On Sun, 30 Jul 2006 02:12:48 GMT, Jose
wrote:

I started this discussion talking about a "wings level skidding turn".
There's no horizontal component of lift generated by the wings if the
wings are level. There is however a couple comprising of the
rightwards force from the rudder, and the induced leftwards force of
wind resistance acting further forward along the fuselage. It's the
couple which causes the plane to turn.

There is also the fact that the thrust vector is more aligned with the
direction of desired flight.

I believe what causes a plane to turn is the couple comprised of
opposing forces which aren't aligned.

This is always true, for any acceleration not in the direct line of
flight. There is no "one thing" which causes anything in aviation
(except at the most fundamental level, where all flight is controlled by
money). In a coordinated turn, there are several forces, as you pointed
out. However, not all turns are coordinated. What makes a car turn?

Same thing that makes a plane turn: unbalanced forces not acting
through the centre of gravity.

(In the case of a car, the initial sideways forces are generated by
the front tires.)

By the way, I'm beginning to realize that it only takes one force to
turn an object, as long as that force is not acting through the centre
of gravity.
Interestingly enough, if the "vertical component of lift" were the
only sideways force acting on the plane, it would cause adverse yaw.
The wing's centre of lift is behind the plane's centre of gravity, so
a pull to the left would cause the plane to turn right.

Are there analogs in aviation of these forces?
Only when taxiing a tricycle(:-)

Jose