Quote:
Originally Posted by liferunner2
TC, the %O2 in the air at altitude is actually less than that at sea level because O2 is a heavier molecule than some of the other constituents of air and actually "settles" into lower lying areas. This coupled with the fact that there is less air overall is one reason why climbers need to carry 02 tanks at extreme altitudes, and why many high altitude mountain lakes have lower levels of O2 in them than their counterparts at sea level.
Chris
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So then how does the SR71 burn fuel at 80,000 ft?
I happen to have a copy of the Pratt & Whitney Aeronautical Vestpocket Handbook, and while it carefully details the atmospheric pressure, viscosity, and temperature at altitudes from 0 to 75000 ft, it doesn't include %O2. None of the equations for engine thrust include a factor of %O2.
Mountain climbers carry oxygen because there's just flat out less air, which means less pressure pushing the air into your lungs AND less oxygen (by quantity). The % O2 is the same (or close enough that its not worth considering)