top of page

Has the Boom gone out of Supersonic Flight

Three startups are racing to create the next generation of supersonic planes – and they're set to go faster than ever before.


Earlier this year a Boeing 787-9 Dreamliner flying from New York's JFK airport to London Gatwick set a new journey speed record. The aircraft, owned by budget airline Norwegian, completed its 3,470 mile journey in five hours and thirteen minutes. In doing so, it became the fastest subsonic plane to travel across the Atlantic.

Boeing 787-9 Dreamliner

The Dreamliner beat the previous record, held by a British Airways plane, by three minutes. But the speed boost wasn't down to technological or engineering advancements – it was down to tailwinds. So strong was the speed boost that the Norwegian flight hit a top ground speed of 779mph. But while that's faster than the speed of sound, the flight didn't break the sound barrier as its speed through the air was ever so slightly slower.

"Most aircraft we have today are in fact slightly slower than they were in the 1960s," says Phil Atcliffe, a senior lecturer in aerodynamics and aircraft performance at the University of Salford. Performance has largely stagnated, he says. "They're more efficient, they don't burn as much fuel, they carry more people, they even fly longer distances but in performance terms they're pretty much the same speed."

Norwegian Air's close call with supersonic flight was a reminder of how much air travel has slowed down in recent years. At present the sound barrier (Mach 1, 767mph) is reserved for military aircraft. Concorde was retired from flight in 2003, three years after the crash of Air France Flight 4590, which killed 113 people, and supersonic flight hasn't returned to the masses since. But a glut of companies are working on bringing back supersonic travel and they're getting closer to making it a reality.

There are two approaches to developing the next generation of supersonic planes: creating private supersonic jets and trying to make supersonic planes for larger groups. Aerion Supersonic and Spike Aerospace are developing private jets for the wealthy and Boom Supersonic is creating plane for economically minded flyer. The goal? To reduce the time spent on long haul flights and make them commercially successful.

The XB-1 demonstrator plane will be used to show Boom Supersonics’ technology can fly at speeds of up to Mach 2.2

Boom Supersonics XB-1

All the next generation supersonic planes being developed use slightly different technologies vary in size and are aimed at different markets. And to add to the confusion none of the companies involved can agree on what speeds they should be travelling at.

Spike's S-512 plane, a windowless business jet, is planned to reach speeds of Mach 1.6 (1,227mph). Aerion's AS2 business jet will have a top cruise speed of Mach 1.4 (1,074mph). And Boom has set its sights on even faster travel: Mach 2.2 (1,687mph). Boom's offering is the only one in the same league as Concorde, which had a maximum speed of Mach 2.04 (1,565mph).

Spike Aerospace S-512

Aerion Supersonic AS2 business jet

These speed differences make a big difference when applied to real-world flights. Boom says New York to London will be possible in 3 hours 15 minutes, with Aerion's plane it will take 4.5 hours and Spike claims potential flight times of 3.3 hours for the same journey.

"Everyone else is thinking slower," Scholl says. "If you go faster – and I think you need to go at least Mach 2.0 for this to work – you're not just saving a couple of hours with the way the flights are scheduled, you're going to save people whole days."

But there's also another hurdle, it's one that may derail supersonic planes all together. Red-tape. The sonic boom from airplanes hasn't been completely eradicated and it's illegal to fly at supersonic speeds above US soil. Concorde's popularity – and what routes it was able to fly – wasn't helped by its supersonic boom. So the latest iterations of supersonic technology are aiming to get around this.

"The AS2 has the ability to fly up to Mach 1.2 without a boom reaching the ground," Barents says. "We term this Boomless Cruise, known technically as Mach cut-off speed. That is about 50 per cent faster than today’s airliners." Boom says it expects its supersonic boom will be "at least 30 times quieter than Concorde's". Spike says it has patent-pending "Quiet Supersonic Flight Technology" that will top a sonic boom reaching the ground.

But these are yet to be fully proven in real-world testing. There may be some respite though as US air traffic officials are looking at rewriting supersonic flight rules. In the future, supersonic planes may need to have their noise certified before they can fly.

There's one thing the supersonic firms can all agree on: the demand exists. "People are looking for a market," Atcliffe says. "They know that travelling in Concorde was popular so they're looking for a way that is close to it, a way to get something better than the standard subsonic airline travel we have today." But this isn't just about dreaming up a revamped Concorde – it's rethinking supersonic passenger flight (and its business model) from the ground up.

"Airlines are flying basically the same jets between the same airports with more or less the same cabin experience," says Blake Scholl, the founder and CEO of supersonic plane company Boom Supersonic. "It's why they all have these frequent flyer programmes to try and lock us in – without those there's no reason to not switch airlines all the time."

At present, all three are working on prototypes. Spike Aerospace says it tested an unmanned, subscale version of its S-512 plane (dubbed the SX-1.2) on seven short test flights in October 2017; Boom will fly a one-third scale plane in 2019 and Aerion Supersonic also wants to test next year. If all goes well, and that's a big if, passenger flights could take place towards the mid-2020s.

That might sound a long way off, but the race to go supersonic again finally has some momentum behind it. "There are really three big areas that have changed since Concorde was designed: aerodynamics, materials and engines," explains Scholl. Wind tunnels can now be replaced by computer simulations, carbon fibre composites are lighter than the materials Concorde was made of and engines no longer require afterburners, he says.

"They add up to enough of an efficiency gain where you can today build a supersonic aircraft that is 75 per cent more efficient to operate than Concorde," Scholl explains. "That means it can be a lot more affordable to passengers". Scholl says Boom started with the economics of flight and then worked back towards and aircraft.

Boom's approach to supersonic travel is to create a 55-seater commercial airliner, which will fly at Mach 2.2 and have seats priced around $5,000 for transatlantic flights (in 1981, a round-trip ticket to London or Paris from New York, about a three-and-a-half hour flight at 1,350 miles an hour, cost about $3,000). Scholl's gamble is simple: he believes Boom can always fill a 55-seater plane, as opposed to Concorde, which had to fill more than 100 seats per flight.

Scholl says Boom's XB-1 demonstrator plane, which will fly next year, is currently being manufactured. The engines have arrived in Boom's hangars and the company is in the process of building the tail and wings. Currently, Boom has 76 orders from five airlines – including Richard Branson's Virgin Group – and despite being smaller the plane looks similar to Concorde. "It's an evolutionary design, rather than a revolutionary design as we already had the revolutionary design in Concorde," Atcliffe says of Boom's aircraft.

As far back as 2015, Aerion agreed a deal to sell 20 of its jets to airline charter service Flexjet. The AS2 plane will be able to carry eight to 12 passengers and is firmly focussed on business uses. "We project a market for 300 AS2s over the first 10 years of production," Brian Barents, the CEO of Aerion says. "We think a business jet is the right place to relaunch supersonic flight, and expect that airline aircraft will follow as we prove the market for efficient supersonic travel."

Aerion has been developing its supersonic technology since 2003, when Concorde stopped its service. In December 2017, Aerion started working with Lockheed Martin, the developer of supersonic fighter planes, on its AS2 plane. "The Aerion AS2 concept warrants the further investment of our time and resources," Orlando Carvalho, an executive vice president, at Lockheed said in a statement at the time.

Nasa has also been working on supersonic flight with its X-planes and Virgin Galactic's long-running attempts to create commercial space travel has seen its VSS Unity pass supersonic speed.

Nasa X-plane

Virgin Galactic VSS Unity

But, despite all the hype supersonic flights are still some years away from reality. And that's if everything goes smoothly. "People have always been interested in supersonic travel," Atcliffe says. There was excitement around travelling at the speed of sound before Concorde was developed, during its operation and long since it went out of service. Much of this has led to no real developments.

This time around though, things may be different. "It's actually beginning to look like it might be converted into hardware," Atcliffe says. "There are lots of indications that it should start happening very soon."