X-59: NASA’s quest to build a ‘quiet’ supersonic plane

CNN  — 

If you’ve heard a sonic boom recently, you probably remember it. The loud, explosion-like bang – caused by a plane flying faster than the speed of sound – can be startling, and even crack windows.

Sonic booms are part of the reason why there are no supersonic passenger planes flying today, and one of the limiting factors to the success of Concorde, which last flew in 2003. The supersonic airliner was restricted to subsonic speeds when flying over land or near coastlines, and current international regulations still limit the speed of commercial transport over land to below Mach 1, or the speed of sound, to avoid the disturbance of sonic booms over inhabited areas.

Now, NASA is working to change those regulations by transforming the boom into a “thump,” paving the way for a new generation of quieter supersonic aircraft. The agency is doing so through a program called Quesst, which is the result of decades of research and is centered around a new aircraft called the X-59.

Distant thunder

The X-59 is the latest in a series of experimental planes which include the X-1, which in 1947 became the first manned aircraft to exceed the speed of sound, and the X-15, which still holds the record for the fastest ever manned flight, set in 1967 at Mach 6.7.

Designed and built by Lockheed Martin in Palmdale, California, under a $247.5 million NASA contract, the X-59 is currently undergoing tests on the ground, in anticipation of a first flight later in 2022.

“It will be significantly quieter than Concorde or any other supersonic aircraft that exist today,” says Craig Nickol, senior adviser at NASA Headquarters. “It’s extremely long and thin: It’s almost 100 feet long (30.5 meters), but has a wingspan of only about 29 feet. The nose is a distinguishing feature on this aircraft: it’s about a third of the length.”

The sleek shape plays a key role in making the aircraft much quieter when traveling supersonically.

How the X-59 could look in flight.

But how does a sonic boom happen? 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.