ANN ARBOR (WWJ) — An Ann Arbor company is giving the aviation industry its long-sought, elusive goal of practical seamless control surface technologies.
A variable geometry airfoil, called FlexFoil, has been developed by Ann Arbor-based FlexSys Inc. And it will be showcased at an aviation industry show called the AIAA SciTech 2014 show this week in Washington, D.C.
A two-minute video of FlexFoil can be viewed on YouTube at https://www.youtube.com/watch?v=9ZpAHxMj5lU.
The FlexFoil replaces jointed wing flaps with a deformable, seamless surface that changes shape for optimized performance throughout the flight regime, saving jet fuel.
Changing the shape of a modern aircraft’s wing in flight has been an elusive goal. Unlike the earlier iterations, which suffered from complexities with the actuators and problems of heavyweight componentry, the FlexFoil control surface technology employed a new approach, called distributed compliance, to achieve practical variable geometry wings – lightweight, reliable and cost effective.
Replacing trailing edge flaps of a Gulfstream Business jet with FlexFoil seamless control surfaces, several flight tests are scheduled by NASA at its Dryden Flight Research Center, in collaboration with Air Force Research Labs, in July 2014. In retrofit applications, the technology can cut fuel consumption by 4 to 8 percen and that number can grow to 12 percent or more on newly built aircraft wit the technology. Other benefits of FlexFoil include significant noise reduction (up to 40 percent during landing) and lowered maintenance costs due to reduced wing loads.
Sridhar Kota, a mechanical engineering professor at the University of Michigan, pioneered the method of “distributed compliance,” a form of structural load sharing by exploiting elasticity to design monolithic compliant structures or joint-less mechanisms. Starting in 2001, he focused the efforts of his newly formed company toward practical applications of his patented technology, and with funding from AFRL proved the viability through various tests to confirm structural integrity and enhanced aero performance.
FlexSys’ design demonstrates wing morphing at practical scales. For instance, as a complete replacement of conventional trailing edge flaps on a Gulfstream Business Jet, FlexFoil seamless control surfaces each extend 14-feet span-wise along with a 2-feet long seamless transition sections on both ends and offer a camber change from minus nine degrees of angle to plus 40 degrees of angle, as well as twist at high rates (up to 50 degrees in a second). The FlexFoil control surface is yet strong and stiff enough to support well over 10,000 lbs. of air loads.
“FlexSys’ FlexFoil technology could enable long-sought aerodynamic benefits of variable geometry wings to be realized on a variety of aircraft without a high degree of structural and control complexity,” said Peter Flick, program manager at Wright-Patterson Air Force Base in Ohio. His team has been working with FlexSys on the FlexFoil technology for several years.
Terry Weisshaar, a world-renowned researcher and retired Purdue University professor and program manager for the Defense Advanced Research Projects Agency Morphing Aircraft Structures, said that “FlexSys has taken an innovative ‘distributed compliance’ approach and created a flight qualified, operationally safe, reliable and efficient new morphing sub-system to change the shape of future aircraft systems to improve system efficiency and capability,” for variable geometry wings.
Using aerospace grade materials and actuators in its design, FlexFoil variable geometry design greatly exceeds the life cycles required of commercial aircraft flaps. FlexFoil variable geometry design greatly exceeded the cycle life required of commercial aircraft flaps and it can be applied to other control surfaces such as leading edge, engine inlets, vertical and horizontal stabilizers. It also has the potential to revolutionize helicopter rotor design. FlexSys has already produced prototypes of variable geometry leading and trailing edges for helicopter rotor blades for potential increase in forward speed, payload and noise reduction.
Given the United States’ aviation community’s $54 billion yearly fuel bill, these savings could be viewed enthusiastically by industry insiders in both the manufacturing and operations spheres. Successful flight tests of the new FlexFoil technology are expected to gain the attention of designers and accountants.
“The potential to save fuel is tremendous with the variable geometry wing,” Kota said. “There is the direct saving due to the reduction in drag provided by the adaptive seamless surface; but there is also a complementary gain in control authority and load-alleviation. Analysis and experimental results have demonstrated that by retrofitting even a variable geometry trailing edge sub-flap, rather than a complete flap replacement, fuel savings of 4 to 5 percent can be realized. The FlexFoil’s ability to twist the control surface span-wise reduces wing stresses. This in turn allows the use of winglets on existing aircraft without requiring costly structural modifications to the wing, which can further cut fuel use by another 6 percent.”
While the aircraft wing application was a focal point of the AIAA show, FlexSys said any object moving relative to a fluid medium, such as helicopters, wind turbine blades, sailboats, automobiles, and pumps, could benefit from FlexFoil variable geometry technology.
Kota founded FlexSys in 2001 by Dr. Sridhar Kota to develop and commercialize his patented designs of shape-morphing adaptive control surfaces and other applications.
More at http://www.flxsys.com.