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Aviation History
1940
1940 - 1911.PDF
JULY 4, 1940, DECOMPRESSION in the R.CA.R The Value of the " Altitude Chamber By LEONARD ENGEL AN investigation in aero-medicine, fraught with jr\ significance not only for aviation but for general medicine as well, has been quietly begun in Canada under the sponsorship of the Royal Canadian Air Force. Hundreds of embryo Canadian pilots under the Com- monwealth Air Plan are receiving part of their training in an altitude chamber which, in effect, takes them up to 30,000 feet without leaving the ground. Detailed records of the high* altitude efficiency of each man with and with- out an ox 'gen mask, as shown in the chamber, are being kept and will be related to his subsequent Air Force per- formance. Within a few years, therefore, Canadian investigators will have accumulated a mass of data covering thousands of airmen, which may go far toward answering one of aviation's oldest questions: how can the man who will"not make a safe or competent pilot be detected in advance? A satisfactory solution to the problem would save both lives and money. The chances of war destroy part of the value of the service records as applied to men on active service, but accidents or their absence from a man's training log should have some con- nection with his efficiency under the high altitude test. _.:,:. To the Sub'Stratosphere Use of altitude chambers for study of oxygen starva- tion and similar problems is new neither in Europe nor in North America. Four other chambers, beside the R.C.A.F. unit, have been in service in North America for some time—at the Mayo Clinic, the Harvard Fatigue Laboratory, the U.S. Army Air Corps aviation medicine station at Wright Field, and at the United Air Lines' Laboratories in Chicago. But this is the first time that such studies have been carried out on a large scale, at least outside of Germany. The Reich has altitude chambers. It also has able scientists, so similar work is probably under way there. The two-hour "trip to the sub-stratosphere," made by an average of sixteen air recruits a day, is also used for teaching the men how to use oxygen masks properly, and what to do about rapidly changing altitude with its effects on ears, sinuses and abdomen. The test is run as follows: — Four men, plus a trained observer who is on hand to make sure that nothing goes wrong with anyone, enter the chamber, and after being shown how to use the oxygen mask, they begin their "ascent" at a rate of about 2,000ft. a minute—pumps, in other words, exhaust the air to simulate air pressure changes in a 2,000ft.- minute climb. At 5,000ft. a stop is made, and the men take a simple code test, which is accepted as the form for each individual. The ascent is then resumed up to 17,000ft. without oxygen, to show the men the effects of oxygen starvation. (The observer, of course, starts using his mask at 10,000ft. to guarantee that he is in full possession of his faculties, just in case anyone should show signs of illness, a rare occurrence. A comparison of the airmen's by now blue fingernails and bluish lips with the ruddy colour of the oxygen-breathing observer is a graphic demonstration of the visible signs of oxygen starvation. Light-headedness is another sign whose im- portance is carefully explained to the R.C.A.F. lads. After " resting " at 17,000ft. level for ten minutes, the men take another and similar code test. A comparison of these first two tests indicates the extent of the effect of lack of oxygen on each individual's mind. People who would go to pieces under conditions of mild oxygen starvation frequently reveal this fact in such a test. (It goes without saying, of course, that individuals vary in their ability to withstand anoxia, but no one can stay conscious more than a few minutes at 24,000ft. or alive at 30,000ft. more than a minute without an artificial oxygen supply according the medical men, notwithstand- ing the tall stories " early birds " tell to the contrary). The Descent The second test concluded, each of the airmen puts on his mask in turn so that the others may watch each man's recovery, which is rapid and impressive. The ascent is then resumed to 30,000ft., with oxygen, of course. A third code test is taken at 30,000ft. The results of this test are generally almost as good as of the 5,oooft.-level test, because the masks provide a normal oxygen supply. The "descent" is then begun at a rate of 1,500ft. a minute with a short levelling-off every five thousand feet. The building-up of pressure in the chamber can, of course, be slowed, stopped or reversed if anyone shows signs of ear trouble or other pains. This type of training thus has an additional usefulness : if the men are to have any such difficulties in real flight, they show up in the chamber, with an observer-instructor in the chamber and one outside (who speaks through a loudspeaker system) on hand to tell the pained party what to do. Handwriting tests are also made at the same time as the coding puzzles are solved. One of the first things anoxia does to a prrson is to turn his writing into an illegible scrawl, as well as to take away ability to spell. Several other novel physiological tests are also made on as many recruits as can be handled. Among them is a spirometer test to measure the amount of oxygen the airmen breathe. The general medical world will probably be particularly interested in this work, since the records being kept will supply the first large-scale study of how much oxygen the human being actually breathes. Selection by Performance No conclusive results in any part of the studies can, • of course, be obtained for months or years yet, and there is a likelihood that they would not be published during wartime if they are ready then. But already the chamber tests are of some influence in determining whether a par- ticular recruit should be permitted to continue flying training or should be kept on the ground. A report that the man's ability decreased sharply over 5,000ft. would serve to tip the instructors' decision toward keeping him on the ground. The records are available to the Air Force instructional staff, of course. This investigation, naturally, does not replace medical examination and selection of Air Force recruits.
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