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On Nov 2, 7:12 pm, Tina wrote:
OK, so the center of gravity (except for some airplanes with really
smart computers) is going to be forward of the center of lift for
stall recovery reasons -- that makes sense. The question I have is,
for a typical GA flying machine -- take a complex single for example
-- what really is the download (I'm thinking of it as induced weight
with fuel burn consequences) supplied by the vertical stabilizer? It
has a reasonable moment arm hanging way back there, but is it as much
as say 100 pounds if the CG is near the forward limit?

This isn't an aeronautical problem, its a basic mechanics problem.
The moment of the CG vs. the center of lift must equal the moment of
the tail plane.

If the airplane gross weight is 2500 lbs, and the CG is 1 foot in
front of the center of lift, that is a moment of 2500 foot-lbs. If
the tail plane is 10 feet behind the center of lift, the force on the
stabilizer is 250 lbs.

Dean


Now for fuel burn increases, factor in the induced drag created by the
deflected elevator to create the required down force.
Glider pilots attempt to maintain a CG at 75-85% MAC (some will go farther
aft), to keep the deflection to create the required down force to a minimum
to create the least amount of drag at cruising speed.

BT