First human invention that broke the sound barrier?

Answer 1

The first aircraft to break the sound barrier under controlled, level flight, was the Bell X-1 rocket plane, piloted by WWII Ace and Edwards AFB (then Muroc AAF) test pilot Chuck Yeager. The events and the subsequent Space Program are depicted in the book "The Right Stuff" by Tom Wolfe, and the movie of the same name. Yeager broke the sound barrier on October 14, 1947, flying at 45,000 feet. It is considered one of the pivotal human inventions and achievements of the 20th Century, and human history as a whole.

Yeager named the Bell X-1 "Glamorous Glennis" after his wife Glennis Yeager. "Glamorous Glennis" or variants of that name were used on all of Yeager's P-51 Mustangs during WWII. Yeager got the selection to fly the X-1 after civilian Bell Aircraft test pilot Chalmers "Slick" Goodlin demanded $150,000 for the attempt, since many test pilots had already died trying to break through the barrier.

What wasn't known at the time of the flight (except by his wife and close friend Jack Ridley, his Flight Engineer) was that Yeager had broken 2 ribs riding a horse 2 days prior to the flight. He was so afraid that they'd remove him from the historic attempt that he went to a Veterinarian to have the injury looked at.

The Bell X-1 design was built to the shape of a .50 caliber Browning bullet, which is known to be stable at supersonic speeds. The addition of a controllable trim stabilizer on the tail further allowed the aircraft to push through the barrier.

The X-1 is restored and currently resides at the National Air & Space Museum.