FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1935
1935 - 0609.PDF
MARCH 21, 1935- FLIGHT. 297 NEXT to NOTHING Some Thoughts on a Topical Subject—the Conquest of the Stratosphere Weighing-up the Advantages and Disadvantages of Flying in Thin Air the Human Aspect HIGH-ALTITUDE fly ing is a subject on which opinions differ considerably. Flying in the less dense air offers opportunities in the way of increased speed for little or no increase in power ; some hold the view that these advantages are so consider able that it is logical to suppose that the long distance routes of the future will follow the '' wide open spaces " above the clouds. Others consider the techni cal and physical difficulties so great as to outweigh the advantages which might be gained. It is quite im possible to be dogmatic on tie subject, and the best that can be done at present is to get a clear conception of the fundamental princi ples involved and bear them in mind when contemplating future developments. The lower region of the earth's atmosphere is known as the troposphere and ex tends up to a height of about six miles, or 32,000ft. Clouds are rarely found be yond tins height. The "Pper region of the atmo sPhere is known as the st'atosphere, and is separ ated from the troposphere bv a boundary region known ds the tropopause. It has long been known Z the densitV and the f P^sure of the air decrease Wiley Post, the American pilot who has recently made several high-altitude flights, wearing his special suit which is supplied with air from one of the engine superchargers. The air is led to the helmet and exhausts via the boots la? aitilude'and h is this hish*l+-+ ,presents b°th the attractions and drawbacks of 20000ft «T flying" At a height of approximately [at'ground 1 density of iiie air is about one-half the density of air K That is to say< the weight of a cubic foot [level ^ At°Ut haH that of a cubic foot of air at ground approxim I ,sllghtly more than 40,000ft. the density is a similar one-quarter of the eround level density. In one-quarter of the ground level density. ier the pressure decreases with heigr *2o,oecft ^i/Sq' in- at ground level, 6flb./sq nearly 1 "bT^ *e Pressure height, being 2f*b-/sq. in. at 40,000ft. 'lt 60,000ft. in. at and just over lib. /sq. height but°° ^e temperature also decreases with "PProximat faCheS a limit at about 40'oooft-, where it is n°t a DnPaJ e;y r7° de§- F-> a value below which it does ^ppear to fall. I>ressures and ? - lcal Poir't of view, the low densities, special prer ,emPeratures are a serious hindrance, in that beings tn k ,nS nave to be takpn tn allnw human ^'deisiteatheand torr.._ensity at ereat move in stich conditions. The very ^Cllpants of E 8reat neignts makes it necessary for the " order to com airCraft to carry special oxygen apparatus mpensate for the reduced quantity contained in every cubic foot of air drawn into the lungs. Electrical heating apparatus has to be carried to prevent numbness, and even to counteract freezing of the pilot's eyes. Low pressure of the surrounding air also brings with it difficulties similar to those which confront a diver coming up from great depths. Experiments have been made with special suits of alternate layers of rubber and silk. For ex ample, such a suit is worn by the American pilot Wiley Post, and it will be observed from the photograph on this page that he wears in addition a helmet not un like that of a diver's suit. Air is led from one of th° engine superchargers to the helmet, and is exhausted through the boots. An in let is provided for emer gency use, by which oxygen from a tank can be turned into the helmet. The height to which a human being can ascend without suffering serious ill-effects varies with the individual. It will be recollected that a few years ago Mr. C. F. Uwins, Bristol's chief test pilot, established a world's altitude record in a Vickers " Vespa " biplane fitted with a Bristol " Pegasus " engine, reach ing a corrected height of 43,976ft. Mr. Uwins was, of course, provided with an oxygen Ripply, and wore an electrically heated suit, gloves and helmet. He stated afterwards that he had suffered no ill-effects of any consequence. Last year an Italian pilot, Commandant R. Donati, reached a new height record of 47,352ft. in a Caproni monoplane, fitted with a 6no h.p. Bristol "Pegasus " engine. That may be taken to represent very nearly the maximum height which a human being can stand without some very special pre cautions, such as a special suit and helmet after the style of Wiley Post's, or enclosing the pilot in an airtight cabin supplied with oxygen either from the engine super charger or from oxygen bottles. The supercharger would have also to supply the required pressure inside the cabin. This would not necessarily be ground level pressure, but it would have to be a good deal higher than the pressure of the surrounding air. The two pilots mentioned were, of course, specially trained and were physically very fit. The average passenger in a commercial aeroplane would not be expected to stand such heights, and, in fact, it seems doubtful
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
