On 3 Dec 2006 21:52:57 -0800, Dan wrote:
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 it can't produce upward force, then the rear of the plane could be
made no lighter than when it is standing still, therefore it could
transfer no _additional_ weight to the nosewheel no matter what the
control inputs. Where is this logic flawed (seriously, I want to
understand if this is wrong...)

Airplanes are normally trimmed (and loaded within limits) so the
horizontal stabilizer provides a relatively small downward force.
This gives positive pitch stability without a major increase in
drag.

If your model of how the elevator works was valid, it would be
impossible for an aircraft to fly inverted since even full down
elevator wouldn't be enough to counteract the nose-down pitch
moment.

You also have to consider that an aircraft on the ground would
pitch around an axis passing through the main landing gear,
not through the wing's center of lift.


ljd