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Aviation History
1953
1953 - 1543.PDF
27 November 1953 697 TWO-SPOOL TURBO-WASP Characteristics of the Pratt and Whitney J57 WITH the exception of young enthusiasts who seem to have a propensity for recording complex designations, readers probably find difficulty in distinguishing one American gas turbine from another. Algebraic symbols and a complete lack of identifying names makes it all too easy for the reader to become lost in a welter of T- and J-numbers. Usually, this is of slight consequence, but the engine described here is very much an exception. The Secretary of the U.S. Air Force, Mr. Harold E. Talbott, has described it as "the Air Force's future engine." After a wait of many months, we can at last introduce this fine piece of engineering in an account which we believe is more detailed than any other to appear in this country to date. The entry of the Pratt and Whitney Division of the United Aircraft Corporation into the gas-turbine field followed no con ventional pattern. Since 1925 die company have been renowned as manufacturers of some of the best—many would say the best —aero-engines in the world. And, apart from quality, no omer firm can match the Connecticut company's production potential; between 1943 and 1945, for example, Pratt and Whitney and their sub-contractors produced a potential horsepower exceeding that of all the omer American manufacturers combined. When, in 1941, mis country introduced the United States to the turbojet, it was decided for several sound reasons to allocate work on the new power-plants principally to the General Electric Company. This left the established engine firms—Pratt and Whitney, Wright and omers—free to maintain their colossal pro- The J57 combustion cham ber is discussed on the next page. The concentric com pressor-drive shafts are visible. gramme of piston-engine work, with which the war was to be won. At die end of hostilities, Pratt and Whitney emerged as the world's greatest manufacturer of piston engines, with unrivalled facilities bodi for research and production. But gas turbines are, as many were men discovering to dieir cost, a new kind of animal. American engineers with real gas-turbine knowledge could almost be counted on the fingers and, on reflection, it is surprising that bom Pratt and Whitney and Wright fell into die trap of believing that the turboprop was easier to develop than the turbojet. In 1945 bom companies started work on 5,000-h.p. single-shaft axial turboprops and, not unnaturally, bom projects caused endless trouble. Eventually, Wright threw up the sponge, abandoned their T35 unit and got in touch widi Armstrong Siddeleys. Pratt and Whitney doggedly beat the T34 into a useable engine, and today, eight years from die start, it is considered ready for installa tion in a number of military transports. Work on die T34 showed Pratt and Whitney that, far from being a simple box of hot air, die gas turbine was going to require more elaborate research facilities, bigger staffs of specialist engi neers, more expensive tooling and a bigger expenditure of time and money than had been required by any piston engine. On die odier hand, it was clear that reciprocating power-units were becoming obsolescent. It is characteristic of Pratt and Whitney that, about 1947, while Rolls-Royce, de Havilland, die General Electric Company and Allison were mass-producing simple and useable turbojets, die biggest firm of all temporarily discontinued jet design and undertook an immense programme of long-term work, little of which could bear fruit in under five years. It is safe to say mat no otiier firm could have done the same. The main effort went into die design and construction of the largest and finest range of engine research facilities in private hands. Largest of these establishments is the Andrew Willgoos turbine laboratory, named after die company's revered chief engi neer, who died in 1949. This impressive establishment—which die editor visited, and described in our issue of January 12m, 1950—is fully equipped for the testing of all kinds of modern power units, botii complete and in component form. High- altitude conditions can be reproduced on an appropriate scale. While all this was going on, the company steadily built up a first-class team of engineers fully capable of putting these facili ties to die best use. And, to keep dieir hand in, and also to make available fully developed engines of greater power than tiiose then in use by the U.S. armed forces, Pratt and Whitney con cluded a licensing agreement witii Rolls-Royce which enabled diem to manufacture die Nene and Tay turbojets. Some tiiousands of these engines, Americanized as die J42 and J48, are now in service with botii die U.S. Navy and Air Force and, like all otiier Pratt and Whitney gas turbines, they are marketed under die name of Turbo-Wasp. By die summer of 1950, die great Willgoos laboratory was at work. But die company had decided die essentials of dieir first turbojet long before diis; in fact, components of the new engine— the J57—had already been made and were taken to the laboratory when it was completed. Pratt and Whitney have always concentrated on engines of high power and low fuel-consumption. The fact tiiat in filling both requirements die engine necessarily becomes relatively complex and expensive is considered a secondary matter. Accordingly, Pratt and Whitney aimed considerably furdier ahead tiian any body else in America in die sure knowledge tiiat the U.S. Air
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