-Z- (z@gundam.com)
Thu, 26 Oct 2000 20:03:05 -0700


> -----Original Message-----
> From: owner-gundam@1u.aeug.org [mailto:owner-gundam@1u.aeug.org]On
> Behalf Of Lim Jyue
> Sent: Thursday, October 26, 2000 09:59
> To: gundam@aeug.org; 'gundam@aeug.org'
> Subject: RE: [gundam] My Grand OYW GM Re-unification Idea... =)
>
> The question remains whether the pilot can take this kind of
> acceleration!

An acceleration of 2.95 to 3.67 G shouldn't be a problem, especially if the
pilot suit is designed like a conventional jet pilot's G suit. Fighter pilots
routinely pull 6 to 9 G, albeit not for extended periods.

Back before we had the Space Transportation System, our astronauts were
subjected to 3 to 6 G in each of the three stages going up and about 8 G during
re-entry. We learned during that time that a lot depends on the pilot's
attitude -- horizontal or vertical with respect to the vector of acceleration,
not mental -- and whether the acceleration was positive (head to foot) or
negative (foot to head). When the acceleration is positive and the attitude
upright, the average maximum tolerance is 5 G for very short periods and 2 to 3
G sustained. Negative G is less tolerable, reducing the maximum to 2 to 3 G for
short term.

Changing to a transverse attitude reduces the pooling of blood in the
extremities, away from the heart, and the drop in oxygenation of the brain that
results in grayout or blackout. Tolerance goes way up, up to 20 G in the short
term and 7 to 9 G sustained.

In the upright attitude with positive 10 G, the blood in the long hydrostatic
columns that supply the brain drops 50 cm (20 inches) -- enough to starve the
brain completely. In the transverse attitude with the same positive 10 G, the
blood level drops only 5 cm (2 inches) -- reducing the flow to the frontal lobes
of the brain and the sinuses, but not enough to incapacitate the pilot. The
flow can be restored by turning the head from side to side.

Vibration in the airframe is actually more problematic. Humans are most
sensitive to vibration frequencies in the range of 4 to 10 cycles per second
because the major internal organs have a natural resonance frequency in this
range. When the organs become resonant with the vibrations of the vehicle,
common symptoms include severe pain, nausea, headaches, and dizziness. You
don't have to go into space to experience this -- a ride in a tank over rough
terrain will do the same thing, especially when the machine guns are firing.

Noise is also a problem. Space boosters produce noise levels of 145 to 175
decibels. That's why the crew cabin is always as far from the boosters as is
physically possible and insulated as well as the can be. But even the air
circulation system is noisy enough that most astronauts have to wear ear plugs
to go to sleep.

-Z-

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