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Specialty Press |
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R-4360 Pratt & Whitney's Major Miracle |
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by Graham White |
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Reviewed By Art Silen, #1708 |
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MSRP: $64.95 USD available through Specialty Press (www.specialtypress.com), or many online and retail bookstores Graham White has again written an engaging, elucidating, and entertaining history of Pratt & Whitney’s last significant radial piston aero engine, the R-4360 Wasp Major. For those unfamiliar with the nomenclature used by the United States Army, the R stands for Radial, and the 4360 indicates the number of cubic inches displaced. Known within the company as the Wasp Major, this was a 28-cylinder radial engine positioned in four banks of seven cylinders, promising horsepower in the 3,500+ range. It was developed by Pratt & Whitney simultaneously with its other premier product, the engine famously known as the R-2800. But unlike the R-2800, the 4360’s gestation was protracted and made all the more difficult because of the technical difficulties that its designers encountered as they strove to produce a reliable aero engine that would generate more horsepower and operate at higher altitudes than had been done previously. Graham White is the author of two earlier books on aero engine development (Allied Piston Engines of World War II, SAE, 1995; and R-2800, Pratt & Whitney’s Dependable Masterpiece, SAE, 2001). This, his latest, might well have been subtitled, “Against All Odds,” because the R-4360 project’s prospects for eventual success, were indeed dubious. Other aero engine companies had tried coupling existing engines with very limited success: Rolls-Royce, with its V-24 Vulture; Daimler-Benz’ DB-610, using two DB-605s coupled to a common crank case; and several other European and American engine manufacturers whose products never reached production. The idea behind the R-4360 was sound enough; add several banks of cylinders to an already proven product. Well, maybe; but again, maybe not, because the new engine required engineering know-how, metallurgy, and manufacturing skills of a magnitude that simply could not have been anticipated when the project was begun in 1940. That the R-4360 ultimately succeeded is a monument to Pratt & Whitney’s perseverance and ability to adapt to changing conditions, and had gas turbine engines not appeared when they did, the Wasp Major might have gone on to be the engine that would have powered America’s aerial fleets in the post-war era. But that was not to be. The reality was that the R-4360 powered a respectable number of late-war and post-war aircraft, both military and commercial, but nothing like the fleets for which it was intended. In point of fact, the number of designs that were to be powered by the engine which never reached production exceeded the number that did. These included the F2G-1 and -2 “Super Corsair”, the Republic XP-72 and XF-12 Rainbow. Other designs were cancelled for reasons unrelated to the powerplant: the Douglas XTB2D “Skypirate” carrier-borne torpedo bomber, the Vultee XA-41 assault aircraft; the Curtiss XBTC-2 and XP-71 (after the P-40, Curtiss could get nothing right); and the Northrop B-35 Flying Wing. In fairness, it must be said that the design specifications against which these designs were built were themselves fatally flawed by the lack of wartime operational experience that underlay them. Those R-4360-powered designs that reached fruition did so because of a combination of luck and dire national need. In the post-war world, the Convair B-36 went into production because in the immediate years we had nothing else that would fly 4,500 miles with a nuclear warload, and even then, the Peacemakers were phased out of Air Force inventory as soon as sufficient numbers of B-47s arrived from the production lines. Similarly, the B-29 off-shoot, the B-50 soon relinquished its role as nuclear bomber to take on reconnaissance and airborne tanker duties. The Glenn L. Martin Company produced the P4M-1Q, powered by two R-4360s and two jet engines housed in two nacelles. Few in number, these aircraft were tasked carrying electronic surveillance equipment along the periphery of the Soviet Union and China, and several are known to have been shot down while on mission. The Douglas C-74 and C-124 Globemaster, and the Fairchild C-119 Packet are well known to those of us whose childhoods are anchored in the 1950s. I can still remember watching a C-124 flying some distance overhead and feeling the pulsing vibration from its four engines. Boeing also produced its model 377 Stratocruiser (yet another offshoot of its B-29 design), to become the C-97 and KC-97 tanker aircraft. And, as is often the case, R-4360-powered aircraft have made their appearance on the racing circuit. The R-4360 represents the ultimate product of its genre, excelling within the technology from which it arose, and yet representing an obsolescent technology whose days were numbered, even as it reached peak performance. Much the same story could be told about clipper ships in the age of sail, and mammoth steam locomotives in the early days of diesel-powered railroad engines. If this were all this book is about, its $64.95 price tag might be off-putting, as relatively few modelers are about to do an R-4360 engine in all its glory. There is more, much, much more. Graham White tells his story well, and it is a tribute to his skills as a researcher and as a writer to tell us about the R-4360 design and development, and of the physical challenges that effort was designed to address; and the resources he uses are first rate: factory drawings, aircraft maintenance and erection manuals, color schematics, graphs, and charts. Those of us living in today’s computerized, digitized, and modular world have little knowledge or appreciation for the challenges Pratt & Whitney engineers faced, and how they succeeded against all odds. The R-4360 was as finely wrought as a proverbial Swiss watch; its machine tolerances were closer than any similar product of its kind; operating temperatures and pressures that had to be controlled were different in degree and kind than anything previous in their designers’ experience; and using energy recovery systems to maximize the design’s operational performance were just a few of the talents and skills its builders had to have to make it work. Sadly, those working on the R-4360 knew that they were moving toward a dead end, because jet engine design was the real cutting edge of aero engine development, even as the R-4360 made its debut. To summarize, this book is everything one could hope for in a design history, and those of us with a bent toward the nuts and bolts of technology history will welcome it. Special thanks to Specialty Press for a review copy. |
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