Descending experiment │ Unconsciousness │Recovery of consciousness
from 12 km. [39,400 ft.] │ after— │ after—
│ │
Sitting without knee bends │1′39″ = 10.85 km. │6′38″ = 7.45 km.
│ [35,600 ft.]. │ [24,440 ft.].
Sitting after 6 knee bends │55″ = 11.4 km. │6′55″ = 7.25 km.
│ [37,400 ft.]. │ [23,786 ft.].
Suspended in parachute │37″ = 11.65 km. │7′40″ = 6.77 km.
harness │ │
│ [38,220 ft.]. │ [22,212 ft.].
│ │
It is to be noted in connection with the stated time and altitude values
that the beginning of unconsciousness, or of the recovery, was
calculated from the withdrawal of oxygen, while in most experiments the
sinking or free fall was begun at the expiration of the 10-second
waiting period. Since in addition to this the stages of altitude were
read off at the moment of unconsciousness, small variations from the
times given in figs. 2 and 3 [not reproduced] are possible
[page 8 of original]
since, especially in the falling experiments, variations occurred
because of the somewhat crude valve control. These variations, however,
are small and may be overlooked since in any case the fall and sinking
time under practical conditions are dependent on the flying attitude at
the moment of the leap from the catapult seat. In addition to this, the
calculated fall and sinking time are influenced to a high degree under
actual conditions by weight and air resistance.
It should be kept in mind in regard to the experiments conducted in the
sitting position that the subjects fell over at the beginning of
unconsciousness and so passed the critical time of greatest load on the
circulatory system in a prone position, while those suspended in the
parachute harness remained throughout the experiment in a vertical
position, the most unfavorable position for loading the circulatory
system.
[Illustration: Figure 1. Speed of ascent in the portable low-pressure
chamber.]
In the writing test shown above [not reproduced] the occurrence of
altitude sickness in a sinking experiment for 12 km. [39,400 ft.]
altitude is shown in this manner: For example, after 1 minute and 20
seconds at 11 km. [36,100 ft.] altitude, the writing is interrupted
because of sudden altitude sickness with unconsciousness, and is resumed
after 4½ minutes at an altitude of 8.8 km. [28,870 ft.], with erroneous
writing. At 8.3 km. [27,230 ft.] altitude the writing becomes free of
errors. This is worthy of special attention because in this case a
person has fully recovered mentally at an altitude of 8.3 km. [27,230
ft.], after 3 minutes of the most severe lack of oxygen, while in
altitude endurance experiments at this altitude severe altitude sickness
sets in after about 3 minutes. Here we are dealing with a process which
in any case is very favorable but which is not yet entirely clear and
which was already observed in earlier experiments of parachute jumps
from great altitudes. Still, it appears from this that a rather long
oxygen lack at altitudes up to 13 km. does not present any great strain
in
[page 12 of original]
the sense of using the last reserves, but, on the contrary, the human
organism seems to react to this loading with a certain increase in
resistance to altitude.
In descending experiments from 13 km. [42,700 ft.] altitude the waiting
time of 10 seconds was retained, but on the other hand exertion in the
form of knee bends was omitted since technical difficulties interfered
with this procedure.
The experiments involving suspension could be done only in the large
low-pressure chamber, since suspension was impossible in the small
low-pressure chamber for reasons of space. Therefore, the ascent to 13
km. [42,700 ft.] altitude was carried out slowly in the main chamber
(without explosive decompression) so that when 13 km. [42,700 ft.] was
reached a certain oxygen lack existed. With this oxygen lack the knee
bends would have presented a great burden which would have falsified too
greatly the results of the experiment. The same conditions were also
given in further experiments at higher altitudes in the main chamber.
For this reason, the 13 km. [42,700 ft.] descending experiments were
carried out partly in the sitting position, partly in the sitting
position strapped in, and partly suspended. They yielded the following
average data: