Low Speed Wind Tunnel Tests
by Gavin Botha
January 19, 2000
I have been involved with several fixed wing aircraft
tests, as well as helicopter tests. These include:
Fixed Wing:
F-18 High Angle of Attack Test, where we tested a Navy Blue Angles
Aircraft at slow flight speeds with the nose of the aircraft flying at
a very high attitude. We tested different types of devices mounted to
the front of the aircraft to aid in controlling the fighter at these radical
attitudes.
 
Results:
During the F-18 test we learned what type of devise provided the best
control for the F-18 flying at these nose high angles. These designs,
which were little wings that popped out of the sides of the nose, were
built and tested on an actual F-18. Someday this may become standard equipment
on certain aircraft.
Helicopters:
Sikorsky Bearingless Main Rotor Test. This
was a new design in helicopter blades, that used modern composite materials
for the blade structure. These new materials allowed the helicopter blades
to bend and twist to the proper control positions without using a bearing
device that is normally needed for a standard rotor blade to rotate.
Results:
The Bearingless Main Rotor test proved that helicopter blades can be built
without using bearings for blade rotation. This would save in manufacturing
costs and is much easirt to maintain. Sikorsky Helicopter Company now
has a production helicopter that uses bearingless main rotors.
Tilt Rotor Aeroacoustic Model. This is a 1/4
scale model of the V-22 Military Tilt Rotor Aircraft. The tilt rotor aircraft
combines the best features of an aircraft and helicopter. A propeller
on each wing can rotate forward, so that it becomes an airplane, and can
then tilt backwards until both propellers are acting as helicopter rotors,
and can hover like a helicopter.
Results:
We are still testing the 1/4 scale Tilt Rotor, but have already learned
valuable information on the performance and noise characteristics of the
propellers. We are trying to lower the noise produced from the blades
so that the aircraft can take off and land from buildings without being
too noisy.
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