by Josh Lew
Last updated: 6:00 PM ET, Wed September 7, 2016
Commercial airplane designers have been able to significantly improve fuel efficiency in recent years with lighter materials and more aerodynamic shapes. The problem is that the efficiency of traditional airliner designs is already near its maximum. Any future changes probably won't decrease fuel consumption by a meaningful amount.
Are flexible wings the answer?
NASA has been testing a new design that features wings with flexible parts instead of the standard flaps that have been a part of airplane wings since the early days of aviation. This new trait could not only increase fuel efficiency, it could also make airplanes much quieter during takeoff and landing.
Best of all, this is a very realistic design. NASA and the US Air Force have already successfully tested a version of the flexible wing on a small passenger jet (a Gulfstream III) over the course of more than two dozen flights. The space agency has said that the wings could be tested on commercial airliners within the next three years.
One smooth surface
The flexible wings have one smooth surface, rather than the separate flaps, spoilers and ailerons that can be seen on today's commercial aircraft wings. The moving parts help the plane turn, ascend and descend, but they increase drag while doing so. Pilots generally adjust the flaps for maximum efficiency when they are at the ideal cruising altitude.
The flexible wings, however, are able to create the ideal ratio between lift and drag throughout the flight, not only while cruising in perfect conditions. According to the wing's designers, the fuel efficiency of airplanes with the single-surface wings would be about 12 percent better than planes with traditional wings.
The design, which is being called FlexFoil, acts much like the movable parts on the trailing (back) part of a traditional wing, but the moving features blend seamlessly into the wing. This means that there is one blend-able surface without any gaps.
Ideal aerodynamics
In an article discussing the idea behind the design, the project's main designer, Sridhar Kota, described flying with the less-than-ideal lift-drag ratio of traditional wings as "not unlike riding to the top of a hill on a bicycle in the wrong gear-you may get there, but with considerably more effort than if you'd switched to a lower gear."
Kota took the analogy a step further by explaining that with the flexible wing, "a plane could switch gears, so to speak, and achieve a more optimal lift-to-drag ratio by changing the shape of its wings."
Close to reality
The first test flights have been successful, and the promise of quieter planes and perhaps even less turbulence in flight sounds great for fliers and for those who live near airports. There is also a potential that the FlexFoil wings could be retrofitted onto existing planes. This would allow airlines to start using the technology sooner.
Usually, when new technology is first announced and tested, it is still a decade or two away from actually being used on commercial planes. This could be the case with FlexFoil, but airlines are hungry for better fuel efficiency now that oil prices appear to be rising again. This could push development of the wings forward at a faster pace, especially if no other efficiency upgrades are on the horizon.
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