Yes, the SR-71 was happiest at mach 3+. At these speeds, metal expansion due to heat would seal the airplane frame up too. Designed for its mission. Insanely, i

Yes, the SR-71 was happiest at mach 3+. At these speeds, metal expansion due to heat would seal the airplane frame up too. Designed for its mission. Insanely, it would literally leak fuel on the ground.