Instruction:
In this applet, the variation of forces and moment acting
on an NACA 2410 wing section is demonstrated.
Use two sliders on the right to change the airspeed and the
angle of attack.
(Question: Why does a pilot have to increase the angle of
attack when he slows the airplane?
Try reducing the airspeed while keeping the same amount of
lift (i.e., weight.) Also note the decrease in lift beyond
a certain angle of attack.)
Deploy and retract the split flap and see its effect. (A flight
instructor will tell you never to retract the flap on a final
approach to landing. Do you see why?)
Pitching moment depends on its reference point. Thus, you are
given two choices: moment about the quarter chord point and
the leading edge.
More detailed information:
For this numerical illustration, forces per unit span are
computed assuming the 1.6m chord length. Within the range of
relatively high Reynolds number chosen (order of several
millions), the Cl and Cd curves are assumed to be independent
on the Reynolds number.
(The data taken from Abbott and von Doenhoff, "Theory of Wing
Sections, pp. 476-477. )
The drag coefficient data with the flap deflection are not
available in the reference above. According to the reference
below, the increment in wing drag coefficient due to the flaps
are approximated as:
for plain and split flaps
where c is the chord length and S the wing area, and the
subscript f denotes the flap. df is the flap deflection angle.
Reference: Aerodynamics, Aeronautics, and Flight Mechanics,"
Second Edition, John Wiley & Sons, 1995, P. 98
CAUTION:
These applets are written to illustrate the behavior of the wing
section for the introductory aerodynamics course (in somewhat
qualitative manner,) and thus not intended for quantitative
estimate of performance, etc.
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