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The following results were derived from Computational Fluid Dynamics(CFD) testing. A model of a Cessna 172
wing was built in a CFD computer. All testing was conducted on an eight foot section of the wing with a
three degree angle of attack. The following graph shows the total amount of lift produced over the wing
section at various wind speeds. The red line indicates the total amount of lift produced by the wing before
the AeroSpoiler was installed. The green line indicated the total lift produced over the same wing section
with the AeroSpoiler installed. These tests were conducted at wind speeds of 50, 100, 150 and 200 MPH. Notice that
at 50-100mph- normal windspeed in thunderstorms, an airplane would begin lifting for a normal flight envelope.
At 150mph- not
abnomal for a tornado or hurricane, the lift on each wing is about 1000lbs of lift per square foot!
As shown in the airfoil drawing below, the
AeroSpoiler not only adds a downward force to the leading-edge, but destroys the airflow across the
top camber of the surface. The decision of installing the
AeroSpoiler at 25% of the chord is based on the angle-of-attack of the wing, as well as CFD testing.
Also, the spoiler blade is raised an inch above the wing
to further aid in breaking the airflow. This is to push the angle-of-attack into the stall zone.
At this point, the tie downs should only be handling the
windload of the aircraft section facing into the wind- the lift should be well below the breaking point of any properly
installed tie down system.
From www.wikipedia.org/airfoil, this image demonstrates the terminology of a wing's airfoil:
Source: http://www.centennialofflight.gov/essay/Dictionary/angle_of_attack/DI5.htm
Direct Link:
Go to this Link
(Public Domain)
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