The aerodynamics of this are interesting.

The most likely reason that a glider exhibits the spiral stability to fly
thermals hands-off is that once it is set up to fly coordinated circles and
the controls released, the controls have just enough friction to keep the
aileron and rudder controls where they were - just a bit of outside aileron
and rudder. If you lube the controls, you may lose the hands-off
thermalling capability.

The other possibility is that the inner and outer wings are flying on
opposite sides of the polar curve with the outer wing on the high speed
side of the polar and the inner wing on the slower side. Discontinuities in
the polar due to separation bubbles may play a part too.

A perfectly symmetrical glider with a perfectly smooth polar and
frictionless controls SHOULD develop a spiral dive from a hands off turn.

Bill Daniels


"Buck Wild" wrote in message
om...
John Jones wrote in message
...
How many gliders can be trimmed for hands off thermalling?



LS4
-Dan