Sound bite: Can supersonic air travel fly again?

That is largely because of physics: specifically, the sonic boom, the thunderclap noise made when an aircraft breaks the sound barrier, which essentially doomed supersonic aviation as a viable business.

In 1960s-era tests, booms reportedly broke windows, cracked plaster and knocked knickknacks from shelves; in 1973, the Federal Aviation Administration forbade civilian supersonic aircraft from flying over land. Planes could go supersonic only over the ocean — most famously, the Concorde, the sleek British-French passenger plane that flew a handful of routes in less than half the average time. But potentially lucrative overland routes were off limits, restricting supersonic travel’s business prospects.

NASA and aviation entrepreneurs, however, are working to change that, with new aircraft designed to turn the boom into a “sonic thump” that is no louder than a car door that is being slammed 20 feet away. That may induce the F.A.A. to lift the ban, which could allow for two-hour coast-to-coast supersonic flights.

“The main reason NASA is working on this is to enable regulation for supersonic flight,” said Craig Nickol, NASA’s low-boom flight demonstration project manager. “The main objective is to open up new markets.” The supersonic age dawned on Oct. 14, 1947, when Chuck Yeager broke the sound barrier while piloting the rocket-powered Bell X-1 over the Mojave Desert. In the following decades, the barrier was also broken by a succession of military jets, once by a passenger airliner (during a test flight of a Douglas DC-8 in 1961) and, ultimately, by regular commercial service from the Soviet Tupolev Tu-144 and the Concorde, both long defunct.

The far more successful Concorde mostly travelled trans-Atlantic routes at about $6,000 to $7,000 per ticket for a three-and-a-half-hour flight in a cramped, noisy cabin, which was nonetheless considered glamorous. The Champagne-and-caviar flights were discontinued in 2003 after 27 years of intermittent profitability and one crash that killed 113 people. What the Concorde’s chief pilot called “the airliner of the future” was consigned to the past.

But the possibility of a supersonic renaissance was arriving even as the Concorde was on its way out. The slide rules and log tables used to design it had been pushed aside by supercomputers, which enabled engineers to test and tweak virtual aircraft designs comparatively cheaply and quickly.

That is exactly what Darpa, the research and development wing of the U.S. Defense Department, and NASA did in 2003 with the Shaped Sonic Boom Experiment, which confirmed that computer-designed modifications to a Northrop F-5E jet would hush the sonic boom in the way the software forecasted. “We flew it and measured it, and our model predicted the boom very well.,” Nickol said. “It was the first time we could prove that we could shape the sonic boom in a way we could predict.” That demonstration set the course for research to follow.

Furchgott is a journalist with NYT©2021

The New York Times