String in the middle does not protect you from a spin

nafod40 wrote:
...
So (my swag analysis) if you are in a right hand turn, the forces on the
wings are as below, with the inner wing having more drag, because it is
slower and must fly at a higher AOA (gained through aileron deflection).
To counteract the forces now trying to rotate the aircraft, one must
toss in some rudder. To then keep from side slipping, one must fly in
what would feel like a skidded turn to balance all of the forces.
...

The inner wing wing has a higher drag *coefficient*, but a lower speed,
so it is not obvious if the drag is higher or lower. Near the speed of
best L/D, drag an lift coefficients increase in the same proportion with
increasing AOA, so if the difference in lift coefficient compensates
exactly for the difference in speed, the same should be true for
drag. At lower speeds the (relative) drag coefficient increase is higher
than the lift coefficient increase and this has to be conterd by some
inside rudder. This is confirmed by experience on most gliders, where
the need for inside rudder increases when you come closer to the stall
speed/angle. But this is an oversimplified view. There are at least to
other source of rolling moment beside the overbanking moment due to
the different speed of both wings. One of them is the difference in
AOA due to the fact that both wings have the same sink speed (vertical
component of velocity) but a different horizontal speed. Another one
is due to inertial forces, the difference between the centrifugal forces
on both wings. These both effects results in an underbanking rolling
moment, so the aileron input has to counter less than the overbanking
moment due to the speed difference. And aileron deflection is not just
a change in AOA, but a change in airfoil shape, and it usually affects
only the outer part of the wing, the inner part may be in the opposite
condition (lower lift on inside wing) so that the global effect is what
is wanted.