It’s been a quarter of a century since commercial passengers could fly to American destinations at beyond the speed of sound. That was on the iconic Concorde, a joint French and English venture initiated in 1954 with first commercial flight in 1976.
The Concorde Revolution
Travel time from Europe to New York was cut to an amazing 3 1/2 hours. Though a fleet of more than 300 were envisioned, cost overruns, public complaints about sonic booms, and a fatal crash resulted in only 13 being built. Because of the noise disruption, since 1973, the U.S. Federal Aviation Administration (FAA) has banned overland civil aircraft flying faster than Mach 1, the speed of sound. Sadly, the Concorde was grounded in 2003; most units are on permanent display in museums and airports in Europe and in New York City, Washington, and Chantilly, Virginia.
Enter NASA in collaboration with Lockheed Martin. NASA initiated the project dubbed Quesst (“Quiet SuperSonic Technology”), and Lockheed Martin won both a preliminary design contract in 2016 and then two years later a $247.5 million contract to design, build and deliver in late 2021 the Low-Boom X-plane assigned “X-59.” Work would be done at the Lockheed Martin “Skunk Works” in Palmdale, California.
Design of a supersonic commercial aircraft is no stranger to the Skunk Works. In 1961, President John F. Kennedy committed the government to subsidize 75% of the development of a commercial airliner to compete with the Anglo-French Concorde then under development. The American aircraft companies were panicking that the Concorde would replace demand for their American-built long-range airliners, and Congress quickly passed legislation authorizing design of an American SST. Lockheed and Boeing both got to work on an SST design, with the Lockheed work at the Skunk Works on a mock-up eventually named the L-2000-7a. Alas, Boeing won the contest. But NOAA and other environmentalists whipped up public opposition to SST’s based on air pollution estimates, and Congress withdrew funding in 1971. So much for the SST … until now.
X-59 Rolls Out
To a cheering audience on site and on TV around the world, Lockheed Martin and NASA jointly rolled-out the first X-59 prototype on January 12, 2024. Though this prototype is not in the configuration of a commercial airliner, it’s the first phase of the goal to fly faster than the speed of sound without generating a loud sonic boom. Instead, the plane is expected to produce what is termed quieter sonic “thumps.”
“Rollout is a major accomplishment, but it also means the next milestone is first flight, and then supersonic flights after that,” said Catherine Bahm, manager of NASA’s Low Boom Flight Demonstrator project, who is overseeing the development and build of the X-59. “Our eyes are on the mission.”
Slower than the Concorde?
The X-59 is expected to cruise at 925 mph (Mach 1.4) at 55,000 feet. By contrast, the Concorde cruised at 1,341 mph (Mach 2.04) at 60,000 feet.
At 99.7 feet long and 29.5 feet wide, the X-59’s shape and the technological advancements it houses will make quiet supersonic flight possible. The X-59’s thin, tapered nose accounts for almost a third of its length and will break up the shock waves that would ordinarily result in a supersonic aircraft causing a sonic boom.
By contrast, the Concorde was 202 feet long and 84 feet wide (wingspan), Amazingly, the fuselage width was only 9 feet 5 inches ( for 4-across seating inside).
Because of the shape of the X-59 nose, there is no windscreen. Forward vision is provided by a digital screen. The cockpit is at a point halfway down the aircraft length.
No word on the number of crew for the X-59, though a NASA video showed 3 crew in full test gear walking down the runway.
X-59 Flight Testing Yet to Come
According to a 2018 article in Aviation Week and Space Technology, flight-clearance testing will be conducted at the Armstrong Flight Research Center (Edwards, CA). That will be followed by acoustic validation including air-to-air Schlieren imaging backlit by the Sun to confirm the shockwave pattern testing. NASA plans to conduct flight tests over U.S. cities to verify the safety and performance of the X-59’s quiet supersonic technologies and evaluate community responses for regulators, whose findings and legislative recommendations could enable commercial supersonic travel over land.
NASA plans to deliver results of the community overflights to the International Civil Aviation Organization and Federal Aviation Administration in 2027. With that information in hand, regulators will be able to decide if a change should be made in rules that prohibit supersonic flight over land – a decision that would be expected in 2028.
Interestingly, there was no mention that I could discern regarding the expected air pollution emitted by the aircraft. That was the issue that sealed the fate of the Concorde in the United States in 1973.
