Concorde 2.0: Can An American Start-Up Bring Back Supersonic Passenger Flight?

Fifty years since the world's only supersonic airliner took to the skies, 16 years after it was grounded for good, can Boom Technology founder Blake Scholl follow in Concorde's trail and ultimately maneuver past it?

Blake Scholl was at Seattle Airport waiting for his girlfriend to arrive when he found himself wondering whatever happened to supersonic flight. Her plane in was epically late and Scholl had time on his hands. Surely someone somewhere was working on this? After all, the technology existed. Scholl, an aviation geek since childhood, knew all about Concorde, which was retired in 2003 despite being considered a technical marvel. It was a rare example of technology going backwards.

It was 2007, the same year the iPhone launched, and Scholl, a software engineer, previously at Amazon but now working for an app developer, couldn’t quite compute this apparent stalling in progress. Flight times on most airline routes had barely improved since the Fifties, when the jet engine replaced propellers.

He set up a Google alert so he could find out the latest developments, curious to see who was working on bringing it back and when. But nothing came up. His interest in flying had already seen him write “Figure out how to start an aviation company” as a bullet point on his to-do list. He bought some text books, he talked about it occasionally to friends. But it wasn’t until 2014, after he’d sold his own start-up Kima Labs to Groupon and was looking for his next project, that he came back to the idea.

Scholl knew that there’s no such thing as an easy start-up, so as a founder you need to pick a mission that inspires you enough so you never wake up in the morning and ask, “Why am I doing this?” He saw former colleagues in Silicon Valley giving their best years to improving things like e-commerce functionality on shopping apps. He wanted to avoid a similar fate.


Supersonic travel went to the top of his list. He expected to stay on it for only a couple of weeks before he understood why no one else was doing it, but started to wonder if a school of stale conventional wisdom on the subject was scaring people off. He ran some numbers using data he found online and realized you might only need to become 30 per cent more efficient than Concorde to make this work. That’s 30 per cent more efficient in fuel consumption versus something that was devised over half a century ago.

In early 2014, Scholl, then 33 and living in San Francisco, started taking aircraft design classes, actually read the text books he’d bought previously, and built a spreadsheet aerodynamics model of how a supersonic aeroplane might fly. That summer, he took it to a Stanford professor who had done a lot of research on supersonic flight and asked, “Can you check my math? Because if this is right, this is all possible. But I don’t have a background in this so tell me what you think.” The professor went through his calculations and told him he was being conservative. “Blake,” he said, “If you’re going to do this you should really try harder.”

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As many people remember it, the reason the world’s only supersonic airliner was taken out of service and sent into the museum business was because of what happened on 25 July 2000, when Air France Flight 4590 crashed into a hotel in Gonesse, 10 miles north of Paris, just 90 seconds after taking off. In truth, Concorde had been feeling the strain since before it even came into commercial service in 1976. And the crash, Concorde’s only fatal accident in 27 years, had nothing to do with being supersonic.

As with many airline accidents, a series of avoidable errors and rank bad luck combined to disastrous effect. The Concorde, over its maximum weight and missing a wheel component, causing it to veer and skid down the runway, should have already taken off at the point where it struck a strip of titanium that had fallen off a DC10’s engine casing following a bodged repair job. A tyre burst, sending a chunk of rubber toward the fuel tank at just the right angle to cause a shockwave which ignited the fuel inside, starting a fire at the rear. Even here the crash wasn’t inevitable but the co-pilot shut off the only remaining functional engine against protocol. The plane didn’t have the thrust to clear the hotel and reach an emergency landing strip, killing all 109 on board and four on the ground.


Bad timing could also have been a metaphor for Concorde’s wider demise. It was born in the post-WWII military arms race of the Forties, was commissioned as a British government project led by designer Sir James Hamilton in the Cold War Fifties, which merged with the French in the optimistic Sixties, when it became clear both countries were working along similar lines and could share skills and more importantly costs. Its name, of course, means “agreement”, though British prime minister Harold Macmillan and French president Charles de Gaulle disagreed on its spelling. De Gaulle won.

But just as it prepared to enter service a decade later, and aerospace minister Michael Heseltine took it on a 45,000-mile worldwide sales tour, the Seventies oil crisis was in full swing. Of the 75 planes initially ordered by 16 airlines, all were cancelled. Even British Airways and Air France, the national carriers of the two countries who’d funded it, weren’t keen but were strong-armed by their respective governments; BA was given five planes, then costing £30m each, for a fiver. Only 20 Concorde airframes would be completed, 14 of them in active service.

As an airliner, Concorde was revolutionary, capable of carrying 100 passengers at Mach 2 (1,535mph), or twice the speed of sound, and around two-and-a-half times the speed of conventional commercial planes. It was foremost an exercise in engineering, its cramped and noisy passenger cabin a lesser priority. This high performance required a lot of fuel, leading to high running costs and high-ticket prices; as much as £15,100 for a London to New York return flight in today’s money. The jet’s infamous sonic boom, caused when the pressure from air waves in its trail was released like a balloon pop, meant it was restricted from flying over-land routes at top speed, most notably over the United States where an actual speed limit was introduced.


It was literally possible to fly to Manhattan for lunch and be back in London to tuck the kids in

For its pilots, nothing came close. “I never got used to it,” remembered Captain John Hutchinson. “I’d pinch myself in disbelief. We were doing 23 miles a minute.” In the cabin, the atmosphere was sociable, excitable, even hedonistic. Gifts for passengers would wait on seats, vintage Champagne and caviar were served; many didn’t want their flight to stop. For Sir Terence Conran it symbolized optimism: he called it the most important piece of design in his lifetime.

For the following decades, Concorde filled a quirky, elite niche, serving CEO commuter regulars, celebrities and bucket-listers. Only its New York route ever turned a profit, maximizing the time it could spend at supersonic speed over water. The high fuel demands meant longer haul Pacific routes didn’t make economic sense.

Following the Paris crash, the Anglo-French Concorde fleet was withdrawn from service. It resumed flying routes in November 2001 with a Kevlar-lined fuel tank, but due to rising costs, and the dwindling demand for air travel in the wake of 9/11, it flew for the last time on 23 October 2003. (Richard Branson tried to buy BA’s fleet but it refused to sell.) It retired as a beautiful failure — in the harshest terms, an iconic and much-loved vanity project.

Against this picture, perhaps it’s no surprise that companies haven’t exactly been jostling for position to follow in Concorde’s wake. To a wider airline industry that is under constant pressure for margins and prefers small and regular efficiency gains on a mass scale, the reinvention of supersonic airliners might seem a fool’s errand.


But the product itself remains compelling, even astonishing. Three-and-a-half hours from London to New York (it’s record time was two hours 54 minutes from New York to London). It was literally possible to fly to Manhattan for lunch and be back in London to tuck the kids in. Among its many regular users, it was a time machine.

Today, you hear time described as the ultimate luxury so often it sounds like an ad slogan for a watch brand. But it’s a finite commodity people are prepared to pay for and, among top earners, increasingly so. Economist Daniel Hamermesh in his book Spending Time suggests that the higher your income, the more time-stress you report. That includes people who spend large tracts of their week in airport lounges, or increasingly adventurous travellers planning to maximize their annual leave days. The international air travel market has grown 2.5 times since Concorde’s final flight in 2003 while the number of global millionaires has jumped 170 per cent within the same period.

Where the big airliner manufacturers fear to tread, recent technological advances have proved encouragement enough for three separate projects in the United States to take up the challenge. Two are focusing on the business jet market. In Reno, Nevada, Aerion Supersonic, founded as long ago as 2002, is working on a 12-seater designed to reach Mach 1.4 with a reduced sonic boom to enable it to fly overland routes for its super-wealthy owners and customers. In Boston, Spike Aerospace Inc is tabling a similar strategy around its 16-seater.


The third, however, is the only one trying to follow in Concorde’s trail and ultimately maneuver past it, by creating a supersonic passenger airliner that, one day, perhaps just a few years from now, we could all buy a ticket for. That’s Blake Scholl’s enterprise.


In a business park on the southeastern outskirts of Denver, Colorado, Boom Supersonic’s headquarters is one of those familiar building-cum warehouses you might drive past in any major city, never stopping to even guess what might be going on inside. Only the number of Ford F-150 pickups puts you in America, and given a good vantage point, the familiar line of the Rocky Mountains to the west would place you in Colorado, America’s second-biggest aerospace state after California.

Scholl, now Founder and CEO of Boom, chose Denver as a base because “to do something this hard you have to have a dream team and if you want to build a dream team you have to choose a place where great people want to live”. There’s the skiing, the hiking, the horse riding, the 300 days of sunshine, the legalized marijuana and the chance to be remembered for being on the team that relaunched supersonic air travel.

One-hundred-and-thirty people work here; two years ago it was half that. About 80 per cent of the team moved to Denver to join Boom. The kind of people who’ve been in charge of the wing on the Airbus A380 (the largest airliner wing ever built); who ran the upper stage of the Falcon 9 rocket at SpaceX; and the propulsion engineer responsible for the Lockheed SR-71 “Blackbird” Mach 3 stealth jet at Nasa.

As you enter the open-plan office, a Boom mission statement proclaims the benefits of making the world smaller: “If we can fly twice as fast, the world becomes twice as small, turning far off lands into familiar neighbours.” Around the first corner, a world map indicates the 500 global transoceanic routes that Boom will be focusing on: London–Sao Paolo; San Francisco–Tokyo; Boston–Paris; Los Angeles–Sydney. Any viable route in which over 90 per cent of the journey is over water.


Downstairs, two pairs of original Concorde seats serve to remind the staff that this is a tangible challenge, and — you’d like to think — double up as a retro breakout area. And in case any visitors still hadn’t picked up on the clues, there’s also a massive plane in the middle of the hangar, alongside a giant banner that reads, “The Future is Supersonic”.

Scholl, an affable, baby-faced, 38-year-old from Cincinnati has the kind of fast delivery and calm assurance that comes from spending a career working on problems and generally overcoming them. You could picture him in grainy footage of the Apollo missions staring into a tiny monitor at Mission Control making notes on a clipboard.

Having so far raised $141m (£107m) in two rounds of funding, the company’s current focus is on building its XB-1 demonstrator, nicknamed “Baby Boom”: a one-third scale, 68ft test plane, to be assembled right here at its Denver HQ. Once built, flown and subsonic-tested this year, the demonstrator will serve as proof of concept to seek further investment to start building the plane itself. This first craft, named Overture to emphasize there are plenty more to follow, will be a premium 55-seat airliner, longer and thinner than Concorde, to be sold directly to airline carriers for $200m each as soon as 2025.

Scholl has said people in aviation often ask him, “How can you do it so soon?” While non-
aviation people say, “Why so long?” The answer is mainly due to the safety testing required before you can put 55 people in the sky. Branson’s Virgin Atlantic and Japanese Airlines have supported registered statements of intent to purchase 30 aircraft at a total of $6bn (£4.57bn).


"If we can fly twice as fast, the world becomes twice as small"

Boom will concentrate on trans-oceanic routes to maximize speed and time-savings by not running into the over-land speed limit problem that Concorde did, and fly at Mach 2.2 (1,687mph). This is the fastest an aeroplane can go before the heat would be too much for existing certified materials. In a complex industry, the strategy is pragmatic: “To make high-speed travel as available to as many people as possible as quickly as possible using only technology that’s been proven safe, reliable and efficient.” To pick the low-hanging fruit and get going.

“It’s amazing what Concorde was able to do [over] half a century ago with slide rules and wind tunnels and wrapping paper,” says Scholl. “The one thing Concorde didn’t do, of course, is offer fares that were really affordable to the public so that you could affect the way people travelled. And so we take tremendous inspiration from Concorde and we basically need to do what they did but do it a little bit more efficiently.”

Boom has strong ties with the Concorde team. In 2018, Boom held an event at Brooklands in Surrey at which Scholl got to lower the Concorde’s famous “droop snoot” nose as part of the ceremony. And in March this year, a celebration of the 50th anniversary, representatives from Boom joined old Concorde alumni to help make it more than just a nostalgia fest.

“They’re cheering us on,” says Andy Cipra, Boom’s senior vice-president of sales and marketing. Concorde pilots and engineers even came out to Denver for a launch party, with duffel bags full of technical documentation they said they would “forget in our office”.


“And so we’ve had access to some stuff that you can’t find in any books,” says Scholl.

The biggest lesson to learn is obvious, he says. “You’ll be able to fly Overture for a quarter the price of a Concorde ticket, or about the same price you’d pay in business class today. That’s the most important thing,” says Scholl. This translates to about $5,000 (£3,770). “So instead of a very tiny number of extremely wealthy people, it makes it available to anybody who flies business class today. Which is tens of millions of people every year. And secondly, you have to put the right number of seats on the aeroplane. So at 55 seats we’re about the same size as a business class cabin in an Airbus or Boeing.”

Fifty-five seats also tallies closely with what BA reported as the average payload of a 100-seat Concorde. “Those seats that fly empty are like perishable goods,” says Scholl. “Once that aeroplane departs, those seats are worthless. Today, industry standards are at about 80 per cent load factor across subsonic. And we’ve designed Overture to be able to achieve similar load factors across many, many routes. And that’s a key part to making the economics work for airlines, which is essential to making this whole thing actually practical.”

In order to do this, of course, Boom has to make the plane itself not only work, but more efficient. Technologically there are 60 years of progress to exploit since Concorde was on the drawing board, most notably, in aerodynamics, materials and propulsion. For aerodynamics, Concorde had to test everything in a wind tunnel, taking months of preparation for each individual set-up. Boom is using a computer simulation. “For our first aeroplane, we’ve already done the equivalent of 335 wind tunnel tests,” says Scholl. “You test many more ideas [and] you can arrive at better ones and that gives you a refined, optimized shape for the aeroplane that’s more efficient.”


Then come the materials used to build that craft. “It’s a very fluid, dynamic shape and you have to build it out of a strong, lightweight structure. Doing that out of aluminium, which is what Concorde’s made out of, would be very, very difficult,” he explains. “On the other hand, carbon fibre composites which are now state of the art in all new large airliners, you can mould into any shape you want. They’re strong, lightweight and they handle high temperatures for high-speed flight better than metal, better than aluminium.”

And lastly, engine technology. Concorde used afterburners at take-off, when extra fuel was burned to add thrust to get its famous delta wings off the ground. “That’s why when it flew over the neighbourhoods around Heathrow, windows would rattle,” says Scholl. Overture will use modern turbofan engines, although these will need modification to fly supersonically and Boom hasn’t yet announced who will supply these. “Turbofan is what flies on every large commercial aircraft today. It’s not new but it didn’t exist back then. They’re dramatically quieter, dramatically more fuel efficient and that’s why when Overture flies over, it won’t be any louder than some of the aircraft that are flying today,” he predicts.


Of the sonic boom, the firm estimates it will be 30 times quieter than Concorde though this isn’t part of their initial concern. “Some of that will come just through the improved aerodynamic shaping of the aircraft,” says Greg Krauland, chief engineer on the XB-1 project. “But in order for our business to close, we don’t need to fly our aircraft over land.”

One of the most technical parts of mastering supersonic flight is the aircraft’s air inlets. Air coming into the engines is also travelling at supersonic speed so engineers must find a way to slow it down before it hits the engines. It took Concorde’s team 10–12 years of development to get its inlet right. At Boom, it took two guys nine months, and they’ve exceeded Concorde’s performance. “Obviously, we have the benefit of lessons learned along the way but that’s primarily because of computational technology and software,” says Krauland.

When hearing the rationale and the sense of certainty within the team, it’s a wonder no one’s been doing it already. “Well, it’s really hard,” says Scholl. “I think that’s the short and the long of it. Most new businesses in Silicon Valley you could start for just a few hundred thousand dollars. Boom will take in the order of 10 years from founding the company to flying the first passenger. And it’ll take a billion dollars of investment. And that’s not for the faint of heart.”

He believes in a future where we can get anywhere in under four hours for less than £100.

This is the most fundamental operational difference between Boom and Concorde: that it’s a private enterprise as compared to a complex bi-national governmental project. Scholl is clear which side he’d rather be on. “It’s a massive advantage because we have to be very focused on doing this sustainably and economically. Concorde, really like the Apollo programme in the Sixties, had to accomplish some impressive technical goals and it had to try and do it before the Russians, and really those were the only two goals.


“When you have government and taxpayers bankrolling it, you don’t need to think about economic considerations,” he says. “We developed aerospace technology for the wrong reason. As a result, we’ve had 50 years of stagnation and it’s time to bring entrepreneurship back.”

Scholl has big visions and is good at communicating them. Useful when you’re trying to get a project this apparently crazy off the ground. That “making the world smaller” pitch is pretty common in Silicon Valley but Boom’s is perhaps the most literal interpretation so far.

He sees a supersonic future where we don’t think of ourselves as living in cities, just living on Earth. In a recent Tedx talk, he spoke of a donor heart needing to get to its recipient and only a supersonic flight being able to deliver it in time. Ultimately, he believes in a future where we can get anywhere in the world in under four hours for less than £100. But he accepts that that’s still a little way off.

The XB-1 supersonic prototype will be powered by three specially adapted General Electric J85-15 engines IMAGE: Spencer Lowell

Like Concorde, Overture will fly at 60,000ft, above turbulence and jet streams and weather systems, twice as high as conventional airliners, where the sky is turning navy. “The sensational thing was that there was no sensation whatsoever,” remembers Mike Bannister, Concorde’s former fleet chief pilot and supersonics expert, whose precise and reassuring burr could only make him a BA captain, or perhaps a Classic FM presenter. “You could balance a pound coin on its edge while travelling at twice the speed of sound and while you were in a 30° bank turn.”

Up there, the air is thinner. You can see the Earth’s curvature. The higher you fly, the more sensitive the environmental impact. And despite the efficiency gains made since Concorde’s time, Overture will arrive also ready to burn a lot of fuel, at a time when sub-sonic airliners are already under severe pressure to reduce emissions.


As it stands, there are no environmental regulations or standards in place for supersonic planes to adhere to, largely because there are no civilian supersonic planes in the air. The International Council on Clean Transportation published a projection of the environmental impact of supersonic travel in July 2018, using Boom as its model. It suggested that a seat on a supersonic flight from Heathrow to New York could burn three to four times the equivalent business class seat on an Airbus A321LR. Compared with economy it was six-to-eight times higher.

The higher you fly, the more sensitive the environmental impact

“It may be fun, fast and revolutionary in performance terms but in environmental terms it may be far from revolutionary. It may be a very backward step,” says Tim Johnson from the Aviation Environment Federation pressure group.

There will also be questions about the noise these planes create around airports for take-off and landing too. And that’s before the sonic boom question. Nasa is currently developing its X-59 QueSSt low-boom demonstrator plane with Lockheed Martin to collect sound data to present to the FAA and help establish a new set of standards to remove the over-land speed limit. In a nutshell, anyone trying to fly supersonically will have some external battles to face too.

“Well, it’s something we think about every day,” says Scholl. “Our goal here is to make the planet more accessible and the worst thing you could do is to harm the planet while you’re doing that. But it’s a myth that supersonic has to burn more fuel. For Overture, our target is the same or better fuel-burn compared to subsonic business class. And so that means there’s no supersonic guilt. And moreover there’s opportunity to actually improve from there.”


“Boom is very aware of its responsibilities and it is building the airplane in such a way that it could be able to migrate onto, for instance, biofuel,” says Bannister. That conversations are happening within aviation circles and between regulatory bodies show just how seriously this quest is being taken.

“In my mind, Boom is the one that has settled on the design parameters that are most likely to be successful,” adds Bannister. “And are most likely to be deliverable in an earlier timescale. Its proof-of-concept airplane is scheduled to fly next year and they are looking at 2025 [for the passenger plane]. I think that’s achievable because if the proof of concept works, it’s more like scaling up to a full-size aircraft. It’s not a reinvention.”

Boom Supersonic founder and CEO, Blake Scholl IMAGE: Spencer Lowell

As a passenger, Scholl has said he finds take-off moving because no other experience gives as direct a perception of what it is to be human. A glance below and you take in all that we have ever created. It’s why he says all Boom planes will have big windows. A certified pilot himself, who paid for lessons from his first internship, he says if he’s at the controls it’s a different emotion: “Ah crap, I’m going to have to land this thing.”


Designing Overture will also be a chance to rethink the whole flight experience, Andy Cipra tells me. A virtual reality mock-up of the cabin indicates under-seat instead of overhead baggage storage and single seats down each side so everyone gets window and aisle. Will the interior cabin light up when the plane hits supersonic speed at Mach 1 the way that Concorde had a Machmeter visible to passengers? Will you need flat-bed levels of comfort given the journey times will be halved?

They are thinking about the end-to-end journey, too. The 55-seat cabin could be reconfigured for longer-haul routes. After all, passengers may end up spending more time in the lounge than they do on the plane. “Imagine seven hours to Australia,” Cipra says.

Parts and sections for the “Baby Boom” demonstrator plane are coming in piece by piece, over 3,700 in total, ready for assembly. It’s on this two-seater that our supersonic futures could be resting. Scholl suggests that the S-Curve theory points towards rapid improvement in supersonic technology over the next 10–20 years, once this toughest and riskiest phase is overcome and a market becomes established.

For supersonic test day, on track for early 2020, the plane will be granted an airworthiness certificate in the “Experimental R&D” category. The XB-1 will be put on a truck in Denver and driven nearly 1,000 miles to the Mojave Air and Space Port in California. Around 25 people will be on the test team, 15 in the control room and 10 supporting the flight line, Boom’s crew chief, aircraft mechanics plus emergency personnel. There’ll be live feeds back to the office too. Piloting the plane will be Commander Bill “Doc” Shoemaker, Boom’s chief test pilot, a former US Navy F-18 Hornet fighter pilot and aeronautics PhD, who is already involved with the plane’s development. The key to piloting at supersonic speeds, he says, is to be able to think five minutes ahead.


“We’ll light up those three engines and we’ll listen on the radio at the tower to see if it’s clear to take-off. And Doc’s going to go down that runway and pull back on the stick and climb into the sky, and it’s going to be a very emotional moment for us and a very historic moment for the world,” says Scholl with surety, as if it were in his diary for 
tomorrow afternoon.

This story originally appeared on

* Minor edits have been made by the editors.

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