Date:24 Jan 98 02:53:18From:Arthur Utay <awutay@worldnet.att.net>Organization:AT&TReferences:1

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Marc Schaeffer wrote: > I'm looking for the formula to convert speed from Mach to mph. M= V/sqrt(gamma*R*T) where M= Mach No. gamma = gas constant = 1.4 for air R = universal gas constant = 53.352 ft-lbf/lbm-R = 287.04 J/Kg-K T= ambient Temperature = degrees Rankine or Kelvin V = local velocity = ft/s or m/s you also have to multiple the term under the square root by a conversion factor either (gravitational constant) 32.2 ft/s^2 or 9.8 m/s^2 to get the units to come out right. (better check my SI units - I don't use them often) for example M=0.5 (in english units) on a 80 °F day: V= .5 * (1.4 * 53.352 * 32.2 * (459+80)) ^.5 = 569 ft/s or 388 MPH -- A. W. Utay awutay@worldnet.att.net C180 N180Y