Until Octob er 14, 1947, no one knew if a plane could fly faster than the speed of sound. Aircraft approaching Mach 1 shook violently, as if hitting an invisible wall. Only a year earlier, British pilot Geoffrey De Havilland had died when his plane broke apart flying close to the speed of sound. Scientists theorized that as a plane reached high speeds, sound waves piled up around it, creating a “sound barrier” that held it back.
After World War II the U.S. military and Bell Aircraft developed the X-1, a “bullet with wings” designed to punch a hole through the sound barrier. The test pilot for the rocket-powered plane was 24-year-old Captain Chuck Yeager. A decorated combat ace, Yeager had cheated death more than once. During the war, he’d been shot down over France but eluded the Nazis with the help of the French Resistance, made it back to his squadron, and returned to the skies.
By mid-October 1947 Yeager had flown the X-1 several times over the Mojave Desert, edging closer to the sound barrier. On October 14 he climbed into the plane with two cracked ribs from a fall off a horse – an injury he kept secret so he wouldn’t be grounded. A giant B-29 carried the X-1 to 20,000 feet and released it. The plane stalled and dropped 500 feet while Yeager struggled to bring it under control. He fired his rocket engines, climbed to 42,000 feet, leveled off, and fired a rocket again.
Then it happened. The shaking suddenly stopped. “I was so high and so remote, and the airplane was so very quiet that I might have been motionless,” Yeager later recalled. But the needle on the speed gauge jumped off the scale. On the ground below, engineers heard the thunder of a sonic boom. Chuck Yeager had punched through the sound barrier.