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Aviation History
1961
1961 - 1404.PDF
"r /7//77//7////////Z77. UNFAVOURABLE FAVOURABLE NEGLIGIBLE Examples of VTOL configurations having negative, positive and negligible ground e/fects from the paper "Ground Proximity Effects Associated with V/STOL Aircraft" (John P. Campbell, NASA Langley Research Centre) VTOL PROBLEMS DISCUSSED... V. K. Merrick of Hawker Siddeley Aviation, and A. R. Howell ofthe National Gas Turbine Establishment. They concluded that, if a performance better than about 1,500ft to and from a height of50ft were required, some form of deflected thrust system must be used. Whatever the system chosen, it appeared that it would alwayspay to deflect the thrust that was installed for the normal parts of the flight plan. In almost every case it would also pay to choose thepowerplant from cruise and climb considerations rather than degrade these for airfield performance. If a performance better than 1,000ft were required, more thrustthan was normally needed for climb and cruise must be installed, and the authors' studies led them to suggest that this additionalthrust might best be provided by specialized lightweight lift engines. In this way it should be possible to minimize the total installedweight of the propulsive/lift system without greatly affecting the climb and cruise performance. General Discussion Among the points arising in the various discussion sessionsfollowing the V/STOL papers at the conference, it was emphasized by Mr F. B. Greatrex of Rolls-Royce and Mr Cochran of GeneralElectric that the effective use of VTOL machines for commercial transport depended on operation between city centres. Mr Greatrexsubmitted that two major problems made this development extremely difficult: these were the factors of noise and of engine-outsafety. Mr Cochran mentioned that the tip-turbine lift-fan com- bination was less noisy with engine and fan running than withthe engine alone, and agreed that, until the noise problem was solved, practical operation between city centres would not be possible. Onthe subject of engine-out safety, he reaffirmed his opinion that the lift fan should be considered in broadly similar fashion to the heli-copter rotor, although the former was less complicated in many ways. The type of operation for which VTOL aircraft would be econo-mic, Dr T. P. Wright of Cornell Aeronautical Laboratories sug- gested, was that of local services for stage lengths between 50 and300 miles. For smaller distances the helicopter would be more efficient, while for longer distances more-conventional aircraft weremore economic. Dr Wright, also, made the point that safety was the key factor in obtaining city-centre operation, either by the use ofmultiple engines or otherwise. ////////////////////////////A1///:/,////////////////////My//////////////////////, Flow recirculation pattern of tilt-duct configuration in banked attitude. An example of this type tested at Langley is the Doak VZ-4 The respective merits of using a large number of separate liftengines, and of combined lift/propulsion powerplants using a deflected jet, were argued more than once during the meeting byRolls-Royce (Mr Pearson) and Bristol Siddeley (Dr S. G. Hooker). Mr Schairer of Boeing said that he was cautious, not about thepowerplant, but about the aircraft/powerplant combination. He refused to vote for a particular engine choice until he knew whatthe aircraft would look like. At present this was uncertain. Mr Schairer asked why, if one had a jet engine driving a lift fan fortake-off and landing, one did not keep the fan running during the whole of the flight. Mr Schairer suggested that we might really be seeking somethinghalf-way between the respective schemes favoured by Mr Cochran and Mr Greatrex. One difficulty was the problem of where to addthe lift units: they could be carried externally, but this would increase drag; while if they were installed inboard the aircraftstructure weight must be increased. For the effective development of VTOL aircraft, the speaker suggested that specific jobs should bedelineated; different requirements applied, for example, to city- centre transports, army reconnaissance aircraft, and ground-supportmachines. An American speaker mentioned the successful flight record ofthe Doak VZ-4 tilt-duct aircraft flown by NASA at its Langley Research Center. In spite of what Mr Schairer had said, thepropeller shrouds on this machine did not stall, even at extreme angles. The power margin was adequate to give safety on theapproach in the event of failure of one engine, but the speaker agreed that a failure in the power transmission system during the shortcritical period at transition could be catastrophic. Mr N. E. Rowe of Hawker Siddeley Aviation commented thatit seemed that aircraft were now to be made to take the engines of the engine manufacturers, and the lift from the wings was becomingunimportant—a point denied by Mr Sutcliffe. In the civil field. Mr. Rowe suggested, economics were of prime importance: itappeared that 1,000-1,500ft take-off distances might well suffice. Mr D. M. Jameson of the Air Registration Board asked whathappened to the STOL aircraft when it met a tail-on horizontal gust. He felt that the g allowance must depend on the stallingcharacteristics, and that the assumption made in the studies by Sutcliffe et al would only hold for civil aircraft if the stall weremild and gave reasonable warning. Paper studies were insufficient, said Mr R. A. Shaw of theMinistry of Aviation. The airframe designers must get down to actual powerplant installation design in order to ascertain theinstallational problems, weights and volumes involved. FORTHCOMING EVENTS Oct Oct Oct Oct Oct Oct Oct Oci Oct Oct Oct 2-7 4 4 4 5 5-6 ( 7 7-8 10 II Oct 12th International Astronautical Congress, Washington DC. London Society of Air-Britain: Sixth Annual Test Pilots' Forum. BritIRE: "Methods Used for the Study of Vibration in Aero Engines," by D. A. Drew. Kronfeld Club: Debate on "Gliding should be Government Subsidized." International Airline Navigators Council: Pacific Regional Meeting, San Francisco. Aerodrome Owners Association (Leeds and Bradford): Conference, Harrogate. RAeS Rotorcraft Section: "Integrated Flight Systems for Multi-engined Rotorcraft Transports," by N. Sullivan, J. A. Simpson and a US representative. Kronfeld Club: Annual Dinner and Dance. Genoa Rally. RAeS (Luton Branch): Film Evening. BritIRE (South Western Section): "General Introduction to Inertia! Navigation," by R. Collinson, and "Components and Techniques Employed in Inertial Navigation Systems," by E. Bristow. Kronfeld Club: USAF Film Evening. RAeS Agricultural Aviation Group: "Agricultural Aviation in New Zealand," by G. G. Lindsay. RAeS (main lecture at Isle of Wight Branch): "Experiences in Constructing and Flying Bell's Recent VTO Aircraft," by J.O'MalleyJr. Guild of Air Pilots and Air Navigators: Lecture, "Stress and Human Performance," by Air Cdre W. K. Stewart. Radar and Electronics Association: "Space Communications" Part I), "Systems and Equipment," by L. F. Mat hews. RAes Astronautics and Guided Flight Section: "Packaged Liquid Rocket Propulsion Systems," by W. N. Neat and K. G. Page. Kronfeld Club: "Indian Expedition," by Brennig James. RAeS: Fifth Lanchester Memorial Lecture, "From Ship Accompanying Waves to Shock Waves of Supersonic Aero- planes," by R. Legendre. International Airline Navigators Council: European Regional Meeting, Paris. Kronfeld Club: Annual General Meeting. RAeS Historical Group: Lecture by Sir Frederick Handley Page RAeS Branch Fixtures (to Oct S): ,Oct 2, Derby. "The SCI," by D Keith-Lucas. Oct 3, London Airport, "The D.H.I2I," by J. P. Smith. Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct II 12 12 12 16 18 19 23-24 2530
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