The cool thing about Welsh was that he was a P-40 pilot at Pearl Harbor assigned to a tiny sattelite airstrip who always stayed up all night playing poker...as a result he and a buddy were awake when the first Jap planes flew over. As a result, he and a wingman were able to get in the air early, allowing him to shoot down several planes that day. His story was one of several featured in the movie Tora, Tora, Tora.
Welch was performing a demonstration flying the new F-100A. His flight card called for a symmetrical pull-up at 1.55 Mach. The maneuver would generate more than 7 Gs. As he began the maneuver, the airflow over the wing suddenly burbled, completely blanking the newly redesigned and smaller vertical stabilizer. The fighter yawed slightly and then suddenly turned partially sideways to the direction of travel. The nose folded up at the windscreen and crushed Welch in his ejection seat. Miraculously, the seat fired and carried Welch clear of the plane as it disintegrated. Ejecting at supersonic speeds is not only hard on the human body, it’s hard on parachutes as well. Welch’s chute was nearly shredded by the violent blast of air. With many panels blown out, the rate of descent was much too fast to avoid serious injury, or even death. When rescuers arrived at Welch’s side, he was barely alive. He died before he could be transported to a hospital. Ironically, Yeager had complained that the F-100A, with its smaller vertical stabilizer, was dangerously unstable. Welch elected to fly it anyway.
By the way, the British did fly a scale model of the M 52 some years after Yeager's famous flight, and that research vehicle did exceed the speed of sound surprisingly smoothly, confirming that the "flying" horizontal stabilizer was the reason why the XS-1 succeeded in exceeding Mach 1.0.