Capt. Geoffrey Thorpe wrote:
"Dan" wrote in message
ps.com...
My impression that the elevator applied varying levels of downward
force to balance the plane about the center of lift. I am not aware
that the elevator could even produce _upward_ force on the tail.


If the elevator couldn't generate an _upward_ force, then you couldn't pick
up the tail on an taildragger, right? Let me assure you, you can pick up the
tail on a taildragger.

Sure you can, but much of that lift is a pitch couple generated by
the prop's thrust line being so far above the locked mains while
standing still, and lifting of the tail while moving is largely due to
the wing's CP being well behind the mains. If you can see the elevator
in cruise flight you'll see that it is down some, to counteract the
downforce of the stabilizer.
The elevator's lifing force in some airplanes might not be
enough to maintain nose-up in inverted flight; aerobatic airplanes have
more elevator travel and the CP and CG may be closer together to reduce
the inherent stability.