Beyond the Boom

The definition of supersonic flight is when an aircraft flies faster than the speed of sound, which means flying faster than 660 miles per hour, or Mach 1 and beyond. When the Concorde operated in the 1970s, many in the aviation community thought that the time had arrived for regular supersonic air travel for passengers. Two-hour flights from New York to Los Angeles looked promising.

However, supersonic flight causes a sonic boom, which can be heard on the ground as a loud thunderclap or explosion (whips, bullets and military aircraft create sonic booms), which is why the FAA chose to limit where supersonic flight could occur. This meant that lucrative overland routes were off limits, and the sleek Concorde could only go supersonic across the ocean, restricting prospects for business travel.

In 2003, the Concorde was retired because of high costs, environmental restrictions on sonic booms, inefficient fuel consumption and other factors. However, NASA and aviation entrepreneurs now seek to reduce the sonic boom to a “sonic thump” that would be no louder than a car door being slammed 20 feet away.

Lighter and more efficient materials, new engines and airframe designs, and perhaps changing legislation may allow supersonic transport once again. As part of the Department of Transportation’s (DOT’s) priority on innovation in transportation, the DOT and the FAA are taking steps to advance the development of civil supersonic aircraft.

The slide rules and log tables used to design the Concorde have been replaced by supercomputers, allowing engineers to test virtual designs quickly and cheaply. Most recently, United Airlines announced plans to buy 15 new supersonic airliners and return to civil supersonic flight in the year 2029. Boom, a Denver-based company will provide United with its Overture aircraft, but it has yet to flight-test its supersonic jet.

While questions and barriers abound, the return to supersonic travel appears promising. Boom is among a handful of organizations vying to offer supersonic service to passengers, including Gulfstream and credible upstarts like Spike Aerospace. Both large-scale airliners and business jet aircraft are in differing stages of design and testing. Boom rolled out the XB-1 in 2020, which is its demonstrator aircraft currently being used in its carbon-neutral flight-test program.

Improved technology and the option to use sustainable fuels have helped shape this supersonic comeback, but Boom sees the most promise with engines specifically designed for supersonic flight. Unlike the approach for the Concorde, which used rip-roaring-loud converted military engines, Boom’s supersonic aircraft will employ modern materials and building methods introduced since the heyday of supersonic flight in the 1970s.

The largest barrier to supersonic flight might be economic. In May of 2021, Nevada-based Aerion Supersonic abruptly announced it would be shutting down after promising partnerships with Boeing and General Electric that also included $11.2 billion in sales backlog for its AS2 supersonic jets. The company had even gone as far as announcing a $375 million manufacturing facility in Orlando, Florida. As of 2021, Boom had secured $270 million in funding from investors such as American Express and its order book currently sits at 70 aircraft, including customers like Japan Airlines and the United States Air Force.

Supersonic flight holds too much upside not to pursue, despite the problems and questions yet to be solved. However, aviation experts don’t believe that
an established aircraft manufacturer will be the one to produce a supersonic civil aircraft anytime soon, as it would likely render the rest of their planes obsolete. The fate of civil supersonic flight likely rests with a maverick outfit like what’s been accomplished by Elon Musk and Space-X or Jeff Bezos and Blue Origin.

With increasingly-sophisticated technology and renewed interest in civil supersonic flight, it may just be a matter of time. For organizations such as Boom, their time may come sooner than others. Boom recently announced a 65-acre location in Greensboro, North Carolina, where a superfactory will manufacture its first Overture aircraft by 2025, and hopefully carry passengers by 2029.

Images courtesy of Boom Supersonic.