Airbus unveils 'Wing of Tomorrow' folding wings project

Another major technological initiative to break cover at the recent Farnborough International Airshow was the upcoming flight-test phase of Airbus’s Wing of Tomorrow program. The project aims to develop next-generation airliner wings so long that they will need to fold at the tip to operate at existing commercial airports.

If you ever found yourself passing time at an airfield watching a glider, one of the first things you would notice is the wings. They're long, slender, graceful and resemble nothing so much as those of an albatross rendered in carbon composites. At least, they do if the engineer who designed them knows anything about their business.

The design has nothing to do with aesthetics and everything to do with form following function. The beauty comes along like the drippings from a Sunday joint for reasons that Pythagoras could explain far better than I ever could.

However, the primary reason for these willowy airfoils is entirely practical. To fly on the wind, gliders need the highest possible lift-to-drag ratio so they can cover the maximum distance with a minimal loss of altitude. To achieve this, the wings need a very high aspect ratio, which is, to put it very simply, the ratio between a wing's span and its average width from its leading edge to its trailing edge.

Boiled down to its essentials and leaving out a lot of details about air flows and vortexes, this ratio states that the longer and narrower a wing is, the more efficient it is. In fact, the best wing from a theoretical point of view should be of infinite length.

Unfortunately, infinitely long wings tend to be something of a nuisance at the airfield, so aerospace engineers need to come up with a compromise, which is where the Wing of Tomorrow comes in.

Airbus is designing high-aspect-ratio wings made from composite materials for future single-aisle commercial aircraft. The goal is a significant reduction in aerodynamic drag, yielding double-digit percentage drops in fuel consumption and carbon emissions.

These wings will have a considerably longer span, with the Airbus A321neo demonstrator aircraft extending the baseline span by up to 5 meters (16.5 ft) per wingtip. And that's where the folding wings come in.

Under ICAO Code C airport gate and taxiway constraints, a current single-aisle airliner like the Airbus A320 or Boeing 737 can only have a wingspan of up to 36 m (118 ft), and the new Airbus wing would exceed this considerably. That means the aircraft with the new super-wings would not fit standard narrowbody gates.

The alternatives to dealing with this problem would be redesigning airports (impractical and expensive) or restricting flight schedules (really expensive), so Airbus wants to make the new wings foldable. But that requires more than just putting a hinge and an actuator in the wing. It also introduces a whole new set of aerodynamic challenges, not the least of which is balancing the wing while accommodating all the additional hardware.

To accelerate testing, Airbus isn't waiting for a fully operational folding wing. Instead, over the next three years, it will fly its demonstrator non-folding wings that have the characteristics of folding versions.

"For more than 50 years, Airbus has spearheaded aviation innovation, continually pushing the boundaries of what’s possible to deliver more efficient aircraft for future generations," said Sue Partridge, Airbus Head of Wing of Tomorrow program. "This is why the Wing of Tomorrow program is such an exciting and rewarding journey to be on. Importantly, the wing is one of the biggest levers we have to improve flight efficiency, which is why the Wing of Tomorrow is so critical for our next-generation single-aisle aircraft. This flight-test campaign will allow us to safely challenge traditional design limits and explore the benefits of longer wings.”

Source: Airbus