After browsing these forums for a few years, I've learned that the speed of sound is entirely dependent on temperature, not pressure. If this is wrong, please correct me. However, I do recall numerous posts from reputable members who harp on this fact.
I fail to understand this fact in the context of what I presuppose about the TAS necessary for aircraft to reach Mach 1 at sealevel versus high altitude.
If a,.....oh I donno...let's say F15 were to fly at Mach 1 over the north pole at sealevel in calm -40F weather conditions, would his TAS be the same as if he were flying at 40k feet since the temperature is somewhat similar? Is the primary difference between these two flight regimes the power requirements for reaching such speeds? Is this where pressure (and thus air density/drag/friction) comes into play?