Date:24 Jan 98 02:53:21From:eertink@nlr.nl (Johan Eertink)Organization:National Aerospace Laboratory NLRReferences:1

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Marc Schaeffer (marcmsc@geocities.com) wrote: : Sorry if this a very basic one. : : I'm looking for the formula to convert speed from Mach to mph. Speed = Mach * Speed of sound Now the tricky part: Speed of sound depends on temperature, according to: Speed of sound = sqrt(gamma*R*T), where gamma = 1.4 R = 287.05 K m2/s2 T = temp in Kelvin at sea level, T = 288,15 K, so Speed of Sound = 340.29 m/s = 761 mph According to standard Atmosphere (ISA): With increasing altitude, T decreases by 6.5 deg per 1000 m, up to 11000 m (troposphere). then it remains constant up to 20000 m (stratosphere), then it increases again through the mesosphere. Johan.