I've never quite bought in to the "horizontal component of lift"
explanation for what causes a plane to turn.

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.

I can also generate a substantial amount of horizontal force from the
wings without the plane turning (think forward slip); it just moves
sideways through the air.

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

For example, in a coordinated left turn, the wings generate a
horizontal force to the left. The tail generates a horizontal force
to the right. The forces aren't aligned, so a couple is generated,
and the airplane turns left.

Without a force to the right, the "horizontal component of lift" to
the left generated by the banked wings would merely cause the plane to
move left -- it wouldn't turn.

Just my $0.10 worth, and I'll happily listen to contradictory
arguments.

Tim.

On Sat, 29 Jul 2006 20:52:00 -0400, Stubby
wrote:

What causes a plane to turn is the horizontal component of the lift
vector. It certainly does not depend on the turn coordinator.
What counts is the center of gravity of the plane, not the tail.



Tim Auckland wrote:
Stubby,

Thanks, I think I've got it now.

As the turn is initiated, the tail has to go right (this is what
causes the plane to turn) and my guess is that the ball initially goes
very slightly left.

However, once a constant-radius turn has been achieved, the ball will
be on the right (outside) of the turn.

Tim.

On Sat, 29 Jul 2006 18:28:28 -0400, Stubby
wrote:

I don't think so. My understanding is the ball rests in a slightly
curved tube, arranged so that gravity tends to center it. Centrifugal
force tries to move it to the outside of the skid, up the curved tube.
Neither of these forces depends on where you mount the turn coordinator.


Tim Auckland wrote:
(Things are so slow in this group at the moment, I thought I'd post
this to get your input on something I've been mulling over...)

If you put a plane into a skidding left turn (wings level) with left
rudder, the ball on the panel goes to the right.

However, I've been trying to work out what would happen to the ball if
it was mounted on the tail.
The rudder is pushing the tail of the plane to the right, so I think
the ball would go to the left.
Can anyone confirm this?

Tim.