Duane Eisenbeiss wrote:
There have been many comments about using the yaw string to determine the
direction of a spin. Most of us will admit that we do not look at the yaw
string while in a spin. One honest pilot even admitted it in print.

Several U.S. pilots have seen the video of the U S Air Force flight tests of
the spin charecteristics of an ASK-21. During a fully developed spins the
yaw string could be seen moving left then right then up and even forward.
The real conclusion to this discussion should be that the yaw string is not
*always* a reliable indication of spin direction.

The yaw string position is always (*) a reliable indication of the relative direction
of the air flow and the glider at the level of the cockpit. Except in case
there is such turbulence that the air flow has a completely different
direction at the cockpit level and the wings level, this implies that to
unstall the glider you want to align the airflow and the glider, and reduce
angle of attack. Hence you have to center the yaw string, whatever
considerations you may introduce about the spin direction.

(*) by definition. I would be curious to hear arguments to the opposite.


--

Michel TALON