Both of you (
95mustanggt, Tom351) do; however, raise interesting points about the speed of sound increasing and decreasing with altitude or the density of the mass it is travelling through.
I would submit the argument that the speed of sound as far as the sceintific communtity is concerned with rating an aircraft's top speed in the Mach designation is based on the speed of sound at mean sea level. Mostly that is because an aircrafts top speed, especially jet aircraft like, say, an F-15E, is obtained at high altitudes where researcher's are unable to accurately predict the changing pressure.
Besides, an aircraft rated at a certain Mach number, say the F-15E at Mach 2.65, is given it's rating at an altitude of about 56,000ft. Does that mean an aircraft that can do Mach 2.65 at 57,000ft is actually faster as far as the military is concerned? No. The rating has to be a constant rating, otherwise the Mach number given to an aircraft would be inaccurate based on a comparative factor when tracking it.
In conclusion, I'd say based on my theory, the Mach number is like an hp number. It's dependant on a conversion formula from another number like torque, in this case, a different designated velocity factor, such as m/s or knot's.
Hehehe, I love this **** !
