NASA reveals secret supersonic airplane that quiets the sonic boom to a thump

One reason that the storied Concorde supersonic jet was finally grounded is because of the sonic boom it generated as it flew fast enough to break the sound barrier. For decades, aerospace engineers have attempted to design supersonic jets that could achieve incredible speeds without rattling windows and angering residents of inhabited areas below the planes' flight paths. Now, NASA and Lockheed Martin have revealed the X-59 experimental aircraft, a supersonic plane that delivers a sonic "thump" rather than the boom. The X-59's first flight is expected later in the year. Capable of reaching 925 miles per hour, the plane could fly from Los Angeles to New York City in less than three hours.

"NASA's X-59 will help change the way we travel, bringing us closer together in much less time," said NASA deputy administrator Pam Melroy.

The X-59's weird proportions are the key to its (relatively) quiet operation.

"It's almost 100 feet long (30.5 meters), but has a wingspan of only about 29 feet," said NASA senior adviser Craig Nickol. "The nose is a distinguishing feature on this aircraft: it's about a third of the length."

"This aircraft may sound like distant thunder on the horizon, or like someone shutting a car door around the corner," he added.

From CNN:

When an aircraft travels at subsonic speeds, the sound waves that it normally creates can travel in all directions; at supersonic speeds, however, the aircraft will leave its own sound behind and the sound waves will compress and coalesce into a single shockwave that originates at the nose and ends at the tail.

When this highly compressed shockwave meets a human ear, it produces a loud boom, which does not occur when the plane breaks the sound barrier, but is rather a continuous effect that can be heard by anyone in a cone-shaped area beneath the plane, as long as it exceeds the speed of sound.

The X-59's shape is designed to prevent the shockwaves from coalescing together. Instead, they spread out, with the help of strategically placed aerodynamic surfaces. The lone engine is also at the top rather than the bottom of the plane, to keep a smooth lower profile that prevents shockwaves from reaching the ground.