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First supersonic flight in rocket-powered research plane

Chuck Yeager breaks the sound barrier in a Bell XS-1 airplane over Rogers Dry Lake, California.

On 14 October 1947, a Boeing B-29 Superfortress lifted an experimental aircraft, built by the Bell Aircraft Company, to an altitude of 25,000 feet. The Boeing pilot opened the bomb bay doors and released the XS-1 #1 over Rogers Dry Lake, California.

U.S. Air Force Captain Chuck Yeager then fired the four rocket motors that powered “Glamorous Glennis” (so named for his wife) and exceeded the speed of sound (Mach 1).

The experimental aircraft reached Mach 1.06 by traveling 700 miles (1,127 kilometers) per hour at an altitude of 43,000 feet (13,000 meters). Mach 1 varies with atmospheric pressure and temperature.

Imagine being the first man to achieve supersonic flight … traveling faster than the speed of sound … but being unable to tell anyone!

Bell X-1
An X-1 being hoisted into a B-29 bomb bay. NASA.

The project was so secret that the Air Force remained mum until June 1948.

speed of sound broken
New York Times, 11 June 1948. Front page.

The Army initially named the experimental aircraft XS-1  (Experimental Sonic-1). Bell initially built three of the supersonic planes that we know today as X-l.

According to, the X-1 had “thin, unswept wings and a streamlined fuselage” which adopted the “lines of a .50-caliber machine gun bullet.”

The X-1 #1 flew 78 times, according to the National Air and Space Museum. On 26 March 1948, Yeager piloted it to 957 miles (1,540 kilometers) per hour. At an altitude of 71,900 feet (21,900 meters), the aircraft reached Mach 1.45. Yeager set a record that day for velocity and altitude in a manned airplane.

Due to safety issues and because the plane guzzled fuel like a thirsty camel, the X-1 aircraft had a standard air-launch. But at least once, on 05 January 1949, Yeager and Glamorous Glennis “successfully completed a ground takeoff from Muroc Dry Lake.”

The XS-1 #2 became the X-1 “Mach 24” research airplane. However, the X-1-3 Queenie exploded on the ground in 1951, injuring the pilot. Bell built three additional planes; two of those also experienced propulsion system explosions.

Safety record: 50-50.

The Air Force gifted the Smithsonian Institution with X-1 #1 on 26 August 1950.

Bell X-1
The Bell X-1 #1 reached a speed of Mach 1.06 on 14 October 1947. On 26 March 1948, the plane reached its maximum speed of Mach 1.45.

Yeager died in December 2020 at age 97. He was the inspiration for Tom Wolfe’s book, The Right Stuff.


#scitech, #space, #science (267/365)
📷 National Air & Space Museum
Daily posts, 2022-2023

By Kathy E. Gill

Digital evangelist, speaker, writer, educator. Transplanted Southerner; teach newbies to ride motorcycles! @kegill

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