ORIGINAL: GREG DOE
Skeeter. Back to the origional question, and answere. If you haven't seen it yet, go to the
"Hurrikane Build Thread" in the 'Q-500 Racing Section' and check out the slotting tool, and
the treatment for the stabilizer. Racers have been doing this to their stabs and rudders for
40 plus years.
We could wright a book on what's happening with wings, and stabilizers at high angles of
attack, but were going to keep it simple. Also we are discussing conventional airplanes,
not duration freeflight, or 3D stuff: pylon racers is the topic at hand.
Think about what happens if you hold an arrow, a few inches from the tip, out the window
of your car. The feathers on the end of the arrow want to take the path of least resistance,
so they end up parrallel to the slip stream. On a conventional airplane, with the center of lift
slightely behind the center of gravity, the stab is trying to assume the path of least
resistance, but in order to keep the nose from diving, we have to incorporate some down
force at the tail. Most of the time we think and talk about the nose of the airplane climbing,
or diving, but actually the tail is going DOWN or UP, and the fuselage is rotating about the
center of gravity, so that moves the nose up and down. Now if we apply excessive elevator
inputs we can force the wing to change direction at such a high angle of attack, that the wing
will stall. Sharp leading edge WINGS will stall much sooner than blunt, (rounded) wings.
The leading edge of the stab, (or rudder) is rarely subjected to such high angles of attack,
that it would stall, and certainly not in our application on a Quickie, or other race airplanes.
I hope this helps explane why sharpe leading edges on stabs and rudders are good design
practice. And as stated, the 1/64" plywood inserts make the leading, and trailing edges very
good at resisting dings, and "hangar rash". Greg