Today's airplane wings have undergone little change since the first jets appeared. Modifications have been limited to small adjustments like winglets, miniscule angle changes or adoption of lightweight material such as carbon composites.
The above video, by FlexSys, shows off the range of motion of the new wing flaps.
NASA has joined hands with the U.S. Air Force Research Laboratory to undertake a much more ambitious project.
Known as Adaptive Compliant Trailing Edge (ACTE), this project seeks to replace traditional wing flaps with flexible wings that can change shape while maintaining a smooth surface. After a round of test flights that concluded in April, this new wing flap shows real potential to reduce noise, reduce weight and save on fuel.
These bendable wings, developed by FlexSys, seek to replace traditional wing flaps. Today's trailing edge wing flaps create a gap in the shape of the wing. The airflow around this gap is not only aerodynamically inefficient, but creates a lot of noise during takeoff and landing. Also, the parts required to make a moving flap add weight to the wing and further reduce fuel efficiency.
Substituting FlexSys' bendable wing onto an existing plane can reduce drag by 3-4 percent. If the wing is adapted to new aircraft design, an estimated 12 percent could be saved on fuel. Eliminating the gap between wing and flap also cuts 4-6 decibels of noise during takeoff and landing.
The ACTE wing uses a FlexFoil surface that can continuously modify its external shape by fitting existing flexible aerospace materials into a jointless skeleton. Due to U.S. regulations, FlexSys is unable to clarify the makeup of the material. FlexSys founder Sridhar Kota explains, however, that FlexFoil's strength lies in the ability of the lattice to distribute stress throughout the structure. With the introduction of actuators, the wing should be able to change its shape mid-flight while handling the same aerodynamic loads as traditional wing designs.
NASA ran a series of test flights between November 2014 and April 2015 using a modified G-III. The goal of these flights was to investigate the effects of the FlexSys wings on efficiency and noise. These test flights used incremental changes in the orientation of the wing flaps. NASA tested configurations between -2 and +30 degrees, but FlexSys claims that configurations between -9 and +40 degrees are attainable. So far, no tests have involved moving the wing flaps in flight.Pete Flick, program manager of the U.S. Air Force Research Lab, states that these tests were completed "without encountering any significant technical issues," and that the new wing flaps are now "ready to dramatically improve aircraft efficiency for the Air Force and the commercial aviation industry."
It is possible to retrofit existing aircrafts with gapless wing flaps, which opens up some possibilities for use in the near future. However, much more remains to be done before FlexSys wings come into widespread use. No testing has yet been done with actuators that would enable in-flight wing flap adjustment. Though promising, this is still a new technology that must go through much more rigorous testing before it can be widely applied to commercial aircrafts.
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