Dallas wrote:
Have you ever seen those short strands of yarn some glider pilots tape to
the front of their canopies? The goal is to keep the strand straight down
the centerline during a turn which can only be accomplished if there is
equal airflow on either side of the hull.

Being a glider pilot, I beg to differ:

First, to keep the yaw string centered in a turn, one must apply some
amount of rudder. A coordinated turn is a turn around all three axes.
The required amount of rudder depends a lot on the glider type and of
course the bank angle.

Second, the optimal position of the yaw string in a turn is *not*
centered, but slightly outside, because the cockpit is situated in front
of the turn radius. (A second reason is that for various reasons you
want the glider to slightly slip into the turn, hence the yaw string to
point slightly to the outside, but that's another story altogether.)

And third, the situation at the windscreen is not the same as the
situation at the rudder.


All that said, the lateral forces at the fin are pretty small during a
coordinated turn. But coodinated flight is only part of the story.