New discoveries in high altitude flying and medical data concerned with stratosphere flight are hoped for results of a novel low-pressure chamber recently developed by Boeing Aircraft Company's Seattle engineers. This chamber is also being used for the training of AAF multi-engined bomber crews.
Named the Stratotrainer, this test unit is capable of simulating altitude conditions equal to or above 50,000 feet and it can create a climb from sea level to 35,000 feet within 2½ minutes.
The Stratotrainer, it is believed, will be responsible for many new developments in operations in excess of 40,000 feet and the high rate of climb possible through its use will enable a study of "aeroembolism," a danger to which high flying pilots are exposed and which is somewhat similar to the "bends" of deep-sea divers.
The interior of the Stratotrainer is equipped with headphones and, in addition, a public address system assures constant communication between the crew and those outside the chamber.
Oxygen fed to the men comes through demand and constant flow type feeds. Also inside the chamber are manometer boards, potentiometers and oximeters which give training crews practice under actual high altitude conditions.
A refrigeration unit, mounted atop the chamber, causes temperature changes inside the chamber which aids in the duplication of conditions in the stratosphere.
The size of the unit permits simultaneous training of a complete flight crew. The Stratotrainer ascent by a flight test crew actually is a final examination, culminating several months of intensive training. Those who successfully pass this test are then ready to take their part in Boeing's continuous quantitative high altitude research program.
Men, garbed in high altitude flying suits, don oxygen masks and exercise for 30 to 40 minutes prior to entering the chamber. After the crew enters, the door is sealed and the motors begin pumping the air out of the metal cylinder.
The crew men need not fear for lack of air to breathe, as they inhale pure, dry oxygen through oxygen masks. When the desired altitude is attained, one of the crew members simulates a faint. Another must remove the oxygen mask and fit the inert individual with an emergency mask. At the altitude of 35,000 feet, there is a 30-second margin of safety in which this has to be accomplished, otherwise the man without his mask would go into a coma and die. While the change is being made, an experienced man in the crew supervises the process, and if need be lends a hand.
The process is repeated until each member of the crew has had his mask changed at high altitudes. It has been found that, in the performance of their duties at high altitudes in a plane, crew members may occasionally get careless and accidentally pull the flexible oxygen line off the outlet. Rapid changes in oxygen systems are required to prevent the individual from suffering ill effects.
In the past, high altitude crews have been trained in the Strato-Chamber which has been used for both crew training and research on reactions of parts and assemblies to the atmospheric conditions of the stratosphere. In the future, the Strato-Chamber will be used exclusively for mechanical research and the Stratotrainer for the training of flight crews in high altitude safety procedures and physiological research.
This article was originally published in the "Industrial Aviation Section" of the July, 1943, issue of Flying magazine, vol 33, no 1, pp 112, 119.
The PDF of this article [ PDF, 3.6 MiB ] includes photos of a B-17 used for high-altitude training and of the Stratotrainer entry hatch area,
Photos credited to Boeing.