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Aviation History
1941
1941 - 0739.PDF
MARCH * 1941. Topics of the Day 241 UP AND UP. . and Down and Down—in the Seat : A Few Facts and Curiosities About Height and "G" Effects QUITE a long time ago it was necessary for earnest" A " licence aspirants to climb to the dizzy heightof 6,000ft.-odd before making a spot landing (if the instructor happened to be watching) on the aerodrome in order to qualify. Possessed of the urge which sent Professor Picard up to rather higher levels, I took the opportunity of obtaining a new experience and klimbed.j almost as high as a Mark I Cirrus flioth would go.\ Sj?-- The desire was a direct reaction of hundreds of c\ci^& and landings from an average height of a thousand Met. The figure reached was the |menomenal one of 9,qpoft.t at which I stalled the Motb/and\ lost sot mu<jh heistft that I had neither the time ndr the mone]| to cont^riie the experiment. The mental and physical effects, however, to one unaccustomed to such things,* excetft in the/slow pro-.*' cess of mountain climbing, were remarkable. / J It was a hot, still day with a good deal of=%round mist and an absolutely cloudless sky. At the time I put down a feeling of intolerable loneliness &$&.' strong sense of unreality to the fact that I had only-done three hours solo and was still unused to the empty appearance of the front seat. Since then I have realised that the strange- nesses were very largely due to comparative lack of oxygen —the effects of which are very similar to the early stages of alcoholic intoxication. The sense of loneliness was merely a sublimated impression. I found that I was no longer particularly interested in anything and had lost the sense of danger, and I naturally put these feelings down to the fact that the earth was a very long way off. I remember trying to work out the effects of height on A.S.I, indications—hence the stall—and finding myself not only unable to do so, but not particularly interested. Adaptability Since that day—I had earache and a headache for several hours afterwards because I was foolish enough to lose the whole of this prodigious height in a matter of seven minutes—I have made myself accustomed to rather greater heights, but the same impressions can be obtained at 15,000 and more feet. It is remarkable how the human machine becomes used to bad treatment; one can dive from 10,oooft. to ground level and clear the ears with a mere swallowing motion. Experienced fighter pilots can probably double the height and increase the steepness <*f dive without even that aid to the Eustachian tubes. The ears, however, are not fed with oxygen, and the feelings which I have described of an amateur attack on the stratosphere must still be apparent to the most ex- perienced pilots at some particular height. The wretched human machine cannot possibly take it indefinitely. Hence the fact that fighter pilots are, I believe, fed with oxygen more or less from the ground upwards. There would obviously be no sense in feeding it suddenly at the height at which it is required. Apart from the fact that this height varies with individual tastes, it is necessary for these pilots to be absolutely on the top line from the moment they leave the ground, and the man with no oxygen at even 8,000ft. is going to be less efficient than another with such an amenity at the same height. Since fighters cannot possibly carry an unlimited amount of equipment, somebody should invent-—and probably has —an oxygen economiser. Both to regulate the amount automatically according to height and also to do away with the waste products so that the pilot is not breathing oxygen and his own exhalations at the same time. With most of the air battles taking place at 30,000ft. and more such a device may win or lose a private war, and even the modern long-range high-altitude fighter cannot carry an unlimited supply of oxygen bottles. Whkh reminds me that, long ago, in the days when it was possible to talk freely about such things, Farn- borough or someone produced a decompressor of great complication and excellence. For those who don't know a decompressor—divers excluded—I might explain that it is jp. think) a device by which pilots can, on the ground, b£ given all the impressions of a flight at, say, 20,000ft. Without, in fact, leaving the ground. Thus saving a great '/deal of expense in the training of unsuitable pilots who , might be left to do a useful job of different work The decompressor is merely a chamber in which the pupil sits while the air pressure is slowly reduced while he i^required to do a series of exercises to test his reactions as the pressure is reduced or the height increased. Oxygen supplies do fail. I believe that the results of exercises -at fairly considerable heights are quite surprising. I know that if you go up, say, to 15,000ft. and start to think about instrument readings it is almost impossible to do so, and at 20,000ft. it is not always possible to distin- guish between, say, the oil pressure and the A.S.I, readings without a great deal of painful concentration. It simply doesn't appear to matter. "The oil pressure reading, old boy, old boy, is just as good; and anyway, I don't care very much." Decompression One of the little tests concerned involves leaving one pupil outside while the other is decompressed. They are both required to carry out the same mental exercises and the times are compared at different heights. The man outside may laugh as he sees the other struggling to add 5 and 7 and to divide by 2 at 21,00'oft., but when his turn comes the story is very much the same in reverse. From what I hear the Farnborough decompressor, though an excellent device, is somewhat expensive, and I wonder whether a firm specialising in scientific gadgets couldn't redesign the thing and produce, say, a couple of hundred at a reasonable price. Then it would be possible for all F.T.S.s, and certainly Operational Training Units, to have one in the same way in which each of these now has a Link Trainer or two. Incidentally, there was a certain amount of silent derision when Mr. Link's instru- ment trainer, with its Wurlitzer organ mechanism and its funny little aeroplane, first appeared in this country. They've proved themselves to be fairly useful and they certainly relieve the tedium of bad-weather days. A somewhat analogous device might be invented for testing pilots' reactions to the effect of g. The.physical results of lack of oxygen and increase of g are vaguely similar, and the latter effects are far more important in their relation to air fighting, since the man wiio can stand the tightest turn may, other things being equal, win an individual fight. Needless to say, structural strength has increased far beyond the limits of human endurance, though some types are so designed that buffeting and forced stalling effects in turns beyond 5^ or*" so are so marked that there is little point in trying to out-turn an enemy. Other tactics or advantages must be brought into action. Nevertheless, g is a very important factor at all times, and I believe that a good deal of research (undoubtedly being carried out) would be worth while. The work should start with a study of the human reactions. The results, with suggestions, could be passed on to the designers. Special air-fighting postures might be devised and the , position of the pilot's seat might be reconsidered in rela- tion to the e.g.—though I doubt, with my weak scientific mind, that the latter can possibly have any bearing on the matter. On the one occasion when I rode in the tail turret of a Virginia, a series of steep turns made me feel even more unhappy than usual, and in that turret one couldn't possibly be farther away from the e.g. INDICATOR.
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