X-59: NASA’s quest to make a ‘quieter’ supersonic plane

(CNN) – If you’ve heard a sonic boom recently, you probably remember it. Aircraft flying faster than the speed of sound can cause a sharp, explosion-like explosion—shocking, and even cracking windows.

Sonic booms are part of the reason why there are no supersonic passenger aircraft flying today, and one of the limiting factors for the success of the Concorde, who last flew in 2003, The supersonic airliner was limited to subsonic speeds when flying over land or near a coastline, and current international regulations still limit the speed of commercial transport over land to Mach 1 or the speed of sound below Mach 1, so as to protect the inhabited areas. In order to avoid the disturbance of sonic boom. ,

Now, NASA is working to change those rules by turning the boom into a “thump,” paving the way for a new generation of quieter supersonic aircraft. The agency is doing this through a program called the Quest for “Quiet Supersonic Technology”—the result of decades of research and centered around a new aircraft called the X-59.

distant thunder

The X-59 is the latest in a series of experimental aircraft including the X-1, which became the first manned aircraft in 1947. more than the speed of soundAnd this X-15Which holds the record for the fastest manned flight ever, which was set in 1967 at Mach 6.7.
Designed and Built by Lockheed Martin in Palmdale, Calif., under $247.5 million NASA ContractThe X-59 is currently undergoing ground testing, with anticipation of a first flight later in 2022.

“It will be significantly quieter than the Concorde or any other supersonic aircraft out there today,” says Craig Nichol, project manager for the Quest program at NASA. “It is very long and slender: it is about 100 feet long (30.5 m), but its wingspan is only 29 feet. The nose in this aircraft is a distinctive feature: it is about a third of the length.”

The sleek shape plays an important role in making the aircraft more quiet when traveling supersonically.

What the X-59 might look like in flight.


But how does sonic boom happen? When an aircraft travels at subsonic speed, the sound waves that would normally be generated can travel in all directions; At supersonic speeds, however, the aircraft will retract its sound and the sound waves will be compressed and contained in a single shockwave that originates from the nose and ends at the tail.

When this highly compressible shockwave meets a human ear, it produces a loud boom, which does not occur when the aircraft breaks the sound barrier, but rather is a continuous impact that is projected into a cone-shaped region under the aircraft. Anyone can hear, as long as it exceeds the speed of sound.

The shape of the X-59 is designed to prevent shockwaves from accumulating together. Instead, they spread with the help of strategically located aerodynamic surfaces. To maintain a smooth low profile, the sole engine is mounted at the top rather than at the bottom of the plane, which prevents shockwaves from reaching the ground.

As a result, NASA believes the X-59 will produce just 75 decibels of sound when traveling at supersonic speeds, compared to the Concorde’s 105 decibels.

“What this means is that this plane may sound like a distant thunder on the horizon, or like someone is closing a car door just around the corner,” Nicol says. “It may also happen that people may not hear the boom at all, and they certainly won’t be shocked if they do, because it will be low and diffuse, and not loud at all.”

change rules

A significant portion of the program will begin in 2024, when a series of test flights will be performed on more than half a dozen residential communities across the US, which have been selected to offer a diverse mix of geographic and atmospheric conditions: “This is a That’s going to be the fun part of the project, because we’re going to engage with the public and generate a little bit of citizen science,” says Nicole.

The plan is reminiscent of an experiment run by the Federal Aviation Administration (FAA) in 1964, when supersonic fighter jets were fly frequently To test the effect of the sonic boom on the public in Oklahoma City.
It didn’t go well with up to 20% of people objection Another 4% filing complaints and damage claims for BOOM. “We don’t want to repeat that, so we’re going to test this plane first at a restricted range,” Nicole says. “Only when we are satisfied with the performance will we go to the communities, and still carefully control the level of the sonic boom.”

Once the X-59 is flown over selected areas, NASA will engage with communities on the ground to assess their response to the noise. The goal is to confirm the theory that a 75-decibel surge would be acceptable.

The data so collected will be submitted to the International Civil Aviation Organization (ICAO), which is in charge of aircraft noise regulations, to persuade them to update them at an international meeting scheduled for 2028.

The first flight is planned before the end of the year.

The first flight is planned before the end of the year.

Darin Russell / NASA

a new generation

NASA believes the change in regulations will open the skies to a new generation of supersonic aircraft on routes not currently permitted, such as New York to Los Angeles, and to cut flight times in almost half. Is allowed.

However, we don’t know what those aircraft will look like and who will build them, as the X-59 is not a prototype, but merely a technical demonstrator.

“Any future design of a commercial aircraft with low buoyancy for supersonic flight will certainly differ from this, although some design elements may translate directly,” says Nicol, pointing to the extended nose, some flight control systems , and the X-59’s unique external sighting system, which, in the absence of an actual forward-facing window due to the aircraft’s streamlined nose, provides the pilot with high-definition displays showing what lies ahead.

Several companies are currently developing supersonic passenger aircraft and plan to fly them in a decade or less, including hermes, Boom And spike, However, it is doubtful that any of them will be able to take advantage of the Quest program’s findings, which will likely inform the next generation of supersonic aircraft.

Nicole believes that such aircraft, with the ability to fly anywhere, will democratize supersonic travel, a key difference with Concorde’s luxury status: “If you look back 100 years, So many advanced mobility technologies, including railroads and airplanes, have begun to look like premium experiences, but as technology advanced and costs came down, they became available to the general public,” he says.

“One of the long-term goals is to make this form of high-speed travel available as a broad application, and there’s really no reason it can’t.”