Who was the first person to break the sound barrier in level flight in 1947?

The first person to break the sound barrier in level flight in 1947 was Chuck Yeager.

On October 14, 1947, U.S. Air Force test pilot Charles “Chuck” Yeager flew the rocket-powered Bell X-1 through Mach 1 over Muroc Army Air Field in California. The aircraft was released from a Boeing B-29 bomber before igniting its rocket engines and accelerating through the transonic region.

Yeager’s flight was significant because earlier aircraft had encountered severe instability and control problems near the speed of sound. The X-1 used a thin, bullet-shaped fuselage and a horizontal stabilizer that helped it remain controllable. Yeager reached roughly Mach 1.05 at an altitude of about 45,000 feet, producing the first officially recognized controlled, level supersonic flight by a person.

The aircraft was named Glamorous Glennis after Yeager’s wife. A famous story says Yeager secretly flew despite breaking ribs in a horseback accident shortly beforehand. The feat made him an aviation legend, although the X-1’s achievement was also the result of a large research effort involving Bell Aircraft, the Air Force, and NACA.