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Aviation History
1945
1945 - 2183.PDF
486 FLIGHT NOVEMBER IST, 1945 CORRESPONDENCE The Editor does not hold himself responsible for the views expressed by correspondents. The names and addresses of the writers, not necessarily for publication, must in all cases accompany letters. THRUST AND GROUND SPEED Effect of Headwinds on Jet-propelled Aircraft HERE is a query which will probably amuse the No. 8 Hats,but which 1 imagine may have presented a little problemto many of Flight's less technical readers. It is simply this: Does a headwind have the same effect upon the ground speedof a jet-propelled aircraft as upon one driven by an airscrew? The question is prompted by the reflection that whereas anffirscrew exerts its thrust upon the air, the jet unit's thrust is pure reaction exerted within the aircraft and quite inde-pendent of the medium in which the aircraft is moving. Theoretically, an airscrew operating in a vacuum can exert nothrust because it has nothing to push against, but a jet unit can because (in the words of the immortal "Horace," was itnot ?) it " pulls itself up by its own braces.'' A beam wind will, of course, produce the same drift forthe same airspeed of both types, but it seems to me that in a headwind the airscrew is thrusting against something that isalready moving in the opposite direction in relation to the ground and thus part of the power exerted is used up before theaircraft begins to move forward in relation to the ground. In a jet-propelled aircraft, however, the whole of the thrustexerted is transmitted, through reaction, to the aircraft to drive it forward. Surely, then, if the power-output and theL/D ratio-are the same in each case, the ground speed of a jet-propelled aircraft will be greater against a given headwindthan that of one driven by an airscrew. After all, is it reasonable to say in one breath that a jet-reaction unit exerts its thrust independently of the surrounding atmosphere, and in the next breath claim that the result ofthe thrust is affected by the movement of that atmosphere over the earth? No " Aerobatic equations," please! Tell me in simple words.TYRO. TWIN TRAINERS Landing Technique with the Oxford I SHOULD like to correct the impression that "Indicator"gave in his article in your last copy of Flight when he stated that wheel landings are unfortunately taught at A.F.U.susing Oxford aircraft. In point of fact three-point landings are taught throughoutthe five weeks' period of day flying that pilots carry out on the A.F.U. course. During the two weeks' period of nightflying it is not considered essential that three-point landings be taught, as the tail-down type of wheel landing on theOxford is equivalent to a three-point landing on all twin- and four-engined Service type aircraft, except, of course, tricycleundercarriage types. This is purely to minimise the risk of damage caused by the comparatively quick drop on to threepoints if the aircraft is held off too high on landing, which is a common fault during the earlier stages of night-flyingtraining. '' Indicator'' also mentioned that the thumb must be on thebrake lever ready for use during a three-point landing, or at the end of a wheel lauding. The method taught at A.F.U.s isto use opposite engine to correct any swing that may develop; this method is usually quite successful, the brake to be usedonly if absolutely necessary, thus eliminating any risk of hosing over due to excessive use of brake. H. D. ROGERS.["Indicator" writes: "My remarks on A.F.U. landings were based on visual evidence rather than on any knowledgeof what should be taught. I accept the correction. As for holding post-touch-down swing on the engines, this may beexcellent in theory, but I never found the urge obtainable (particularly at very low speeds with fixed-pitch airscrews) tobe sufficient to deal with deviations other than those of a very gradual nature."] CAMPAIGN AWARDS Designed to Commemorate Victories 111AVE for weeks past read with mixed feelings the opinionsof your correspondents upon the award of campaign stars to aircrew personnel. May I endeavour to reply to these and also support Fit. Lt. Werner (Flight, October irth) ? Most of your correspondents do not realise that the campaign stars are to commemorate a decisive victory by our Forces, and as such are issued to personnel serving in those Forces up tothe time of victory. The Aircrew Europe Star is no exception. All your correspondents have forgotten that, for 4! years, adesperate battle raged over the skies of Europe. Upon the battle depended the outcome of all battles. So as the man ofthe 8th and ist Armies received recognition by the Africa Star, those aircrew who participated in the longest battle of the warand gained unquestionable victory over the Luftwaffe before D-Day receive their recognition with the Aircrew Europe Star. I feel sure that a man who joined the 8th Army after thefall of Tunis would not dream of claiming the Africa Star. I cannot, therefore, agree with '' Celer '' (Flight, October 1 rth),who apparently considers that all aircrew should wear the Europe Star which commemorates a victory achieved befortthey took up operational flying. Neither do I agree that the opposition after D-Day was heavier than before, and I am surestatistics would add weight to my opinion. Regarding the position of instructors, I agree that theydeserve recognition for their magnificent work, but I suggest- that as most of them receive either the A.F.C. or A.F.M. (thesemedals take precedence of those under discussion), their reward is ample. For my part I find, as do many others, complete satisfactionand content in being able to say, " I have been privileged to fly with the finest body of men in the world—the Royal AirForce." R. E. WAKEFORD (W/O.). SALUTE THE AMATEUR A C^A.G. Pilot's ExperienceI READ with much interest Indicator's "Salute theAmateur" (Flight, October 18th). The C.A.G. scheme enabled myself and a friend to take up flying and obtain our"A" licences, but when waT broke out we were both con- sidered too old for flying with the R.A.F., and at that timetoo inexperienced to join A.T.A. In 1941, however, when we had both grown a bit older, we were invited to join the R.A.F.and serve for three months as Link instructors, afterwards to become non-operational pilots. The gentleman at the Air Ministry told his tale well and weboth became L.T.I.s. When we tried to remuster after three months, however, we encountered many snags! My friend,taking advantage of our terms of entry, gave up the R.A.F. in disgust and joined A.T.A., where he made speedy progressand flew many types. He was killed—lost at sea—-whilst on ferry duties after the war in Europe had ended. After numerous applications and representations to put meon flying duties or give me my release, I finally made it after twelve months "binding." After that all went well and 1served as an elementary flying instructor, obtaining an A17, category until the intensive glider expansions in 1944. TheS*with others, I was given a flip or two in a glider and became a glider instructor. Some of us also lent a hand at tugging whenoccasion arose. After being awarded the A.F.M. for my ser- vices I was, because of my great age (41), declared redundantand posted to a holding unit, though my own station was one of the few ia Training Command still working at full pressure. Notwithstanding some 2,000 hr. of accident-free flying, anA2 category and an AiB medical category, I found myself on the " deck," where I remained in comparative idleness untilmy release. While I am grateful lor the experience, even in a non-opera- tional capacity, I still feel that the R.A.F. could have made quicker and better use of us if they had accepted us at the out- break of war. As it is, a great many of us seem to have achieved our usefulness not because of the R.A.F. but in spite of it! EX-AMATEUR. REFUELLING IN FLIGHT A System with Dual AdvantagesI N reply to the criticisms of F. Humley (Flight, October i8th)of refuelling in flight, it appears he has not realised that this method is not only a method of "assisted take-off," buta method of safely increasing pay-load by reducing fuel load. It has been shown that over a given distance with onerefuelling the fuel load can be decreased by one-third, taking into account the safety measure of returning to base if contactis not made. With present machines this saving means bv far a greater increase in pay-load than it did with pre-war
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