By Smithsonian's National Air and Space Museum
On October 14th, 1947, Captain Charles E. "Chuck" Yeager, flew the Bell X-1 aeroplane 700 miles per hour over the Mojave Desert, California.
Yeager became the first person ever to travel faster than sound and the first to create a sonic “boom”.
How fast did Yeager need to fly to go faster than the speed of sound that day?
Well, that isn’t quite as straightforward a question as it first seems. The speed of sound as it travels through a medium, like air, is affected by factors such as temperature.
Flying at 43,000 feet over the desert, the temperature would have reduced the speed of sound to around 660 mph, almost 100 mph slower than at sea level.
But to break this sound barrier, Yeager needed a special plane.
The Bell X-1 was designed to test whether aeroplanes could handle the stresses of flying near the speed of sound. Many aeronautical engineers believed the strain would break a plane up creating a natural limit to how fast humans could fly.
The X-1 was modelled on a .50-caliber machine gun bullet, an object designers knew flew faster than sound. The plane had a single 6.000-pound-thrust rocket engine to power it to supersonic speeds.
On October 14, 1947, X-1 was carried up to an altitude of about 29,000 feet by a B-29 Bomber and dropped from the bomb bay. The rocket engines then fired and the X-1 climbed to over 40,000 feet where it reached the mythical 660mph.
On previous flights Yeager encountered problems of flying at speeds close to the speed of sound. The compression of the air by the speeding plane caused the flight control system on the tail to stop working and Yeager to lose control.
With modifications to the X-1, Yeager and his team overcame every hurdle and finally broke the myth of a sound barrier with a thundering sonic boom. A deafening sound caused by the plane compressing sound waves together until they form a single roaring shockwave.
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