- LONDON - A wing lined with fans that generate lift could pave the way
for silent planes of the future.
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- The FanWing is the product of a privately
funded, four-year research effort by Patrick Peebles, an inventor based
in Rome. He sees it as a niche aircraft, bridging the gap between conventional
fixed-wing planes and helicopters.
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- The concept is simple: cylindrical fans
fitted to the leading edge of both wings blow air across the wing to generate
lift and push the aircraft forward.
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- Small flaps in front of the fans control
the thrust and lift by changing the angle at which air enters the fan cages.
Steering is achieved by differentially moving these flaps.
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- Peebles says the FanWing is much better
than a conventional wing for coping with turbulence. The reason is its
lack of sensitivity to changes in flight attitude, known as the angle of
attack. Coupled with its inability to stall (suddenly lose lift at low
speed) and the strength of its large, triangular-section wing, the result
is an extremely stable and tough aircraft.
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- Initial trials were held at the University
of Rome, but now Peebles is in Britain to do a series of wind-tunnel tests
at Imperial College, London that will provide data on the efficiency and
flight characteristics of a full-scale craft.
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- Radio-controlled models have already
demonstrated the FanWing's aerodynamic properties and its short take-off
and landing (STOL) capability.
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- Peebles is cautiously optimistic. "It's
still at an early stage of development and there are unresolved issues
on design details," he says. "But so far, its stability and efficiency
are as we predicted, which is very encouraging."
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- One of the first applications of the
technology is likely to be in small, quiet unmanned spy planes.
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- "The FanWing is highly suited to
surveillance because it's efficient, virtually silent and extremely stable,"
says Peebles. "Larger, manned versions could be used for short-haul
freight, passenger and emergency-services operations, or where high lift
at low speed are desirable."
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- Besides the leading-edge fans, the most
striking feature of the latest FanWing prototype is the way its tail boom
sweeps upwards. The reason for this is twofold: the fans create greater
downdraft than a conventional wing, so raking the angle of the boom keeps
it out of the turbulence and enables it to act as a vertical tail. At this
stage, the rear tail surfaces are fixed, though this may change as development
proceeds.
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- One of the questions the Imperial College
tests ought to answer is how the FanWing will glide when the power is switched
off. Research will focus on the optimum angle of attack needed to keep
the fans turning to sustain flight. In the event of a total power failure,
it may be necessary to completely disconnect the motor from the fans to
ensure they run as freely as possible.
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- Current indications are that a FanWing
aircraft will be about twice as load efficient as a similarly powered conventional
aircraft. Peebles believes that modifications to the fan-blade shape and
changes in the wing design may further improve these figures.
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- The next step in the FanWing's evolution
is the construction of a full-size 12ft wing section.
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- Looking further ahead, Peebles says the
combination of greatly reduced noise with high payload capacity could eventually
make a short-haul, 20-seat commuter plane an attractive proposition. Such
an aircraft could ferry passengers to big airports from outlying districts,
doing the job cost-effectively and with little impact on the environment.
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- Seaplanes may also benefit from the STOL
characteristics of the FanWing. They would be able to operate in much rougher
weather than current planes.
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