Whether they are blended with bodies, braced by trusses, have embedded engines or are attached to conventional fuselages, future airliners will have wings. The shape of those wings, how they are made and where, will depend on when the next generations of commercial aircraft emerge.

On both sides of the Atlantic, researchers are looking to three basic time horizons: near-term, upgrades to current products, including rewinging; medium-term, new aircraft to enter service around 2025; and long term, aircraft to enter service beyond 2030, possibly with new and unconventional configurations.

In the U.K., designing and building wings for civil aircraft is one of four pillars of an investment strategy to secure and grow the aerospace industry. Wings for all Airbus aircraft and Bombardier’s C Series are produced in the U.K., and they are a large part of the business of major Tier 1 supplier GKN Aerospace.

Industry is reeling from the U.K’s unexpected vote to exit the European Union (EU). Airbus UK in April warned its employees of the dangers of leaving the EU. After the vote, Airbus CEO Fabrice Bregier says the future will depend on the U.K.’s competitiveness and openness relative to other countries.

At stake is Airbus UK’s position as the center of excellence for wings within the European manufacturer. Airbus Germany, already the center for high-lift systems and vertical tails within the company, has long coveted the larger wing manufacturing role, as has Spain, which now assembles all horizontal tails.

The U.K. has stepped up its investment in civil aerospace research and development, in 2013 committing more than £3 billion ($4 billion) in government-industry funding over 10 years to be focused on wings, engines, aerostructures and complex systems. In 2015, this was increased to £3.9 billion through to 2026.

But the U.K. government may come under pressure to increase its support, as leaving the EU is expected to cut its industry off from European research funding, including the 10-year Clean Sky 2 program now getting underway and involving €4 billion ($4.4 billion) in government-industry funding through to 2024.

The Clean Sky Joint Undertaking says it is too early to speculate on the implications of the vote to leave. The U.K. is an important player with a high number of participants and will remain a member until it leaves the EU. But the U.K.’s R&D strategy—managed by the Aerospace Technology Institute (ATI)—was crafted on the assumption that its industry would also access EU funding sources.

Against the background of uncertainty created by the Brexit vote, Airbus and the ATI are putting the finishing touches to the “Wing of the Future” program of R&D projects jointly funded by Airbus, the U.K. government and Tier 1 partners including GKN and Rolls-Royce, as well as suppliers.

“For ‘Wing of the Future,’ we are managing different horizons in parallel,” says Charles Champion, Airbus executive vice president of engineering. “The short-term horizon is if we had to rewing an aircraft, what kind of wing would we put on it? Mid-term is what would be the best wing for, say, 10 years from now? And the next horizon, which is more like 2030, is what type of overall aircraft configuration will it be?”

New configurations are important because of the aircraft elements that affect the wing. “Where do you put the landing gear, because it is a big disturbance for the structure of the wing?” he says. “Then there’s the engines. The trend is toward higher bypass ratio than on the [Airbus] A320neo or A350, so where do you position those engines versus the wing?

“Or is it contrarotating open rotors, and where would you put such engines, on the wing or the fuselage?” he says. “If you put the gear in the fuselage and engines at the tail, then you have a golden opportunity to have a clean wing and natural laminar flow from the beginning. This is what we are testing within Clean Sky under the BLADE [Breakthrough Laminar Aircraft Demonstrator in Europe] program.”

The starting point for Wing of the Future is the A350. “This is our first large-scale carbon wing, and we have seen a number of challenges,” says Champion. “First is shape, and achieving the best possible profile. You really need to be knowledgeable about how the flow goes over the wing to have an optimum shape. It looks easy, but in reality when you fly the aircraft it is not so easy.”

A second issue was flexibility, and the A350 moves the wing load more inboard than on previous Airbus aircraft. “There is more bending than previously to have a different shape in flight. The important point is to optimize the cruise position. This is different to the wings we have done in the past, which are rather stiff. It is a compromise between aero and structures.

“We also droop the flaps in the cruise and play with the spoilers,” he adds. “So it is our first wing where we start to use the movable surfaces that are there for control and high lift to adapt the shape of the wing in a simple manner. It is a trend we are seeing for the future.” 

A major challenge for carbon fiber is manufacturability, and the A350 wing is the first to be assembled horizontally instead of vertically. “With traditional metal wings, we put the trailing edge in the jig, then the leading edge, put the ribs in, then cover both sides,” says Champion. “The A350 is horizontal, which allows us to go to a pulsed line where the wing moves along the line.”


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This story is a selection from the March 14, 2016 issue of Aviation Week & Space Technology. New content posted daily online.

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One of the first elements of Wing of the Future is the Airbus Wing Integration Center (AWIC). This £37 million development and testing facility will be built at the company’s Filton site near Bristol, England, with U.K. government support through the ATI. The AWIC will replace the existing structural test facilities used for R&D and in-service support and expand them to handle future wing designs. It will be an open facility, allowing its partners to work with Airbus on wings.

To open in 2017, the AWIC will have an 80 X 40-m (260 X 130-ft.) concrete “strong floor” and unique movable metal “strong wall” to which wings will be attached for structural testing. Both will have a 1 X 1-m grid into which actuators and test rigs can be installed, says Mark Van Der Zwalmen, head of the wing test center. The movable wall will allow Airbus to test longer-span, high-aspect-ratio wings, but can be separated into two halves to test two shorter wings at the same time.

To house 300 engineers, the AWIC will be a major expansion of Airbus’s Filton site, already home to 2,000 engineers working on wings, fuel systems and landing gear. Given the U.K.’s focus on being the premier supplier of wings, the uncertainty caused by the Brexit vote is particularly acute in Bristol—which voted overwhelmingly to remain in the EU, not least because it is home to both Airbus’s wing engineering center and GKN’s wing manufacturing plants.

In addition to wing design and testing, Filton is home to Airbus Group Innovations’ 3-D printing “plateau” and digital manufacturing laboratory. On the same site, GKN makes wing components for Airbus aircraft, including the A380, having acquired the manufacturing operation from the European airframer in 2009.

​Filton is also GKN’s U.K. center for additive manufacturing, while the company’s nearby Western Approach plant, opened in 2012, manufactures carbon-fiber wing spars and assembles complete trailing-edge structures for the A350. It also produces composite wing spars for the A400M airlifter.

Completing the wing-related cluster is the National Composites Center (NCC) in North Bristol, which opened in 2011 with Airbus and GKN among the founding members. The NCC is what the U.K. calls a “High-Value Manufacturing Catapult,” created to act as a conduit for government and industry funding to bridge the gap between laboratory research and industrial-scale manufacturing.

Airbus UK moved its research center at Filton to the NCC, where it now conducts all of its composites R&D, working with its Tier 1 partners, says Airbus Research and Technology Manager Allan Kaye. Germany and Spain have similar centers, but while they work with thin composite skins for tails, the U.K.’s focus is on thick carbon-fiber structures for highly loaded wings, he says.

For GKN, the NCC is one of several composites research centers, but it focuses on automated fiber-placement (AFP) technology that is key to achieving high production rates with carbon-fiber structures. The NCC has two Coriolis Composites robotic AFP machines, one provided by GKN, and a larger Accudyne Systems gantry machine, says Stephen Suddell, NCC sector lead for aerospace.

Touring these sites provides a clear view of the U.K. industry’s deep involvement with European research and manufacturing programs. On display at the NCC is a large-scale test article for a highly loaded composite inner wing, built under the EU-funded €101-million Advanced Low-Cost Aircraft Structures (ALCAS) program led by Airbus UK and involving 61 partners across Europe. Technologies demonstrated on this wing are used in the A350.

Also on display is the ground demonstrator for the natural-laminar-flow (NLF) wing section built by GKN for Clean Sky’s BLADE project. The company built the leading edge and upper cover for the starboard NLF section that will be installed by Airbus on an A340-300, along with a Saab-designed port section, for flight testing beginning in 2017.

But displayed alongside the EU-supported ALCAS and BLADE test articles is a winglet lower skin produced under the U.K.’s £12 million STeM (Structures Technology Maturation) project. Cofunded by GKN and the government, and involving Bombardier, Spirit AeroSystems and GE Aviation, STeM aimed to support new concepts in wing design that improve aerodynamic performance.

Produced at the NCC on a Coriolis machine, the winglet replaces hand layup of woven carbon-fiber over a honeycomb core with a unidirectional fiber AFP skin and internal waffle structure that produces a single-piece part. The design reduces weight, cuts fastener count 50% and time per fastener 25%, and could lower manufacturing costs by 20%, says GKN, which produces winglets for Bombardier.

The Bristol area also illustrates how hard it would be to dislodge the U.K. from its niche as a wing supplier, because of the scale of investment already made here, as well as at Airbus’s wing plant in Broughton, Wales, and Bombardier’s Belfast, Northern Ireland, site, where the advanced composite wing for the C Series airliner is produced.

This investment is evident at GKN’s Western Approaches plant. Here the company produces composite front and rear spars for the A400M wing using automated tape laying. The spar is laid up flat and drape-formed in a mold tool, a technology developed under the EU-funded TANGO program that preceded ALCAS, says Chris Gear, GKN Aerospace chief technology officer.

The rear spars for the A350 wing use later AFP technology. Each C-shaped spar is made in three sections, each made two at a time on either side of the mandrel onto which the automated machine places the fiber, 16 tows at a time. GKN has four AFP machines, with a fifth going in as A350 production ramps up.

On completion, GKN-developed “sacrificials”—thin layers of woven carbon-fiber—are hand-positioned where the spars interface with other structures and components. After curing, these are machined to provide a precise join that does not require shimming, saving time in assembly. The spars are then placed in a jig and wing trailing-edge components are installed and then drilled using automated machines.

A gantry robot is used for the thicker inner and center spar sections and robot arms for the thinner outer section. Jigs can be positioned on both sides of each robot arm. Once in its jig, the wing section is moved by an automated guided vehicle. The three wing sections are brought together in a fixture where the butt joints are laser-scanned and splice plates machined, which allows the spars to be bolted together without shimming. The wing sections are then separated and transported to Broughton for final assembly.

Despite the automation already in use, producibility is a major focus for Wing of the Future and not just for carbon fiber. “The starting point for the future is the A350, but that does not mean the next wing will be composite,” says Champion. “Producibility, and reducing recurring cost, is much more important than it used to be. If we were to do a wing for a new single-aisle aircraft, we would target at least the cost of the current wing. The challenge for a carbon wing is to come up with a demonstrated cost base equivalent to the A320 metal wing today after however many thousand aircraft.”

Airbus is pushing A320 production up to 60 a month and eyeing rates as high as 63. “The point is to be able to produce at a high rate, which is a challenge, as we see today with the A350,” Champion says. The next aircraft will be designed from the outset for high rates. “Some people are stretching the target to 100 [a month], as an ambition. That is an order of magnitude more than what we have done up to now.”

Wing technologies will be selected that can reach that target rate quickly, which is a challenge for composites. “Carbon is not as easy as metal in some aspects,” he says, such as determining whether composite defects are acceptable or not. “That is why simplifying the process to manufacture carbon will be important: autoclave or nonautoclave; prepreg or dry material?”

GKN is involved with both composites and metallics, and expanded its portfolios with the acquisitions of Volvo Aero and Fokker Technologies. In metallics, Gear says friction stir welding (FSW) could “revolutionize” the use of aluminum and aluminum lithium (Al-Li). He also cites the potential for use of lightweight Al-Li in GLARE, an aluminum/glass-fiber laminate used in A380 fuselage sections produced by Fokker. The Dutch company also brought experience with welded thermoplastic composites, used in the A380 wing leading edges and Gulfstream G650 rudder and elevators.

“In the wing of 10 years from now, you could see tailoring of composites, additive manufacturing, metallic bonding, natural laminar flow,” says Gear. “There is an open debate between metal bonding, thermoplastics and carbon-fiber bonding. The issue is rate, and drilling is the challenge. You either have to automate it or get rid of it, through FSW, welding or bonding. We are already friction-stir-welding stringers on to skins for business jet wings in the U.S.”

Manufacturability is a key issue for future laminar-flow wings. In addition to measuring the drag reduction in flight, BLADE is assessing two approaches, by GKN and Saab, to manufacturing wings with the tight tolerances needed to produce the smooth surfaces required for laminar flow. “One of our bets is to go toward natural laminar flow, but the challenge is the cost,” says Champion. “You can do something perfect for one wing, but when you have to produce 60 a month you need something very robust.”

BLADE will continue NLF flights under Clean Sky 2, which will also test large-scale hybrid laminar-flow control (HLFC) demonstrators. “The jury is still out [on HLFC], but it is an interesting concept—particularly if it is passive. If it is active, it is more challenging, but it also depends on the configuration of the aircraft. For a propeller aircraft, controlled flow could be of interest,” he says.

Another part of Wing of the Future is figuring out how to make full use of all the moving surfaces. “We started in the A350 with the flaps and ailerons, so why not the Sharklet [winglet]? How can you actively use it to improve drag and alleviate loads?” Champion says. “Irrespective of how the wing is manufactured, can you go a step further in load alleviation, and what type of control surfaces will you need?” In this, the U.K. is working with Airbus’s high-lift plateau in Bremen, Germany, which is funded by the national LuFo research program.

The aerospace R&D linkages between the U.K. and EU will be hard to unravel, and Airbus and its Tier 1 suppliers, such as GKN, that have operations in both have a key role to play in ensuring expertise and investment is not lost in the divorce. But the U.K. government can expect its aerospace industry to look for additional support to stay competitive in the coming years.