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Aviation History
1957
1957 - 1039.PDF
26 July 1957 129 In production for the U.S. Navy as the powerplant of the McDonnell F3H Demon, the J71-A-2 bears little resemblance to the non-afterburning 171 depicted below. In this photograph the hot parts are covered with heat-reflecting metal foil, the propelling nozzle being on the left. Allison J71-A-11. Single-shaft turbojet. Sixteen- stage compressor, cannular combustion chamber with ten flame tubes and three-stage turbine; variable-area propelling noizU for establishing optimum conditions. Diameter, 47.6in overall (37in basic); length, 191in with extension pipe (172in a« shown); dry weight, 4,090 Ib; mass flow, about 160 Ib/sec; pressure ratio, 8.3:1; maximum thrust, 10,200 Ib at 6,100 r.p.m. with s.f.c. of 0.8. AIRCOOLED MOTORS (FRANKLIN ENGINES). AircooledMotors, Inc., Liverpool Road, Syracuse 8, N.Y. Since World War 2 Aircooled Motors, as manufacturers of the well-known range of Franklinengines, have become the dominant firm in the propulsion of American helicopters in all but the largest sizes. In fact, two years ago the companyissued a claim that three-quarters of all the helicopters of American design then flying were powered by their engines—Bells and Hillersbeing predominant. In our aero-engine review of April 9, 1954, we described the most-used helicopter engine, the 178 h.p. Franklin 6V4. The most important unit to have been developed during the past year is the "Turbosuper-charged 335." Equipped with an exhaust-driven turbo-supercharger, this engine is noteworthy for its compact design; it is expected that itwill be directly applicable, without airframe alterations, to helicopters at present powered by Franklin 200 engines (6V4) and that the installedweight will be only 40 lb greater. Full performance of the turbo- supercharged engine is not yet forthcoming, pending certification, butAircooled Motors are prepared to state that it will have a minimum sea-level rating of 210 h.p. and that it will maintain this rating to analtitude of 12,000ft. ALLISON. Allison Division of General Motors Corpn., Indianapolis6, Indiana. It is no longer possible for a small or weak organization to undertake the development of advanced aircraft powerplants. As adivision of one of the world's biggest companies, Allison should be placed in an increasingly strong competitive position, but their pastperformance has not been outstanding. After having delivered many thousands of liquid-cooled piston enginesduring World War 2, the company entered the gas-turbine business in 1946 by being assigned the task of developing and producing the J33and J35, both of which had been designed and developed by General Electric. With these two engines Allison have built up an outstandingrecord of production and field-service. The company's weakness— which strong measures should now have cured—has been their inabilityto design a competitive engine of their own. Earliest of the home-grown Allison gas-turbines was the T38 turbo-prop, which was developed in coupled form as the T40 described below. This family of engines eventually led to the more advancedT56 which, as a result of protracted and painstaking development, is now serving as an acceptable and efficient powerplant in the militaryC-130 transport. Great efforts are now being expended in producing from it a powerplant for airline use designated Allison 501. Further-offin development is a more advanced turboprop, together with the coupled T54. Turbojet development has been centred on the J71 engine and aspecial version of the J33 for the propulsion of missiles. Today large- scale development is in hand upon exceedingly powerful turbojets forsupersonic applications and leading eventually to engines powered by high-energy fuels. This work is being undertaken under contract toboth the U.S.A.F. and U.S. Navy, but it is reported that the company have failed to win the important contract for the WS-110A powerplant. Putting Allison's house in order is a tremendous task which has beentackled in a most business-like manner and on a scale which few but General Motors could afford. Research and development ability hasbeen enormously strengthened during the past 18 months both in respect of facilities and staff, and an initial outlay of $75m of G.M.money has been set aside to finance the bulk of the expansion and the initial development of four major engine projects. The company's tech-nical staff is extremely active and is working along a broad front, but the level of production is never again likely to match that which hasbeen maintained since 1946. J33. A simple centrifugal engine stemming directly from the workof Whittle, the J33 was the first gas-turbine to go into production in America. It is also the only American-designed centrifugal turbojet tohave gone into service. Total production is now approximately 15,000 and a fair number remain to be delivered. Many thousands are in service in Lockheed T-33 trainers and theirderivatives, and in several types of Grumman naval fighter. An overhaul period of 1,200 hr has often been achieved by these engines. More than2,000 special J33s have now been delivered for the propulsion of cruise-type missiles, particularly the Martin TM-61 family of Matadorsand the Chance Vought Regulus 1 of the Navy. Typical of the missile engines is the J33-A-37, rated at 4,600 lb at its one and only throttleopening. Without affecting reliability Allison have substantially reduced the cost of the missile engine, the main requirement specifying a totallife of but five hours. A high proportion of the missile engines are shipped direct from the factory for installation and testing by enlistedmen in field squadrons. J3S. A standard U.S.A.F. axial engine rated at 5,600 lb dry and7,200 Ib with afterburner, this engine remains in wide service in such aircraft as the F-84G and F-89. Total production amounted to morethan 14,000 when contracts were completed in the summer of 1955. J71. In the development of this turbojet Allison attempted to obtaina high pressure-ratio from a single-spool engine without using variable- incidence stators, and the development of the unit has been somewhatprotracted. The J71 first ran in 1950. It is now in moderately large production in two major versions. Onemodel, the J71-A-9 or -11, powers the Douglas B-66 series of multi- purpose U.S.A.F. aircraft. Very different in appearance are the versionswhich are being delivered to power the McDonnell F3H Demon transonic fighters of the U.S. Navy. Typical of the fighter engines is the J71-A-2,which, with its afterburner, has an overall length of 284.6in and weighs 4,869 Ib for a reheat thrust-rating of 14,000 Ib. In addition to theseunits many J71s were installed in early SM-62 Snark missiles and a small number were built for the early Martin SeaMasters. Of theseapplications only the B-66 and F3H are of importance, and both aircraft will cease to be built next year. J89. Not yet officially announced by Allison, numerous reportsdescribe the J89 as a large high-pressure two-spool turbojet with a design-rating of 25,000 lb. Sponsored by the U.S. Air Force, it isdescribed as "a kind of prototype" intended to lead to a unit suitable for use with high-energy fuel in the WS-110A programme. As suchit is in competition with General Electric projects; and, despite a favourable technical evaluation within the U.S.A.F., the Allison designis reported to have been rejected. Were it to go forward it would do much to keep Allison working nearer to capacity. Navy Turbojet. Since 1954 Allison have been under contract to theU.S. Navy to develop a high-pressure turbojet in the 25,000 lb-thrust class. At the time of design this was the largest projected engine in theWest. A considerable amount of company money is reported to have gone into the programme but complete cancellation was reported tohave taken place in the spring of this year. Missile Turbojet. Two months ago it was unofficially stated thatAllison were developing a lightweight, short-life turbojet matched to the requirements of certain species of missile. Thrust was placed in the3,000/4,000-lb bracket and it was inferred that the engine would provide cruise propulsion for a supersonic air-launched weapon. Allisonwere claimed to hold a development contract. T40. Little further work has been done on this coupled turbopropduring the past twelve months. Substantial flying-time has now been logged by the T40-powered R3Y boats of the U.S. Navy and reliabilityis satisfactory. T54. Consisting of two T56 power sections coupled to a singlepropeller-shaft, this 7,500-h.p. powerplant is still an active project. It is scheduled to power an XF-84H test-bed, in which it will be matchedwith a supersonic propeller. T56. During the past year this attractive turboprop has flown some60,000 hr in the Lockheed C-130s of Tactical Air Command, and the rate at which flight-time is being increased is rising rapidly.Its configuration is similar to that of the commercial Model 501 (illustrated) except for the location of the reduction gearbox above thepropeller-shaft to permit the intake duct to lie underneath. The engine is installed as a self-contained "package" complete with 15ft-diameterAeroproducts propeller. Flight-operations are conducted entirely at 13,820 r.p.m. with the propeller turning at 1,106 r.p.m. The singlepower-lever governs the fuel flow, and automatically alters the propeller pitch to suit the ruling flight condition. Model SOL Now in an advanced stage of development, the Allison Allison Model 501-D13. Single-shaft commercial turboprop. Fourteen-stage compressor, cannular combustion chamber with six flame tubes and four-stage turbine. Width, 27in; height, 36in; length, 145.2in; dry weight, 1,750 Ib; mass flow, 39 Ib/sec; pressure ratio, 9.25:1; maximum rating, 3,740 e.h.p. (3,460 s.h.p.-l- 726 Ib) at 13,820 r.p.m. with s.f.c. of 0.54; maximum continuous cruise rating at 25,000ft at 360 kt, 1,850 s.h.p. + 145 Ib, also at 13,820 r.p.m., with s.f.c. of 0.458.
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