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Aviation History
1944
1944 - 1766.PDF
214 FLIGHT AUGUST 24TH, 1944 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. "PENNIES FOR PLANES" An Appeal by Air-Comdr. Sir Adrian Chamier MAY I, on behalf of the Air League, ask for the courtesy of your columns to persuade your readers and their friends tu take part in a great national scheme of Pennies for Planes? When you hear planes in the air to-day, remember that you owe your freedom to British aviation. To remind you of that debt look up and once, on every day that you see a plane (or many planes) in the sky, say " Thank you." At the same time, transfer a penny from your money pocket lo another unusual pocket—or if you are a lady, from your purse to a corner of your bag. You have paid your debt for the day. in the evening when you turn out your pockets or bag you will find this lone penny in an unusual place; put it in a match-box on your mantelpiece. Don't hoard your pennies; change them for a sixpence or a shilling as they collect. When you have half a crown take it to your local branch of the Air League or send it by postal order (crossed) to the Air League, la, Pall Mall East, London, S.W.i. ,Your money will be used to help thousands of young people lo karn to fly, and many hundreds of older people to experi ence the convenience of air travel at home or to Empire destina tions. In this way we shall stimulate an industry which will give employment to thousands of gallant airmen who are fight ing for us to-day. J. A. CHAMIEK. IDLE WILD AIRPORT Disposition of Runways I WOULD like, rather belatedly, to ask a question in con nection with the most interesting layout and article on Idlewild airport in your issue of July 6th. Using the rive E-W runways, saturation is estimated at 360 movements an hour, which implies good weather rather than t: J visibility conditions. But what happens when, owing to a change in wind, some aircraft have to use one of the long diagonals? It seems that either some aircraft will operate diagonally to others, or that all aircraft will be concentrated on to one runway. Neither alternative would leem satisfactory, as the one suggests danger and the other acute congestion, even if only for one day in the year. I feel that there must be an obvious answer which I have missed, because the point is of radical importance in the basic layout of all major airports. For balanced saturation I should have thought that an equal number of runways must be pro vided in all essential directions, except that this number may be increased in the direction or directions used under bad visi bility. In other words, the number of runways to be provided in a particular direction is not dependent on the wind-rose at all. Either there should be none, or there should be the appro priate number to give balanced saturation during every day • in the year. GRAHAM DA WBARN. JET PROPULSION FOR AIRCRAFT Balanced Pressure and Gas Velocity AS I have only now got hold of a copy of Flight for July •**• 20th, may I reply, rather late, to Mr. E. Burke? Without getting down to molecular motions (though gas pressure is, of course, produced by random molecular motions), but regarding the gases in the jet tube as simply a mass of. matter, I maintain that the inertia of that mass—its resistance to being accelerated astern—is the only "force" that can possibly balance that part of the internal pressure which is left "unbalanced" due to the existence of the open jet hole. The driving thrust, then, is impeller-pressure x area of jet. (The furnace is simply a volume multiplier.) And this thrust must be equal to P in the formula P — mf, where m is the mass being accelerated and / the acceleration. I have tried, with inadequate data alx>ut temperature, pre- sure gradient, etc., to estimate acceleration, and velocity after acceleration, along a reasonable length of tube, and have come to the conclusion that I was wrong in saying that I should be rurprised to find that velocity was not supersonic. It now appears to me that quite a good thrust can be got without supersonic velocity. Nevertheless, I feel that some qualification must be needed to the statement that sound-velocity is the greatest possible for gases emerging from a tube What about gases from a gun? Do they move slower than the projectile? . - My doubt about thrust augmentors was not whether they were worth while—admittedly they are not—but whether, in theory, they ought to be. By entraining air during the process of acceleration we increase m but diminish /. And any transfer of velocity from one body to another necessarily involves loss. Our object in a jet is to get the emergence-pressure as low as possible, which implies getting the velocity as high as possible. And entrainment of air inside the tube is clearly not compatible with that object. So that it appears that the only time when a thrust-augmentor might be useful is when emergence-velocity would otherwise be supersonic—supersonic to what, by the way, . the aircraft or the outside air? L. SHELFORD BIDWELL: 4 POST-WAR A.T.C. Already Working on " Empire " Lines Y OUR correspondent "Flying Citizen," in suggesting that the post-war A.T.C. might be established "as a truly Empire Youth Service in which young men of all the Dominions, Colonies, etc., could take part . . . even in the remotest corners of the Empire " is thinking on much the same lines as those on which the Corps is already working. Almost all of the self-governing Dominions, also India, already have their own Air Training Corps (or an equivalent), in most cases closely identified with their own Air Forces, and the several Corps are all enthusiastic about a close and friendly co-operation. A recent development is an exchange of news about A.T.C. and other air activities throughout the British Commonwealth. For its own part the A.T.C. is determined to do what it can within its field to make its own cadets '' Empire Air conscious " —if the phrase may be permitted. An exchange of cadets, possibly on an Empire Air Scholarship basis, is one of the possi bilities of the post-war A.T.C. Air Marshal Sir Leslie Gossage, Chief Commandant of the Corps, has recently urged every cadet to learn all he can about air developments in the Empire. "I believe,' he said "that Britain's future greatness will depend very largely on our air communications with the rest of the British Commonwealth, and the use which the Empire makes of the great air power we have built up together." W. STUART MASTERS. WHERE IS THE LUFTWAFFE ? A Possible Explanation RECENTLY a major topic of conversation has been " Where is the Luftwaffe ? " I would like to put forward a sugges tion as to the reason for its disappearance. When the Germans attempted to evacuate their troops from around Stalingrad the only possible way to do so was by air. As the Luftwaffe was short of transport aircraft, a large propor tion of the available bomber force was transferred to the job of extricating what they could of the surrounded German army. These aircraft were so slaughtered by the Russian pursuit 'planes and ground defences that the Luftwaffe's bomber force was so reduced as to be almost negligible. It was further depleted in Tunisia. In order to compensate for the loss in aircrews, the period of training was shortened. That was probably the reason why many of the German air craft which attempted to raid London just before the intro duction of the flying bomb did not press home their attacks, but jettisoned their bombs on meeting a heavy barrage. The German fighter industry was almost destroyed by the persistent attacks of the British and American bombers, and, realising that it would be impossible to meet our onslaught by sheer weight of numbers, the Germans decided to concentrate on quality, as shown by the evolution of the Messerschmitt Me 163 rocket-propelled fighter reported to be built on the revolutionary flying-wing principle. When (and if) our jet- propelled fighters join the battle our pronounced superioritM in quality will once again become apparent. Other suggestions as to why the Luftwaffe has not shown up in very large numbers may be put forward, but, as far as I can see, this is the most likely explanation. R. E. GREGORY.
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