In October 1947, 24 year-old Air Force test pilot Charles E. “Chuck” Yeager flew an experimental Bell X-XS-1 rocket-propelled aircraft out of Edwards Air Force Base (then called Muroc Army Air Field) in California to break the sound barrier at a speed of Mach 1.07.
At 10:25 AM, at an altitude 20,000 feet, Yeager’s aircraft (named Glamorous Glennis) was released from the belly of a Boeing B-29 over Roger’s Lake (the largest dry bed in the world).
Blasting four, paired rocket motor chambers, Yeager broke through the sound barrier as he increased airspeed to almost 700 mph and soared to an altitude of 43,000 feet. The XS-1 remained at supersonic speeds for 20.5 seconds, with none of the buffeting that characterized high-speed subsonic flight. The Air Force and the National Advisory Committee for Aeronautics (the forerunner of NASA) did not make the event public until Jun 10, 1948.