraft was also used as a Vought corporate airplane (Fig. 13.3) In the late 1960s and into the early 1970s an F4U-7 by the name "Blue Max" was extensively raced, sponsored by Flight Systems, Inc. (Fig. 13.4) . Immediately after World War II racers almost had their pick of service aircraft. However, a few experimental aircraft were up for grabs . It seems Curtiss was only too happy to get rid of their failed attempts at producing a fighter aircraft. Among the ones to end up in racer 's hands were the beautiful XP-40Q and the not so beautiful XP-60E. With a potent two-stage, two-speed R-2800-10, the XP-60E could have been a viable contender. Interestingly, Curtiss modified the airplane for owner James DeSanto, who literally sold the farm in the form of his flying school to finance this project. Unfortunately, the tail surfaces failed during a test flight and DeSanto was forced to bail out thus ending the flying career of the P-60 series . Due to several unfortunate and fatal accidents, the Thompson Trophy Races were ended in 1949. Unlimited class air racing would not recommence until 1964. This time the venue would be Reno,

656

Racing

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Fig. 13. 3 Race number 90 was later acquired by Vought Corporation as a corporate airplane. (Bob Stevens photo courtesy of Warren M Bodie.)

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Chapter 13

Fig. 13.-1 F-IU--1 "Blue Max" entered in the 1971 California 1000 Races. (Photo by Warren M Bodie)

Nevada. Picking up from the 1949 Thompson races, aircraft of choice were, again, World War II fighters. Lessons learned from the ensuing fifteen years resulted in radically modified racers. Perhaps the personification of this development was Daryl Greenamayer 's remarkable Gmmman F8F Bearcat (Fig. 13.5) . When the races were resurrected in 1964, thought was given to having a racehorse start, i.e. , a standing start. With this in mind, Greenamayer modified the Bearcat's landing gear by converting it from hydraulic operation to pressurized nitrogen. This not only reduced weight but more importantly, gave a considerably faster cycle time . Of course, the downside was that it was a one-shot deal, in other words, the gear could only be cycled once per flight Oil cooling drag was eliminated by fairing over the oil cooler airscoops in the wing root Of course, the engine would not survive without some method of taking heat away from the oil. This was accomplished by using a "boiler" system, in other words, the oil cooler was immersed in water and consequently boiled it off during the course of a race. This idea was not new; the Germans used it in their highly modified record breaking aircraft, the Messerschmitt Me 109R or Bf 209, which captured the absolute world 's air speed record at 469 mph. Again, this was a one-shot deal: the water tank needed to be replenished after each flight In fact it has been argued that this airplane was a one-flight airplane. Greenamayer's R-2800 was a mix of the best R-2800 components available: a -44W nose case; -30W power section; and a single-stage, two-speed CB-17 blower. A slower turning prop with relatively low tip speed, i.e. , less than 900 feet per second, offers more efficiency over one that exhibits a tip speed of 1000 feet per second or greater. Several remedies were at the disposal of Greenamayer; however, the R-2800-44W utilized the lowest propeller reduction ratio of any R-2800 . At .350:1 , the -44W's propeller reduction ratio allowed Greenamayer to use a larger diameter, slower turning prop from a

658

Racing

Fig. 13.5 By far the most radically modified R-2800 powered F8F Bearcat, Darryl Greenamayer s "Conquest 1, " garnered many victories including an outright world air speed record for piston powered aircraft. (Bob Stevens photo, courtesy of Warren M Bodie.)

Douglas AD Skyraider. Fortunately, the Skyraider 's engine, the Wright R-3350, used the same SAE 60 spline propeller shaft as the "C" series -44W nose case. This meant the Skyraider's propeller was a relatively simple bolt-on. Greenamayer corresponded with Pratt & Whitney in the 1960s for advice on such things as how much manifold pressure he could use and blower ratios. He also corresponded with DuPont on the feasibility ofusing nitromethane. Rather surprisingly, considering today 's litigious society, attitudes were far more enlightened back in the 1960s before the advent of frivolous multi-million-dollar law suits. Pratt & Whitney sent a flurry of internal memos to their top R-2800 engineers for answers to Greenamayer's questions. Standard blower ratios for a CB-17 are 7.29: 1and8.56: 1. Initially, Greenamayer ran the engine in low blower-7.29: 1. In the quest for more power, Pratt & Whitney engineers studied the prospect of running at full throttle with a 9: 66: 1 blower ratio . This ratio was manufactured for a limited number of civilian "E" series that did not go into production. Concerns were raised as to whether the blower drive gears would hold up driving a 9.66 :1 ratio at 80 inches of manifold pressure at 3000 rpm. Clearly, this set-up did work as evidenced by Greenamayer winning numerous Reno Unlimited Championships and breaking the world speed record for piston driven aircraft at 484 mph. After its racing days were over, Greenamayer donated the aircraft to the Smithsonian National Air and Space Museum in Washington, D.C. (Ref. 13.2).

Multi-Engined Aircraft Although conventional wisdom says single-engined aircraft are more suitable for racing, several notable exceptions to this belief have raced over the years, the Douglas A-26 Invader being one of

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Chapter 13

those exceptions. Despite the fact that they were relatively difficult to obtain after World War II because they were still a state-of-the-art, front-line aircraft, several wound up in private hands during the 1940s . Perhaps the best known A-26 racer was Milton Reynolds ' "Reynolds Bombshell" (Fig. 13.6). Reynolds made his fortune by manufacturing some of the earliest ballpoint pens, most of which did not work. One of the early accomplishments of Reynolds ' A-26 was twice setting new round the world records of 76 hours, 56 minutes; and later, 73 hours, 5 minutes. The "Bombshell" was flown by well-known race pilot Bill Odum, who was to lose his life, flying a highly modified P-5 lB, in a tragic accident during the 1949 Thompson. This accident also claimed the life of a young mother and 13-month-old son. This accident was the last straw: too many pilots had lost their lives in racing accidents. Unlimited racing was put on hold until 1964 (Ref. 9.11). Don Husted piloted an A-26 to very credible sixth place in the 1946 Bendix Trophy Race. The course ran from Van Nuys, California, and finished at Cleveland, Ohio, a distance of 2048 miles. Husted 's average speed in the A-26 was 367 mph (Fig. 13. 7). One would never expect a Martin B-26 Marauder to be raced and yet that is exactly what happened in the 1949 Thompson-or nearly did! To be raced by Lee Cameron, he arrived beyond the check-in deadline and thus could not compete.

Fig. 13. 6 Douglas A-26s were not immune to the racers urge to see how fast she'll go. The Reynolds Bombshell broke the round the world record- twice. (Cou rtesy of the National Air & Space Museum, Smithsonian Institution. Photo No . JA 37621)

660

Racing

Fig. 13. 7 Another A-26 that saw action at the hands of the racers, Don Husted's A-26 raced in 1946 at the National Air Races. (Photo by Warren M Bodie.)

References 13.1 Huntington, Roger, Thompson Trophy Racers. The Pilots and Plans ofAmerica~· Glory Days 1929- 1949, published by Motorbooks International. 1989. 13.2 Internal Pratt & Whitney memos dated 1966. 9.11 Mesko, Jim, A-26 Invader in Action, Squadron/Signal Publications, Carrollton, Tex., 1980.

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Chapter 14

The Future

Preserving a Piece of History As a part of our rich aviation heritage, the R-2800 has proved its worth. If there were such a thing as an Aircraft Engine Hall of Fame, the R-2800 would be front and center. From its beginnings in the late 1930s to its phase-out from production in the early 1960s, the R-2800 powered a diverse range of military and civilian aircraft. From small, high performance military fighters to large, four-engined transports and everything else in between, the R-2800 fulfilled its promise of dependable power. Always at the forefront of piston engine and manufacturing technology, it represented a prime example of what U.S. design, development, manufacturing , and good old ingenuity was capable of. Although its days of powering front-line military aircraft and transport category aircraft are now a distant but fond memory, there 's no denying that this loud and raucous power plant endeared itself to everyone who flew behind it. Like any high performance piston engine, its needs had to be taken care of and in return the R-2800 would give hours of trouble free running. Unlike the modern gas turbines that eclipsed it, the R-2800 had charisma and personality. On a cold morning, many a flight engineer or pilot has fussed and cussed at the R-2800 as it took its own sweet time to come to life. The pilot or flight engineer needed the dexterity of an organ player, the skill of an engineer and a little luck to operate this charismatic aircraft engine. Yes, this pampered lady could be a monumental pain in the rear but treated nicely it would reward with its own brand of mechanical music. It still sends chills down the spines of aviation enthusiasts, or any enthusiast of high performance engines, to watch the wonderful acoustical, pyrotechnic, and smoke screen antics of this wonderful old engine being brought to life. Sensitivity to machinery is a prerequisite for operating an R-2800 . Abused and it will bite back in the form of low time between overhaul, high fuel consumption, and other maladies. This is an old lady that does not take well to mistreatment.

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Chapter 14

Parts Availability It's amazing what nostalgia will do for the survivability of a piece of old technology. In the case of the R-2800, it's fortunate that it exudes the necessary nostalgia to ensure its future. However, nostalgia does not supply badly needed parts that are all but irreplaceable. It is indeed fortuitous that, thanks in part to the huge number of engines manufactured during and after World War II, a large number of repair parts are still available as NOS (New Old Stock, or Neat Old Stuff, depending on your viewpoint). Nevertheless, care is taken during the overhaul and maintenance of these now increasingly rare artifacts. Nothing is arbitrarily dispatched to the scrap bin unless it is blatantly obvious that a component really has expired. Things that are taken for granted in a modern engine, such as bearings, cannot receive a similar cavalier attitude of just popping out the old ones and slipping in new components . Bearings, for example, are refurbished by removing the remaining lead and rep lating, pistons are carefully inspected and if they measure within Pratt & Whitney tolerances, are reused. Every component is now a precious piece that, in many cases, is irreplaceable. In the event an irreplaceable part, such as a crankshaft, needs to be replaced another is scavenged from a "donor" engine. A few high replacement parts such as pistons are being reproduced in Brazil or Poland. As good as these pistons are, they are not up to the durability of the originals. Even though replacement parts are manufactured to the same specifications as the originals, it is a fact of life in manufacturing, particularly high precision parts, that regardless of how much documentation was used in specifying a part, a few "tweaks" were introduced into the manufacturing process. The British call this the "Fred Factor. " In other words a mythical manufacturing line worker by the name of Fred introduced small but key improvements into the production of parts. This may entail the melt point of aluminum for an intricate casting, the feed rate for a machine tool, how much coolant to apply to a cutting tool, or a myriad of other ideas incorporated into the manufacturing process. Much of the Fred Factor ideas simply came from experience and intuition. This was rarely, if ever, documented. In today 's tightly controlled, computer operated and controlled manufacturing environment, the Fred Factor, for better or worse, has all but disappeared. Lower oil control rings are becoming scarce, but compression rings are still available as NOS. Top compression rings are all interchangeable between all series of R-2800 so that feature eases this problem . Second and third compression rings are different between "B" engines and "C" engines . The "B" uses a fifteen-degree taper and the "C" uses a seven-degree taper. Front cam rings are another high attrition rate part that is now getting in short supply. But again, refurbishment is possible by regrinding and re-nitriding. Nevertheless, the day is fast approaching when this difficult to manufacture component will have to be remade. Crankshafts are so ruggedly designed and built that provided an engine has not suffered a major internal failure, they typically only need a light honing and polishing. When the journals do not meet specification, the master rod journal can ground down up to 0.020 inches and the main bearing journals, to 0.007 inches. Of course, when a journal is ground undersize, an oversize bearing needs to be fitted. It is not possible to compensate by adding more lead . Special, oversize bearings are required. "CB" rear cylinders and "B" series front cylinders are increasingly difficult to come by. The front "B" series cylinders have been modified and adapted for use on Pratt & Whitney R-2000s and R-1340s thus soaking up the available supply. Rear "CB" cylinders tend be a higher attrition part than the fronts because they nm hotter and therefore suffer more failures .

664

The Future

Modificatio ns With the scarcity of some parts and the desirability of others, R-2800s have been dramatically modified to keep them running. One of the more popular and obvious to the eye, is the fitting of " C" cylinders to a "B" power section. C-46 operators, in particular, would perform this modification to the R-2800-S l. The resulting engine was known as an R-2800-S lMl, the "Ml " designation standing for "modification 1. " However this modification was not performed because of the lack of "B" cylinders but rather the better cooling offered by the " C" cylinders. When in commercial service, the airlines performed many modifications such as the R-2800-34Ml. American Airlines modified -34s to -34Ml status for their Convair 440s with water injection. Until their worth in warbirds was recognized, NOS "B" cylinders could be had for a song, particularly rears . Four-blade, SO-spline propellers are now a scarcity and yet many WWII aircraft powered by "B" engines with SO-spline prop shafts had four-blade props. In order to maintain the authenticity of aircraft such as P-47s, "C" nose sections have been grafted onto "B" power sections. With the " C" nose, a 60-spline propeller shaft is used and fortunately, four-blade, 60-spline props are relatively common. A P-47 parked on the ramp with a three-blade propeller just wouldn't look right. Of course, it is not a simple bolt-on conversion, however, it is a relatively easy modification .

War birds As the days of commercially operated R-2800s draw to a close, another chapter in the R-2800 's life is opening up. By the late 1960s it became apparent to a number of enthusiasts that the great aerial armadas that made a major contribution to mankind's greatest conflict were fast disappearing. The scrapping drives of the late 1940s and 19SOs had taken their inevitable toll. Some models of aircraft, built in the thousands, had all but disappeared. Even the P-47, the most produced U.S. fighter ever, was close to extinction in the late 1960s. With none flying in the U.S. and only a few flying with third world countries the situation was dire. Thankfully, organizations such as the Confederate Air Force saw the writing on the wall in the 1960s and immediately started to purchase whatever they could. Starting at a grassroots level, the warbird community has now burgeoned into big business. As the value and historical significance of these now retired warriors was recognized, their monetary value escalated into the stratosphere. Long gone are the days when one could find, for example, a derelict F4U at the local airport, even though this was a common sight in the 19SOs and 1960s . Thanks to the dedication of owners, these aircraft are restored to impeccable standards of workmanship. However, even though, for the most part, workmanship is of the highest order, the same cannot be said for historical accuracy. Unfortunately, very few restored F4U Corsairs flying today, for example, have the correct engine . Few flying Corsairs have the two-stage, intercooled supercharger they are supposed to have. And yet by comparison, interestingly, no P-S lD Mustangs are flying with single-stage supercharged engines . In fact the single-stage Merlin is almost regarded as a joke among Mustang aficionados, so it's puzzling why this attitude is not prevalent with the R-2800 powered warbirds. Especially since they are air-cooled and therefore are visible for the enthusiast to see what engine resides inside the cowl, it is immediately apparent that an incorrect engine is installed.

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Chapter 14

Therefore, the historian and modeler should be cautioned about using a restored warbird as a historical reference. For the most part they are quite inaccurate. Seeing an F4U-l with a "C" series engine with a single-stage blower is bad enough but when aviation enthusiasts are convinced that that is the way it was built is sadder still. The engine of choice for R-2800 powered warbirds is the CB-16, which was never even a military engine. Worse yet, the correct engines and two-stage superchargers are available. It is not unusual to see an F4U-l , powered by a CB 16, walk off with a prestigious warbird award-even the judges don't know the difference. A similar situation has occurred with P-47s. Again, the engine of choice seems to be the CB-16, a totally incorrect power plant for this aircraft. The General Electric turbosupercharger, in many cases, has been removed or deactivated. The argument one typically hears is: " ... but these aircraft are never flown at high altitude so why use the two-stage, intercooled supercharger?" or "why install the turbo when we never fly over 12,000 feet? Besides, the areas taken up by the intercoolers make great baggage compartments! " Of course, the response to that is buy a Beech Bonanza: similar performance at a fraction of the cost. Thankfully, a few of these priceless, historical artifacts are being restored correctly with the correct power plant and all systems operational. Still, historians and enthusiasts need to be ever vigilant when visiting an air show featuring warbirds. Don 't be fooled by what appears to be an immaculate looking aircraft and thinking it is correctly restored.

Other Restored R-2800 Powered Aircraft Fortunately for all of us, various groups have taken it upon themselves to keep some of the less glamorous but still significant R-2800 powered aircraft flying. These include a Martin 404 restored as a Coast Guard aircraft, Convair 440 restored as a T-29, Fairchild C-82, and a Curtiss C-46. As one could imagine, operating large transport aircraft is an expensive undertaking. Nevertheless, it indicates the amount of charisma and interest in these now unique aircraft. For the organizations putting forth the effort to keep them airwo1thy it is a cause that deserves all of our collective support.

Commercial Operations Once a common sight and sound, the roar of the R-2800 is now a rare occurrence. A few niche markets are still soldiering on with R-2800 powered aircraft such as the DC-6, Convair twins, and a few C-46s. Now that Corrosion Comer has been shut down, the DC-6 and C-46 population in South Florida has been decimated. Also contributing to this sad state of affairs is the lack of spares, not only for the engine but more significantly, airframe parts. Items such as brakes and tires have all but grounded the C-46 . DC-6s seem to have faired better with regard to airframe parts. Nevertheless, operating a 50- to 60-year-old plus transport aircraft as if it were a brand new airplane and loading it beyond its legal maximum gross weight takes its toll. Factor in incompetent or lack of maintenance and the situation looks even worse. The niche markets remaining seem to be the Caribbean, South America, and Alaska, with a sprinkling of aircraft in other parts. Once an aircraft ends up in the Caribbean, South America, or Central America, its death warrant has been signed. Rather than being treated as historical masterpieces of a bygone age, they are simply treated as commodities to be used up then junked.

666

The Future

Fire fighting has, ironically, saved a number of significant aircraft. For example, many of the surviving B-17 s served as firefighters until their historical significance and value escalated. The DC-6 is not quite at the stage of the B-17 so many are still being put to good use fighting fires in the West. One would hope that their days of retirement under the loving care of enthusiasts is in the near future. Ironically, the illicit drug trade saved a number of C-123s. Due to their load carrying ability and capability of operating out of rough strips, drug smugglers found them to be ideal, until the DEA started using more sophisticated surveillance equipment. The Canadair CL-215 is a more modem R-2800 powered aircraft but even this is suffering the indignity of being conve1ted to gas turbine power. Still, the CL-215, even R-2800 powered, has many years ahead of it fighting one of Mother Nature's worst natural disasters.

Museum Aircraft and Rare and Extinct Types At the present only a handful of R-2800 powered transport aircraft reside in museums. For the most part they are Curtiss C-46s, due to this aircraft's significant role during World War II and the fact that it survived the great scrapping binges. At least one Martin 202 survives in a museum albeit in derelict condition. As time passes by it is the fervent hope ofthis writer that more transport category aircraft are preserved, either in airworthy condition or as static displays in museums. The situation for front-line military aircraft is much better with some significant omissions. Despite the fact that huge numbers of Martin B-26s were built and it proved to be one of the most successful and significant medium bombers of World War II, very few have survived, in fact it's on the brink of extinction. As of this writing only one remains in flying condition albeit inaccurately restored with Hamilton Standard propellers, etc. , and the U.S. Air Force Museum has one example. There is a possibility that one or two other B-26s may be restored from wrecks. A similar fate has befallen the Northrop P-61. Again the Air Force Museum has a P-61B and the Smithsonian has a P-61 C in storage. Both aircraft are in excellent condition. One group of hardy souls have taken upon themselves the task of restoring a P-61 that crashed into a mountain. When finished it will be close to being a "data plate" restoration, i.e. , very little of the original aircraft will be utilized . Nevertheless, this effort is highly commendable if for no other reason than the enormity of rebuilding, almost from scratch, a large and complex military aircraft. Another P-61 resides in a Chinese museum stored outside in less than ideal condition. Rumor has it that this aircraft is for sale but at an exorbitant price. A few P-6ls were purchased by civilians for fire bombing, however, this activity took its inevitable toll and its days were ended by being destroyed in accidents. An aircraft that personified the technology of installing and cooling a high performance, turbosupercharged radial, the AJ Savage has just about disappeared off the face of the earth. Pensacola's Naval Aviation Museum has the sole survivor of this very advanced aircraft. Of the experimental aircraft powered by an R-2800, it appears that only the Northrop XP-56 Black Bullet has survived, albeit hidden away in storage at the Smithsonian. None of the Curtiss P-60

667

Chapter 14

series survived. The same fate befell the Fleetwings XBTK-1, Vought XTBU-1 , North American XB-28 . Of the helicopters, nothing has survived of the Bell HSL-1 and only pieces of the Sikorsky S56 appear to have survived.

Epilogue The brilliant engineers who conceived the R-2800 were the brightest and best that the United States had. They were graduates of the finest engineering schools and extolled the qualities so necessary for a demanding discipline . The problems, redesigns, and new generations that were developed, always seeking more power, for less fuel consumption and lower weight, kept this dedicated team continually on their toes. These contradictory goals were not only met by these engineers, designers, and manufacturers, they were exceeded by a handsome margin. It is thanks to them that the Allies enjoyed such an advantage over the Axis foes . Postwar, the R-2800 demonstrated itself as a metaphor of converting guns to plowshares. The fledgling postwar airline industry relied heavily on the reliability, power, fuel economy, and time between overhauls of the R-2800 . At the same time, while the airlines were finally enjoying the profits to be reaped from aircraft powered by a reliable power plant, the great aerial fleets of just a few short years prior were being disbanded and the aircraft scrapped at a furious rate. We will never again see the type of technology employed by the R-2800-technolog y such as highly sophisticated supercharging systems, workmanship of an incredibly high order, all internal parts machined and highly polished, ingenious carburetion systems; those days are gone forever. The present generation can enjoy what the brightest and best minds of the early to mid-20th century could achieve . For that we should all be grateful. The End (Phew.. ! ! !)

668

Index

Abbreviations are used to indicate figures (j) and tables (t). "A" series engines (general) development chronology of, 100-101 external configuration, 24/ P&W production photographs, 104/ X-77 as first of series, 23 See also Military specifications, "A" series A-20 Havoc tracked landing gear experiments with, 526 A-26 Invader -71 engine used in, 422/ A-26Bs in flight, 420f 422/ B-26K variant of, 415 , 418f 42lt defensive armament, 42 lt engine mounts, 415 , 416/ forward armament, 415 , 419f 420f 42lt glass-nosed version, 415 , 418/ Heinemann design of, 415 manufacturer designations for, 417, 419 specifications, 421 t tricycle landing gear, 415 , 417/ XA-26 prototype, 415 , 416/ ABC Dragonfly engine configuration, 3/ fatigue failure, overheating, xx-xxi introduction of, xx See also Bradshaw, Granville Accessory section, front ("C" series) general configuration, 164, 167/ Accessory section, rear ("A" series) accessory drive gears, 94 configuration, 97/

669

Index

Accessory section, rear ("A" series) (continued) generator, 120V/400Hz, 94, 96 hydraulic pump, 94, 96 synchronizer/synchrophaser, 94, 95 tachometer generator, 94 See also Starting systems ADI (anti-detonation injection) altitude performance improvements (by series), 296t authorized ADI mixtures, 218 in Bendix PT-13 carburetor, 311, 313, 314[ in commercial applications, 563, 564 in DC-6, 578/ engine run-up check of, 620 flow rates, typical, 21 7 in F4U-4, 44Qf low temperature, problems with, 216-217, 313 power-to-weight improvements (by series), 296t R-2800 engine nomenclature for, 217 typical installation, 219 in Walker 's highly boosted R-2800, 218-219 water injection, initial use of, 216 wet takeoff ADI pressure/flow, 621 See also Detonation; Operation, engine AF-2W aircraft. See Grumman Guardian Air induction systems in C-46, 547, 549/ in C-82 Packet, 526, 527/ cockpit controls for (F4U-6/AU-l Corsair), 451/ in DC-6, 577, 579/ F4U-l/-2 Corsair induction scoops, 453 , 454/, 455/ in F4U-l Corsair, 428, 429/, 434/ in F4U-5 Corsair, 437, 448/ in F4U-6/AU-l Corsair, 445 , 447, 451/ in F4U-7 Corsair, 447 in F6F Hellcat, 503 -504, 505/ in F7F Tigercat, 512, 515f in P-61NB Black Widow, 473 -474, 474/, 475/ in P-61C Black Widow, 475 , 478/ for "Sidewinder" supercharger, 437, 477/ in XP-56 Black Bullet, 538, 540 AJ-1/AJ-2 Savage -44/-44W engine in, 532-533 , 535/, 537/ AJ-2 characteristics, missions, 537

670

Index

AJ-1/AJ-2 Savage (continued) Allison J-33-10 jet engine in, 533 cowling assembly, 535/ exploded view, 533/ GE. type CH-5 supercharger in, 532-533, 534/ in-flight photographs, 532/ oil system, 53 6/ in Pensacola Naval Aviation Museum, 667 specifications, 537 Allison J-33-10 in AJ-1 Savage, 533 Allison V-1710 inline engine, 134, 135/ 543 Aluminum tensile strength, forged vs. cast, 61 American Bosch DF18RU/LU magnetos, 73/ 76 Anderson, Elaine, xiif Anderson, Ray, xvi Arana, Carlos, xvii Archer, Harold, xii Arcing, electrical of Curtiss Electric propeller brush assemblies, 332 of high-tension ignition systems, 77, 78/ 79/ Augmented exhausts in Convair Twins, 582, 583/ 585/ 586 in Sikorsky S-56, 601 , 604/ See also Exhaust systems

"B" series engines (general) -25 engines specified, produced, modified, 129 -63 single-stage engine for P-4 7, 131/ first Ford engine shipped, 129 Ford production photographs, 112/ 126/ initial design changes, summary of, 127-1 28 NACA turbo-compound engine study, 211/ program evolution/design objectives, 125-126 P&W production photographs, 104f 105/ two -4ls converted to fuel-injected -45s, 129 two-stage -8 (B2G) type test conducted, 129 two-stage (BAG) model tests conducted, 128 two-stage engine released to production, 129 See also Military specifications, "B" series

671

Index

B-23 Dragon dual rotation propellers on, 558-559/ in-flight sketch, 559/ B-26 (Martin) Marauder -5 engine in, 497/ -43 engine in, 499/ APU (auxiliary power unit), 494, 496/ A1my Air Force serial numbers, 50lt B-26A, side view, 496/ B-26B, three-quarter front view, 498/ B-26C in flight, 498/ B-26F, front view, 500/ B-26G in flight, 502/ crew positions, 493/ early accidents with, 493 exploded view, 495/ NACA engine cowl (B-26G), 5/ "One-a-day in Tampa Bay," 493 specifications, 497 t, 499-500t surviving specimens, 667 USAAF-RAF designations for, 494 B-26K (Douglas A-26 Invader variant), 415 , 418/ 42lt Baffles, cylinder. See Cooling, cylinder; Cowlings Bearings cam ring bearings, front/rear, 63 corrosion of, 65 counterweight bearings, failures of, 114/ 114-115 crankshaft, 39 development of (historical note), 63 layered bearings, 65 lubrication of, 85 main, 62 master rod bearings/journals, 39, 63 -66, 631 master rod bearings, reverse loading of, 65-66, 631 oil transfer bearing, propeller shaft, 160-161 , 163/ propeller thrust bearing (Curtiss Electric), 325, 327, 328/ rocker arm, 25 rocker arm pivot bearings, shortage of, 112-113 , 113/ rolling element, propeller shaft, 67 thrust bearing, "C" series propeller shaft, 161 Beckwith, Gordon, xiif Bell HSL-1 augmentor cooling system, 612/

672

Index

Bell HSL-1 (continued) drive shaft installation, 614/ front transmission system, 609, 615f in-flight photograph, 609/ major sub-assemblies, 61 Of pivoting engine mount, 611/ rear transmission system, 613/ rotor pitch/throttle control synchronization, 610, 612 specifications, 612t throttle control, servo-assisted, 609-610 Bendix Corporation Bendix-Scintilla DF 18RN/LN magneto, 73/ Bendix-Scintilla distributor, 74, 74j,' 76 carburetors (See Carburetors, Bendix) DLN-10 low-tension ignition system, 212, 214-215 , 214-215j,' 216j,' 217/ Bird, Clarence, xii Birman, Rudolph, 428 Blow-by, piston ring, 30 Blue Angels, 520 BMEP (brake mean effective pressure) during cruise, 623 , 624 effect of carburetor icing on, 629-630 during engine run-up, 619, 620 of R-1340 Wasp, 15 typical R-2800, 28 of 1920-era engines, 15 See also Operation, engine Bodie, Warren, xvii Bradshaw, Granville, xx Breguet Type 76 Deux Ponts design development/details, 595 in-flight photograph, 595/ specifications, 596t Briggs, Nonmm, xiif Bristol Aeroplane Company forged engine crankcases, 13 Jupiter engine, 13 See also Feddon, Roy British Fleet Air Arm (FAA) Mk. II Corsair for (F4U-l), 457, 458t Brown, Don, 17

673

Index

"C" series engines (general) introduction to, 144 development, milestone events in, l 94- l 96t P&W production photographs, 104(, 105/ See also Military specifications, "C" series C-46 -43 engine for, 551/ air induction system, 547, 549/ at Corrosion Comer, 567/ cowling configuration, 549/ design history, 546-547 "double bubble" fuselage construction, 546 flying "The Hump," 546, 547 in-flight photograph, 546/ landing gear configuration, 550/ major sub-assemblies, 548/ postwar employment of, 547 specifications, 548t C-69E Constellation -83 engine for, 292/ Wright engines in, 557 C-82 Packet air induction system, 526, 527[ design history, 524 in-flight photograph, 525/ load ramps/clamshell doors, 524, 525/ main landing gear, 526, 528/ nose landing gear, 526, 529/ oil system, 526, 527/ ski landing gear, 526 specifications, 528 tracked landing gear system, 526 C-123 Provider C-123B on skis, 487/ cowl design, 486, 488/ diverse roles of, 486 exhaust system, 486, 489/ Fulton Device on, 486 main landing gear, 486, 490/ nose gear, 486, 49 lf oil cooling system, 486, 489/ origin/development of, 485-486 specifications, 487t XC-123 on runway, 485/

674

Index

"CA," "CE" series engines (general) design improvements in, l 98 -l 99t See also Military specifications, "CA," "CE" series CA3 engine ("CA" series) right side view, 239/ specifications for, 23 7t CA15 engine (" CA" series) front, side views, 239/ 573/ 588/ 593/ specifications, 23 8t CA18/CA-18A engines ("CA" series) right side view, 245/ specifications, 240t, 245/ Call, Thomas, 656, 657/ Cam rings/cam followers ("A" series) cam followers , 3~{, 34[ cam ring bearings, front and rear, 63 configuration, front cam ring, 32/ functional description, 31-32 reduction gearing, 32-33, 33/ 34, 64 single can1 rings, disadvantages of, 33 support plates, front and rear, 32/ 63, 64{ See also Valve trains Cameron, Kevin, xvi Cameron, Lee, 660 Canadair CL-215 fire bomber role of, 589, 590/ Carburetor performance requirements, 299 Carburetors, Bendix PR-58 on "C" series engines, 300 in F4U-4 Corsair, 436/ 43 7/ Carburetors, Bendix PR-64 on -32 engine, 442/ on "E" series engines, 200, 300 in F4U-5 aircraft, 140, 142/ 437, 442/ 448/ Carburetors, Bendix PT-13/PR-58 on "A," "B" series engines, 300, 301/ accelerator pump, 311 , 3 12/ anti-detonation injection (ADI), 311 , 313, 314{ automatic mixture control (AMC), 302, 304, 306/ C2f F4U-l carburetor "Y" duct, 428, 431/ fuel/air circuits in (sectional view), C2-C3/ fuel feed valve, 307, 308/ functional description, 301 icing of (See Icing/deicing, carburetor)

675

Index

Carburetors, Bendix PT-13/PR-58 (continued) idle spring, idle needle, 310 major sub-assemblies, 300-301 manual mixture control, 3 10, 31 Of metering system, 311, C3f on -8 engine (with triple venturis), 427/ on -lOW engine, 130/ in P-61 Black Widow, 473-474, 475 Pesco positive-displacement fuel pump, 301, 305/ regulator assembly, description of, 303-304[, 305 regulator assembly, air section, 306 regulator assembly, fuel section, 307, C2f regulator assembly, operation of, 308-310, C2-C3f throttle body assembly, 302, 303-304/ "water regulator" in, 313, 3 14/ See also ADI; Fuel injection Carburetors, Chandler Evans CECO PR-64 in semi-production -30W, -32W engines, 300 in semi-production F4U-5 , 264t See also Carburetors, Bendix PR-64 Carburetors, direct port injection limitations of, 300 Luftwaffe use of, 88, 313 See also Fuel injection Carburetors, downdraft on -10 powered Hellcats and P-6ls, 140, 142/ on early R-2800s, 89 in F4U-6/AU-l , 445 Carburetors, float type limitations of, 299-300 in small to medium engines, 88 vs. injection, 88 Carburetors, Stromberg. See Carburetors, Bendix PT-13, Bendix PR-58 Carburetors, updraft. See Carburetors, Bendix PR-64 Carlson, Larry, xiif, xvi, 191-194 Cartoons, training, 378 Castor oil, xx CB16 engine ("CB" series) in Howard 500, 598 as R-2800 replacement, xxii side view, 596/ three-quarter left front view, 245/ three-quarter right front view, 594f top view, 588/

676

Index

Chase Aircraft Company (C-123), 485 Chenoweth, Opie, 216 Chevrolet R-2800 production sunm1ary, l l 7t Chilton, Roland Chilton floating "bifilar" damper, 36 Choking, cylinder, 28, 29 Chrysler XIV-2220 engine in XPNP-60, 543 in XP-47H, 406t, 407/ Cleland, Cook, 655 , 656/ Coking, oil in exhaust valve rocker boxes, 25 and piston ring sticking, 31 See also Cooling, oil Combustion processes, fuel, 86-88 Commercial applications, Double Wasp introduction, 563 ADI, use of, 563 , 564 aging aircraft/engines, problems with, 664, 666-667 high power, degradation caused by, 564 by manufacturer/aircraft, 570t See also specific aircraft; Racing applications Commercial engines, Double Wasp (general) introduction, 225 modifications to, 665 operating curve index, 295t parts availability, problems with, 664 P&W/AN specification designations, 228 supercharger designations for, 226, 226t See also specific engines; Commercial specifications, Double Wasp; Operation, engine Commercial specifications, "A" series A4-G, 229t A5 -G, 23lt S 1A2-G, 229t S 1A4-G, 230t S 1A6-G, 232t S2A4-G, 23 lt S2A6-G, 232t SA-G, 229t SSA5-G, 23lt C011U11ercial specifications, "B" series 2SB-G, 233t 2SB3-G, 233t

677

Index

Commercial specifications, "B" series (continued) S2B-G, 232t SSB2-G, 234t TSBl-G, 233t Commercial specifications, "C" series 2SC-G, 234t 2SC13-G, 235t 2SC14-G, 235t 2SC14W-G, 236t 2SC15-G, 236t SSC22-G, 237t TSC2-G, 235t Commercial specifications, "CA" series CA3, 237t CA15/-15A, 238t CA17, 238t CA18/-18A, 240t CA19, 240t Commercial specifications, "CB" series CBI , 24lt CB2, 24lt CB3 , 24lt CB4, 242t CBS , 242t CBll , 242t CB12, 243t CB13 , 243t CB14, 243t CB15, 244t CB16, 244t CB17, 244t CB18, 246t Commercial specifications, "CE" series CE4, 246t CE16, 246t CE21 , 247t Commercial specifications, "E" series El2, 248t E22, 248t VSEll-G, 247t VSSE21-G, 247t Compression ratio "C" series vs. "B" series, 144-145 typical, R-2800, 28

678

Index

Connecting rods, master "B'' series distress in, 150 bearings/bearing journals, 39, 63 -66 evolution of, 157/ fabrication/polishing of, 66, 67/, 106 linear vibration, master rod contribution to, 36 one-piece vs. split, 38-39 reverse loading of, 631 Connecting rods ("A" series) in built-up crank exploded view, 40/ cylinder assembly/disassembly order, importance of, 66-67 lubrication, 84 rod failure, consequences of, 66 Connecting rods ("C" series) in -18W vs. -42W engines, 437/ " CA" and "CB" rods, 157 Connecting rods ("D," "E" series), 158 Connors, Jack, xvi Constellation in-flight photograph, 568/ military version (C-69E), 292/, 557 Contra-rotating propellers . See Propellers, dual rotation Convair Twins (240/340/440) exhaust augmentor system, 581 -582, 583/, 585/, 586 Martin 404, competition from, 586 Model 110 prototype, 5 8 lj Model 240, CA15 engine for, 588/ Model 240 in flight, 5 84f Model 440 on runway, in flight, 584.f. 585/ specifications, 5 87 t T-29 (military) versions, 586, 587/ wing and tail deicing procedure, 631 Cook, Lt. Orval, 3 5 Cooling See Air induction systems Cooling, cylinder Cooling, early radial engines Cooling, oil Cooling, rotary engines Cooling, water Cooling systems Cowlings Liquid-cooled engines Valves, cooling of

679

Index

Cooling, cylinder cooling fin area vs. horsepower, 145, 145t forged vs. cast cylinder heads, 148-149 inter-ear deflectors for, 27/, 146f by propeller blade shank cuffs, 318t, 327, 329f sheet metal baffies around, 26-27, 27/, 28, 146f See also Cowlings Cooling, early radial engines introduction, 1-2 Heron contributions to, 2-4 poultice head, 2 Cooling, oil in AJ-1 Savage, 536f Bell HSL-1 augmentor cooling system, 612f in C-82 Packet, 526, 527f C-123 oil cooling system/cockpit controls, 486, 489f cockpit oil cooler controls in F4U-4 Corsair, 435/, 438f in DC-6, 577, 580f in F4U-l Corsair, 428, 43 lf in F4U-4 Corsair, 432, 438f in P-47 Thunderbolt, 381, 392f in P-61 Black Widow, 474f 475 in PV-1 Ventura, 465 viscosity at start-up, problems with, 635-636, 637f water-immersed "boiler" oil coolers, 658 in XP-56 Black Bullet, 540 Cooling, rotary engines, 2 Cooling, water of P&W R-2060, 18 U.S . Navy antipathy toward, 11 water-immersed "boiler" oil coolers, 658 See also Liquid-cooled engines Cooling systems F4U-6/AU-l Corsair, 447, 452f See also Air induction systems; Cooling, oil Coriolis force supercharger problems with, 191 , 200 Corrosion Comer, 564-569 Corsair Mk. II for British Fleet Air Arm (FAA), 457, 458t Counterweights/dampers ("A" series) Chilton floating "bifilar" damper, 36 counterweight bearing failures , 114-115 location of (phantom view), 33f

680

Index

Counterweights/dampers ("A" series) (continued) Royce vibrational damper (V-12 Eagle), 35 Salomon ("hockey puck") pendulum dampers, 35, 39, 40j 61/ second-order counterweights, 36, 37j 38, 38/ Taylor research on, 35 See also Vibration, torsional Counterweights/dampers (" C" series) in -29 engine (on XP-56 Black Bullet), 538, 540 bifilar counterweights in, 15 lj 15 2 4-1 /2 order vibration, optimization for, 15 2 Cowlings air flow control flaps in, 4, 5j 6f on AJ-1 Savage, 535/ in C-46, 549/ in C-123 Provider, 486, 488/ drag reduction by, 4-5 , 7 NACA cowl, aerodynamics of, 4 NACA cowl, typical (for B-26G), Sf in P-47 Thunderbolt, 380-381 ring cowls for rotary engines, xx Townend cowling ring, 4 See also Air induction systems; Cooling, cylinder Crankcase ("A" series) crankcase assembly, configuration of, 61-62, 62/ forged vs. cast aluminum, 61 Crankcase ("C" series) crankcase assembly, configuration of, l 49j 149-150 Crankshaft ("A"/"B" series) "A"/"B" series, assembled, 61/ bearing, front, 39 built-up crank, 39, 40 development/evolution of, 4 l -60t, l 54t failures of, 39-40 Ford production line, 112/ lubrication of, 85 P&W vibration analyses, 41-60, 156 Salomon counterweights on, 35, 39, 40, 40j 61/ See also Vibration, linear; Vibration, torsional Crankshaft (" C" series) "C" crank, involute face splines in, 150-15lj 152 " CA," "CB" crankshaft configuration, 152, 153/ evolution of, 154t P&W vibration analyses, 156 See also Vibration, linear; Vibration, torsional

681

Index

Crankshaft ("D" series) configuration of, 152 Crankshaft ("E" series) configuration of, 152, 155/ Crankshafts ("E" series) evolution of, 154t Cullen, James K. , 11 Cummings, David, xvii Curtiss, Glenn, 10 Curtiss Aeroplane Company, 10 Curtiss Wright Company, 542 Cylinders ("A" series) assembly/disassembly order, importance of, 66-67 choking, 28 , 29/ cooling (See Cooling, cylinder) cylinder barrel/head configuration, 23-25 , 25f 28 Cylinders ("B" series) Ford cast cylinder barrel production, 111, 113/ Cylinders (" C" series) cast aluminum head limitations, 144, 145 forged cylinder head, configuration of, 145 forged cylinder head, manufacture of, 148 inlet/exhaust valve assemblies, 14 7t temperature, forged vs. cast cylinder heads, 148-149

"D" series engines (general) configuration of, 142-143 dual rotating propeller shafts in, 143 in Nmthrop XP-56 (Black Bullet), 140, 142-143 single- vs. two-speed nose in, 142 See also Military specifications, "D" series Dampers. See Counterweights/dampers Davis, June, xiif Davisson, Bob, xii DC-3 , 564/ DC-4 (C-54 Skymaster), 566/ DC-6 (commercial versions) ADI system, 578/ air induction system, 577, 579/ at Corrosion Comer, 566/ DC-6A/6B, differences between, 574 design history, 571-572 fire hazard in, 577

682

Index

DC-6 (commercial versions) (continued) in-flight photograph, 57 lf oil cooler installation, 577, 580t QECs, interchangeability of, 577 slotted flaps , 574, 575f specifications (DC-6/6A/6B) , 572t DC-6 (military versions) Harry Truman's "Independence ," 574, 576f MATS use of, 574 U.S . Navy use of, 575 DC-7, 567f De Havilland Comet fatigue failure of, xxii De Seversky, Alexander, 379 Deicing. See Icing/deicing DeSanto, James, 656 Descent and landing approach rpm, setting, 632 cowl flaps , setting, 632 engine stability, CHT during, 631 low airspeeds, propeller forward pitch during, 633 mixture control during, 632 propeller reversing, 632 rejected landing, power/ADI settings for, 632 reverse loading, master rod bearing, 631 taxi and shutdown, 633 See also Flight operation; Ground operation Desludging blower clutch, 196, 504, 624 Hamilton Standard propellers, 362-363 Detonation, fuel combustion processes for, 27, 86-88 during full-power takeoff roll, 634 manifold pressure/temperature as factors in, 133, 300 from piston ring failure, 634 and Unilever power control, 382, 384 See also ADI (anti-detonation injection) Direct drive noses ("C" series) helicopter applications of, 171 Distributors ("A" series) compensated (even-firing) earns in, 76 drive mechanism, 76 functional description, 76 General Electric integral, 79, 80f

683

Index

Distributors ("A" series) (continued) pressurizing vane pump for (Scintilla), 77, 79/ See also Ignition systems, high-tension; Ignition systems, low-tension Distributors ("C" series) distributor drive gear trains, 166-167 Drag, reduction by cowlings, 4-5 , 7 Dragonfly engine. See ABC Dragonfly engine Dual rotation propellers. See Propellers, dual rotation

"E" series engines (general) configuration, 200-201 , 201/ 202/ See also Military specifications, "E" series E-12 engine typical commercial installation, 205/ E-22 engine typical commercial installation, 206/ Ely, Roland, xii Engine mounts Bell HSL-1 pivoting engine mount, 611/ discussion of, 94 dynafocal principle, 94, 96/ in F4U-5 , 437, 439, 448/ Lord engine mount, exploded view, 95/ in P-61 Black Widow, 475 , 478/ snubbing disc (damping), 94/ solid, in F4U-4, 437 typical mount arrangement, 96/ in XP-56 Black Bullet, 540, 541/ See also QEC (Quick Engine Change) Esgar, Jack, xiif Exhaust ducting See Exhaust systems Exhaust systems augmented exhausts, defined, 4, 7 exhaust augmentor system (Convair Twins), 581-582, 583/ 585/ exhaust ducting ("D'' series), 143 exhaust system experiments, 213t in F4U-5 Corsair, 439, 439f 449/ in P-47 Thunderbolt, 381-382, 383/ Sikorsky S-56 augmentor system, 601 , 604/ Sikorsky S-56 ejector type system, 601 , 605/ See also Valves, exhaust

684

Index

F-2G/XF-2G Corsair discussion of, 453-454 photograph, 456/ specifications, 464t See also F 4U Corsair F4U Corsair (general) British Fleet Air Arm (FAA) version (F4U-l), 457, 458t development history, 423 as dual rotation propeller test bed, 457/ dual rotation propellers on, 457/ incorrect restoration of, 665 , 666 main landing gear components, 425/ specifications, variations and permutations, 456t, 458-459t, 462-464t tail wheel, tail hook, 425/ 426/ XF4U, 424/ 456t See also F-2GIXF-2G Corsair; Racing applications F4U-l/F4U-2 Corsair -1 air intake/induction system, 428, 429/ -1 air-to-air intercoolers, 428, 431/ -1 dual oil coolers, 428, 431/ -1 "Y" duct (to carburetor), 428, 429/ -8/-8W engine in, 42/ 142/ 426, 432 "birdcage" version, 450, 455/ differences between -1 , -2, 426, 460 flush induction scoop (for R-4360 versions), 453 , 454{ foreign object engine damage, 428 as night fighter, 459t, 460/ R-4360 powered experimental aircraft, 447, 450, 453/ 453-454, 454/ 455/ 464t raised induction scoop (for R-4360 versions), 453 , 455/ specifications, 456t, 458t, 459t two-stage supercharging, 426-428 updraft carburetors in, 140, 142/ 426 as "Whistling death,'' 428 wing fold location, 424{ See also XF4U-l Corsair F4U-3A, -3B Corsair -14W engine in (-3B), 461/ -16 engine in (-3A), 461/ specifications, 459t F4U-4 Corsair -18W engine in, 432 -18W engine milestones, 198 ADI system, 440/

685

Index

F4U-4 Corsair (continued) chin air scoop, 432, 432/, 435/, 436/ cockpit oil cooler, flap controls, 435/, 438/ cutaway view, 433/ dual air-to-air intercoolers, 435/ exhaust system, 439/ induction system (phantom view), 434[ main landing gear components, 425/ QEC configuration, 441/ single elliptical oil cooler, 432/, 438/ specifications, 462t tail wheel, tail hook, 425/, 426/ F4U-5 Corsair -32W engine in, 200-201 , 437, 439, 443/, 445/, 446/ air induction system, 437, 448/ dual air-to-air intercoolers, 437, 447/ dual cowl-mounted airscoops, 437, 448/ engine mounts, 439, 448/ front view, 443/ PR-64 updraft carburetor, 437, 448/ "Sidewinder" supercharger in, 437, 443/, 446/, 448/ specifications, 462t triamesed exhaust ejector stacks, 439, 449/ See also "Sidewinder" supercharger F4U-6/AU-l Corsair -83 engine for, 449/ air induction system, 445 , 447, 451/ engine cooling system, 447, 452/ general configuration, 449-450/ induction system, cockpit controls for, 451/ specifications, 463t F4U-7 Corsair engine installation and induction system, 44 7 specifications, 463t F6F Hellcat -10 engine in, 130/ air induction system, 503-504, 505/ armament, 516/ blower clutch desludging, 504 development of, 503 downdraft carburetors, 140, 142/ float-equipped F6F, 504, 507/ in-flight photograph, 503/ oil cooling system, 504, 506/

686

Index

F6F Hellcat (continued) specifications, 508-5 llt supercharging, 503 , 504 F7F Tigercat - l 8W engine milestones, 198 air induction system, 512, 515f front view, 514/ internal configuration/components, 513f main landing gear, 515f nose gear, 515f specifications, 5 l 7-5 l 9t turbosupercharger failure (XP-50), 512 F8F Bearcat -30W engine in, 520-521 , 521/ " C" series engines in, 520 in-flight photograph, 520/ oil cooling system, 521 , 523/ specifications, 522t FAA. See British Fleet Air Arm (FAA) Fairchild C-82 cowling air flow control flaps , 6/ Fatigue failure in ABC Dragonfly engine, xx of de Havilland Comet, xxii discussion of, 642 Feddon, Roy develops forged crankcase, 13 develops forged cylinder head, 144 sleeve valve designs of, 25 sleeve valve engine designs of, 25 , 219-220 Fire bomber (Canadair CL-215), 589, 590/ Firing impulses and crankshaft torsional vibration, 15 6 Firing order, ignition, 74 Fleetwings XBTK, 553 , 553/ Flight operation BMEP fluctuations/pressure pulsations, 624-625 , 629 climb power blower settings/blower shift, 622-623 climb power/fuel flow, 622 cruise power, sequence for setting, 623-624 cylinder head temperatures, importance of, 620-621 engine analyzer, typical patterns on, 626-628/ full authorized [takeoff] power, 621-622 upwind takeoff, importance of, 621

687

Index

Flight operation (continued) wet takeoff, ADI pressure/flow during, 621 See also Ground operation; Descent and landing Ford, Edsel, 107, 110/ Ford Motor Company Aircraft Engine (River Rouge) Plant, 106 automobile vs. aircraft engine production, 103, 105-106 "B" series engines, 1q[, 126/ cast cylinder barrel production, 111, 113/ combination build stand/test stand, 115f, 119/ first "B" series engine shipped, 129 P&W license fee, 106-107 R-2800 production milestone events, 107, 109-111 R-2800 production summary, 108-109t Foreign object engine damage in F4U Corsairs, 428 Fuel, aircraft engine octane ratings, xxi PN scale development, xxi See also Detonation, fuel Fuel injection "B" -4ls converted to fuel injected -45s, 129 Luftwaffe use of, 313 U.S. Navy objections to, 313, 314-315 See also Carburetors, direct port injection Fuel metering, speed density, 315 Fuel supply. See Carburetors; Superchargers Fulton Device on C-123 Provider, 486

Gears . See Reduction gearing (various) General Electric Corporation Turtleback magneto, 79, 80/, 81 , 398/ See also Turbosuperchargers, General Electric Generator, rear section (120V/400Hz), 94, 96 Generator drive, high-speed, 292/ Glenn L. Martin Company, 10 Governors, propeller. See Propeller governors Green, A.W.F., 40 Greenamayer, Daryl, 658-659, 659/ Ground operation introduction, 617 ADI system check, 620

688

Index

Ground operation (continued) engine run-up, cautions regarding, 619-620 fuel booster pump, actuating, 618 hydraulic lock during, 618 idling/idle mixture, 619 oil stand pipe, importance of, 636, 637/ oil viscosity, problems with, 635-636 starting procedure, 618-619 See also Descent and landing; Flight operation Grununan Guardian design history, 530 in-flight photograph (AF-2 versions), 530/ specifications, 530 Gun synchronizer, 94, 95

H-3130 sleeve-valve engine, 18, 19 Haigh, Richard, xvi Hamilton Standard Propellers company formed , 17 See also Propellers, Hamilton Standard Hamm, Hilton, xiif Harnesses, ignition. See Ignition systems Hartog, Den, 40 Helicopter applications direct drive noses ("C" series), 171 , 601 output shaft ("C" series), 171/ See also Bell HSL-1 ; Sikorsky S-56 Hendershot, Jesse, xvi Hendy, Fred, xiif Heron, Sam biographical note, 2-4, 4f cylinder head design of, 23 PN scale development, xxi sodium-cooled valve development, 2-4, 5, 25 Hickner, Bob, xiif High-altitude performance of Curtiss Electric propeller brush assemblies, 332 of Curtiss Electric propeller speed reducer, 327 of high-tension ignition systems, 77, 78j 79/ improvements in (by engine series), 296t Pikes Peak high-altitude test, 132, 133/ See also Superchargers Hispano-Suiza V-8 engine, 10, lOj 11

689

Index

Hobbs, Luke biographical note, 13, 13/, 18-19, 21 resolves counterweight bearing failures , 114-115 Hooker, Sir Stanley, 133, 134[ Hornet, P&W, 16 Horsepower and overboosting, 228 of R-2800 vs. R-4360, 218 vs. cooling fin area, 145, 145t See also individual engine specifications Howard 500 design history, 598-599 in-flight photograph, 598/ specifications, 599t Hughes D2A/XA-37/XP-73 -49 engine in, 554/, 555 design development of, 554 Husted, Don, 660, 661/ Hydraulic lock danger of, 100 in ground operation, 618 prior to test-cell startup, 651 Hydraulic pump ("A" series), 94, 96

Icing/deicing, carburetor BMEP, effect on, 630 carburetor air temperature, setting, 629 carburetor icing, indications of, 629-630 deicing procedure, 630 Icing/deicing, propeller anti-icing device, Hamilton Standard propellers, 337/, 350/, 351 , 352/ Icing/deicing, wing and tail (Convair) deicing procedure, 631 Ignition systems, high-tension introduction, 72 firing order, 74 harnesses, G.E., 79, 81/ harnesses, Scintilla, 77, 77/, 78/ radio shielding in, 72, 75 twin-engine installation, typical, 81/ See also Distributors; Ignition systems, low-tension; Magnetos Ignition systems, low-tension CB-16 engine fitted with, 217/

690

Index

Ignition systems, low-tension (continued) discussion of, 212, 215 DLN-10 magneto cross section, 215/ simplified schematic diagram, low- vs. high-tension, 214[ step-up transformers, cylinder head, 216/ Ignition systems ("C" series) spark advance operating unit, 167-168, 169.f. 170.f. 183 Ignition timing, variable ("C" series), 26 Intake pipes/intake manifolds ("A" series) initial configuration, 22-23 nine-manifold configuration, 8 9, 91/ rubber couplings/split clamps, 91.f. 127/ See also Air induction systems Intake pipes/intake manifolds (" B'' series) flanged "pork chop" clamps, 127/ See also Air induction systems Isfdeld, Bill, xii

Jordan, Don, xvii

Kaiser, Henry J. , 485 Kartveli, Alexander, 3 79 KC-97 (at Corrosion Comer), 569/ Kennedy, Bill, xii Khurt, Wes, xii Koffel, John, xiif Krill, Art, xiif

Lanchester, Frederick, 35 Langley, Samuel P. , xix Law, Pete, xvii Liberty engine Pikes Peak high-altitude tests of, 132, 133/ Lindbergh, Charles, 2 Liquid-cooled engines Allison V-1710 F32, 134, 135.f. 543 Chrysler XIV-2220, 407.f. 543 P&W X-1800, 18, 538 See also Cooling, water Lubrication, rotary engine castor oil, xx

691

Index

Lubrication, rotary engine (continued) total loss system in, x,-x Lubrication systems ("A" series) first branch, functional description of, 84 second branch, functional description of, 84-85 third branch, functional description of, 85 de-aeration baffies, 82, 83/ dry pump system, 80, 82 low pressure oil system, 86 main oil pressure pmnp, 82, 83/ oil pressure relief valve, 86, 87/ oil pressure/temperature ranges, 87 overall lubrication system (cutaway view), 84f pressure relief valve, temperature compensation of, 82 scavenge pumps, 82, 82/ supercharger clutch lubrication, 84, 85 "top hat" oil shield, llLif, 114-115 Lubrication systems ("C" series) introduction, 172 first branch, 173 second branch (supercharger oil supply), 173 third branch (crankshaft), 173, 182 fourth branch (cam rings, accessory drive gears), 182 fifth branch (access01y drive gears, propeller), 182 sixth branch (booster pump, torquemeter), 183 seventh branch (spark advance mechanism), 183 detailed sectional view, 174-181/ front scavenge/torquemeter pump, 171-172, 172j 178/ functional description, 183-184 low pressure oil system, 184-185 rear scavenge pump, 184[ Ludvigsen, Karl, xvii Luftwaffe Arado Ar 232B, 524 direct port injection carburetors in, 88 fuel injection in, 313 FW-190, QEC on, 366/ ME-109R water-inunersed "boiler" oil coolers, 65 8 Messerschmitt ME 323 , 524 QEC concept development, 365 WWII V-12 engines in, 437

692

Index

Magnetos ("A" series) American Bosch, 73/, 76 Bendix-Scintilla DF18RN/LN, 73/ dual, failures of, 27 General Electric Turtleback, 79, 80/, 81/ magneto drive gears, lubrication of, 86 nomenclature code for, 74-76 See also Ignition systems, high-tension; Ignition systems, low-tension Maintenance and overhaul introduction, 636 blower impeller removal, 642/ blower section removal, 642/ crankcase front section removal, 641/ crankcase rear section removal, 641/ crankshaft gear (cam driver gear) removal, 640/ cylinder hold-down studs, inspecting, 644, 646 engine assembly sequence, 646-64 7 engine disassembly sequence, 63 7-63 8 engine preservation, packaging, 652-653 fatigue failure, discussion of, 642 fits/clearances/tolerances, checking, 644, 646 front cylinder removal, 639/ inspection criteria, 638-639, 642-644 Magnaflux part inspection, 645/, 646 nose case removal, 639/ piston removal, 640/ propeller shaft gear coupling removal, 640/ propeller shaft runout, checking, 638/ test cells, rigid/suspended cable, 647-648, 648/, 649/ test club, 649, 650/ test hookups, required, 651 test procedures, prestart/preliminary, 651 torquemeter checks, 651-65 2 Malcolm, Charles, xiif Manifold pressure during approach, 632 and automatic engine controls, 13 7-13 9 under carburetor icing conditions, 629-630 during climb, 622 during descent, 631 effect on induction temperature, 136

693

Index

Manifold pressure (continued) as factor in detonation, 133, 300 and supercharger impeller end thrust, 134 during takeoff, 621 Manly, Charles, xix Manufacturing, R-2800 Chevrolet production summary, 117 t Ford production summary, 109-lllt manufacturer SIN code designations, l l 6t Nash-Kelvinator production summary, 116t, 118t by Pratt & Whitney, 101-103, 103-105 yearly production summary, 296t See also Ford Motor Company Marcucci, Al, xvii Martin, Glenn, 10 Martin Twins (202/404) CA15 engine for, 593/ competition with Convair Twins, 586 design development of, 5 91 in-flight photograph (202), 592/ in-flight photograph (404), 593/ specifications (202), 59 lt specifications (404), 592t McBumey, Craig, xvi McCutcheon, Kim, xv McDermott, Jack, xiif McRae, Grady, xiif Meade, George biographical note, 12, 17 develops sleeve-valve engines, 18, 19, 5 3 8 Meloy, George, 39-40 Merlin engine. See Rolls-Royce Merlin engine Meyer, Bob, xiif Miami International Airp01t, 564-569 Military-commercial designation cross-reference, 293-294t Military engines, R-2800 Double Wasp (general) Army-Navy numerical suffixes for, 227-228 horsepower ratings, 228t military applications (by aircraft model), 375-378t military designation cross-reference, 293 -294t specifications for (See Military specifications, (various)) See also specific engines; R-2800 (general)

694

Index

Military specifications, "A" series R-2800-1 , 249t R-2800-5 , 250t R-2800-6, 250t R-2800-7, 250t R-2800-11 , 255t R-2800-13 , 255t R-2800-15 , 256t R-2800-17, 257t R-2800-19, 260t R-2800-21 , 260t R-2800-39, 270t R-2800-X-2, 249t R-2800-X-4, 249t Military specifications, "B" series R-2800-8/-8W, 25 l-252t R-2800-9, 251-252t R-2800-10/-lOW, 251-252t R-2800-12 , 255t R-2800-16, 256t R-2800-20, 260t R-2800-25 , 262t R-2800-26, 262t R-2800-27, 262t R-2800-31, 265t R-2800-33 , 267-268t R-2800-35 (semi-production), 269t R-2800-41 , 27lt R-2800-43 , 273t R-2800-45 , 273t R-2800-47, 275t R-2800-49, 276t R-2800-51 , 277-278t R-2800-53 , 277-278t R-2800-59, 280t R-2800-63 , 280t R-2800-65 , 282t R-2800-67, 282t R-2800-69, 282t R-2800-71 , 283t R-2800-75 , 283t R-2800-79, 285t

695

Index

Military specifications, "C" series R-2800-14/-14W, 256t R-2800-18/-18W/-1 8WA, 257t R-2800-22/-22W, 26lt R-2800-24 and X-24, 26lt R-2800-28 , 263t R-2800-34/-34W/-34WA, 267-268t R-2800-34A, 269t R-2800-36, 269t R-2800-37W, 270t R-2800-38W, 270t R-2800-40/-40W, 27lt R-2800-42W, 27lt R-2800-55 , 279t R-2800-57, 279t R-2800-61 , 280t R-2800-73 , 283t R-2800-77, 285t R-2800-81 , 285t R-2800-83/-83W/-83WA, 287-288t R-2800-85/-85W/-85XA, 287-288t R-2800-87, 289t R-2800-89, 289t R-2800-91 , 289t R-2800-93 , 290t R-2800-101 , 29lt, 292/ Military specifications, "CA" series R-2800-46/-46W, 275t R-2800-95 , 290t R-2800-97 , 290t Military specifications, "CB" series R-2800-48 , 275t R-2800-50, 276t R-2800-50A, 276t R-2800-52/-52W/-52WA, 277-278t R-2800-54, 279t R-2800-99W, 29lt R-2800-103W, 29lt Military specifications, " CE" series R-2800-44/-44W, 273t Military specifications, "D" series R-2800-23 , 26lt R-2800-29, 263t

696

Index

Military specifications, "E" series" R-2800-30W (production), 265t R-2800-30W (semi-production), 263t R-2800-32W (production), 267-268t R-2800-32W (semi-production), 265t Moffett, Rear Adm. W.A., 11 Moss, Sanford biographical note, 131-13 2, 13 2/ Pikes Peak Liberty engine tests, 132, 133/ Mounts . See Engine mounts Museum aircraft, 667-668

NACA (National Advisory Committee for Aeronautics). See Cowlings Nash-Kelvinator R-2800 production summary by dash number, 118t R-2800 total production by year, 116t Nassau, Jim, xiif Nene engine (Rolls-Royce), 13, 14/, 436/ Niles-Bement-Pond, 11 Northrop, Jack P-61 Black Widow design, 4 71 XP-56 Black Bullet design, 538 Nose section ("A" series) description, configuration of, 67-68, 68/ See also Reduction gearing, propeller Nose section (" C" series) configuration, 159/, 160/ design advances, 158 front section cutaway view, 158, 161f Nose section ("D" series) single- vs. two-speed nose, 142

Oil temperature, "B" series reducing, design modifications for, 127 See also Coking, oil Operation, engine introduction, 617 operating curve index, 295t See also ADI (anti-detonation injection); Descent and landing; Flight operation; Ground operation; Icing/deicing, carburetor; Maintenance and overhaul Osborne, Clay, xii

697

Index

Overboosting dangers of, 137, 207 and horsepower increases, 228 preventing (-18W engines), 193-194, 197/ and R-2800 vs. R-4360, 218 See also Carburetors; Manifold pressure Overhaul, engine. See Maintenance and overhaul

P-47 Thunderbolt (general) -21 engine released to production for, 129 dorsal fins , 386, 386f 403t dual air-to-air intercoolers, 379-380, 381/ dual oil coolers, 381, 382/ early design history, 379 engines used, 3 8 7 t exhaust system, 381-382, 383/ fuselage ducting configuration, 379-381 , 380/ incorrect restoration of, 666 on assembly line, 379/ specifications, variations and pennutations of, 388t, 389t, 392-397t, 399-404t, 406t, 408t, 412-413t Unilever power control, 208-209, 382, 383f 384 See also XP-47H; XP-47J; XP-72 (P-47 derivative) P-47B/XP-47B Thunderbolt side, in-flight views, 389/ specifications, 3 88t P-4 7C Thunderbolt -63 engine for, 13 lf 398/ in-flight view, 391/ specifications, 388t, 390t P-47D Thunderbolt -11-RE photograph, 391/ -25-RE bubble canopy, 400t, 405/ -25-RE in-flight photograph, 405/ -30-RE, blunt-nosed ailerons on, 40lt -40-RA dorsal fin, 386, 386f 403t specifications for (all variants), 390t, 392-397t, 399-403t P-47G-l-CU Thunderbolt three-quarter rear view, 405/ P-4 7M Thunderbolt -14W engine for, 409/ specifications, 408t top rear view, 41 Of

698

Index

P-47N/XP-47N Thunderbolt -73 engine used in, 411/ clipped wing tips on, 41 Of specifications, 408t, 412-413t, 414[ P-60. See XPIYP-60 (Curtiss) P-61 Black Widow -10 engine in, 473 , 473/ -25 engine designed, modified for, 129 -57 engine in, 475 , 477/ -73/-77 engines in, 473 , 477/ at Air Force Musewn, Smithsonian, 667 bubble canopy on (P-61E), 484[ cockpit layout, 480/ ditching, sketch of, 480/ downdraft carburetor, 140 engine installation (-A/-B), 473-474 engine installation (-C), 4 74-4 7 5, 4 78/ exploded view, 472/ induction air/intercoolers/cowling (P-61C), 475, 478/ induction air/intercoolers (P-61A/P-61B) , 473-474, 474/, 475/ main landing gear, nose gear, 4 79/ oil cooling in, 4 74f 4 7 5 P-61A in-flight photograph, 471 P-61C three-quarter view, 476/ photo recon. variant (F-15A), 484/ specifications, 476t, 481-483t spoilers and full-span flaps , 471 supercharging, alternative approaches to, 4 71 , 4 73 XP-61D side view, 483/ Page, Ralph, xiif Parkins, Wright, 156-157 PBM-5 Mariner, 492, 492/ Pierce, Bev, xiif Piston rings collapse of, 3 0 configuration of, R-2800, 31/ failure during takeoff roll/takeoff, 634 functional description, 29-30 hammering, 3 0 high-temperature failure, 634-635 oil control, dual, 3 1 oil scraper, 31 ring flutter, 30

699

Index

Pistons ("A" series) configuration, 28 Pistons ("B" series) domed heads on, 128 PN (performance number) scale, xxi Poultice head, 2 Power management, engine, 136-140 Power recovery (engine test), 115f Power-to-weight improvements (by series), 296t Pratt, Perry, 21 Pratt & Whitney Aircraft Company British government orders, 102 engine production license fees , 106-107 expansion of East Hartford facilities, 101-102 formed by Rentschler, 11-12 French government orders, 101-102 R-2800 engine production, photos of, 103-105f U.S . government orders, 101-103 Propeller governors double capacity governor developed, 3 l 8t electric governor head developed/tested, 320t governor drive gear train ("C" series), 169 Hamilton Standard Hydromatic, 353-354, 354.f, 355-357/ C4-C8f high-pressure oil supply ("C" series), 159, 160-161, 16lf, 163f oil source ("A" series), 86 speeder spring, Hamilton Standard Hydromatic, 354, 357f See also Propellers, Curtiss Electric; Propellers, Hamilton Standard Propeller shaft ("A" series) configuration, 70, 72f splines on, 70, 72f See also Reduction gearing, propeller Propeller shaft (" C" series) configuration, 158-159, 162f thrust bearing for, 161 Propellers, Curtiss Electric adapter plate, speed reducer, 327, 329f bearings, thrust, 325, 327, 328f brake assembly, 323/ 324 cuffs, blade shank, 3 l 8t, 327, 329f development chronology, 3 l 7-320t electric motor/speed reducer, 322-323/ 324, 330f exploded view, 32lf functional description, 321 , 324-325

700

Index

Propellers, Curtiss Electric (continued) governor, functional description of, 325, 326f 329 hub, one-piece, 325, 327/ pilot/flight engineer control of, 324-325 pitch and feathering switch operation, 324, 325 reliability concerns regarding, 33 1-3 32 ring gear/blade gear quadrant, 324/, 325/ slip ring and brush assembly, 3 l 8t, 322f 331/ See also Propellers/propeller blades Propellers, dual rotation on Douglas B-23 , 558-559/ engine designations for, 227 on F4U Corsair, 457/ Hamilton Standard development of, 318, 319-320 in Northrop XP-56, 140, 143 on XP-56 Black Bullet, 140, 538 Propellers, Hamilton Standard air separator plug, 353, C4f anti-icing device assembly, 337f 350f 351 , 352/ barrel, 337f 338, 339f 340 barrel supports, 339f 340 blade angle stop rings, 343f 348 blade assembly, "E" shank, 340, 341/ blade balancing plug, 34 lf 342 blade bushings, 340, 34 lf 342 blade gear segment, 339f 34lf 342 blade packing, 339f 342 cam styles, 346, 347/ cams, coaxial, rotating/fixed, 343f 345 chafing ring, 34lf 342 distributor shell assembly, 337f 349, 352/ dome and barrel seal, 343f 349 dome assembly, 337f 343f 344, 347/ dome breather hole/breather assembly, 337f 343f 351 dome pressure relief valve, 362, C4f dome retaining nut, 343f 349 dome shell, 343f 348 dynamic forces acting on, 332-334, 333f 334/ engine shaft extension, 351-353 , 352/ governor, functional description of, 353-354, 354/, 355-357f C4-C8/ high-pressure oil supply for ("C" series), 159, 160-161, 16lf 163/ Hydromatic hub assembly, exploded view, 337/ major subassemblies of, 332

701

Index

Propellers, Hamilton Standard (continued) model designations (basic/blade/special), 334-336 piston, 343f 346, 348 roller assemblies, 343f 348 shim plates and shims, 339f 344 speeder spring, governor, 354, 357f sp1"d er, ...,...,6 .J .J , ..,..,8 .J.J , ""9l.( .J.J 'J spring pack assemblies, 339f 344 thrust plate, blade bushing, 34lf 342 thrust washers, 340, 34lf See also Propellers, Hamilton Standard (Operation); Propellers/propeller blades Propellers, Hamilton Standard (Operation) introduction, 3 53 air separator plug, 353, C4f feathering, 359-361 , C7f feathering installation, typical, 363f governor, functional description of, 353-354, 354f 355-357f C4-C8f maintenance of, 362-363 on-speed condition, 355f 358, C5f overspeed condition, 356f 358-359, C6f sludging in, 362-363 speeder spring, governor, 354, 357f underspeed condition, 356f 357-358, C4f unfeathering, 361-362, C8f See also Propellers, Hamilton Standard Propellers, variable pitch dynamic forces acting on, 332-334, 333f 334[ high-pressure oil supply for ("C" series), 159, 160-161 , 16lf 163f need for, 132 propeller governor oil source ("A" series), 86 propeller shaft oil transfer bearing (" C" series), 86 See also Propellers, Curtiss Electric; Propellers, Hamilton Standard Propellers/propeller blades blade tip shock waves, problems with, 465 contribution to torsional vibration, 35-36 development chronology, 317-3 21 t dynamic forces acting on, 332-334, 333f 334[ Hydromatic steel/aluminum propellers tested, 320t P&W vibration analyses (in SMRs), 41-60 synchronizing, synchrophasing, 95 tip speed constraints, 68-69 10-foot aluminum NACA propeller tested, 319t 12-foot aluminum propeller tested, 318t

702

Index

Propellers/propeller blades (continued) 18-foot magnesium propeller tested, 3 l 9t See also Propellers, dual rotation; Propellers, variable pitch; Reduction gearing, propeller Pumps, oil. See Lubrication systems; Propellers, Hamilton Standard Pusher aircraft. See XP-56 Black Bullet Pushrods. See Valve trains PV-1 Ventura/PV-2 Harpoon -31 engine in, 465 , 4 70/ as Lockheed Lodestar derivative, 465 multi-role capability of, 415 oil cooler, 415 PV-2 loading torpedo, 467/ PV-2s in flight, 467/ RAF PV-1 , 466/ single-wheel main landing gear, 465, 469/ specifications, 468t USAAF PV-1 s in flight, 466/

QEC (Quick Engine Change) interchangeable (in DC-6 commercial versions), 577 Luftwaffe development of, 365 R-2800-18W in F4U-4, 441/ R-2800-32W in F4U-5, 446/ See also Engine mounts

R-985 Wasp Jr., 15 R-1340 Wasp BMEP of, 15 design specifications, 13, 14 first flight of, 16 first production orders, 16 first test run (illus.) , 15/ Navy requirements for, 11, 12 one-piece crankshaft, 14 R-2060, configuration of, 18 R-2800 (general) altitude perfom1ance improvements (by series), 296t design series of, 22 initial configuration/specifications, 22-23 military-commercial nomenclature cross-reference, 293-294t oil stand pipe, importance of, 636, 637/

703

Index

R-2800 (general) (continued) power-to-weight improvements (by series), 296t prototype engines for, 23 X-80 as development mule, 23 See also specific components and series; Commercial specifications (various); Military specifications (various); Operation, engine R-2800-5 in B-26 Marauder, 497f specifications for, 250t R-2800-8/-8W Bendix PT-13 carburetor on, 427f front view, 253f in F4U-l Corsair, 142f specifications, 251-252, 253f updraft carburetor on, 140 R-2800-10/-lOW Bendix PT-13 carburetor on, 130f blower desludging (in F6F Hellcat), 504 first engines tested, shipped, 131 front, rear views, 254[ in F6F Hellcat, 13Qf, l42f specifications, 25 l-252t supercharger for, cutaway view, 136f R-2800-14/-1 4W in P-4 7M Thunderbolt, 409f seven-eighth left front, top views, 258f specifications, 256t R-2800-18/-18W/-l 8WA in Curtiss YP-60, 543 , 544t, 545f left side view (-18WA), 436f milestone events in (SSC22G), 198 QEC configuration (in F4U-5), 446f right side view, 186-187/, 25~( single elliptical oil cooler for (in F4U-4), 432, 438f specifications, 25 7t three-quarter front view, 189, 190f three-qua1ter rear view, 188/, 189 top view, 259f See also Superchargers (" C" series) R-2800-22/-22W milestone events in (2SC 13G), 198 side views, 264/, 5 l 6f specifications, 26 lt

704

Index

R-2800-25 blower design modified, 129 designed for P-61 (Black Widow), 129 specifications, 262t R-2800-27 in North American XB-28, 531 specifications, 262t R-2800-29 on display (rear view), 264[ specifications, 263t torsional vibration problems, 538, 540 in XP-56 Black Bullet, 140, 142-143, 538, 539j 540 R-2800-30W automatic engine control, 204 front, rear views, 521/ introduction, 204 side views, 205j 266/ specifications, 263t, 265t typical installation, E-12 version, 205/ R-2800-31 left side view, 4 70/ specifications, 265t three-quarter left front view, 266/ R-2800-32W automatic engine control in, 204 front view, 442/ in F4U-5 Corsair, 200-201 , 437, 439, 443j 445 , 446/ F4U-5 mount for, 439, 448/ F4U-5 QEC configuration, 446/ rear views, 20lj 442/ side view, 272/ "sidewinder " supercharger on, 201j 202-203j 272j 442/ specifications, 265t, 267-268t triarnesed exhaust stacks, 439, 448/ typical installation, E-22 version, 206/ R-2800-34/-34W/-34A -34Ml modification to, 665 aircraft applications , 198 in Curtiss XF-15C, 542 in Grumman Guardian, 530/ milestone events (2SC14G), 198 in PBM-5 Mariner, 492 specifications, 267-268t, 269t

705

Index

R-2800-42W in postwar F4U-4s, 432, 437/ specifications, 27 lt three-quarter right front view, 272/ R-2800-43 in B-26 Marauder, 499/ left side view, 274/ specifications, 273t three-quaiter left rear view, 551/ R-2800-44/-44W in AJ-1 Savage, 532-533 , 535f 537/ left side view, 274/ right side view, 537/ specifications, 273t R-2800-48 in Grununan Guardian, 530 specifications, 2 75t R-2800-51 -5 lMl modification, 665 specifications, 277-278t R-2800-52/-52W/-52WA in Douglas B-26K, 415 specifications, 2 77 -2 7 8t R-2800-57 bottom view, 281/ specifications, 279t in XP-47J Thunderbolt, 384/ R-2800-59 side view, 281/ specifications, 280t top view, 398/ R-2800-63 for P-47D/C, 13 lf 398/ right side view, 281/ specifications, 280t three-quarter rear view, 131/ R-2800-71 side view, 422/ three-quarter right front view, 284/ specifications, 283t R-2800-73 bottom view, 284/ in P-47N, 411/ specifications, 283t

706

Index

R-2800-75 front view, 286/ specifications, 283t R-2800-77 specifications, 285t top view, 28qf R-2800-83 /-83W/-83WA for C-69E Constellation, 292/ right side view, 573/ specifications, 287-288t top view, 292/ in XA-26D, 415 R-2800-99W in C-123 , 485 specifications, 29lt R-4360 (Wasp Major) cutaway view, 414/ in F4U-l aircraft, 447, 450, 453/, 453 -454, 455/, 464t in Goodyear F2G aircraft, 453 , 454, 456/ Ryder cylinder development for, 12 three-quarter left front view, 219/ vs. R-2800, 218 in XP-72 (P-47 derivative), 414/ Rabel, Armin, xiif Racing applications introduction, 655 "Blue Max" F4U, 657/ Call races "Number 90" FG-1, 656, 657/ Cleland-modified air scoop in FG-2, 655 -656 Cleland races "Lucky Gallon" FG-1, 655, 656/ DeSanto races, loses, XP-60E, 656 Greenamayer 's highly modified F8F Bearcat, 658-659, 65Qf Husted races A-26, 660, 661/ Reynolds A-26 "Bombshell," 660, 660/ Thompson Trophy race, 655 , 656 Radial engines, early ABC Dragonfly, x,-x Manly engine, xix Sallnson (French), xx Rare and extinct aircraft, 667-668 Reduction gearing, cam ring-crankshaft, 32-33, 33/ Reduction gearing, propeller ("A"/"B" series) aerodynamic need for, 68-69 fifteen pinion, 16:9 ratio, 69, 71/

707

Index

Reduction gearing, propeller ("A"/"B" series) (continued) lubrication of, 84 six pinion, 2: 1 ratio, 69, 70[ six pinion, 5:2 ratio, 69 Reduction gearing, propeller ("C" series) functional description, 159-160, 162/ Rentschler, Frederick biographical note, 9/, 9-10, 11-12, 17 vice president, Wright Aeronautical, 9/, 11 Republic P-47 Thunderbolt. See P-47 Thunderbolt Reynolds, Milton, 660, 661/ Ricardo, Sir Harry, 30/ Richards, Andrew, xvii Rings , cam. See Cam rings Rings , piston. See Piston rings Rocker arms. See Valve trains Roets, Jim, xiif Rolls-Royce Eagle engine torsional vibration in, 35 Rolls-Royce Heritage Trust, xvi Rolls-Royce Merlin engine blade frequency problems with, 465 in Curtiss XP/YP-60, 543 speed density fuel metering in, 315 supercharger design, 132, 133, 137 600 series engine, 563 , 564/ Rolls-Royce Nene engine, 13, 14[, 533 Rotary engines, aircraft functional description, xix-xx lubrication, xx ring cowls, xx Royce, Sir Henry, 35 Royce vibrational damper (V-12 Eagle), 35 Ryder, Earle A. biographical note, 12 cylinder cooling research, 26

Salomon ("hockey puck") pendulum dampers, 35, 39, 40/, 61/ SB2C (Curtiss), 555 Scavenging, oil importance of, 126-127 See also Lubrication systems

708

Index

Sceggel, Elton, xiif Shielding, interference in R-2800 ignition systems, 72, 75 Short Memorandum Reports (SMRs), 41-60t Siddeley, S.D. design of, 23 "Sidewinder" supercharger introduction, 200-201 dual air-to-air intercoolers, 437, 447/ in F4U-5 aircraft, 437, 443/, 446/, 448/ impellers, hydraulically driven, 43 7 impellers, sectional view of, 202-203/ induction system, 437, 477/ origin of name, 201 , 437 on R-2800-32W engine, 20 lf, 202-203/, 272/, 442/ three-quarter rear view (line drawing), 444/ See also Superchargers ("C" series) Sikorsky S-56 (HRS-l/H-37A) augmentor exhaust system, 601, 604/ ejector type exhaust system, 601, 605/ H-37 A in flight, 602/ left-hand engine, sketch of, 607/ load carrying capacity, deployment, 605 major components of (sketch), 603/ noise problems, 601 power package layout, 606/ specifications, 605t throttle control, servo-assisted, 601-602 transmission/hydromechanical clutch, 602, 604, 608/ Simoon, Wright (engine), 13, 16 Sims, Lt. Turner A. , 35 Sleeve-valve engines P&W H-3740, 18, 19/ P&W X-1800, 18, 538 Roy Feddon work on, 219-220 Sludging/desludging in Hamilton Standard propellers, 362-363 supercharger clutch, 196 Sodium-cooled valves, 2-4, 5, 25 See also Heron, Sam Sorenson, Charles, 106, 107 Spark plugs cold plugs, use of, 635 -636

709

Index

Spark plugs (continued) damage from piston ring failure, 634 dual, importance of, 2 7 fouled plug, on ignition analyzer, 627/ ground fouling, 635 lead fouling, 636 LS 86 spark plug, sectional view, 75/ shielding, 7 5 See also Ignition systems; Operation, engine Speed density fuel metering, 315 SSB2G engine production release of, 129 Stand pipe, oil, 636, 637/ Starting systems combustion staiters, 100 development, chronology of, 97-98t direct crank, 98, 99/ electric inertia, 98, 100 hydraulic lock, danger of, 100 Stroukoff, Michael, 485 Sud Ouest S.0.-30P Bretagne, 597, 597/ Superchargers (general) air/fuel mixture dynamics, 89 basic design factors , 135 centrifugal, fuel atomization in, 88 combustion processes, discussion of, 86-88 Hooker research on, 133, 134[ impeller end thrust, compensating for, 134 mechanical vs. turbosupercharging, 134 metallurgical problems with, 132 Rolls-Royce Merlin design, 132, 133 , 137 Sanford Moss research on, 133, 134/ slinger ring, fuel feed from , 88 sludging/desludging, clutch, 196, 504, 624 two-stage supercharging, necessity for, 133-134 variable impeller speed, importance of, 88-89 See also Flight operation; Turbosuperchargers, General Electric Superchargers ("A" series) blower drive gear lubrication, 84-85 , 85/ clutch lubrication, 84, 85 , 85/ collector section, 92f 92-93 drive gears/clutches, 89, 92, 92/ drive system torsional vibration, 89, 92

710

Index

Superchargers ("A" series) (continued) impeller/diffuser, single-stage, two-speed, 89, 90 intermediate rear section, 93-94 Superchargers ("B" series) on -8 engine (in P&W F4U-l , -2), 426, 428, 432 aftercoolers in, 13 5 early design (for R-1830 powered F4F-3 Wildcat), 135, 136/ impeller fluid coupling ("accelerator") in, 139-140, 141/ intercoolers in, 13 5 P&W face-to-face impeller configuration, 135, 136j 137/ R-2800-lOW supercharger, cutaway view of, 136/ total production, single- and two-stage, 140 valving and controls for, 137-139, 138j 139/ Superchargers ("C" series) on -18W engine (in F4U-4), 432 automatic boost control, 193-194, 197/ auxiliary impeller assembly, 189 "CA' and "CB" slinger rings, 193 Coriolis force, problems with, 191 , 200 description of, 187, 189 drive couplings, exploded/phantom views, 192/ fuel feed valve, 193, 194/ hydraulic coupling slip measurement, 193 hydraulic couplings, functional description of, 191 regulator for (on -8 engine), 428 , 429/ second-branch oil supply for, 173 "sidewinder" (on -32W engine) (See "Sidewinder" supercharger) See also Turbosuperchargers, General Electric Swansson, Al, xiif Synchronizer/synchrophaser, 94, 95

T-29 (Convair) aircraft, 586, 587/ T-36A (Beech) development history, 556 in-flight sketch, 556/ specifications, 557t Tachometer generator, 94 Tappets/tappet rollers configuration, 32-34, 32-34/ lubrication, 85 , 86 Taylor, E.S. pendulum damper research, 36

711

Index

TBF (Grumman), 555 Telephone, notches on, 38-40 Temperature carburetor air, setting, 629 cylinder head, importance of, 620-621 of forged vs. cast cylinder heads, 148-149 of fuel charge as detonation factor, 133, 300 See also Cooling Teneyck, Bob, xiif Test stands, engine Ford combination build stand/test stand, 115/ 119/ power recovery using, 115/ Thompson Company self-adjusting pushrods, 26 Tillinghast, T.E. , 216 Torquemeter ("C" series) functional description, 163-164, 165/ pistons/piston assembly for, 166/ Travis, Jim, xvii Turbo-compounding application to Wright R-3350 engine, 210, 212/ discussion of, 209-210 early NACA study (" B'' series engine), 211/ in exhaust system experiments, 2 l 3t VDT (variable discharge turbine) development, 210-212 See also Turbosuperchargers , General Electric Turbo Engineering Company, 428 Turbosuperchargers , General Electric discussion of, 204, 206-207 electronic regulator, 207-208, 208/ in Hughes D2A, 554-555 mechanical vs. turbosupercharging, 134 models/applications of, 21 tO overspeeding, 206-207 in P-61 Black Widow, 474-475 turbocharger designations/applications, 210t, 387 Type CH-5 , cutaway view, Clf Type CH-5 , in AJ-1 Savage, 532-533 , 534[ Type CH-5 , in P-47 Thunderbolt, 379, 380/ Unilever power control for, 208-209, 382, 383/ 384 waste gate (butterfly valve) in, 206, 207, 208/ 381-382, 382/ 383/ See also Superchargers Turtleback magneto (G.E.), 79, 80/ 81/

712

Index

Unilever power control, 208-209, 382, 383f 384

Valve failures valve springs, early failures of, 13-14 See also Valves, exhaust Valve springs early failures of, 13-14 Valve timing "A" vs. "B" series, 26 "A/B" vs. " C" series, 169 of early-series RT-2800 engines, 32 variable, in "C" series engines, 26 See also Cam rings/cam followers Valve trains ("A" series) front row lubrication, 86 pushrod configuration, 26 pushrods, Thompson self-adjusting, 26 rear row lubrication, 85 reduction gearing, 32-34, 32-34f 63 , 64/ rocker arm lift ratio, 25 rocker arm lubrication, 85 , 86 rocker arm pivot bearings, shortage of, 112-113 rod bearing failures , 26-27 tappets/tappet rollers, 32-34, 32-34( valve clearance adjustment, 25-26 See also Cam rings/cam followers Valve trains ("B" series) one-piece pushrods in, 127 rocker arm pivot bearings, shortage of, 112-113 Valves, exhaust for "C" series engines, 147/ high-temperature problems with, 25 rocker boxes, oil coking in, 25 sodium-cooled, 2-4, 5, 25 Valves, inlet for "C" series engines, 147/ configuration, 25 Valves, sleeve Feddon designs for, 25 Valves, sodium-cooled, 2-4, 5, 25 Vandermark, Bruce, xvii

713

Index

Vibration, linear of "B" and " C" series crankshafts, 156 master rod/link rod contribution to, 36 P&W analyses of (in SMRs), 41-60t second-order counterweights, 36, 37j 38, 38f Vibration, torsional of "B" and "C" series crankshafts, 156 and counterweight gearing, 36, 38 origins of, 34 propeller contribution to, 35-36 P&Wanalyses of (in SMRs), 41-60t in Rolls-Royce Eagle V-12, 35 in supercharger drive systems, 89, 92 in XP-56 Black Bullet, 538, 540 See also Counterweights/dampers Vibration stress, propeller, 3 l 8t Vickers-Armstrong Warwick in-flight photograph of, 55'2f Wallis design of, 55 2 Vought F4U Corsair. See F4U Corsair Vultee V-11 as R-2800 "B" series test mule, 128 Vultee Y-19 as R-2800 "A" series test mule, 100, lOlf

Walker, Frank and AD I system optimization, 215 and aviation fuel tests, 218 in group photo, xiif and highly boosted R-2800 "B" engine, 218-219 Wallis, Sir Barnes, 552 Walter, Willie, xvii Warbirds, incorrect restoration of, 665 -666 Waring, Dana, 143 Wasp Jr. (R-985), 15f Wasp engines naming of, 13 See also specific engines Water injection. See ADI (anti-detonation injection) Wellman, Dick, xv-xvi "Whistling death" (F4U Corsair), 428 Whitney, Dan, xvii

714

Index

Willgoos, Andy, 12, 15, 21 Wright Aeronautical Corporation, 11 Wright brothers, 10 Wright Company, 10 Wright-Martin Company, 11 Wright R-3350 turbo-compound engine, 210, 212/

X-77 engine first "A" series engine, 23 initial configuration/specifications, 22-23 X-80 engine as R-2800 development mule, 23 X-1800 sleeve-valve engine, 18, 538 XB-28 (North American) design details, specifications, 531 side view, 531/ XF-15C (Curtiss), 542, 542/ XF4U-l Corsair specifications, 456t XF4U in flight, 424/ XP-47H Thunderbolt Chrysler IV-2220 engine in, 406t, 407/ three-quarter front view, 407/ XP-4 7J Thunderbolt -57 engine for, 384/ front view, 409/ intercooler, 385, 385/ line drawing of, 3 84/ specifications, 406t supercharging system, 384-385, 385/ XP-56 Black Bullet -29 engine for, 140, 142-143, 538, 539/ 540 air induction system, 538, 540 dual rotation propeller on, 140, 538 engine mount, 540, 541/ general configuration, 140 longitudinal instability of, 540 oil cooling system, 540 pilot egress from, 143 propeller, jettisoning, 143 right side view, 539/ at Smithsonian, 667

715

Index

XP-56 Black Bullet (continued) torsional vibration problems with, 538, 540 XP-72 (P-47 derivative) specifications, 413 t three-quarter rear view, 414[ XPNP-60 (Curtiss) alternative engines for, 543, 545/ on runway (YP-60), 543/ specifications, 544t XTBU-1 (Vought), 555/ XTB3F aircraft. See Grumman Guardian

716

About the Author

Born in the aftermath of World War II in 1945, Graham White spent his fo1mative years in England. Like many aviation enthusiasts, he got his start in aviation by racing U control model airplanes. Upon reaching driving age his interests shifted to cars and soon after, car racing. This passion consumed the next eight years of his life. Graham White moved to the Bahamas in 1969 after being offered a job there. Even though he was still racing cars while living there, his interests were shifting to aircraft, in particular, aircraft engines. Those wonderful round radials were fascinating to him. While living in the Bahamas, he was drawn to the many piston powered aircraft that visited Freeport International Airport, including Lockheed Constellations, Martin Twins, Convair Twins, Curtiss C-46s, and all the Douglas transports . He spent many happy hours roaming through a Douglas A-26 Invader, a refugee from the abortive Bay Pigs invasion, hidden in the weeds-that is, until it was used for fire practice. After five glorious years in the Bahamas, Florida beckoned. It was while living in Florida that Graham White got his private pilot's license and purchased a Cessna 150. He eventually racked up over 2000 hours in this aircraft before selling it. Florida also provided the opportunity to further explore the world of piston powered aircraft. South Florida in the 1970s and 1980s was a haven for large piston powered transports. In particular, the northwest corner of Miami International Airport, known as "Corrosion Corner," attracted Graham White's interest. He was a kid in a candy store roaming around the "Corner" with all kinds of engines, propellers, landing gear and other cast-off components laying around. He also visited the numerous engine overhaul shops located in the Miami area. It was during these visits that the remarkable workmanship and quality exhibited

717

About the Author

by these engines hit home. Even poking around in the scrap bins would often yield gems for his office. Items such supercharger impellers, master connecting rods-which can be made into beautiful clocksand other precision components caught his attention . Of course, it was not long before he befriended the operators of these wonderful aircraft and had the opportunity to catch rides on them to all points in the Caribbean.

In 1982 Graham White had the opportunity to purchase a Rolls-Royce Griffon liquid cooled V-12 engine from England. Although it was in derelict condition, he set to and over the course of a year converted this derelict into a showpiece. This was soon followed by a Pratt & Whitney R-2800, purchased out of Corrosion Comer, which got the same treatment as the Griffon. It is now not only a showpiece but a runner as well, complete with a purpose-built trailer designed and built by Graham White. The R-2800 is just one of Graham White's pride and joys. Other engines in his collection include an ultra-rare Continental IV-1430 Hyper engine, Packard built Rolls-Royce Merlin and two Pratt & Whitney R-4360s. Some people 's mission in life is to save the whales; Graham White 's is to save the engines. To this end, his intention is to get all the engines in his collection into running condition. These fast disappearing masterpieces may then be enjoyed and appreciated by those who would normally not have this opportunity. This includes aviation groups, university students, boy scout troops and other organizations. Graham White married later in life, thus becoming a stepfather to four beautiful daughters . His adoring wife, Diane, is very supportive of his unusual pastime. In addition to spending time with his family, Graham White is active in SAE, Rolls-Royce Owners Club, Rolls-Royce Enthusiasts Club, Rolls-Royce Heritage Trust, EAA including EAA Warbirds of America, The Napier Power Heritage and American Aviation Historical Society (AAHS). As this book is going to print, Graham White is involved in founding the Aircraft Engine Historical Society (AEHS). It is the goal of the AEHS to acquaint aviation enthusiasts with the proud heritage of aircraft engine development. The AEHS will expose students, educators and historians to the characteristics, idiosyncrasies, development and manufacture of the finest and most powerful examples of prime movers. For more information about the AEHS and related activities, see the AEHS website, http: //www.enginehistory.org .

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