Machmeter formula
Wow sir. I think I'm getting connection! Yes the basic instrument relies on inputs of Static pressure and Dynamic pressure. There is a formula which relates these pressures to the Mach number which we know is the TAS/local Speed of Sound and is used to run (program) the instrument.
I think the derivation starts from the velocity of sound being proportional to the sq. rt. of the temperature, involves the gas equation ( I think the PV=mRT one) and gives a quite simple equation for Mach number ( I know latest designs include air data computer input but that is a much later sophistication). I'm looking for the several equations which when manipulated and simplified give the relation ship.
You really sound like you can show me!