Winglet wizards Aviation Partners is forming a partnership with FlexSys to certify and commercialize wing-morphing adaptive-control surfaces that have the potential to boost airfoil performance over a wide range of angles of attack, indicated airspeeds and Mach numbers.

“Aviation Partners has few press conferences,” says Joe Clark, API founder and CEO. “But this truly is the next big disruptive technology. It enables us to morph the shape of the wing to get peak wing performance over the entire mission profile.” Clark envisions both forward-fit and retrofit applications.

Dr. Sridhar Kota, FlexSys founder, says his systems eliminate dozens of moving parts, fairings and air gap seals used in conventional flap and slat systems, while saving weight. They also can improve aero performance over a wide range of lift coefficients (0.1 to 1.2) and they reduce airframe-generated external noise by as much as 40%.

A FlexSys patented “FlexFoil” wing-morphing system, with 19-ft.-long panels, recently was installed in place of the trailing edge flaps of a Gulfstream III. NASA supervised 50 hr. of flight tests of the system. The remarkable flexibility surfaces allowed them to move from 9 deg. up to 40 deg. down, along span-wise twisting the panel at up to 30 deg. per second. While the FlexFoils on the G III testbed were hydraulically actuated, they also can be powered by electric actuators.

Clark says that there a dozens of applications for the technology, but he wants Aviation Partners FlexSys to focus on winglets and ice-protection systems. “We believe we can get another 1.7% drag reduction over our existing split scimitar winglet” by adding FlexFoil morphing to winglets and trailing edge surfaces outboard of the ailerons. FlexFoils could even change the camber, as well as airfoil shape, of winglets to optimize performance for takeoff, climb, cruise, descent and landing. An active load alleviation function may also be incorporated.

The morphing surfaces are seen here in an extended position.

Hank Thompson, API’s COO, also says FlexFoils have the potential to replace pneumatic boots as leading-edge de-ice systems. Twisting and morphing the leading edge surface fitted with a FlexFoil system could remove ice accretion more effectively than boots. Thompson cited Bombardier Q400 and ATR 42/72 as two aircraft than potentially could have improved de-icing performance with FlexFoils.

Clark pointed out that “the technology is not inexpensive to develop.” FAA-certified production actuators will have to be designed, built and approved. STCs will have to be developed. But Dr. Kota notes that ground test articles already have been tested to 5x the life of airliners with no resulting fatigue issues. Loads are distributed throughout the entire structure, resulting in very small stress concentrations.

Aviation Partners FlexSys intends to bring its first FAA-certified product to market within 18 to 24 months, according to Clark. Aviation Partners Boeing winglets are installed on more than 5,400 Boeing jetliners, and they’ve saved more than 5 billion gallons of jet fuel in the process. Squeezing another 1.7% more fuel efficiency out of those aircraft would be quite an accomplishment.