Sound Barrier: The Flight

Supersonic flight was finally and conclusively achieved on October 14, 1947.  Yeager gave the following recap of this famous flight:

He (Cardenas) dropped the X-1 at 20,000 feet…The moment we picked up speed I fired all four rocket chambers in rapid sequence.  We climbed at .88 Mach and began to buffet, so I flipped the stabilizer switch and changed the setting two degrees.  We smoothed right out, and at 36,000 feet, I turned off two rocket chambers.  At 40,000 feet,  we were still climbing at a speed of .92 Mach.   Leveling off at 42,000 feet, I had thirty percent of my fuel, so I turned on rocket chamber three and immediately reached .96 Mach.  I noticed that the faster I got the smoother the ride.  Suddenly the Mach needle began to fluctuate.  It went up to .965 Mach–then tipped right off the scale.  I thought I was seeing things!  We were flying supersonic!  And it was smooth as a baby’s bottom.  I was thunderstruck.  After all the anxiety, breaking the sound barrier turned out to be a perfectly paved speedway.  I estimated I had reached 1.05 Mach. (Later data showed it was 1.07 Mach–700 mph)

Footage of the Bell XS-1 from the SDASM Archives.


Chuck Yeager’s life was never the same after October 14, 1947 (once the word got out) and neither were aeronautical limits.  He admitted he was lucky to be “the one”, someone else would have done it eventually.  Perhaps Woolams, if he had not been killed, or Goodlin, if he had not held out for a better contract, or Hoover, if Yeager’s broken rib had been revealed.  The Navy was working on a similar project as well.  But on that day he was the one that strapped into the X-1 cockpit and punched through the sound barrier.  

Yeager and his girl.

SDASM Museum docent, Bob Curry was an aeronautical engineer at the NASA Armstrong Flight Research Center (formerly Dryden) where many of the experimental X-planes were tested (including the X-1).  He did not work directly on the  X-1 program but knew and discussed the program with engineers who did. He made the following point,  “The misconception is that experimental airplanes are demonstrators of a new technology, or proof of concept, as if the X-1 was built to prove supersonic flight was possible. In truth, the engineers and scientists were not in doubt about whether supersonic flight was possible.  The purpose of the X-1 was not to prove that point, but instead to provide a way to obtain controlled, high quality experimental data that could be used to validate theory, design tools and concepts.”  This was the true value of the X-1 program.

Explore a few more images from our collection related to the anniversary here.


1.  Richard P. Hallion, Supersonic Flight Breaking the Sound Barrier and Beyond, Redwood Books, Trowbridge, 1972 revised 1997.

2.  Dana Marcotte Kilanowski (conducted oral history interviews) with Chuck Yeager, Bob Cardenas, Bob Hoover, Jack Russell and James Young, The Quest for Mach One. Penguin Group, 1997.

3. Chuck Yeager and Leo Janos, Yeager, Bantam Books, 1985.


San Diego Air & Space Museum

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