Folding wings and open fan engine: Airbus reveals 'radical' design for A320 successor

New aircraft, due to hit the market in second half of next decade, will have 20% to 30% fuel savings on current generation

Airbus has revealed the initial design concepts behind its next-generation single-aisle aircraft, as it develops a successor for its best-selling A320 Neo family of jets and focuses on decarbonisation.

Over a two-day Airbus Summit in Toulouse this week, the world’s biggest plane maker highlighted proposals on key technology for the new aircraft, including propulsion systems, wing design, advanced composition materials, electrification, automation and connectivity. This is part of aviation's “fourth revolution” to make flying more sustainable, Airbus executives said.

“We cannot do it with incremental optimisation, this will come with disruption, this will come through clean sheet design,” Bruno Fichefeux, head of future programmes at Airbus, told the innovation summit.

The new aircraft, which will be able to fly entirely on sustainable aviation fuel (SAF), will target a 20 per cent to 30 per cent fuel-burn reduction compared with the models flying today, thanks to developments in wing design, engines and systems.

“It’s a research and technology phase, where we mature many technologies, and when we combine them together we need to look at what are the best trade-offs – which paths do we open, which do we close? We are not there yet,” Mr Fichefeux said.

Lighter but stronger advanced composite materials will be used to build lighter aircraft, allowing for a “substantial” reduction in mass. That will lead to an increase in fuel efficiency.

Key technology for the new aircraft includes propulsion systems, wing design and advanced composition materials. Photo: Airbus

Folding wings

Longer, thinner and narrower wings will be another feature of the new narrow-body. To ensure the aircraft fits into existing airport gates, it will also feature folded wing-tips. The design draws on principles of “biomimicry”, where engineers study and imitate the flight of birds. Mimicking the flight of the albatross, the aircraft will have a longer wingspan in flight, increasing lift and reducing drag.

The Airbus Wing Of Tomorrow programme in the UK is designing the technology to fold the wings.

One of the big challenges is making sure that the folding wing system works reliably, ensuring that they are aerodynamically and structurally efficient. This is important given that today the Airbus A320 family aircraft takes off or lands every two seconds, said Sue Partridge, head of Wing of Tomorrow programme and UK country manager at Airbus.

“The demand for single-aisle aircraft is huge today and will be huge in future, so we need to make our aircraft and wings at high rate and at cost that's sustainable for our business,” she said. “Industrialisation of our new technologies is absolutely key.”

The programme has completed two of three full-scale wing demonstrators. “As for our folding wing technology, we are putting that through its paces today in our test centres,” said Ms Partridge.

Engine tests by end of decade

For the engines, Airbus is exploring several options, but the main contender is the open fan engine concept, in which fan blades that generate thrust are larger and not contained by a nacelle, the cowling that contains the fan in current-generation engines. This allows air to move efficiently through the engine, reducing fuel consumption, Airbus said.

Engine maker CFM, a joint venture between France's Safran and GE Aerospace, is working on the Revolutionary Innovation for Sustainable Engines (RISE) open fan engine demonstrator, which aims to show how this technology could reduce fuel consumption and carbon emissions by 20 per cent compared with current single-aisle aircraft.

Airbus is planning to perform flight tests of the open fan engine on a modified A380 flying test bed by the end of the decade, it said.

The open fan engine is “much more rewarding, much more challenging and much more revolutionary” than the “evolutionary” ducted fan engines, Frank Haselbach, senior vice president of propulsion engineering at Airbus, told the summit.

“We would like the open fan to succeed,” he said. “It shows the biggest potential for the future … but clearly we have to look at our options.”

Christian Scherer, chief executive of the commercial aircraft business of Airbus, said the “jury is out” for the engine technology decision. Airbus will pursue a product that “offers a step-change in economics and environmental signature,” he added.

At an aircraft engine's bypass ratio of 15 or 16, the benefits of a large fan are wiped out by the additional drag created by a very big duct, Mohamed Ali, senior vice president and chief technology and operations officer at GE Aerospace, told the summit. The current bypass ratio on jet engines is at 11 to 12, so that point is not too far.

An open fan design can take the bypass ratio up to 60. “That is the fuel burn opportunity that we are thrilled and excited about,” he added.

A bypass ratio is a key measure of the efficiency and performance of jet engines, referring to the ratio of air bypassing the engine core versus air passing through it.

During the summit, Airbus showcased the concept of a tube-and-wing aircraft that could have either wing-mounted or rear-mounted open fan engines.

Electrification, automation and hybrid-electric propulsion, which supplements the use of conventional jet fuel or SAF with electricity from batteries or fuel cells, are some of the areas Airbus is working on.

“Imagine for one second that we have an aircraft that could onboard during its life-cycle all the technologies that will improve step by step … it will be a game-changer, radically different,” said Karim Mokaddem, head of aircraft of tomorrow research and technology at Airbus. But he acknowledged that “what is in front of us is a huge mountain of challenges, of unknowns”.

Airbus is focusing on fuel efficiency of its new jet because the added price of sustainable aviation fuel 'will be huge', an executive has said. Photo: Airbus

Certifying new architecture

Airbus is currently working on “aerodynamic and structural integration” to adapt the aircraft to the open fan engine that will change the plane's aerodynamics and noise levels, Mr Haselbach said.

“We have to adapt the aircraft to that new engine architecture,” he said.

Airbus is also looking “very carefully” at the testing and certification of the new architecture, he added. This includes component tests being conducted now, full-scale ground tests in Ohio later on, and then demonstrating the engine compliance on an A380 flying test bed for propulsion.

Hybridisation, or combining different energy sources instead of relying solely on jet fuel, is another area of work for Airbus, said Mr Haselbach.

The next-generation single-aisle aircraft will use electric systems for taxiing in and out of the airport, make air-conditioning more efficient and anti-icing on the wings to reduce energy consumption, Maud Delourme, head of multi-systems engineering and integration at Airbus, told the summit.

More automation could include the use of artificial intelligence to assist pilots by automatically detecting runways and obstacles to support automatic landing and taxiing at airports, she said.

Passenger experience

“If I had to sell this aircraft to a passenger, I would simply say that it is an aircraft that is radically different in terms of fuel-consumption and therefore it is a sustainable aircraft,” Mr Mokaddem told The National on the sidelines of the summit.

The passenger experience on the aircraft will be much improved, with better connectivity onboard. “If we reach this level of hyper-connectivity, it’s an aircraft on which you will be able not only to work, but also connect and talk to your family, to see your movies,” he added. “The passenger experience will be different.”

One of the most important selling points Airbus is emphasising for airlines is the economic benefits that result from 20 per cent to 30 per cent fuel efficiency.

“We are doing all this because we already know that the added price of SAF will be huge,” he said. “And therefore, if you want to maintain the ambition of connecting people today and even more people tomorrow, we need to propose to the airline something that is reducing the cost of operation, which is likely to increase because of the SAF price. And that’s why we are focusing on the performance of the aircraft.”

Decarbonising aviation

Airbus underlined its efforts to develop new technologies for a future aircraft designed to help decarbonise aviation.

“We want to [fill] this major gap [with the current A320 model] which is not incremental, which is not optimisation,” Mr Fichefeux said. “We need to make sure that these technologies come to maturity and that we can bet our design on, and we are not there yet.

“Our target … would be to introduce an aircraft in the second half of the next decade.”

However, he conceded that “we are not there yet”, in terms of maturing the technologies.

'Gloves off' competition

Airbus chief executive Guillaume Faury said the new aircraft would rely on disrupting technologies and is the “next big thing on the agenda” for the company.

He hinted that developing the next-generation single-aisle plane is likely to heat up competition with its US arch rival, Boeing.

“If you look on the other side of the Atlantic, it's not unlikely that they will look at this product as well. So, it's probably going to be a gloves-off competition for the next generation of single aisle [aircraft],” said Mr Faury.