History of Research in Space Biology and Biodynamics
 
 
- PART V -
 
Tolerance to Total Pressure Change: Task 78504
 
 
 
[79] Another task of Project 7850 is Tolerance to Total Pressure Change (Task 78504), which seeks to determine human and animal responses to negative or positive total pressure change in the range of one to ten atmospheres occurring in .005 to five seconds and in single or multiple cycles.46 Task scientist from 1956 until he left the service in mid-1958 was Captain (Doctor) Donald F. Patterson, an Air Force veterinarian who like Captain Recht was assigned to the Veterinary Services Section of the Aeromedical Field Laboratory's Laboratory Services Branch (now Laboratory Branch). At present the task scientist is Lieutenant William Ward.
 
In explaining the objectives of this task, Captain Patterson pointed out that the physiological effects of 47
 
... increased pressures on the human body surface have been studied in relation to undersea diving, but investigations in this area have been largely concerned with slowly increasing pressures such as are encountered in descent beneath water. The effects of abruptly increasing, or rapidly cycling pressures as are exerted on the body due to windblast and deceleration during high speed bailout have not been adequately studied... Abrupt external pressures, transmitted hydraulically through the blood vessels, may exceed the rupture points of small vessels in various organs including the eye.
 
As the above quotation indicates, this task is another of the research activities of the Aeromedical Field Laboratory with a bearing on high-speed escape from aircraft. But the range of possible applications extends far beyond the escape problem. The physiological effects to be studied by this research task are also present in explosions, for instance atomic blasts, and are relevant to various problems of manned space travel. Recent interest in the use of a fluid medium for attenuating the acceleration and deceleration forces encountered in rocket flight makes experimentation on the effects of various pressure patterns extremely pertinent; conceivably, the attenuation of g-forces would be offset (at least in part) by a sharp buildup of pressure, caused by the g-loading and increased weight of the fluid itself. Finally, there is a need for basic research to distinguish the effects of pressure change per se from the effect of other forces that in practice may be applied at the same time. However, the Aeromedical Field Laboratory is primarily interested in positive not negative pressure changes-in compression not decompression-since the latter is already a subject of extensive research at the Aero, Medical Laboratory of Wright Air Development Center. Some work is also being done at different locations on abrupt positive pressure change-using shock tubes and other specialized test facilities-but there is need for much more research on the subject.48
 
Although the Aeromedical Field Laboratory has been devoting intermittent...
 

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80]  (MISSING PHOTO)
Car Crash With Dummy Subject
 
[81] efforts to this task since 1955, no actual tests have yet been performed. As a result of manpower and fund limitations, the task has not progressed beyond the stage of planning and preparations. Certain items of test equipment have been assembled, and members of the laboratory staff are familiarizing themselves with their operation. Other items have been designed (with help from other units of the Air Force Missile Development Center's Directorate of Research and Development), including principally a chamber capable of exerting "pressure in the range of 1 to 5 atmospheres to the body surface of rabbits."49 But the Center is still in the process of obtaining the apparatus, which probably will not be available until the latter part of 1958. It will then be used in exploring the effect of varying combinations of magnitude, onset, and duration of compression on animal test subjects. Ultimately, it may be desirable to obtain larger and more exacting equipment for testing similar pressure changes with primates and human subjects, but small animals must first lead the way.50
 

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