FlexFoil aims to seamlessly boost airplanes' fuel efficiency


January 17, 2014

FlexSys' variable geometry airfoil, the FlexFoil

FlexSys' variable geometry airfoil, the FlexFoil

If there's one thing that needs to be aerodynamic, it's an airplane wing. Conventional wing designs however, suffer from a glaring weakness in this respect: the joint where the main wing meets the trailing flaps. Michigan-based FlexSys has developed a way to optimize wing aerodynamics with FlexFoil, a seamless variable geometry airfoil system that could deliver fuel savings of up to 12 percent.

In development since 2001, FlexFoil is made from what is described only as "aerospace materials," and is seamlessly integrated into the trailing edge of the wing. It can be retrofitted into existing wings, or incorporated within new ones.

Based on a technology known as "distributed compliance," the morphing structure integrates actuators and sensors that, according to Flexys, results in "large deformations in shape morphing with very small strains."

According to a 2006 paper co-written by the inventor of the system, mechanical engineer Dr. Sridhar Kota, the foils are "optimized to resist deflection under significant external aerodynamic loading and are just as stiff and strong as a conventional flap."

More precisely, they can reportedly tolerate "well over" 10,000 lb (4,536 kg) in air loads. Additionally, the design is said to distribute pressure more evenly throughout the wing, resulting in less strain in any one area.

When retrofitted onto a wing, FlexFoil can reduce fuel consumption by a claimed 4 to 8 percent, with that number climbing to 12 percent for "clean sheet" builds. The system is also said to reduce wind noise by up to 40 percent on landing, and to lessen build-up of both ice and debris.

What's more, the technology could be applied to anything that moves relative to a fluid medium – that could include things like helicopter rotor blades, wind turbine blades, boat rudders, or pump impellers.

FlexFoil was officially introduced to the public this week at the AIAA (American Institute of Aeronautics and Astronautics) SciTech exposition in Washington, DC. Plans call for flight tests to be performed this July at NASA's Dryden Flight Research Center, where the flaps of a Gulfstream business jet will be replaced with the foils.

A prototype foil can be seen morphing in the video below.

Source: FlexSys

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

This Is interesting Technology...

Ryan Gibbons

What's old is new again. The Wright brothers used wing warping as a control surface:

This is the same principle.


I sure would like to get a peek at the actual technology. Maybe a computerized cutaway showing the internal geometry?

From the article my limited brain cannot determine what is really going on.

From a rotary wing standpoint it would be fabulous to be able to dynamically tune each rotor for the instantaneous aerodynamic requirements at any given moment. Unfortunately I don't see it being able to morph a rotors shape, let's say, 264 times per minute (approximate rpm of a BlackHawk system). Also, can it withstand the tremendous forces due to the centrifugal loads? Around 40 tons at the blade root!

Even if it was nothing more than the trailing edge flaps used for balancing the whole rotor, it would certainly improve the ability to keep the system tracked and balanced.

It's a shame that as a society we don't learn from the past but I'm glad that in individual disciplines they can and do.

On with the future.

Bryan Haslett

Uh, Takis, did you watch the video? They mentioned the Wright brothers connection right at the beginning. It's not like they're trying to hide it.


Is the "fixed wing" design now morphing into a "control wing"? I hope so. I have waited for the control wing since I became aware of it in 1995.

Also, the aerodynamics of a car could change as speed changed. But how long will it take the manufactures to contact Flexsys? If I was Flexsys, I would contact them.

Don Duncan

Contrary to popular opinion there are still some very intelligent and creative people here in Michigan.

Don't forget Nils Joel Skrubb who created the Packard Merlin by redesigning completely to American Standards a fine design from England. Some say it won the big war.


Lewis Dickens

now if I can get an economy version for my microlight and my prop,,,wow what a concept


This looks like a very viable and safe way to enhance efficiency and speed. The ability to retrofit this FlexSystems to existing aircraft is certainly market appealing on a global scope.

It appears by institutes you have associated yourself with this will "Fly High"...pun intended. I see this creative technology especially valuable initially in the GA, Turbo Prop market as well as business jets. Six (6%) helps a lot and 12% is another game changer. When you couple the FlexSystem Technology with NexGen engines even in the smaller aircraft markets...with some of the new materials and aerodynamic tweaks...20% -23% fuel savings is very possible. Superb Job!


Apparently car aerodynamics would also benefit greatly. I remember seeing (perhaps here) examples of DIY aero retrofits where people closed all the various door, hood, and trunk gaps to achieve noticeably better mileage - of course at the expense of having an easy to open door :) A flexible cover would solve that, at least for the joint sides.


Certainly not novel, they tested these wings on F111s last century. They called it a "Mission Adaptive Wing" then....

Ian McIntosh

The wright brothers warped their wing, that's true, though this is a bit different. The concept has been hovering around for a while, I have been watching it quite closely. There are other companies developing similar concepts, too. The article and the video do not actually reveal much news, except for the fact of planned test flights. The challenge, though, is not in the mechanisms, it is in the surface materials, and I would be surprised if they had fully solved that issue. After the flights, we'll know more.


Distributed, in-situ sensing and biomorphic design will revolutionize how we get around. Take some Doritos to a nearby beach sometime, and shoot HD video of seagulls as you feed them by hand, and you get a sense of just how much we have to learn from our backyard friends. Couple that with structural computing and programmable, intelligent surfaces, and things start getting real fun...

Roland Delhomme

Great answer to reduce drag coefficient on under 250 Kt airspeed light aircraft!

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