NASA Quesst Mission Could Revitalize Supersonic Travel, but Quieter

After 50 years of the Federal Aviation Administration banning commercial supersonic travel over land, NASA is trying to make this type of flight possible with its Quesst mission, which will gather data to hopefully prove a reduction in the intensity of sound that reaches the ground.

The mission has two goals: design and build NASA’s X-59 research aircraft with technology to reduce the sound of the sonic boom, and then fly the aircraft over a few U.S. cities, collecting data from those communities to see how loud people thought the sound was and sharing this information with FAA and international regulators.

The X-59, a 99.7 foot long aircraft with a 29.5 foot wingspan, is currently being built by NASA and Lockheed Martin to fly faster than the speed of sound—known as Mach 1. The X-59 will fly at 55,000 feet above Earth at Mach 1.4, the equivalent of 925 miles per hour. A normal aircraft typically flies at approximately 550 mph, meaning that the new aircraft could enable people to travel to destinations in almost half the time. 

Current aircraft traveling faster than Mach 1 creates a sonic boom—a loud, thunderous sound—the disruption from which has caused the FAA to ban commercial supersonic air travel over land.

“The main reason for the sonic boom is because at supersonic speed air can’t get out of the way fast enough, or before the airplane actually gets there, and so that generates all these shock waves generated off the airplane. And as they travel to the ground, they come together to create a lot of pressure disturbance, which then your ears pick it up as a sonic boom,” Gautam Shah, Quesst’s manager for the community response phase, told Nextgov. “A lot of the technology involves [the] shaping of the aircraft, so that all these individual shockwaves that are generated from the disturbances get generated in a different fashion.”

These differing shockwaves, he explained, remain separate as they reach the ground, resulting in a softer general noise, rather than a loud, unified one. That shaping comes down to an extra long nose—about a third the length of the whole aircraft—that alters the pressure as the plane moves forward and a set of wings and tail that can keep those sound waves separate.

Furthermore, the underside of the aircraft is smooth to help create the softer sound and the engine is not below the wings, like in commercial aircraft. 

“That smooth underside helps alter those pressure disturbances as they go down,” Shah said.“And the engine, it’s a conventional engine being used in some military aircraft today, so its location is near the back of the airplane where it’s subject to slower speed: the subsonic air has to go into the engine, so its location is further back [and it’s on the top].”

“What’s happened is that over the course of time as technology has improved, we can now do a lot of computations in advance to see what type of shapes will result in what type of pressure gets generated and be able to do that in rapid enough fashion to see how we can make changes to ultimately get an airplane that will achieve that,” Shah said.

And though the X-59’s 38-foot-long nose helps with aerodynamics, it makes traditional features of aircraft challenging.

“The long nose makes it difficult for a pilot to see forward because of that 38-foot-long nose, and so because of that the airplane does not have forward facing windows,” Shah said. “Instead, we have this external vision system which is a series of cameras, which then provide a very high quality high resolution digital display to the pilot, which is in many cases even better than windows because you can overlay radar information, other graphics on top of that.”

The X-59 also incorporates elements of existing aircraft: a modified version of the F-18 engine and landing gear from the F-16, as well as the canopy and ejection seat from the T-38, which are integrated together. 

“That has a series of benefits because you have hardware that already exists,” Shah said. “It also has challenges because now you’re trying to integrate those different hardware pieces in a way that maybe they weren’t originally designed to do. But in the end, that’s the best approach that was taken to be able to utilize what we can for existing components.”

The X-59 is an experimental aircraft that will not carry passengers. Instead, commercial aviation companies may decide to incorporate some of these technologies into future aircrafts. The X-59’s unique shape and technologies should produce a sound like a gentle thump that is expected to be around 75 Perceived Level decibels, about the equivalent of a car door slamming 20 feet away. 

Before community testing, the X-59 will undergo design and safety performance testing.

NASA is planning for the X-59 to fly over four to six communities across the U.S., but the specific communities are still in discussion, as they must meet the agency’s requirements. The agency will be asking the communities if they heard anything; whether it was noticeable or not; and, if it was noticeable, was it annoying? NASA will also measure the sound on the ground in those communities. It will share the sound measurements and community responses with the FAA and international regulators, which could have the agency modify the rules to be based on volume, thus creating a sound instead of speed limit. 

The project started in 2018 and is expected to conclude in 2027. 

“This is a very special mission to be able to develop these technologies, to demonstrate them on an actual aircraft. And I think one of the most unique aspects is [that] the public is involved in providing the data that we’ll actually use as part of this research effort,” Shah said. “It’s not just a NASA effort that we share our technology and show it to the world, but we’re actually involving the public in the development of that technology.”

“I’m really excited about it,” Shah added. “It's a pretty neat project to be involved in.”

NASA’s Advanced Air Vehicles Program and the Integrated Aviation Systems Program are organizing the mission, which is being managed by individuals at Langley Research Center, Glenn Research Center, Ames Research Center and Armstrong Flight Research Center.