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96-154 NASA and the U.S. Air Force today
unveiled a jet-powered aircraft equipped with
state-of-the-art flight control technologies that will
demonstrate a computerised flight control system that learns
as it flies --especially important for the demands of ultra
high-speed flight. Called the Low-Observable Flight Test
Experiment (LoFLYTE), the 8-foot-4-inch aircraft, announced
at a briefing in Oshkosh, WI, has been developed by Accurate
Automation Corp., Chattanooga, TN, for NASA and the Air
Force. The program contracts are being administered through
NASA's Langley Research Centre, Hampton, VA, and the Air
Force Wright Laboratory, Dayton, OH, under the Small
Business Innovative Research Program. The experimental LoFLYTE aircraft
will be used to explore new flight control techniques
involving neural networks, which allow the aircraft control
system to learn by mimicking the pilot. The model is a Mach 5 waverider
design -- a futuristic hypersonic aircraft configuration
that actually cruises on top of its own shockwave. Waverider
aircraft, powered by air breathing hypersonic engines, would
fly at speeds above Mach 4. LoFLYTE represents the first
known flying waverider vehicle configuration, but upcoming
flight tests at NASA's Dryden Flight Research Centre,
Edwards, CA, will be flown only at low subsonic speeds to
explore take-off and landing control issues. The remotely-piloted aircraft has
been designed to demonstrate that neural network flight
controls are superior to conventional flight
controls. Neural networks are computer systems
that actually learn by doing. The computer network consists
of many interconnected control systems, or nodes, similar to
neurons in the brain. Each node assigns a value to the input
from each of its counterparts. As these values are changed,
the network can adjust the way it responds. The aircraft's flight controller
consists of a network of multiple-instruction, multiple-data
neural chips. The network will be able to continually alter
the aircraft's control laws in order to optimise flight
performance and take the pilot's responses into
consideration. Over time, the neural network system could be
trained to control the aircraft. The use of neural networks
in flight would help pilots fly in quick-decision situations
and help damaged aircraft land safely even when controls are
partially destroyed. The main objective of LoFLYTE is to
demonstrate the utility of such a flight control system that
learns through experience, said Robert Pegg of Langley's
Hypersonic Vehicles Office. In addition to experimenting
with neural networks, the flight of the model also is key as
a low-speed demonstration of a hypersonic vehicle . "We're
very interested in both outcomes, both the neural net
technology and the flight characteristics," he
said. "We see a big advantage to using this
type of control system in a hypersonic vehicle," Pegg said.
"At those high speeds, things happen so quickly that the
pilot cannot control the aircraft as easily as at subsonic
speeds." The initial configuration for the
aircraft was developed at Langley. Accurate Automation Corp.
will then integrate the neural network technology into the
Langley design. successful tests of the waverider concept in
Langley's 12-foot Low-Speed Wing Tunnel and 30 by 60-foot
Full Scale Tunnel preceded the development of this model
aircraft. The construction of the model was
completed at SWB Turbines, Appleton, WI. The company also
provided the small turbine engine that powers the model. The
shell of the model was built at Mississippi State's Raspet
Flight Research Laboratory and then shipped to SWB Turbines
so that the radio control gear and the engine could be
installed. The waverider was chosen as the test
bed for the neural networks because the configuration has an
inherently high hypersonic lift-to-drag ratio. If neural
networks can control this "worst-case scenario"
configuration, then they should be able to handle virtually
any other configuration. The waverider configuration was
also chosen because it allows for long hypersonic cruise
ranges of up to 8,000 miles. At an altitude of 90,000 feet,
a Mach 5 waverider would fly at a rate of one mile per
second. "We want to make the public aware
that he government is getting a good return on its
SBIR-invested money," Pegg said. "We hope this project will
help us further demonstrate to the public that the SBIR
program is a viable investment for the American
people." Technologies being implemented in the
LoFLYTE program could eventually find their way into
commercial, general aviation and military
aircraft. - end -
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