26 April 1948: At Muroc Field (now known as Edwards Air Force Base), in the high desert of southern California, North American Aviation test pilot George Welch put the prototype XP-86 Sabre, 45-59597, into a 40° dive and broke the Sound Barrier. It is only the second U.S. aircraft to fly supersonic. The first was the Bell X-1, piloted by Chuck Yeager, only a few months earlier.
Or, maybe not.
Mr. Blackburn speculates—convincingly, in my opinion—that Secretary of the Air Force W. Stuart Symington, Jr., ordered that Welch’s excursions beyond Mach 1 were to remain secret. However, during a radio interview, British test pilot Wing Commander Roland Prosper (“Bee”) Beamont, C.B.E, D.S.O. and Bar, D.F.C. and Bar, stated that he had flown through the Sound Barrier in the number two XP-86 Sabre prototype (45-59598). Once that news became public, the U.S. Air Force released a statement that George Welch had flown beyond Mach 1 earlier, but gave the date as 26 April 1948.
It wasn’t long after the first flight of the XP-86 on October 1, 1947, that Welch dropped into Horkey’s [Edward J. Horkey, an aerodynamicist at North American Aviation] office at the Inglewood plant. He wanted to talk about his recent flight and some “funny” readings in the airspeed indicator. He had made a straight-out climb to more than 35,000 feet. Then, turning back toward Muroc Dry Lake, he began a full-power, fairly steep descent.
“I started at about 290 knots,” Welch was explaining to Horkey. “In no time I’m at 350. I’m still going down, and I’m still accelerating but the airspeed indicator seems stuck like there’s some kind of obstruction in the pitot tube. I push over a little steeper and by this time I’m through 30,000 feet. All of a sudden, the airspeed indicator flips to 410 knots. The aircraft feels fine, no funny noises, no vibration. Wanted to roll off to the left, but no big deal. Still, I leveled out at about 25,000 and came back on the power. The airspeed flicked back to 390. What do you think?”
“. . . You may be running into some Mach effects. . . .”
— Aces Wild: The Race For Mach 1, by Al Blackburn, Scholarly Resources Inc., Wilmington, Delaware, 1999, at Pages 147–148.
The “funny” reading of the airspeed indicator became known as the “Mach jump.” George Welch was the first to describe it.
The Sabre became a legendary jet fighter during the Korean War. 9,860 were built by North American, as well as by licensees in Canada, Australia and Japan.
George Welch had been recommended for the Medal of Honor for his actions as a P-40 Warhawk fighter pilot in Hawaii, December 7, 1941. He was killed while testing a North American Aviation F-100A Super Sabre, 12 October 1954.
© 2018, Bryan R. Swopes