Beware the
unnecessary use of coarse control, particularly rudder and particularly
near the ground!

IAN STRACHAN
Lasham Gliding Society

I did a few calculations of an imaginary glider with a stall speed
of 32 knots, a min sink speed of 43 knots, and
a wingspan of 87 feet.

In a 50 degree bank at 54 knots (good thermalling speed if you
believe)

www.stolaf.edu/people/hansonr/soaring/spd2fly/

the fuse and ASI says you are at radius 180 ft circling every
7 seconds. The inner wingtip is 3/4 of that distance, and
3/4 of that airspeed, and should be stalled. The outer
wingtip is 5/4 of that distance from center, and 5/4
of that airspeed, and producing excellent lift.

Now throw in a down aileron near the wingtip, increasing the
AOA of the inner wing. Now have the student
not compensating for adverse yaw, and the instructor yelling
"get that string centered right now!"

Now have the student jam in lots of rudder, and watch the
difference in airspeed and AOA during this coarse
movement.

This is probably why coarse rudder is often used to
coarsely demonstrate a spin entry...

This is also why I fly a glider with a short wingspan and
a weak rudder... (getting a worse L/D design was faster
than getting better skill)