When the first prototype of Concorde (retired Anglo-French supersonic airliner) took its maiden flight from Toulouse in 1969, it was hailed as a revolutionary chapter in the field of civil aviation. The market was predicted for 350 aircraft, and the manufacturers Sud Aviation (later Aerospatiale) and the British Aircraft Corporation (BAC) received up to 100 option orders from many major airlines. Concorde created headlines by achieving transatlantic range while supercruising at twice the speed of sound for 75% of the distance.
Despite delays and cost overruns, the project was deemed a game-changer for civil aviation, as since its maiden service flight on 21 January 1976 with Air France from Paris-Roissy and British Airways from London Heathrow, Concorde quickly captured flyers’ attention. Transatlantic flights became the main market, with Washington Dulles and New York JFK becoming the operational hubs for these jets. While Air France and British Airways operated 20 such airframes together, they could only operate them for transoceanic flights, as going supersonic, despite more than halving travel times, brought another menace: sonic booms over the ground.
However, the story met a horrible ending on 25 July 2000, when Air France Flight 4590 crashed shortly after takeoff, killing all 109 occupants and four on the ground. Although the remainder of the fleet came back to service eventually, they were retired in 2003, 27 years after beginning their commercial operations.
Since then, aviation geeks have been wondering: Will there be another supersonic passenger jet, or will concerns like deafening sonic booms and exorbitant costs push things back again? However, companies like Boom Supersonic, Spike Aerospace, Exosonic, and Hermeus are bringing the concept back to life.
Promising days ahead?
In August 2022, American Airlines pre-ordered 20 Overture aircraft from Boom, with the option to purchase an additional 40. With a $10 million initial investment, Japan Airlines too followed suit with a pre-order for an additional 20, and United Airlines promised to purchase 15 from the venture.
Boom claims that the jets, which are anticipated to be built in 2025 and make their flight by 2029, will carry 80 passengers on over 600 routes and reduce travel times by up to 50% compared to their subsonic counterparts.
Private companies are not the only ones participating; NASA is developing the X-59, a supersonic aircraft, through its “Quesst” programme. Its purpose is to reduce the noise of the infamous “boom” in order to avoid the problems of the Concorde, which was only permitted to reach supersonic speeds over the ocean.
In order to measure the ground response to the sound, the jet is scheduled to fly over a few residential communities in the United States in 2025. The data will then be submitted to the International Civil Aviation Organisation in an attempt to change noise regulations. Opening hundreds of new airline routes to supersonic travel could result from its success.
According to Boom, passengers could travel from Miami to London in less than five hours, Tokyo to Seattle in four and a half hours, and New York to London in three and a half hours.
According to reports, Spike, which is creating an 18-passenger business jet that might be completed by 2028, is trying to increase speed even more in order to transport passengers from London to New York in as little as 90 minutes.
While Boom is aiming for net zero by 2025 and says Overture will “run on 100% sustainable aviation fuel, making it the first new commercial aeroplane to have such capability,” Spike is aiming for net zero carbon by 2040.
As per Boom, its jets will have “engine updates, without afterburners, and an automated noise reduction system” to ensure takeoff is no louder than subsonic planes. Exosonic, which is developing a 70-passenger aircraft with VIP suites, says its sound will be quieter than that of regular traffic. Both companies are also working on lowering the boom through various technologies.
Battling headwinds
However, not everyone is assured about the prospects of supersonic flights being an instant hit in the coming days. Teal Group Senior Consulting Analyst Bruce McClelland is one of these sceptics.
“The problems are both economic and political. The faster an aeroplane flies, especially supersonically, the more it encounters an exponential increase in drag. That requires a lot more engine thrust, which requires a lot more fuel. Concorde needed as much as eight times more fuel to move one passenger from New York to London compared to a Boeing 747, so that’s expensive,” he said.
“There’s also the cost of developing, building and testing a plane. The development of modern jetliners runs into the multiple billions of dollars. I don’t see there being sufficient demand for a large production run, so it’s going to have to be priced pretty high. Given the physical limits, I don’t see a way to overcome this,” he added.
The United States and the Soviet Union developed but later gave up on supersonic flight due to prohibitively high costs. Concorde was the only successful endeavour, and the French and British governments provided funding for it.
Kevin Michaels, Managing Director of AeroDynamic Advisory, said, “Boeing was developing its own supersonic aircraft back in the 1960s, and it dropped out when it saw that the US government wasn’t going to support it. There are only two airlines that used Concorde, BA and Air France, and it never made money for the manufacturers that produced it. If the manufacturer can’t make money producing it, then it’s not going to be a viable market in the long run. The economics of being part of an airline are what ends up killing you, and that was one of the biggest lessons from Concorde.”
Additionally, there is a great deal of uncertainty regarding the engine’s manufacturer. With a statement stating that the commercial aviation supersonic market was “not currently a priority,” Rolls-Royce recently ended its collaboration with Boom. Since then, Honeywell Aerospace, Safran, and General Electric have all declared that they will not be manufacturing the engine.
“That left only Pratt & Whitney, and they said it’s not core to them and their brand, and they’re focusing on other projects. Engines take years and years and years of development, and a brand new one costs billions of dollars. These five companies are the only companies that have a remote chance of pulling this off technologically, so as it stands, Boom doesn’t have an engine,” Michaels added.
Boom is currently developing a purpose-built turbofan engine called “Symphony” for its Overture supersonic airliner.
Ecological issues
Boom will probably encounter more obstacles even if it sorts out the engine hurdle. NASA’s project probably wouldn’t be ready in time for Boom’s anticipated 2029 takeoff, and it’s unclear if the sonic noise problem can be resolved.
Additionally, there is the matter of customer demand. Flights across the Pacific that could have attracted customers are not feasible due to the current supersonic jets’ limited range before requiring refuelling.
Most importantly, a lot of people have questioned the sustainability claims at the moment, as the supplies of sustainable aviation fuel are still scarce.
“The claim that Boom’s flights will be offset by using only sustainable aviation fuel strikes me as stretching credibility. The only way that works is if the producer of a supersonic aircraft has its own source for SAF. Otherwise, operators will be forced to queue up with everyone else and take whatever they can get their hands on, most of which will probably be plain jet fuel. SAF right now is more expensive than regular jet fuel, so it just adds to the operating costs. Right now, known SAF production represents only a small fraction of a per cent of the total worldwide demand for jet fuel, and the most optimistic scenario I’ve seen is that this might ramp up to 30% by 2050,” McClelland said.
There are chances of airlines ending up facing criticism if they use their limited supply of SAF for supersonic travel (pumping multiple times as much fuel per passenger as a regular aircraft). Aerion Supersonic, the massive business jet company that went out of business, is all too familiar with these challenges. A group of industry experts founded the company in 2004, determined to create a $120 million supersonic aircraft that would first take to the skies in 2029. At the time, this project was regarded as the most promising option in the supersonic world.
However, it never built an aircraft and, after 17 years of trying, declared bankruptcy, stating that it was having difficulties in raising capital to achieve the next steps in the manufacture and regulatory approval of the company’s supersonic aircraft.
“Aerion was very highly thought of in the industry. It was aimed at business aviation and charter companies rather than commercial flight, so there was a much smaller capacity. It had a really interesting design, they were extremely well-funded, and they had some of the big OEM manufacturers on board. Then one day, they announced chapter 11 bankruptcy, and it was over. There’s only been one successful entrant into the jetliner business globally, and that’s Embraer in Brazil,” Michaels noted.
Future possibilities
None of this means that supersonic travel will never again be possible. However, the challenges indicate that, should it ever regain traction, the business aviation sector is more likely to see success than large-scale commercial aircraft. That’s at least the opinion of Michaels.
“Demand for supersonic travel is there, but it’s very niche. It doesn’t lend itself to commercial airlines. It lends itself to lower capacities, and ultra-high-net-worth individuals. So, is it something that’s going to revolutionise the airline industry as we know it? I don’t think so,” he said.
There is still hope that we could one day be flying around the world in a few hours and in a semi-sustainable manner if NASA’s project is successful. This is because sustainable aviation fuel will become more widely available, operating costs can be reduced, and supersonic jets can travel farther.
We may have to wait a bit longer before we can hop over to Australia in half a day, though, as reaching that destination by 2029 appears to be more of a marketing gimmick for airlines like United and American.
Supersonic travel remains a captivating vision for aviation’s future. While technical, financial, and ecological challenges persist, ongoing innovations and renewed interest suggest the dream of faster-than-sound passenger flight may yet become reality again.