- Historic Sites
1947 Fifty Years Ago
Birth of the Sonic Boom
October 1997 | Volume 48, Issue 6
To break the barrier, the X-I was loaded into the bomb bay of a B-29 and released at twenty-five thousand feet with Yeager in the cockpit. He climbed to forty-two thousand feet on two of the engine’s four chambers, then switched on a third and watched his speed indicator zoom to seven hundred miles per hour, 1.06 times the speed of sound at that altitude. Observers on the ground heard a sonic boom, a sound that would become familiar in years to come. Yeager shot upward until his fuel was exhausted and then glided to a landing at Muroc Army Air Field in California. The Air Force did not officially announce the achievement until June 1948, though Aviation Week magazine had leaked word the previous December.
Not long afterward, a pair of planes even more distinctive, though much less important, than the X-I were launched. On October 21 the jet-powered Northrop YB-49 Flying Wing took to the air for the first time, landing at Muroc thirty-four minutes after leaving its factory in Hawthorne, California. As its nickname suggests, the YB-49 had no tail or fuselage, greatly reducing its weight. In theory, the resulting increase in range would make it valuable as a long-range bomber. In practice, packing everything inside the 172-foot wing—pilot, fuel tanks, and cargo space—made the airfoil too thick to take advantage of modern aeronautical science, and its unconventional shape made it hellishly difficult to control. In a June 1948 crash the pilot Glen W. Edwards (for whom Muroc was renamed in 1950) and four other crewmen died. Northrop eventually built eleven Flying Wings for the Air Force, but in 1949 the contract was canceled and the planes were chopped to pieces. Northrop revived the single-wing idea in the 1980s with its radar-invisible stealth bomber, this time with a computer to control its extremely unstable flight.
Then, on November 2, Howard Hughes flew his mammoth HK-I wooden flying boat—popularly called the Spruce Goose, though it was made mostly of plastic-impregnated birch— for the first and only time. Hughes had built the 150-ton plane during the war as a troop transport, using seven million dollars of his own money and eighteen million from the government. It was designed to seat 500 civilians or 700 soldiers. After flying seventy feet above California’s Long Beach Harbor for about a mile, Hughes denied that his flight had anything to do with a congressional committee that was investigating the boondoggle. Still, the plane never flew again. None of the armed forces could find any use for it, and it was eventually turned into a museum near Long Beach.