How NASA’s New Supersonic Jet Replaced Boom with a Quiet Thud

Imagine leaving work a little early on a Friday afternoon in LA or San Francisco and winding up with a drink on the beach in Maui before cocktail hour ends. Imagine Seattle to Tokyo in four hours, New York to London in three plus.

Many in the fledgling supersonic sector believe that supersonic commercial flights are not only possible, but are working toward aircraft design, construction, and certification within the next five to ten years. They say flying faster than the speed of sound will not only revolutionize air travel, but offer travelers the ultimate luxury: time.

Boom, Spike and Exosonic have different concepts for their supersonic jets, designed to travel between Mach 1.4 (1074 mph) and 1.8 (1381 mph), while Destin’s and Hermes’ Hypersonic constructs can theoretically travel at Mach 5.0, or 3836 miles per hour. Most remain in the theoretical concept stage. Boom’s only demonstration, the XB-1, has begun initial flight tests, with supersonic tests scheduled for later this year.

Progress has been slow due to high R&D costs due to the unique technical challenges of supersonic flight. “The hurdles are substantial,” notes Vic Kachuria, CEO of Spike Aerospace, which is developing a 12- to 18-passenger supersonic aircraft called the Diplomat. “Boom, ground noise, safety, regulatory, environmental, infrastructure. It’s a lot.”

The sonic boom remains the biggest obstacle to development, said David Richwine, NASA’s deputy project manager for technology on the X-59, an experimental aircraft designed to reduce boom noise and vibration. “When we piled up the challenges facing supersonic, solving the boom was the biggest,” he says. “Acting on this will free up commercial operators to work on some other issues.”

Sonic booms have been going on ever since Chuck Yeager broke the sound barrier in the Bell X-1 in 1947. The boom — a loud sound created by shock waves when an aircraft passes the speed of sound — was initially seen, oddly enough, as a sign of progress since it ushered in the supersonic era. was seen as In 1963, President John F. Kennedy launched an initiative called Supersonic Transport (SST) that brought together government and industry, with the goal of building a commercial supersonic aircraft capable of carrying 300 passengers. , flying at Mach 3, or 2301 mph.

But by the end of the decade, most people saw the sonic boom as a public nuisance. In 1968, an F-105 flyover at the Air Force Academy blew out 200 windows of its famous chapel, injuring a dozen people. From 1956 to 1968, the Air Force had to deal with nearly 40,000 claims against its supersonic warbirds, covering damages from broken windows and cracked plaster in homes, to claim that the speed of sound exceeded the speed of sound. The cattle have gone mad.

Concorde, the world’s first commercial supersonic airliner, didn’t help. Developed jointly by the British and French, its transatlantic flights often ended in American cities with broken windows and vibrations that rattled local residents. In 1973, Congress and many authorities around the world banned supersonic air travel on Earth, reducing supersonic’s ability to accelerate commercial air travel.

Always an expensive and fuel-intensive aircraft, Concorde made its last flight in Britain in 2003, landing at an aviation museum in Bristow, where it became a fixed display.

Now, NASA, working with Lockheed Martin, hopes to revive supersonic commercial air travel by reducing the speed. The team overseeing the X-59 Quest (stands for Quiet Supersonic Technology) project is promoting the idea of ​​lifting the supersonic speed limit once sonic booms become a non-issue.

“Instead of a rule based solely on speed, we’re proposing that the rule be based on sound,” said Peter Coyne, the X-59 program’s integrated mission manager. “If supersonic flight isn’t loud enough to disturb someone below, there’s no reason why an airplane can’t fly supersonic.”

Other aircraft, including a modified Northrop F-5E jet, demonstrated in 2003 that the shape of the aircraft could be used to reduce the intensity of the sonic boom. The X-59 is designed to take that a step further, creating a sonic “thud” that measures around 75 decibels, roughly the sound of a washing machine.

The X-59 concept was first floated in 2018, with NASA offering Lockheed Martin a $248 million grant to develop the jet. After extensive computer modeling and wind tunnel testing, the X-59 was officially unveiled to the world in January at Lockheed’s California Skunk Works facility. The slender, needle-nosed aircraft is 99.7 feet long and 29.5 feet wide, looking like a sleek, futuristic fighter jet, with the cockpit retracting halfway along the fuselage.

It is designed to fly at 1.4 times the speed of sound, or 925 mph. The X-59 reuses parts from other warbirds, including landing gear from the F-16, the canopy and ejection seat from the T-38 supersonic training jet, and some engine systems used in the U-2 spy plane.

A top-mounted engine allows for a smoother bottom to prevent shock waves from merging behind the aircraft, thus reducing the potential power of the sonic boom. The aircraft has undergone ground tests, with flight tests expected by the end of this year. The X-59 will fly at an altitude of about 55,000 feet at a speed of 1.4 (1074 mph), about the same speed and altitude as a commercial supersonic jet, collecting data on its “silent climb.” The data, NASA says, “should help regulators revise the rules that prohibit commercial supersonic flight on Earth.”

The configuration places the cockpit halfway down the length of the aircraft, which means the pilot does not see through the forward-facing window, but instead uses high-resolution cameras that feed a 4K monitor in the cockpit. , called the external vision system. .

Once the X-59 flies, it will undergo safety testing, then a period of acoustic evaluation before NASA begins a series of test flights over selected cities where pre-briefed citizens will determine I will provide feedback to help determine if the technology achieves acceptable noise. The surface

A voice call would be welcome news for commercial supersonic startups. Spike Aerospace is doing its work while also drafting NASA research. Like the X-59, its purpose is to slow down the sound waves by flattening them so that they travel upward and largely cancel each other out. Exosonic is also positioning its 70-seat aircraft as a “silent” sonic boom.

The X-59 may achieve its immediate goal of reducing sonic boom, but its application to a commercial aircraft would still be difficult. Commercial concepts still have major problems with raising enough capital to bring a final product to market, and then there are questions of sustainability — something that didn’t exist in 1969 when the Concorde first flew. Richwine acknowledges that after the boom hits, “emissions are the next biggest challenge, so we have to look at alternative fuels, electric and hydrogen.”

NASA has begun peering down all these rabbit holes. Boom has built its plane to run on 100 percent sustainable aviation fuel (SAF) while Spike is exploring electric and hydrogen.

Supersonic manufacturers are optimistic, despite significant technical challenges and a general consensus within private aviation that the projects would be too expensive to bring to market, with limited demand from airlines and other buyers.

Inside the arena, however, optimism prevails. “I definitely think there will be supersonic flight,” says Rich Vine. “It’s a more complex configuration than a normal airplane, so it will take time, but we’ll get there. For commercial airlines, it will probably be 15 years.