If an airplane's wings could twist like the
wings of a bird, structures for maneuvering could
be streamlined and simplified. The Wright brothers
understood this, and incorporated twisting, or wing-warping,
into the very first airplane in 1903 to enable the
craft to bank for turns.
NASA has returned to the Wright's century-old concept with a new twist: a supersonic jet aircraft at NASA's Dryden Flight Research Center on Edwards Air Force Base, Calif., has been flown with wings that deflect when special leading and trailing edge control surfaces are activated. The aircraft is the Active Aeroelastic Wing (AAW) F/A-18. The flexible wing provides roll, or bank, comparable to that achieved by a standard stiff-wing F/A-18, while the experimental jet does it with less need for coordinated tail surface inputs to complete a turning maneuver.
Researchers hope this will lead to a revolutionary new rationale for aircraft design. Stiff wings and heavy control surfaces that use hinges were necessary as 20th century aircraft mechanically coped with the need for faster speeds and larger sizes. While the AAW airplane still relies on hinges to prove its point, the availability of strong, flexible composite structures and miniaturized computers and motors point the way toward seamless wings that will one day bend to achieve flight control as effortlessly as a bird does.
The results can include greater fuel efficiency in several ways. Seamless wings create less drag; seamless control surfaces can weigh less than conventional control surfaces; and, a "smart" airplane with seamless wings could one day use computers to sense its most efficient flight configuration, and change its shape to match.
Passengers may one day enjoy smoother flights in bumpy air with computer-operated seamless wings, and the military sees smooth, seamless control surfaces as a way to enhance radar-defeating stealth qualities.
NASA is working with Boeing and the U.S. Air Force on the AAW project. The quest for a morphing aircraft that changes its shape in flight to meet requirements is ongoing at several NASA aeronautical centers. More information about the Active Aeroelastic Wing F/A-18 is available at: http://www.dfrc.nasa.gov/Newsroom/FactSheets/FS-061-DFRC.html, and at: http://www.dfrc.nasa.gov/Newsroom/NewsReleases/2002/02-57.html. Photos of the AAW F/A-18 are on the NASA Dryden Web site in the Gallery section at: http://www.dfrc.nasa.gov/Gallery/Photo/AAW/Small/index.html.
An artist's conception of a future morphing airplane is on line at: http://www.dfrc.nasa.gov/Gallery/Photo/Morph/HTML/ED01-0348-1.html