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 Calculate Mach Number

 Method to Calculate the Mach Number of an Airplane





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How to Calculate the Mach Number

Mach Number is an important aerodynamic parameter which relates the velocity of the airplane of any flying vehicle with the speed of sound.



The Mach Number is Defined as,

Mach Number = V/a = Velocity of the Flying Vehicle divided by the Speed of Sound


Since, the units of both velocity and speed of sound are m/s in SI units and ft/s in English units the Mach Number is a non-dimensional quantity.


The formula for the speed of sound is,


Speed of Sound, a = squareroot (gamma*R*T)

The value of gamma is 1.4.

The value of R is 287 J/kg.K


Since, the temperature varies with altitude according to the standard atmosphere model, the value of the speed of sound varies with the altitude also. And since, the speed of sound varies with altitude so does the Mach Number.


The Mach number is different at different altitudes for the same velocity of the airplane or flying vehicle.


An alternative formula for the Mach Number is then,

Mach Number, M = Velocity of Flying Vehicle divided by squareroot (gamma*specific-gas-constant*temperature).


Download Free Program to Calculate the Mach Number