"Bill Daniels" wrote:

Tape two yaw strings (which then become pitch strings) on each side of the
canopy at the lowest and most forward part you can still see.

The string angle difference between minimum sink and stall is large so the
bright red, wiggling strings angled up steeply are a good visual stall
warning.

That must be true only for unflapped gliders, or it's valid only for
one specific flap setting in a flapped glider. Or you have to make
different coloured markings for each and every flap setting.

Aldo Cernezzi