On 17 November 2015, Aerion announced that Ken Ricci’s Flexjet had placed a firm order for 20 of the company’s supersonic AS2 business jets at $120 million a time. Almost instantly, the whole business aviation industry recognised that a game-changing moment had arrived. All that is now required is that Aerion and its giant partner, Airbus, get out the spanners and the composite kit and get fabricating – oh, and of course, there is the small matter of finding an engine to power the beast.
However, and the sceptics should take note of this, the engine issue is highly unlikely to be a show stopper. As Aerion CEO Doug Nichols points out, there may be no off-the-shelf complete engine that the Aerion team can walk up to and pop into their shopping cart, but there surely are a few well-proven cores about that are more or less fit for purpose.
“We’re talking to the major engine manufacturers and we all recognise that we have a challenge to resolve. The AS2 would love a low-bypass ratio engine – a ratio of around one would be near perfect. Conventional commercial engines with their huge fans and high bypass ratios would create massive drag at supersonic speeds. Plus you want as much of the air as you can get going through the core, not bypassing it,” Nichols explains.
If that were all there was to it, you could tick this box as solved, but the problem is that when you start cranking all that air through the core, the noise level rockets up. Ergo, you fall foul of community noise regulations. So the Aerion/Airbus/engine OEM team have some design issues to resolve. The likely resolution will be a modest bypass ratio of about 3:1, enabling certification to Stage 4/Chapter 4 noise standards.
A rich source of confusion in the way many have viewed the Aerion supersonic project is to suppose that Aerion’s business case requires legislative change in its favour. “Absolutely not,” says Nichols. “Our business model works inside the current legislative envelope, both as far as community noise regulations and high altitude atmospheric pollution levels are concerned,” he emphasises. Nor does Aerion expect relaxation of regulations regarding sonic booms, as the aircraft is designed to operate efficiently below the speed of sound, in fact achieving its maximum range of 5,300 nm at Mach 0.95.
There has already been speculation in the press that Ricci intends to situate his AS2s on the east and west coasts, when he gets them, so that their routes require minimal subsonic travel time over US soil. Being subsonic over land will keep the AS2 from falling foul of noise regulations, though it will be a more expensive option over the US than subsonic jets. However, the time gain that the AS2 promises will be more than enough to justify both the price tag and the fuel burn for those for whom time is a scarce and precious commodity. “If it matters to your business to be two hours ahead of the competition, then this model works for you,” Nichols says.
Nichols thinks that the probable route Aerion will take with the initial engine choice for the AS2 will be to build the engine around an established core, with a bypass ratio of around three. “At this level we know we can satisfy Stage 4 noise requirements while maximising our range inside the legislated envelope. There is no question but we could get a lot more range if we did not have the noise issue to worry about. However, we are working with what is, not with how we would like things to be,” he notes.
In addition to picking an appropriate core and modifying it to suit, Aerion will need a smart fan and some very sophisticated metallurgy work, since the engine will run at higher temperatures for longer periods than conventional jet engines. But again, all the basic engineering for this is already in use every day in military jets that hurtle along at high Mach numbers.
“We have two speed points where we get the kind of range that we are looking for. One is at Mach 1.4, which the AS2 will do over water or across land in China, for example, where they do not have sonic boom regulations, and the other is at very high trans-sonic speeds, around Mach 0.95, where we get great efficiencies,” he notes. The end result will be the AS2 shaving two to three hours off trans-Atlantic flights and up to six hours off trans-Pacific flights.
Nichols can’t praise Airbus highly enough as a partner. “They have just been a tremendous force to help us advance this programme. Working with Airbus has been the watershed event that allowed us to move the AS2 out of the design dream and into the engineering and launch stage. Our collaboration agreement with Airbus is extensive. They are committed to helping us through the multiple phases to get the aircraft certified and into production. As we advance the programme we’ll have discussions on what Airbus’s role will be in helping us actually manufacture the jets on the production line. Our plan calls for producing three AS2s a month once we have manufacturing rolling, but we are planning for the facilities to go to four and even five if market demand justifies it,” he comments.
One of Airbus’s many roles is in the fabrication of the AS2’s composite fuselage and wings. “Airbus has extensive experience in composite fuselage and airframe manufacture; they’ve already made great progress in designing airframe structures at Airbus Defence & Space in Spain,” Nichols says.
The agreement between the two companies provides for Airbus to take design responsibility for all the tightly integrated aero structures, which include the fuel systems, the fly-by-wire, the landing gear, fuselage and wings, Nichols explains. “Airbus is clearly a world leader in advanced composites and aero-structure design and fabrication, so they are taking the design lead on this. Aerion will be the fundamental integrator for the aircraft, which includes all the aerodynamics. Our engineers and aerodynamicists are the best in the world and we are very confident in our ability to deliver on this side,” he adds.
Aerion is already conducting studies to find a location for the final assembly site for the five aircraft it plans to build for the certification and flight testing process, and also for series production.
So is Nichols confident that Aerion can deliver on the timeline he has sketched out, with first flight in 2021 and first delivery to Flexjet in 2023? “Absolutely,” he says.
“We and Airbus spent a considerable amount of time examining all the activities that are required to move the AS2 through the critical design review stage and on up to the integration of the engine with the airframe, first flight and ultimately, certification. We have collectively vetted our schedule and we know it to be robust, so we have a very high degree of confidence in the timeline that we have made public. There is a tremendous amount of energy going into putting the stages of the next phase into place, both in the US and Madrid,” he comments.
“Ri
ght now we are looking to a hard launch by the end of 2016, with decisions over the engine being absolutely key to this.”
INAIRVATION, a joint venture between Lufthansa Technik and interior components fabricator F/List, has been awarded the interior design contract. Nichols points out that INAIRVATION preferred partner Design Q, headed by CEO Howard Guy, already has a full-scale wood and foam mock-up of the AS2 in its workshop, from the front of the flight deck to the aft pressure bulkhead.
“On the ramp the AS2 will have a fantastic presence, with its long, dart-like shape, but when you go into the mock-up you see that it is really spacious inside. It’s like a G450 or Falcon 900 in cross section, in fact wider as you move aft. It is going to be a very comfortable and luxurious cabin for a four to six-hour flight, as greater speed makes for shorter flight times. We’re getting to our destinations a lot faster than conventional business jets,” Nichols notes.
So is this a fresh start for the supersonic age of commercial as well as business aviation? Nichols points out that the economic imperatives for a commercial airline are very different. It is hard to imagine the same premium being placed on time, to justify the ticket prices an airline would have to charge. However, with some airlines already dipping a toe in the water as far as offering business jet style cabins to those willing to pay for the luxury, anything is possible.
Nichols says that Aerion’s sales team are having conversations in every direction, with emergency evacuation and government special missions being two possible avenues where buyers might emerge. Some high net worth individuals and Heads of State may well find the AS2 irresistible, while a few freight companies may well want to think about same day deliveries between continents using the AS2. This is certainly going to be a project to watch…