NASA's recent green aviation tests included the Active Flow Control Enhanced Vertical Tail Flight Experiment, for which 31 tiny devices called sweeping jet actuators were installed on the tail of a Boeing 757 ecoDemonstrator aircraft to determine what -- if any -- impact the devices had on the aerodynamics of the tail.
Credits: NASA/Boeing
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NASA researchers
have wrapped up a series of flight experiments with Boeing's
ecoDemonstrator 757 airplane, testing technologies designed to reduce
fuel consumption and emissions.
The first of these tests, the Active Flow Control Enhanced Vertical
Tail Flight Experiment, assessed the effect of tiny devices called
sweeping jet actuators. Thirty one of these devices were installed on
the aircraft’s vertical tail, which provides stability and directional
control during takeoff and landing, and tested to determine what – if
any – effect they had on the aerodynamics of the tail and rudder
surfaces.
"If we can control the flow of air over the vertical tail on demand,
we believe we can provide enough side force during take-off and landing
that aircraft manufacturers can safely make the tail smaller," said Mike
Alexander, lead systems engineer for the flight tests at NASA's Langley
Research Center in Hampton, Virginia. "The ability to reduce the size
of the vertical tail would reduce weight and drag and decrease fuel
consumption and emissions."
To validate this theory, the ecoDemonstrator made six roundtrip
flights April 9-15 between Boeing Field in Seattle and the Strait of
Juan de Fuca, a body of water just north of the Puget Sound that marks
the international boundary between the United States and Canada. The
active flow control technology was tested in a variety of configurations
and flight conditions, including simulated engine failures.
"Initial flight test results seem to validate the wind tunnel testing
we did with a Boeing 757 tail that was outfitted with this same active
flow control system. But we still have a lot more analysis to do," said
John Lin, active flow control experiment principal investigator at
Langley.
Wind tunnel tests were performed late in 2013 at the National
Full-Scale Aerodynamic Complex at NASA's Ames Research Center in Moffett
Field, California. Results from these tests suggested future aircraft
designers may be able to scale down the size of the vertical tail by
about 17 percent and reduce fuel usage by as much as 0.5 percent, which
quickly adds up to big savings.
With this experiment finished, the next stop for the ecoDemonstrator
757 is Shreveport, Louisiana, where another set of NASA researchers will
test wing coatings designed to minimize insect residue.
Tests will be performed on five samples of different coatings applied
to the leading edge slats of the airplane's wings to see whether the
coatings prevent bug residue from collecting on the wings during flight.
Repelling insect residue could help smooth airflow over the wings --
another effective means of reducing fuel consumption.
Between
April 27 and May 15,
the aircraft will complete 15 days of flying around the Shreveport
area, selected because of logistical and climate considerations, and its
plentiful supply of quality bugs.
"The ecoDemonstrator aircraft is an excellent research platform and
we’re excited to be able to partner with Boeing in making more
efficient, safe, and greener aircraft," said Fay Collier, NASA's
Environmentally Responsible Aviation (ERA) project manager.
The active flow control and wing coating experiments on board the
ecoDemonstrator 757 are part of several ERA technology demonstrations
designed to further the goals of reducing aircraft fuel consumption,
noise and emissions.
With the exception of Boeing proprietary technology, NASA knowledge
gained through the ecoDemonstrator research will be publicly available
to benefit industry.
For more information about NASA’s aeronautics research, visit:
http://www.nasa.gov/aero