Sounds like it would be a usefull instrument for a hot air baloon.
After all, you need to know which way the wind is blowing.

On Jan 29, 4:51 pm, "COLIN LAMB" wrote:
No one has mentioned that yaw strings work on helicopters, too.

Just as important to avoid adverse yaw on a helicopter - and no, the
"downwash" does not render them useful.

Colin