Almost exactly 20 years after the Aerospatiale/BAC Concorde's final revenue flight from New York touched down in London in October 2003, a commercial jet will once again cross the Atlantic at speeds faster than sound. At least that is the ambition of Tom Vice, chief executive of Aerion, one of a trio of US-based start-ups hoping to return aviation to the supersonic age during the next decade.

With the backing of industry heavy hitters Boeing, GE Aviation, Honeywell, and most recently Spirit AeroSystems, the Reno, Nevada-based company's Mach 1.4 AS2 12-seat trijet is the most advanced of the three projects, and perhaps has the best chance of overcoming the environmental, technological, and economic barriers faced by a prospective 21st century supersonic jet programme.

British Airways and Air France had not long resumed their scheduled Concorde services after the fatal accident at Le Bourget and were about to announce their termination altogether, when Aerion emerged in 2003. The firm hoped to tap into a market of time-poor business travellers who relied on Concorde's transatlantic services and engage with one or more of several engine manufacturers and airframers known to be considering supersonic projects.

For the next decade or so, the firm, financed by billionaire Robert Bass, had a major presence at the major business aviation conventions, enlisting big names such as veteran aerodynamicist Richard Tracy, chief engineer of Bill Lear’s LearAvia in the 1970s, and regularly briefing a sceptical media that it was months from a major OEM partnership.

However, long after most of the press had written off Aerion as a vanity project with little chance of getting off the ground, some big suitors started to show an interest. In 2014, Airbus agreed to work with Aerion, giving the start-up its long-promised OEM partner. The airframer would provide the resources of its engineering centre in Wichita and, eventually, its aerostructures plants in Europe.

Aerion AS2 640 c Aerion

Aerion AS2


At the time, Aerion suggested that the European company was less interested in developing its own larger supersonic transport than in the laminar flow technology that went into the AS2's wing. Arieon had designed the wing, according to then-chief executive Brian Barents, to cruise most efficiently at both M1.5 and subsonically at M0.95, one-tenth of a Mach number faster than any current airliner.


In 2017, with supersonic projects appearing to become less of a priority at Airbus amid a senior leadership shake-up, it was Lockheed Martin's turn to get involved. At the end of 2017, the US defence contractor committed to a 12-month feasibility study with Aerion into a configuration of the AS2 featuring three high-bypass GE Aviation engines.

While that tie-up itself ran out at the end of 2018, it paved the way for arguably Aerion's most significant partnership announcement, at the National Business Aviation Association show in Orlando in October 2018. GE Aviation, long mooted as Aerion's most likely propulsion provider, finally declared its hand, with the launch of the first commercial supersonic engine in five decades.

GE said it was developing the Affinity for the AS2 as well as potential future projects from other manufacturers. The FADEC-controlled medium bypass-ratio engine, based on the core of the CFM International CFM56 and mated to a new low-pressure module, will allow, according to GE, efficient supersonic flight over water and subsonic flight over land.

While Aerion also confirmed at the show that it was working with Honeywell on the cockpit and cabin configuration, a further coup was Boeing's decision, announced in early February this year, to provide "financial, engineering and industrial resources" to the supersonic jet developer, as well as help with flight testing. Boeing also made an undisclosed but "significant" investment in Aerion.

Seattle's interest in resurrecting faster-than-sound commercial flight came as its main rival was backtracking. At Airbus's annual results announcement in Toulouse in the same month, incoming chief executive Guillaume Faury confirmed that the manufacturer does not want to be "distracted" by supersonic efforts, given its commitment to reducing the company's environmental impact.

However, Steve Nordlund, vice-president and general manager of Boeing NeXt, the company's innovation laboratory, insists that supersonics is very much on its strategic agenda as part of a "mobility transformation" initiated by the aerospace group that will "safely and efficiently connect the world faster than ever before".

GE Aviation – which built its first supersonic jet engine in the mid-1950s, the J79 that powered the Lockheed F-104 Starfighter interceptor – says it began a process to define a final engine configuration for the AS2 in May 2017 after two years of "preliminary study". It says the twin-shaft, twin-fan powerplant is potentially part of a family of supersonic engines.

Brad Mottier, vice-president and general manager for business and general aviation at GE Aviation, witnessed the very early days of Concorde as an exchange student in Paris. "It was so new and exciting," he recalls. However, half a century later, he says the Affinity is a very different engine to the Rolls-Royce/Snecma Olympus 593 that powered the original supersonic airliner.


"It’s a 21st century engine that will feature all the commercial and military technologies that we have been using in all our advanced engines. Compared with the Olympus, this engine takes off without an afterburner, and climbs and super cruises without an afterburner," he says. While GE is not disclosing the bypass ratio, Mottier says it will be the "highest of any supersonic engine".

GE will go through a series of component tests this year before "moving towards a product design review with Aerion in 2020". The engine, says Mottier, has a new low-pressure system, two-stage fan, and exhaust nozzle, but with "basically the same commercial core that we have today", and designed to power "a very efficient subsonic aircraft that will also fly supersonic".

Affinity engine 640 c GE Aviation

Affinity engine

GE Aviation

The latest company to join the AS2 programme is US aerostructures specialist Spirit AeroSystems. It announced on 21 February that it had entered an agreement to "begin immediately" the preliminary design of the AS2's forward pressurised fuselage. The deal will allow Aerion to take advantage of "Spirit's highly efficient manufacturing processes," says Spirit chief executive Tom Gentile.

While Aerion has been making most of the running in terms of securing the support of established industry players, two other start-ups, Spike Aerospace and Boom Technology, are also confident of having their prototypes flying at supersonic speeds early in the 2020s, although details on how they plan to scale up and industrialise their projects are less clear.

In October 2017, Spike flew an unmanned 1/10 scale demonstrator to assess the low-speed aerodynamics of its proposed S-512 supersonic transport. It plans to follow that up with two flights in April and summer, says chief executive Vik Kachoria. The company will work with a prototyping specialist to build a dual-piloted two-thirds scale demonstrator ready for supersonic testing by 2020.

Kachoria says Boston-based Spike is talking to two potential engine suppliers for the M1.6 6,200nm (11,500km) range aircraft and "hoping to make an announcement soon". It has already worked with companies including Aernnova, Greenpoint Technologies, and Siemens on aspects of the design.

Spike S-512 valid as of March 2019 640 c Spike

Spike S-512

Spike Aerospace


Spike has talked about a 2023 target date for customer deliveries, but that does seem highly ambitious, given that it is at least two years from having a full-scale demonstrator in the air and is still to announce its plans to industrialise production. In addition, it faces the challenges of certificating what would be the first supersonic commercial jet in over 50 years, as well as securing a launch customer.

Another supersonic jet developer that has made a lot of noise, but has struggled to meet some of its stated scheduled targets is Colorado-based Boom. At last year's Farnborough air show, chief executive Blake Scholl confirmed that a planned first flight for its two-seat XB-1 supersonic demonstrator, originally set for 2017, had been delayed from late 2018 to 2019.

The company now tells FlightGlobal that its team is "heads down and focused" on the demonstrator, which is powered by three GE Aviation J85s, and has "moved to the build stage". It says the XB-1 will "prove in flight the key technologies for safe, efficient travel at M2.2", and will help define the design and engineering of the proposed 50-seat, all-business-class Overture airliner with 4,500nm range.

The company earlier this year secured $100 million additional investment, bringing total funding to $141 million, allowing it to "advance work" on the Overture, says Scholl. Last year, Chinese travel service provider International also said it was making a "strategic investment" for an undisclosed amount in the start-up.

Boom also announced, at Farnborough, a $10 million injection from Japan Airlines (JAL), together with a "pre-order" for 20 aircraft. It is the closest any of the three developers have come to winning an actual order, and JAL is the first carrier to make a financial commitment to a supersonic jet programme, says Scholl. Air France and British Airways were handed their Concordes for a nominal sum.

Boom c Boom Technology 640

Boom: JAL likes the looks

Boom Technology

As part of the deal with the Japanese carrier, which gives it the "option to purchase up to 20 aircraft through a pre-order arrangement", JAL is "collaborating [with Boom] to refine the aircraft design and help define the passenger experience for supersonic travel". The two companies had been in discussions for a year before the July announcement, said Scholl at Farnborough.

While Aerion has no confirmed orders ahead of the programme's formal launch, it has one letter of intent (LOI) for 20 examples from US fractional ownership operator Flexjet, and says it has an undisclosed number of further refundable LOIs. Spike, meanwhile, says it has signed two customers and will be making an announcement in March.

Lockheed Martin is the final player among the would-be supersonic developers, although its motives are different. Alongside its collaboration with Aerion, which ended at the end of 2018, it has been working on its own concept, as part of a NASA project. The company said in November that it had begun milling the first part of its X-59 Quiet Supersonic test aircraft at its Palmdale, California plant.

Lockheed intends to fly the X-59 in 2021, with a major objective of the test programme being to collect data from residents on the impact of the quieter sonic boom generated by the aircraft. Those responses will help NASA establish an acceptable commercial supersonic noise standard to replace existing regulations that ban faster-than-sound travel over land.

The company has designed the X-59 to cruise at 55,000ft at about M1.23, replacing the sonic boom with a sound as loud as a car door closing. Lockheed sees reducing the noise experienced by the overflight of aircraft breaking the sound barrier as crucial to opening the door for supersonic jet developers.

The success of the new supersonic start-ups depends on them overcoming many hurdles. Falling at any of them will make their ambitions impossible to achieve. The first is raising sufficient cash not just to convince the authorities that their highly innovative designs are safe for passengers to fly in, but to take them to industrial production and support operators.

Unlike Concorde, there are no taxpayer research and development dollars – NASA studies aside – to pour into bringing a programme to market. In addition, the developers are private concerns, backed by entrepreneurial visionaries with finance raised on the markets, rather than the state-backed combines behind the original supersonic airliner.

However, Aerion's success in attracting endorsement from the likes of Boeing, GE Aviation and Honeywell, and Boom's ability to convince one of the world's blue-chip airlines to back its project and raise tens of millions of dollars of additional capital shows that there is faith out there in their schemes.

There are also technical, environmental and regulatory challenges. Concorde’s failure was largely down to the refusal by authorities to permit supersonic flight over land, which largely restricted its market to the transatlantic. Aerion, Boom, and Spike, as well as their engine partners, will have to come up with aircraft that operate efficiently at subsonic speeds, as well as fly faster than sound.

The final obstacle is the market itself, and the question of whether there are enough passengers out there willing to pay a premium for the gift of time. Many business jets already fly long distances at close to M1, and come with the latest connectivity systems to ensure that those in the back enjoy not only the utmost comfort, but can stay in touch with their business from their office in the sky.

So, are there enough high-net-worth individuals or time-starved senior executives happy to pay that bit more to arrive a few hours earlier, for business or personal reasons? Mottier believes there are. "Business aircraft have got bigger, more comfortable, longer range," he says. "Shortening the time of the flight is the last piece. That's why we’re excited to be involved with this project."

Source: Flight International