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Parachuting from 20 miles altitude

  1. Apr 22, 2007 #1
    The guy who parachuted from 20 miles up in the atmosphere - did he heat up significantly through friction with the air and how fast was he moving?
     
  2. jcsd
  3. Apr 22, 2007 #2

    mgb_phys

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    At 20mi the air is rather thin. I imagine the limit would be the speed of sound - which is rather lower at 20mi than at sea level.
    As you reach denser lower levels of the atmosphere you will slow down as you encounter more friction - if you designed the aerodynamics correctly you should be able to slow at a rate so that you don't heat too much. In fact with a temperature n the stratosphere of <-50degC, cooling would be more of a problem.
    I think the USAF record only used a stabiliser parachute to prevent spin - it relied on drag on the body to slow down to a point that the main chute could open safely.

    I think the experiment that
     
  4. Apr 22, 2007 #3

    russ_watters

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    Good answer. Here's the guy, Joseph Kettinger: http://www.centennialofflight.gov/essay/Dictionary/kittinger/DI29.htm

    No, frictional heating is not a significant issue here.
     
  5. Apr 23, 2007 #4

    Mk

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  6. Apr 23, 2007 #5

    mgb_phys

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    Interesting point - I suppose you could argue there is no such thing as air-friction. It is only the momentum of air molecules hitting you in the direction you are travelling.
     
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