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Aviation History
1945
1945 - 2007.PDF
394 FLIGHT OCTOBER IITH, 1945 AlRSCREWS Co. was developing an engine of this type, and it seems a pity that it was not encouraged officially. Mr. Fairhurst pointed out the safety advantage of this arrangement that in case one engine stopped, the other continued to drive its half of the airscrew. The drop in efficiency by having a feathered airscrew in front of the operating one was some 5 per cent. Reversible-pitch airscrews have come to the fore, and Mr. Fairhurst had something to say of them also. The two major problems to be solved by the airscrew designer were the need for very high rates of pitch change (40-50 deg. per second) to avoid over-speeding the engine, and the design of blades to take care of the higher blade-root stresses caused by the negative thrust. Many other aspects of airscrew design and construction were dealt with by Mr. Fairhurst, but space will permit of referring to one or two only. He paid a tribute to the compressed-wood blade, but thought that with speeds rising above 450 m.p.h. and demanding thinner sections manu- factured to closer tolerances the "wood blade would have to give way to metal. Duralumin blades would continue where the wood blade left off tor high-speed fighters, and would possibly be followed by hollow or even solid steel blades. The latter would be especially suitable for super- thin sections and should make possible thickness/chord ratios of 16 per cent, at the spinner circumference. De-icing was important because of the reduction in pro- pulsive efficiency arising from ice accumulation, and also on account of the serious vibration set up. The ultimate solution might be the thermal method in which a resistance element on the leading edge of the blade is heated by an airscrew-driven alternator. The only drain on the aircraft 3QOOO WBGHT FT. 2I5O-355OLB. DUMi 15O0-235O IB. WOOD DOUBLE FOUR WEIGHT IIOO-2IOO LB. DURAL 900-I+OOL8. WOOD IO.OOO 7OO- 93O LB. WOOD 6,000 HP DOUBLE FIVE WEIGHT I35O-45OOLB. DURAL HOO-25OO LS. WOOD DOUBLE FOUR .WEIGHT IIOO-25OOLB. DURAL 9O0-I650LB. WOOD. 8,000 H.P DOUBLE FIVE WEIGHT T5OO-5BOOIB- DURAL U7Q.T353OIB. WOOD DOUBLE FOUR WEIGHT I30O-2I00 LB, DURAL IOO0-I4OOL3. WOOO IO.OOO H.R i Pictorial analysis of future airscrew types for engines from5,000 h.p, to 10,000 h.p. If turbine units replace piston engines beyond 5,000 h.p., these weights will be on the highside. batteries was of about 90 watts to give 250 watts per blade. Eventually a separate alternator, mounted on and driven by the engine, might feed current to the blade elements via slip rings. RATIONALISING SERVICE QUALIFICATIONS WITH the rapid demobilisation of Service aircrew personnel,the need for rationalisation of flying qualifications be- comes more acute than it has ever been. A number of releasedR.A.F. pilots, for instance, will be hoping to obtain posts in civil aviation, yet will not expect to start, so to speak, fromscratch in the obtainment of the various necessary licences. The position has recently been somewhat clarified as far asnavigational qualifications are concerned. Until now it has been possible for those in possession of R.A.F. Air Navigators'Certificates to arrange with the Ministry of Civil Aviation for exemption from parts of the civil examinations, but the rightto such exemption has always been defined in terms of courses covered rather than of certificates obtained; tjjese-tetst-frav*fact, no value, in or out of the Service,--as a record of ficiency. Since the 20th of last mojotfi? however, the issue of'such certificates by the K.A.F...has been discontinued, and their place has been taken by. Navigation Warrantsbeing awarded to past and present navigators. Thcsp Warrants will be officially recognised in ciill avia R.Ae.S. LECTURE PROGRAMMET HE following lectures have been arranged by the RoyalAeronautical Society, for the present session, at the Insti- tution of Mechanical Engineers, Storey's Gate, St. James'sPark, S.W.I, at 6.30 p.m. A later one will be at the Institute of Civil Engineers, Great George Street, S.W.i. October 18th.—" Aircraft Engine Oil Cooling," by F. Nixon, B.Sc, M.I.Aut.E., F.R.Ae.S. November 1st.—"A Critical Review of German Long-range Rocket Development," by W. G. A. Perring, F.R.Ae.S. November 15th.—"Australia and Empire Air Transport," by W. Hudson Fysh, D.F.C. (First British Empire Lecture).November 2gth.—"Aspects of (Jerman Aeronautical De- velopment," by W. J. Stern. December nth.—" Meteorology and High-altitude Avia-tion," by Professor Dobson, F.R.S. Visitors will only be admitted by ticket obtainable throughmember of the society. D.H VAMPIRE PULL-PUSH : A rear view of the U.S. Navy's new Ryan Fireball, the FR-i, powered by both a Cyclone and a jet-propulsion unit. It is armed with four0.5m. m.gs., carries two 1,000-lb. bombs, and can fire rockets.
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