Leveling off at 42,000 feet, I had thirty percent of my fuel, so I turned on rocket chamber three and immediately reached.96 Mach. I noticed that the faster I got, the smoother the ride. Suddenly the Mach needle began to fluctuate. It went up to.965 Mach - then tipped right off the scale... We were flying supersonic. And it was a smooth as a baby's bottom; Grandma could be sitting up there sipping lemonade.

Yeager: An Autobiography (ed. Bantam, 1986)