The X-53 is a modified F/A-18 test plane fitted with active aeroelastic wing (AAW) technology. An AAW is a flexible wing that may be aerodynamically twisted to improve roll maneuverability of high-performance aircraft at high speeds. The concept turns the natural aeroelastic warping of a wing of high speed aircraft (that is traditionally minimized by incorporating a stiff geometry into the design) into a benefit by the use of multiple leading and trailing edge control surfaces activated by a digital flight control system.
AAW techniques employ the energy of the air stream to achieve this desirable wing twist with very little control surface motion. The wing then creates the needed control forces more effectively than in conventional wing design. At higher dynamic pressures, AAW control surfaces are used in such a way as to allow wing twist for added control force capability instead of trying to overcome control surface losses due to wing elastic twist. AAW control can also minimize both drag at low wing strain conditions and structural loads at high wing strain conditions.
Future application of AAW technology will lead to up to a 20% reduction in aircraft takeoff gross weight due to the elimination of the horizontal tail surfaces that exist in most modern aircraft. Future manned and unmanned aircraft will benefit from this technology, expected to translate into reduced production and operational costs.
More information on the AAW and the X-53 from the U.S. Air Force research laboratory website