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Aviation History
1957
1957 - 0153.PDF
FLIGHT, 1 February 1957 155 V.T.O.L. Powerplants Novel Suggestions from an American Engine Manufacturer ON Wednesday last, at the Institute of the Aeronautical Sciencesmeeting in New York, Mr. P. G. Kappus of the General Electric Company's Flight Propulsion Laboratory Department,was due to give an outstanding summary of the powerplant layouts which can be considered for V.T.O.L. aircraft. A summary ofhis paper follows. He began by saying that, in the military field, there was anurgent need for increased mobility and dispersal; and while the helicopter had proved of tremendous importance to the armedforces it had inherent speed limitations and made very high demands on skilled maintenance. From true V.T.O.L. systems avariety of support vehicles as well as combat types would emerge, combining high subsonic as well as supersonic speed capabilities,with no need for runways. Possibly even greater was the importance of commercial andcivil V.T.O.L. vehicles. High-speed V.T.O.L. feederliners promised to replace not only the airport-city coaches, but also theshort-haul transports on to stage-lengths of up to several hundred miles. It might come to pass that fewer and larger airports wouldeach serve several cities about 100 miles away. Big, supersonic airliners would operate medium and long-range services whileV.T.O.L. feederliners would provide inter-city and city-airport transport Mr. Kappus also suggested giving the family-car true V.T.O.L.capability: "Looking ahead twenty to thirty years 3 here's anopportunity for true progress that may well dwarf the tremendous evolution that started with Henry Ford's Model T." The lecturer emphasized that "Practical V.T.O.L. capabilitywill be reached only through powerplants of extremely low weight, combined with acceptable cruise fuel consumption. It would notbe achieved through the use of present conventional engines." Although money was being spent to develop radical V.T.O.L.airframe concepts, not enough was being done to find the pro- pulsion system. Turning his attention to methods and arrange-ments, Mr. Kappus said, "Our latest engines build up much of their required high-speed thrust as a result of their own speed ina fascinating boot-strap operation. The thrust at high supersonic Mach numbers has little relationship to the take-off thrust, and wecan visualize engines powerful enough to propel airplanes with Mach numbers as high as the structure can stand, and yet deliver-ing a take-off thrust considerably below gross weight. Another point is that there are a great many important applications forV.T.O.L. where supersonic speed is not needed, and where cruise thrust requirements are quite modest. In this case, a propulsionsystem of extremely wide power range is required, combining very high take-off thrust with a cruise thrust, at good fuel economy,of less than 10 per cent of full power. Here, the required flight performance of the engine is far under the power level needed O« OMMATOR _TL TURBOJET TURBO-FAN TURBOPROP THRUST VECTORCONVERTER ATTITUDE CONVERTERS W SEPARATE-THRUST gagft.1—4 L M TURBO-FAN P Q AIR- BREATHERS WIN6 - SUPPORTED A Rotating engine mount. B C D E F G H J Cascade deflector. Rotating tailpipe. Fan-lift, conversion jet. Fan for lift ond cruise. Mechanical propeller interconnection. Pneumatic propeller interconnection. No propeller interconnection. Jet tail-sitter. THRUST-SUPPORTED K Propeller tail-sitter. L Mechanical fan drive. M Pneumatic fan drive. N Jet cruise, jet lift. O Jet cruise, rocket lift. P Turbojet. Q Shaft turbine. R Rocket. Fig. 7. The V.T.O.L-propulsion family. for V.T.O.L. V.T.O.L. will not just happen. We have to makea determined effort to create propulsion systems with novel and very specific characteristics, representing a new advance in power/weight ratio which combine efficiency at very low partial load with tremendous take-off power. "One of the most important objectives in the near future shouldbe a thorough investigation and evaluation of the most promising V.T.O.L. engine systems, properly matched with airframes thatutilize their inherent capabilities to the fullest extent and result in the ideal engine/airframe combination for the various militaryand commercial requirements. Fig. 1 presents a 'family tree' of V.T.O.L. engines that shows quite some variety in the pro-pulsion field. Our tree has two main branches, leading to engines for wing-supported systems on one side and for pure thrust-supported vehicles on the other." Fig. 2 (left). Turboprop for V.T.O.L. aircraft. Principle: Two or four pneumatically interconnected propeller turbines powered by a common gas generator. Application: Tilt-wing or deflected-slipstream aircraft. Fig. 3 (below). Turbojet propulsion. Principle: Four lightweight turbo- jets for take-off and landing (two shut down, two produce thrust during cruise). Application: Fixed-wing high-speed, with short hovering time. 7 ENGINES FOR CRUISE & HOVERING 3 ENGINES FOR HOVERING ONIT REACTION CONTROL CRUISE NOZZLE HOVERING CASCADES
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