"Mark James Boyd" wrote in message
...
| I read that Bruce Bohannon breathed 100% oxy for over an
hour prior
| to his 40K+ RV flight, and know that it is standard
practice to
| turn the oxy on before takeoff of wave flights at Minden
(where
| 25k+ wave is common in winter).
|
| Bruce said he pre-breathes to purge nitrogen. I
understand
| Fossett and his NZ pal are also big oxy users. I'm
interested in
| what his altitude record attempts will look like after he
is
| done with speed records. I wonder at what altitude a
pressure suit
| is a good idea...

I seem to remember that at altitudes around 52,000 ft or so,
the air pressure is so low that the boiling point of water
approaches the temperature of the human body. You don't
work too well if your blood boils !
So I guess that at anything above 50,000 ft you should have
a pressure suit.
(The RAAF Aviation Medicine Student Notes define three Zones
of the atmosphere for physiological purposes:
"The Physiological Zone" = sea level to 10,000 ft. Human
can operate without any major physiological deficiency.
"The Physiologically Deficient Zone" = 10,000 to 50,000 ft
Increasing amounts of supplemental Oxygen are required to
support life.
"The Space Equivalent Zone" = anything above 50,000 ft .
Effectively no Oxygen available, and where (the airforce)
rarely operates.)
Cheers, John G.