Eric Greenwell wrote:

Does anyone know of documentation that supports the idea showing the
pilot the AOA will actually improve a glider pilot's thermalling? Or
even that the range of AOA needed to be "efficient" is too small for a
pilot to obtain it easily by using airspeed, or by just looking out the
canopy, once he's flown the glider enough to be familiar with it?

This document addresses the "best" thermalling speed, as part of an
effort to include climbing ability in handicapping gliders:

http://www.tux.org/~milgram/papers/thermaling2005.pdf

It's written by Judah Milgram, the translator for "Fundamentals of
Sailplane Design". I'm still digesting it, but it seems to say the
theoretical speed is slower than you would deduce from the straight
flight minimum speed; in fact, for bank angles less than 30 degrees, the
best speed is actually lower than the straight flight minimum sink speed.

There are some caveats: without polar measurements in a turn, you have
to make some assumptions that may not be true, and ignore real world
handling issues from flying slowly.

Practically speaking, I suggest that circling "efficiently" (regardless
of the value of an AOA meter in achieving it) only has value in weak,
smooth thermals; otherwise, where you are in the thermal is more
important than minimizing your glider's sink rate, so you have to fly
fast enough to maneuver well and accept losses from the excess speed and
bank angle changes.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org