The return of supersonic travel is an appealing thought. Nearly 75 years have passed since Chuck Yeager broke the sound barrier in level flight for the first time, and it’s more than 50 years since Concorde first made this kind of travel a reality for the paying public. Nevertheless, modern aircraft still can’t fly faster than sound.
But maybe it’s time to try again? With all the wonders of modern materials, digital engineering and the bottomless pockets of celebrity billionaires, surely it’s possible to bring supersonic commercial aircraft back to the skies? Perhaps skilled engineers could build a supersonic jet (almost) as cheap and quiet as regular subsonic airplanes? And if the affordable part doesn’t work out, maybe business aviation could step in?
Are supersonic planes coming back?
It certainly seems so. Dozens of projects to build commercial supersonic aircraft have been initiated, and some prominent airlines have already announced plans to buy small fleets of these planes.
As for 2021, not a single company has built a full-scale prototype yet. But several firms are in the process of testing the tech that could be used on them.
The main challenge is the reduction of sonic boom, the strong sound wave produced when an aircraft flies faster than the speed of sound. It can shatter windows and cause injuries, so the Concorde – the only supersonic airliner which saw extensive use – was restricted to flying above oceans. In a large number of countries those restrictions have been codified into law, and flying faster than sound is only allowed for military jets, and only when it is unavoidable.
Is supersonic flight illegal?
In many countries, including the US, commercial supersonic flight remains banned. But there are attempts to change that. In 2020, the US Federal Aviation Administration (FAA) established a special corridor over Kansas, where the civilian supersonic aircraft could be tested. If the tests are successful and the new aircraft do not produce destructive supersonic booms, the ban may be lifted.
So, a lot depends on the efforts to develop these quiet supersonic jets. Both private companies and government agencies such as NASA are involved, and although the technology is not yet proven, only one success might be enough to show the feasibility of the idea.
With that in mind, it seems like hardly a day goes by without the announcement of another supersonic business jet project. Some of them disappear after a couple of press releases, others manage to raise impressive sums of money. They are so numerous that it’s difficult to make sense of them all.
Here at AeroTime we have taken a close look at the existing proposals and fashioned them into an easy to read list, making it easy to track their progress over the coming year. The more realistic and closer to completion the proposal, the higher the ranking. Unfortunately, we had to exclude proposals that have either stalled or been discontinued – so, for example, there is no Sukhoi-Gulfstream S-21.
Research aircraft, such as Lockheed Martin X-59 QueSST, are also not included – they don’t carry passengers. With one notable exception, hypersonic proposals – the ones that promise to fly faster than Mach 5, or five times the speed of sound – have been excluded too. Yes, projects by Hermeus, Boeing and HyperMach look exciting, but they are too complicated to be realistic in the short term. Hypersonic commercial flight is the next step, which is possible only after supersonic transports prove their worth.
So, without further delay, let’s check out 10 most promising supersonic business jet projects.
Honorable mention: Aerion SBJ, AS2 and AS3
But first, an important player that has just been eliminated.
For a long time, it seemed that Aerion – a venture by Texan billionaire Robert Bass – was leading the supersonic race. It secured some prominent financiers and engineers, and its natural laminar flow design, which would have greatly increased the efficiency of the aircraft, seemed promising.
In 2004 the Aerion SBJ was unveiled, capable of carrying up to 12 passengers at Mach 1.6 – nearly twice the speed of regular airliners. In 2014, it gave way to an updated model called Aerion AS2, which would have produced almost no sonic boom while cruising at Mach 1.2 thanks to a number of futuristic design features. In March 2021, the Aerion AS3 – a near-hypersonic version, capable of cruising at Mach 4, or four times the speed of sound – was revealed.
Meanwhile, trouble was brewing. Initially, Aerion had partnered with Airbus on the development. By 2017, Airbus had abandoned the company, but it received support from Lockheed Martin and General Electric. Both of those companies bailed on the project by 2019, but Boeing agreed to partner – right at the time when the American giant got entangled in the 737 MAX debacle.
By the start of 2021, Aerion had amassed more than 300 orders, completed wind tunnel testing of some models, and started building a factory in Florida. But, in May 2021, the company went bust, reportedly due to lack of funding. The promise of the sleek red fuselage of the AS2 gliding above the clouds faster and smoother than anything before was shattered, never to see the light of day.
2017-vintage rendering of the Aerion AS2 (Image: Aerion)
With Aerion’s story out of the way, let’s return to more viable options.
10. SAI Quiet SuperSonic Transport (QSST)
The X-59 QueSST technology demonstrator, a collaboration between Lockheed Martin and NASA, is scheduled to conduct its maiden flight in early 2022. It is a poster child of the supersonic race, and is intended to test the possibility of reducing sonic boom – the very thing that limited the operations of first generation supersonic airliners.
Not many people know that the roots of the X-59 date back to a particular business jet – the QSST, in development by Supersonic Aerospace International (SAI). The company, created by Michael Paulson, the son of Gulfstream founder Allen Paulson, contracted Lockheed Martin’s Skunk Works division to develop a 12-seat, Mach 1.8 aircraft which would produce virtually no sonic boom in cruise flight.
But the development was plagued by problems. By 2010 the company had almost disintegrated, only to reemerge in 2013 with a new project – a larger and sleeker supersonic jet. However, new publicity did not help to generate more funds, and the project stalled. On the strength of Lockheed Martin’s work for SAI, NASA selected it to build the X-59.
But what happened to SAI and its plans? Nobody knows. The company’s website still displays the last update from 2014, and Michael Paulson, Allen’s son, has disappeared from public view. Yet, a lot of money and time was poured into the development. Could SAI emerge again?
SAI QSST (Image: SAI)
9. EON nxt-01
Eon Aerospace was founded by South African billionaire and tech entrepreneur, Priven Reddy. In August 2021 he announced the launch of his own aerospace startup – L.E.A.P., short for Leading Edge Aviation Propulsion (not to be confused with the LEAP, a successful turbofan engine by CFM international).
Since then L.E.A.P. has been quietly renamed Eon, but has retained its ambitious plans. The first product from the company – the nxt-1 – is supposed to use quiet sonic boom technology, have the speed of Mach 1.9, and fly at an altitude of 60,000 feet (18,000 meters).
The company also promises to operate with net-zero carbon emissions, develop a bladeless engine for the improved version of the jet, and conduct the first service by 2029. The aircraft will have between 65 and 88 seats, which would make it viable for airlines. Nevertheless, just as with any aircraft, it can have a bizjet variant. If built, it most likely will. It also promises to feature the same low-boom technology from the X-59 QueSST demonstrator, which would mean that the nxt-01 could fly above land without shattering windows and eardrums with its sonic boom.
Eon’s promises are attractive. Yet, the company does not have any experience in aerospace manufacturing, and has not demonstrated any achievements besides a host of beautiful 3D renders of its upcoming product. Can it fulfill its promises? Let’s hope so.
EON nxt-01 (Image: EON)
8. Unnamed Russian supersonic jet
Russia had countless projects to build small supersonic commercial aircraft throughout the years. It all started with the proposal to convert the MiG-25 supersonic interceptor for passenger service in the early 1960s, and never stopped.
There was the Tupolev Tu-144, and several initiatives in the 1990s, and several more in the 2000s. But the real kick-start was given in 2018 when Russian President Vladimir Putin floated the idea of adapting the Tu-160 strategic bomber for passenger service. As bizarre as that idea was, it prompted Russia’s United Aircraft Corporation (UAC) to react and produce some viable concepts for a small supersonic jet.
The latest news is that drone company Kronshtadt is going to manufacture an unmanned technology demonstrator for the project, but neither deadlines nor specifications are clear. It is only known that several variants are being studied – among them an eight-seat business jet and a 30-seat airliner, both capable of flying at Mach 1.8, having the range of up to 8,000 kilometers, and featuring an indigenous version of the low-boom design.
While it has been announced that the United Arab Emirates (UAE) is interested in collaborating with Russia on the project, its future is unclear. In April 2021, the head of state conglomerate Rostec called the project “economically unfeasible”. Rostec actually owns UAC, so, if the parent company does not see much point in pursuing the project, it might follow the fate of dozens of previous supersonic transports proposed in Russia.
One of the projects for the Russian supersonic business jet (image: TsAGI)
7. Unnamed Chinese hypersonic jet
This is the one and only exception to the rule of excluding hypersonic projects in AeroTime’s list.
Recently, China has proposed a lot of strange and science fiction-inspired aircraft concepts. Among them is the idea of building a six-seat hypersonic commercial aircraft by 2035. While the development is very secretive, the goal is clear, and it has a deadline – the latter being a feature that most other hypersonic proposals lack.
China’s recent progress with hypersonics actually lends credibility to this idea, and since the development is being conducted by government-funded research institutions, it does not have to abide by the ever-present laws of commerce. This means that China might build it despite no promise of profits.
A possible concept of the Chinese hypersonic passenger jet (Image: Science China Press)
6. Unnamed Virgin Galactic supersonic aircraft
Richard Branson’s Virgin Galactic announced its entry into the market in August 2020. The aircraft will carry 19 people at an altitude of 60,000 feet (18,000 meters) and at the speed of Mach 3, the company said.
On their own, those numbers look impressive – most other supersonic bizjet projects barely scratch Mach 2, and are somewhat smaller. But it is difficult to tell how seriously the company takes this project as no further information has been revealed – no deadlines, no costs, nothing. Is Virgin Galactic’s project just a way to attract attention?
On the other hand, the company has demonstrated that it can impress – when its Unity flew Branson to the edge of space. Maybe, one day, the supersonic jet project will take off too.
Virgin Galactic supersonic jet (Image: Virgin Galactic)
5. Lockheed Martin Quiet Supersonic Technology Airliner (QSTA)
Lockheed Martin is the first entry on our list which seems to have a decent chance of coming to fruition.
The company worked on the X-59 QueSST for the better part of the past decade, gaining knowledge and know-how on quiet supersonic flight technology. After partnerships with SAI and Aerion failed one after another, Lockheed Martin decided to do the job itself.
Its own supersonic airliner project was unveiled in 2019 – a 40-seat Mach 1.8 project with a V-tail and a range of 5,200 nautical miles (9,600 kilometers). By 2023, Lockheed Martin hopes to achieve significant milestones by testing the X-59, and begin designing the QSTA in earnest.
The aircraft is going to be a bit bigger than a regular business jet, and is one of those projects which aims to operate with regular airlines. Nevertheless, if successful, it will probably have a bizjet variant, especially if Lockheed Martin manages to be one of the first companies to build a commercial supersonic aircraft with low-boom features.
Lockheed Martin QSTA (in the foreground) with the X-59 QueSST (Image: Lockheed Martin)
4. Unnamed Japanese supersonic jet
Japan Aerospace Exploration Agency (JAXA) has been mulling the idea of a supersonic commercial jet for quite some time, and even tested a small-scale prototype in 2005.
In June 2021, JAXA organized a body called the Japan Supersonic Research (JSR) council, which includes Mitsubishi Heavy Industries, Kawasaki Heavy industries and Subaru – all working towards making a 50-seat supersonic jet that would consume at least 13% less fuel and have a 50% smaller sonic boom than the Concorde.
No further information was revealed but, judging by the companies involved, it seems like a solid project.
JAXA Supersonic Jet concept art (Image: JAXA)
3. Exosonic Supersonic Jet
Exosonic’s proposal is simple: it wants to make a 70-seat Mach 1.8 passenger plane which, in terms of individual tickets, would be as cheap as a regular business class ticket today.
This does seem like a bit of a stretch given that other supersonic transport proposals involve either smaller speeds, smaller capacities, or avoid talking about the price. But, in September 2020, Exosonic was awarded a contract by the U.S. Air Force Presidential and Executive Airlift Directorate – the agency that runs the United States’ Presidential and Executive Airlift fleet.
On top of that, in October 2021 Exosonic secured another big contract for supersonic drones, which suggests that the U.S. government takes the company seriously.
Exosonic Supersonic Jet (Exosonic)
2. Spike S-512
Spike Aerospace is a bit of a mystery. On the one hand, it is one of the most successful and prominent supersonic transport projects of this new generation. It was established in 2014, tested a subscale prototype by 2017, and has been staying in the zeitgeist with constant updates.
On the other hand, little is known about the company and its projects beyond several 3D renders and an ever-receding deadline. Initially it promised to operate the jet by 2018; as for late 2021, no tangible results have been published – even the demonstrator flights have been kept secret with no pictures or results revealed.
Nevertheless, it does seem to hold a lot of promise. Spike’s business jet is expected to be a low-boom, Mach 1.6 capable aircraft configurable to carry between 12 and 18 passengers. One of its main features is the windowless cabin, with screens all over the walls. The idea could certainly make the engineering of the plane easier, but it is yet to be successfully implemented or tested.
Spike S-512 (Image: Spike Aerospace)
1. Boom Overture
Together with Spike and Aerion, Boom Technology is one of the most talked-about companies, and one of the leading voices in supersonic flight research. The concept for the Overture airliner was revealed in 2016 and has undergone significant changes since then as the firm researched the market.
Boom’s concept is much simpler than those of its competitors: its top speed is only Mach 1.7, and the aircraft does not have any ultra-modern features such as a windowless cabin or even a low-boom design. While this means that the Overture would only be allowed to fly over oceans, it could make up for that with a cheaper price and shorter development time.
The company has built a one-third scale technology demonstrator, received a contract from the U.S. Air Force, and accepted several dozen orders from major airlines. It expects to test a full-scale prototype of the Overture by 2026, and begin mass-producing the jet by the end of the 2020s.
Presenting itself as a successor to the Concorde project – even down to hiring people who worked on the legendary jet – Boom Technology is aiming high. And while the aircraft itself seems unremarkable when compared with other entries on this list, it also appears to be the most realistic, and has the highest probability of being built.
Boom Overture (Image: Boom Supersonic)
But there is one more obstacle standing between the supersonic projects and the reality: their impact on climate.
Are supersonic planes environmentally friendly?
Not necessarily, but they can be. In recent years aviation has made huge improvements in terms of its environmental footprint, and many companies claim they can keep their supersonic creations to the same standard.
Almost every company on this list mentions the efficiency and the low environmental impact of their upcoming jets in the promotional material, saying that they want to vastly improve on Concorde’s not-so-stellar emissions record.
Environmental regulations in many countries have increased dramatically since the first generation of supersonic jets, and the public’s awareness of how important it is to reduce emissions has risen. On top of that, the output of emissions is directly tied to the consumption of fuel. More efficient aircraft which pollute less are also a lot cheaper to fly – an equation which determined the incredible rise in efficiency (and size) in the last generation of aircraft engines.
So, can companies which promise to make aviation faster also deliver on their promise to make it more environmentally friendly? Only time will tell