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.
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.
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
NASA's Dryden Flight Research Center