Hi everybody, technical question. Any engineers or other technical people have solid knowledge of this?:

What, if anything, has an effect on Critical Mach Number?

"Critical Mach Number is the free stream Mach number which produces the first evidence of local sonic flow."

My interpretation is that for a given airfoil, the Critical Mach Number is a constant and doesn't change. Is my interpretation correct?

I would also go on to say that the Indicated Airspeed corresponding to Critical Mach decreases with altitude (since we all know that due to the decrease in temperature as altitude increases, TAS increases for a given IAS), but the mach number which produces the evidence of local sonic flow does not change. .80 mach is .80 mach

Thanks for your help!