As has been pointed out in the past on RAS, pieces
of wool taped to both front/sides of the canopy perform
quite well as angle of attack indications in unflapped
gliders. The angular change between max LD and stall
is surprisingly noticeable. Once 'calibrated' for
the stall position and min sink and best glide positions
they are helpful for optimizing thermalling technique
but don't grab the attention well enough to be a safety
stall warning.

Certainly good value for money.

John Galloway