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[MF3D.FORUM:345] Re: speed of sound & 1/fl

  • From: Tloc54452@xxxxxxx
  • Subject: [MF3D.FORUM:345] Re: speed of sound & 1/fl
  • Date: Wed, 29 Mar 2000 20:30:05 EST
> Yes, and maybe no. Does anyone know how much the
> speed of sound changes with altitude (air pressure).
> If you are at 10,000 ft altitude does the speed of
> sound change enough that the 5s/mi or 3s/km "rule"
> is significantly off?

More specifically, for the standard atmosphere (which
is a political agreement) speed of sound at sea level is
340 m/s and at 11 km, it's 295 m/s.  It stays at 295 to
25 km, and then rises to 338 m/s at 47 km.  it holds at
338 to an altitude of 53 km.  See - it's just political.
So 5 +sec/mi is good enuf.

John B