(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, even shattering windows.
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 does this through a program called Questst – for “Quiet SuperSonic Technology” – which is the result of decades of research and centered around a new aircraft called the X-59.
“It will be significantly quieter than the Concorde or any other supersonic aircraft in existence today,” said Craig Nickol, project manager of the Quest program at NASA. “It is extremely long and thin: it is almost 30 feet long (30.5 meters), but has a wingspan of only about 29 feet. The nose is a distinguishing feature of this aircraft: it is about a third of the length. ”
The slim shape plays a key role in making the aircraft much quieter during supersonic travel.
But how does a sonic boom come about? When an airplane travels at subsonic speeds, the sound waves it normally creates can travel in all directions; however, at supersonic speeds, the aircraft will leave its own sound and the sound waves will compress and coalesce into a single shock wave starting at the nose and ending at the tail.
When this highly compressed shock wave meets a human ear, it produces a loud bang, which does not occur when the aircraft breaks the sound barrier, but rather is a continuous effect that can be heard by anyone in a cone-shaped area below the aircraft, as long as it exceeds the speed of sound. exceeds.
The shape of the X-59 is designed to prevent the shock waves from coalescing. Instead, they spread out using strategically placed aerodynamic surfaces. The lone engine is also located at the top rather than the bottom of the plane, to maintain a smooth lower profile that prevents shock waves from reaching the ground.
As a result, NASA believes the X-59 will produce only 75 decibels of noise at supersonic speeds, compared to the Concorde’s 105 decibels.
“That means this plane might sound like a distant thunder on the horizon, or like someone closing a car door around the corner,” Nickol says. “In fact, people may not hear the thump at all, and if they do, they certainly won’t be startled because it will be low and scattered, and not that loud at all.”
The pivotal portion of the program will begin in 2024, when a series of test flights will be conducted over half a dozen residential communities across the U.S. selected to provide a diverse mix of geographic and atmospheric conditions: “That’s going to be a fun part of the project.” , because we engage with the public and generate a little citizen science,” Nickol says.
Once the X-59 has flown over the selected areas, NASA will contact the communities on the ground to measure their response to the noise. The goal is to confirm the theory that a 75 decibel explosion is acceptable.
The data collected in this way will then be presented to the International Civil Aviation Organization (ICAO), which is responsible for aircraft noise regulation, to persuade it to update it at an international meeting scheduled for 2028.
A new generation
NASA believes a regulatory change would open up the sky for a new generation of supersonic aircraft, which would be allowed to fly over routes that are now prohibited, such as New York to Los Angeles, and cut flight time by about half.
However, we don’t know what those planes will look like and who will build them, because the X-59 is not a prototype, but just a technology demonstration.
“Any future design of a low-boom commercial aircraft for supersonic flight will certainly be different from this one, although some design elements can be directly translated,” said Nickol, pointing to the extended nose, some flight control systems and the aircraft’s unique external vision system. X-59, which provides the pilot with high-definition displays showing what lies ahead, lacking a true forward-facing window due to the aircraft’s streamlined nose.
Nickol believes that such aircraft, with the ability to fly anywhere, would democratize supersonic travel, making a big difference to Concorde’s luxury status: “If you look back 100 years, many of the advanced mobility technologies, including railways and aircraft, started out as premium experiences, but as technology progressed and costs dropped, 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 widespread application, and there’s really no reason why it couldn’t happen.”