TOO HIGH FOR HUMANS

Korero (AEWS), Volume 2, Issue 1, 17 January 1944, Page 13

TOO HIGH FOR HUMANS

By

in This Week

When a Flying Fortress climbs “ upstairs,” its crew moves into a new world—they could’nt stay alive there without scientific miracles to protect them

It seems strange that gasoline will boil away at 65° below zero.

Yet until the engineers figured out that one, and a thousand other sub-strato-sphere problems, our Boeing Flying Fortresses couldn’t function at modern combat altitudes —and men couldn’t live long enough to fly them up there. Thanks to ingenious research, however, scientists have so minimized the hazards that the stratosphere has become not only to-day’s aerial battlefield but will be to-morrow’s trade and passenger route for civil planes.

Nevertheless, life is different away up yonder where a man can’t whistle and a hairy bass voice becomes disconcertingly —where a fellow who is stiff with the punishing cold can be sunburned to a crisp at the same timewhere two hours sitting in a comfortable padded chair will exhaust you— your blood is liable to fiz like ginger ale.

Such is life in a region where there isn’t enough oxygen to support a candle flame—and where the better you feel, the nearer you are to death. For although we laymen have become as blase about altitude figures as we have about billiondollar budgets, 40,000 ft. is still alien territorv for man.

Notwithstanding this, an R.A.F. flyer in a Spitfire shot down a JU-86 last November from above 40,000 ft., while two others scored victories over Junkers planes flying at 50,000 ft. although the men were virtually paralysed by cold.

To appreciate flying at such heights we must begin with the fact that at sealevel we live in an air-pressure of 14.7 lb. per square inch ; in other words, we have about 30 tons of air holding our bodies together. But at an altitude of 40,000 ft. it drops to a mere 2-17 lb. per square inch, meaning that the air is six times as “ rare ” as at sea-level. Which complicates everything. For example, a 1,000 horse-power engine tuned for sea-level won’t deliver 200 h.p., at that height. And since a man’s “ carburettor ” can’t function any better than an engine’s on such a thin diet of oxygen, the first hazard of the Flying Fortress crew is anoxia, or “ oxygen starvation,” a threat virtually eliminated by the elaborate but fool-proof oxygen equipment provided.

Much like intoxication, anoxia first dulls the senses, then affects the judgment ; consequently you are blissfully unaware of your condition as you go from bad to worse. After ‘one-half hour at 18,000 ft. the typical victim’s faculties are sadly impaired, yet he is feeling great. He can’t do simple arithmetic problems ; his handwriting deteriorates into a scrawl, yet he’ll be making silly faces at nothing and giggling like a schoolgirl. If you stay at 18,000 ft. for more than a half hour (without oxygen) you begin to see double and you are so deaf you can hardly hear the motors roar ; so ossified you can drive an ice pick through your hand and hardly notice it ; so senseless you can’t distinguish between the tastes of mint and onion. Fits of boisterous laughter or blind rage may seize you. On an early test flight to 20,000 ft. without oxygen, one fellow was on the verge of killing the pilot because the latter’s red neck infuriated him beyond reason. The only thing that saved the pilot’s life was the fortunate fact that the passenger couldn’t find a weapon with which to bash in his head.

You can't even whistle

Up to a certain point anoxia can be combated by breathing oxygen from an ingenious face mask connected to a supply tank. Thus, at 10,000 ft. the flyer will adjust the valve to give him 30 per cent, oxygen, making up for the deficiency in pressure. At 20,000 ft. he will increase the ratio to 50 per cent. —at 33,000 ft. he will have to breathe pure, 100 per cent, oxygen.

From here on up, however, even 100 per cent, oxygen is not sufficient in itself ; it must be administered under pressure so as to drive it into the blood stream. This means either a pressure suit or a pressure cabin such as is used on the Boeing Strato-liners with such success. It is this lack of pressure which makes it impossible to whistle (there being no back-pressure against the lips) ; or which pitches male voices so high.

Not only must oxygen be available for men at their fixed posts, but also for those moving about the ship and, in an emergency, for those who may have to resort to their parachutes. Each Fortress crewman carries his own “ bailout bottle ,r containing a 15-minute oxygen supply. If he has to “ hit the silk,” he will disconnect himself from the main tank and slip on his emergency mask (worn around the neck) which is hooked up to a 2-1- lb. bottle in his trouser leg.

Another worry of the Flying Fortress crews is aeroembolism or “ stratosphere bends.” Caused chiefly by the release of nitrogen bubbles in the blood stream and tissues, the simplest analogy is the way ginger ale fizzes when you uncap the bottle ; the room pressure being lower than that in the bottle, the gas escapes in bubbles.

You become a Ginger-ale Bottle

In a rapid ascent to 30,000 ft. the human body virtually becomes a bottle of ginger ale, and as outside pressure decreases, nitrogen in the blood turns to bubbles. Generally unnoticeable at 18,000 ft. they get so big at around 30,000 ft. that most people suffer from them, and the agony may become unendurable.

Fortress crews combat this hazard by breathing 100 per cent, oxygen as they exercise moderately for about a half-hour before taking off. In this fashion as much as 95 per cent, of the nitrogen in the system can be eliminated and the danger obviated.

Fatigue is another concern of the high-level bombers ; it is so acute that a man can only stand about two hours a day regularly in a sub-stratosphere. And, on top of this, cold is probably their most punishing handicap, since temperatures “ upstairs ” drop about one degree for each 280 ft. above sea-level. This means that you can count on its being around 12 0 below zero at 20,000 ft. ; 48° below at 30,000 ft. ; 67° to 102 0 below from 35,000 ft. on up —even over the Equator !

Such cold dulls the senses so that at 40° below a man is only about 13 per cent, efficient. Planes are heated, of course, but when the bomb-bay doors and hatches are opened in action, cold air streams in at several hundred miles an hour. The electric flying suit seems to be the solution. But until it is more widely available, your typical Fortress crewman wears up to 50 lb. of clothing and gearwhich is something if you’re taking off in a ground temperature of ioo° in Africa !

Naturally, there are numerous other problems involved in getting away up —metals contracting, lubricating oil turning to foam, electric sparks jumping bigger gaps in rarefied air, gasoline boiling as atmospheric pressure drops, &c. Many of them have been encountered first in actual operations ; others in ingenious pressure chambers which permit engineers on the ground to simulate any altitude conditions.

The advantage of the new devices is dramatized by the case of a Fortress pilot whose oxygen supply failed at 35,000 ft. during a formation flight. Without warning, he suddenly ran amuck among the other ships in the squadron, weaving in and out like a drunken driver. Nothing but the skill of his fellowpilots enabled them to avoid a crash until his co-pilot got the ship under control.

Even among such fine physical specimens as Army airmen, individuals vary greatly in their susceptibility to anoxia, aeroembolism, even low temperatures. Just as the bomber pilot and the fighter pilot must have different temperaments, so must the high-altitude man have physical qualifications different from the ordinary flyer —qualifications we are just beginning to learn. Other things being equal, for example, it appears that a short, stockv fellow is less liable to “ black out ” in the recovery after a dive-bombing operation than is a tall lanky pilot. The latter, on the other hand, will probably have a higher tolerance for anoxia.

Altogether, aviation physiology has a fascinating field ahead of it on the job of picking the men best qualified to withstand conditions away up yonder. And next time you read about a successful raid of American high-level bombers make a note that it has taken much more than an uncanny bomb-sight to produce that skill !