Noise level supersonic vs subsonic1/19/2024 These studies, along with tens of thousands of claims against the Air Force for property damage-horses and turkeys had supposedly died or gone insane-led the F.A.A. By the end, about one in four said that they could not learn to live with the noise. People complained of interruptions to their sleep, conversations, and peace of mind, and about the occasional crack in plaster or glass. Louis and asking citizens about the hundred and fifty or so booms the planes created the authors concluded only that, after repeated booms, “some reaction may be expected.” (“Sonic boom’s a top-priority public-relations problem,” an Air Force major told The New Yorker, in 1962.) A clearer picture emerged in 1964, when Operation Bongo II created more than a thousand sonic booms over Oklahoma City. Over ten months in 19, the Air Force and the Federal Aviation Administration (F.A.A.) ran Operation Bongo, flying B-58 bombers over St. In a technical summary written in 1960, NASA scientists warned that “shock-wave noise pressures” might be “of sufficient intensity to damage parts of ground building structures such as windows, in addition to causing annoyance.” The full extent of that annoyance, however, would take a while to gauge. But these initiatives started before sonic booms were fully understood. NASA began working on supersonic transport upon its founding, in 1958, eventually settling on a design by Boeing. Plans for the plane that would become the Concorde-the first commercial “supersonic transport,” or S.S.T.-began in the nineteen-fifties. The boom sweeps over everything below it-a kind of sonic broom that is about a mile wide for every thousand feet of plane altitude. Contrary to what you might imagine, a plane causes a sonic boom not just once, when it breaks the sound barrier, but continuously for the entire time that it’s supersonic. Bullets travel fast enough to cause sonic booms, as do the tails of whips. (Often, sonic booms go boom-boom.) It’s no coincidence that sonic booms sound like thunder thunder is a sonic boom, caused by shock waves expanding around lightning bolts. A zone of low pressure follows-the trough of the wave-and then normal air pressure returns, creating its own sound. They begin to build up, and this single, merged wave reaches the ground all at once, creating a boom. But when the plane itself exceeds that speed-at around seven hundred and seventy miles per hour at sea level, or around six hundred and sixty at cruising altitude-it catches up to the waves expanding in front of it. The principle behind the boom is simple: sound travels through the air in the form of compression waves, so called because they occur as air gets denser and sparser as a plane flies, the waves expand in all directions at the speed of sound. Like all supersonic flyers, Yeager trailed a sonic boom behind him. He did it in a tiny, orange-colored plane called the Bell X-1-essentially, a cockpit and two wings connected to a rocket engine. In 1947, Chuck Yeager, the Air Force test pilot, became the first person to break the sound barrier.
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