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Aviation History
1946
1946 - 0993.PDF
andAIRCRAFT ENGINEER Editorial Director Editor Assistant Editor - Art Editor - G. GEOFFREY SMITH, M.B.E. C. M. POULSEN MAURICE A. SMITH. D.F.c (W/NG CDfi., H.A.F.V.R.) JOHN YOXALL FIRST AERONAUTICAL WEEKLY IM THE WORLD ; FOUNDED WOQ Editorial, Advertising and Publishing Offices: DORSET HOUSE, STAMFORD STREET LONDON S E1 Telegrams : Flightpres, Sedist, London COVENTRY : BIRMINGHAM, 2 : 8-10, CORPORATION ST. KING EDWARD HOUSE, Telegrams: Autocar, Coventry, T ,E W . S T RD.E .E J • T, , _ '' Telegrams: Autopress, Birmingham.Telephone : Coventry 5210. Telephone: Midland 7191 (7 lines). Telephone : Waterloo 3333 (SO line*.) MANCHESTER, 3: GLASGOW, C.2 • 260, DEANSGATE. 26B, RENFIELDST. Telegrams: Iliffe, Manchester. Telegrams; Mine, Glasgow. Telephone: Blackfriars 1412. Telephone: Central 4857. No. 1952. Vol. XLIX. SUBSCRIPTION RATES : Home and Abroad : Year, £3 I 0. Registered at the G.P.Q. as a Newspaper May 23rd, 1946. f> months, £| 10 t. Thursdays, One Shilling. Outlook Rocket Power for AircraftT ECHNICALLY the rocket-propelled Me 163 inter- cepter, discussed together with other rocket fighters in this issue, was one of Germany's most creditable achievements. Tactically its value was never proved, due principally to shortage of concentrated hydrogen-peroxide, hydrazine-hydrate and methanol for its Walter rocket. Willy Messerschmitt regarded it as an unwelcome and unpromising stepchild, left on his doorstep by Lippisch, and fumed at its adoption; his own conception of a target-defence intercepter was an Me 262 with one or two auxiliary rockets giving a rate of climb of over 9,000 ft/min. The prospects for this class of aircraft, lately discussed by Mr. W. G. Carter, were considered by the Germans to be such that development of pure-rocket fighters with their severely restricted endurance was slackened, but, significantly, rocket power was specified for at least two prototype aircraft of exceptional interest. The first (D.F.S. 228) was a pick-a-back-launched reconnaissance machine to operate between 60,000 and 80,000ft and capable of protracting its endurance by glides and zooms ; the second (D.F.S. 346) was intended solely for super- sonic research flying. Likewise launched by a parent air- craft the 346 had twin rockets and it was hoped to develop it for flight at Mach 2.6 at 100,000ft (1,700 m.p.h.). The pilot lay prone in a jettisonable pressure cabin and special precautions were taken to protect him from the heat developed by skin friction. For aerodynamics research machines such as the 346, propulsive rockets offer tremendous thrust for small size and weight at the expense of heavy, but acceptable, fuel loads. The turbine jet is not yet a serious competitor in this field, though the athodyd (ram jet or propulsive duct) may eventually be preferred for certain purposes. What- ever the ultimate application of the rocket power for air- craft, the time is ripe for the fullest investigation of its possibilities. Why Helicopters ?A NYONE who^as examined the mechanisms of a helicopter might well wonder if all this complica- "" tion is really going to lead us to the desired goal. The transmission to the main rotor is an involved and highly-stressed piece of ironmongery. In addition there is, in most single-rotor types, an airscrew at the back, the sole purpose of which is to counteract the torque ol the main rotor and give directional control. It is driven through a long shaft with universal joints, and the pitch control for it has to run the whole length of the fuselage. All this spells weight and cost, and it does appear that the small helicopter for two or three people will, on this account, always be very expensive to buy and will re- quire a lot of maintenance. In the larger class these objections may not be quite so serious, because these machines will, presumably, be used for commercial work and thus have a chance of earning their keep. But for the private owner these considerations will be all- important. In the somewhat unwarranted enthusiasm for the heli- copter, the airscrew-propelled type with '' windmilling'' rotor seems to have come to be regarded as a back number. But is it? What does the helicopter have to offer which such types as the jump-start Cierva Auto- giro and the Hafner Gyroplane cannot achieve? It can rise vertically and descend vertically, while the others do need a certain amount of forward speed. This advantage looks very attractive, but in practice it is not nearly so great. The most dangerous period of a helicopter's flight occurs during vertical ascent in still air. If the engine should stop before a height of 200--300 ft has been reached, there will be what Mr. Hafner recently termed '' a discontinuity in the flight path " ! No matter how quick the pilot is in getting his rotor into fine pitch for auto rotation, the machine will hit the ground before it can gain sufficient forward speed. Thus the vertical ascent in still air should only be under-
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