Later, I realized that the mission had to end in a let-down because the real barrier wasn't in the sky but in our knowledge and experience of supersonic flight.
Chuck YeagerWhat good does it do to be afraid? It doesn't help anything. You better try and figure out what's happening and correct it.
Chuck YeagerLeveling 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.
Chuck Yeager