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History of Research in Space Biology
and Biodynamics
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- - PART IV -
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- MAJOR ACHIEVEMENTS IN
BIODYNAMICS: ESCAPE PHYSIOLOGY AT THE AIR FORCE MISSILE
DEVELOPMENT CENTER
- 1953-1958
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- [45] During recent
years the Air Force Missile Development Center has made important
contributions to the Air Force human factors program in two broad
fields: space biology and biodynamics. Under the heading of space
biology, it has been engaged in research on biological effects of
cosmic radiation, on sealed cabin environment, and on subgravity,
all of which have been discussed in previous historical
monographs.1 Under the heading of biodynamics-which can be
defined as the study of the effects of mechanical forces on living
tissues-its research efforts cover a variety of problems ranging
from the merits of automotive seat belts to patterns of
deceleration in space flight. At first glance, some of these
problems of biodynamics have little in common. In each case,
however, the research program is centered around a unique Holloman
complex of test facilities, of which the 35,000-foot high-speed
test track is only the best known example. Moreover, each of the
various research tasks in biodynamics is in some measure an
outgrowth of the deceleration and windblast studies which began at
Holloman Air Force Base in 1953 under the direction of Doctor
(Lieutenant Colonel and later Colonel) John Paul Stapp, and which
were related primarily (though not exclusively) to the problem of
escape from high-performance aircraft.
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- The research project that Colonel Stapp
personally brought to Holloman when he came to assume command of
the Center's Aeromedical Field Laboratory in April 1953-Biophysics
of Abrupt Deceleration-was specifically oriented toward the study
of high-speed escape from aircraft. The escape problem remained
one of the most important research topics of Project 7850,
Biodynamics of Human Factors in Aviation, that was drawn up in
1954 to supplement and in large measure to supersede the former
project. Research on this same theme has been reoriented but by no
means eliminated since March 1958, when Project 7850 was rewritten
as Biodynamics of Space Flight. And it was a series of experiments
directly related to escape physiology, Colonel Stapp's own
rocket-sled rides on the Holloman track, that first brought
nationwide attention to the Holloman aeromedical
organization.
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- The high-speed escape problem was one of
imposing magnitude. A pilot bailing out at transonic
or supersonic speed had to face first the ejection
force required to get him out of his plane, then the sudden
onslaught of windblast and wind-drag deceleration, likely to be
followed by dangerous tumbling and spinning. Any one of these
forces taken separately was a potential cause of injury or death,
not to mention the anxiety on the part of aircraft pilots who did
not know if they would survive or not in case of ejection. For, at
the time research on this problem at Holloman began, the escape
systems available were either admittedly inadequate or of unproven
worth for aircraft having performance capabilities above mach one
in speed and 45,000 feet in altitude.2 Since aircraft with this range of performance were
already in existence, and were destined to assume ever greater
importance in the Air Force inventory, there was a glaring need
for reliable data on human tolerance to all the forces that could
be encountered in escape at the indicated speeds and elevations.
The fact that such information was not already available was
another case of the lag, often deplored by aeromedical scientists,
between aircraft design and human
factors
research.3
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- Test Directive 5200-H1 for Biophysics of
Abrupt Deceleration, dated 15 April 1953, proposed to remedy this
situation at least in part, setting forth as its objective:
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- A program of experiments with the High
Performance Linear Decelerator to study tolerance and survival
limits for (1) Linear Deceleration, (2) Windblast in a Linear
Deceleration Field, (3) Tumbling in a Linear Deceleration Field,
and (4) Linear Deceleration with Tumbling and Windblast, as
factors of the problem of escape from high speed, high altitude
aircraft . . . . Recommended limiting values established by these
experiments will determine the design of escape devices and the
choice of ejection seats or of ejection capsules for a particular
aircraft.
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- This test directive, with later
amendments, was the official basis for Colonel Stapp's research at
Holloman until Project 7850 became fully operative early in 1955.
It stated further that the "current military need" was to study
tolerance to deceleration up to fifty-five g's, but this
[46]
figure was subsequently
revised,4 and all such figures were naturally
for rough guidance only. In any case, the maximum number of g's
was only one of the factors involved in this study. Not only were
tumbling and windblast to be explored, as stated in the directive,
but also the rate of onset and duration of g-forces would be
considered as affecting the total deceleration that a human body
can withstand. The research assignment was thus arduous and
complex, but, as Colonel Stapp once stated in a slightly different
connection,
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- . . . . one factor is
encouraging. There are only two models [male and female] of the
human body currently available, with no immediate prospects of a
new design; any findings in this research should provide permanent
standards.5
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- In his own previous
experiments on the 2,000- foot deceleration track at Edwards Air
Force Base, California, Colonel Stapp had already experienced
forces up to roughly 46 g's at 500 g's per second rate of onset.
Both this experiment and one in which a co-worker withstood over
38 g's at 1370 g's per second produced definite signs of shock but
no permanent ill effects. Colonel Stapp also directed chimpanzee
tests while at Edwards, exposing the animal subjects to plateaus
of 65 g's, rates of onset of approximately 3400 g's per second,
and peaks of about 150 g's, without finding the lethal point or
even the point of irreversible injury. However, the duration of
decelerative forces was always very short. Durations ranged from
.15 to .42 second in the human experiments, which attained a top
speed of only 226 feet per second; and there were no experiments
on deceleration combined with windblast and
tumbling.6
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- Thus the Edwards tests did
not adequately answer the questions posed in the project
Biophysics of Abrupt Deceleration. They clearly suggested that the
human body, if properly positioned and secured, could endure any
aircraft crash forces in which the aircraft itself
survived,7 but they did not duplicate the
conditions of highspeed escape. For the latter purpose, the
Holloman high-speed track, originally built in 1949 as a rail
launcher for the Snark missile was especially well suited. It was
3550 feet long (before the first of a series of track extensions)
and was fully instrumented. It also had a water braking system as
compared with the mechanical friction brakes used on the 2000-foot
Edwards deceleration track. The water brakes permitted both high
deceleration forces and a wide range of duration and rate of
onset.8
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