Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!samsung!uunet!lhdsy1!yzarn
From: yzarn@lhdsy1.chevron.com (Philip Yzarn de Louraille)
Newsgroups: rec.skydiving
Subject: Re: Skydiving at supersonic airspeeds
Message-ID: <1027@lhdsy1.chevron.com>
Date: 30 Jun 91 04:10:49 GMT
References: <1991Jun24.135815.8781@cc.curtin.edu.au> <3547@oucsace.cs.OHIOU.EDU> <1991Jun27.180343.8816@cc.curtin.edu.au>
Organization: Chevron Oil Field Research, La Habra, CA.
Lines: 22

In article <1991Jun27.180343.8816@cc.curtin.edu.au> tcliftonr@cc.curtin.edu.au writes:
>To get a free fall time of 277 seconds, a peak velocity of 460 mph
>was obtained.  Definitely a world record, which still stands, but
>not supersonic.  Even at -50 degrees, the speed of sound is still
>greater than 500 mph.
>
At -50 degrees and at the altitude where the jump would be made, the
speed of sound would be below 500 mph. At sea level and under
Standard Condition (atmospheric) does the speed of sound reach 500 mph.
But as the altitude increases, the density decreases (the air molecules
get further apart per unit volume) so it takes longer for collisions to
happen, hence the compressional waves (sound) take longer to cover the
same distance.

Speed of sound, Mach 1, is the speed of sound at sea level. When an
airplane reaches the speed of sound at altitude, it is going faster then
the speed of sound for that altitude.
-- 
  Philip Yzarn de Louraille                 Internet: yzarn@chevron.com
  Research Support Division                 Unix & Open Systems
  Chevron Information & Technology Co.      Tel: (213) 694-9232
  P.O. Box 446, La Habra, CA 90633-0446     Fax: (213) 694-7709