BREAKING THE SOUND BARRIER
When an aircraft breaks the sound barrier, it travels faster than the speed of sound, which is around 770 miles per hour in the air. The first person to do this was Chuck Yeager on 14 October 1947, flying the X-1 rocket plane. Yeager, a World War II combat fighter, was chosen to fly the experimental plane, which was built by Bell Aircraft. The X-1 was shaped like a bullet and had short, highstrength wings. The plane was flown to an altitude of 7,600 metres by another aircraft before being released.
When the plane broke the sound barrier, it had reached heights of 12,000 metres. At this altitude, air is less dense and its pressure is lower than at sea level. To break the sound barrier in these conditions, Yeager flew just over 662 miles per hour.