We've moved small Cessnas by lifting the nose wheel that way, and of
course the mains are aft of the CG. I don't know where the center of
lift is, though: that would be the question. I'd guess -- and it's
only a guess -- it might be a third of the way along the wing chord
for a straight winged airplane.



€€On Nov 3, 1:34 pm, Larry Dighera wrote:
On Fri, 02 Nov 2007 18:12:58 -0700, Tina wrote
in .com:

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?

Of course you mean the horizontal 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?

I would estimate, for a C-172, sans cabin occupants, it takes about 50
lbs of down force on the horizontal stabilizer to lift the nose wheel
from the pavement.

I'm no engineer, and I know this is not the answer to you question,
but it gives you a feel for the force involved. You can try this
yourself the next time you're at the airport; just make sure you are
putting your hand over the spar on the inboard portion of the
horizontal stabilizer near the fuselage to prevent permanently
deforming any aluminum.