I've got pitch strings on both sides of the canopy of my ASW-19, Bill,
but I've not seen this behavior. I'll make an effort to look carefully
the next time thermals appear in Pennsylvania! As was said earlier in
the thread, though, strings on the canopy are greatly affected by yaw.
They might help indicate lift, but they won't really be useful AOA
indicators. And if AOA instruments average out rough air fluctuations,
they won't be too useful as incipient lift indicators. Tough problem!

-John

Bill Daniels wrote:
Many pilots who have tried the "pitch strings" report that they give advance
warning when entering an area of lift. When you enter the edge of a
thermal, the strings show a sharp increase in AOA several seconds before the
vario shows lift. This improves the efficiency of "dolphin flying" by
providing an earlier signal of when to start a zoom. One pilot on a
marginal final glide told me, "Without them, I wouldn't have made it home."
An ASI gives the same signal but it's weaker and harder to interpret.

Most AOA sensors have some damping to smooth the signal in rough air.