This Day in 1947, Supersonic Flight & the .50 BMG

When John M. Browning designed the .50 BMG, odds are he had no idea the cartridge would lead to one of the greatest achievements in aviation history.

On Oct. 14, 1947, Charles "Chuck" Yeager became the first human to break the sound barrier in a controlled-level flight.

The sound barrier — or Mach 1 — is approximately 1,125 feet per second, or 768 miles per hour at sea level, in dry air at 68 degrees Fahrenheit.

Piloting an experimental Bell X-1 rocket plane, Yeager was able to break the sound barrier and safely return to Earth. His aircraft — which was inspired and designed after the Browning .50-caliber bullet — was able to stabilize as speeds became supersonic.

Preceding Yeager's historical feat of aviation, several experienced pilots attempted supersonic flight, only to come up short of their mark. Flights remained subsonic, mainly due to aerodynamic flaws in airplane design, which would cause aircrafts to destabilize as they approached the sound barrier. Pilots would often experience violent turbulence and even catastrophic malfunction.

Essentially a "bullet with wings," the Bell X-1 took shape from the .50BMG. Its cockpit was in the nose of the aircraft, which was shaped to maintain similar aerodynamic and gyroscopic properties of the .50 caliber bullet.

The .50 BMG — or 12.7x99 NATO — was a scaled-up version of the .30-06 Springfield cartridge. It entered service in 1921, and remains in use today as a long-range rifle and machine gun cartridge. Depending on barrel length, current U.S. M33 ball rounds are known to travel around 2,910 feet per second (mach 2.61), with 12,413 foot-pounds of energy at the muzzle.

Yeager piloted the bullet with wings at age 24, after becoming an ace fighter pilot during WWII. In 1952, he set a new speed record of 1,650 mph, which was more than twice the speed of sound. Yeager remained in service with the U.S. Air Force, training test pilots and commanding the Air Force Aerospace Research Pilots School. Among dozens of other noble accomplishments, Yeager flew approximately 127 air-support missions during Vietnam, and was promoted to Brigadier General in 1968.

In 2002, Yeager flew his last supersonic flight at the age of 79.

Interestingly enough, the accomplishments of both Browning and Yeager continue to influence the U.S. Armed forces and NASA. The .50 BMG and other Browning-designed weaponry remain in modern combat, while the achievements of Chuck Yeager continue to inspire advancements in aviation and astronautics.

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