65 Years of supersonic flight

When test pilot Charles ‘Chuck’ Yeager fractured two ribs just days before he was scheduled to take an historic flight, he refused to let it ground him. Whilst concealing the injury from everyone except his wife Glennis, and fellow pilot and friend Jack Ridley, Yeager found an ingenious way to compensate for his reduced mobility. At Ridley’s suggestion, Yeager used a broom handle to lever shut the aircraft’s hatch, allowing him to complete the flight despite his impairment. In 1947, in his Bell X-1 aircraft, Yeager flew faster than anyone before him, breaking the sound barrier for the first time.

The speed of sound travelling in air is around 340 metres per second. In aviation, this speed is known as Mach 1, and flight faster than this is known as supersonic. As an aircraft approaches Mach speeds, sound waves build up in front of the plane; when the aircraft exceeds Mach speed, it passes through these sound waves, creating a shock wave known as a sonic boom that can be heard from the ground.

In his historic 1947 flight, Yeager achieved Mach 1.07. Six years later, Scott Crossfield achieved the next significant milestone in the history of supersonic flight, reaching Mach 2 in a Douglas Skyrocket. However, Yeager soon regained his title as fastest man alive, and continued to test the limits of aviation technology throughout his 60-year career.

Yeager retired from test flights long ago, but the search for ever-faster speeds continues. The Lockheed SR-71 Blackbird holds the air speed record for manned flight, with top speeds exceeding Mach 3. Unmanned aircraft can travel faster still, with experimental planes reportedly reaching 16,700 miles per hour – a staggering Mach 22. At this velocity, aircraft need to be able to withstand temperatures that would melt steel and so require complex thermal protection systems. But the first supersonic flight depended upon something far simpler: a broom handle lever, and a determined pilot.