(Teacherjh) writes:

To weathervane, you need differential force. A steady wind while on
the ground allows such a force to develop. A steady wind in the air
does not. However, a gust in the air does (the resistance would be
due to inertia, and centered at the center of gravity).

I think that there's a lot of confusion in this thread about the terms
"relative wind" and "weathervaning". "Weathervaning" is an informal
term for the yaw moment contribution due to sideslip angle, where a
conventional aircraft naturally tends to align itself with its
relative wind; "relative wind" is the wind in relation to the
aircraft's longitudinal axis, not to the ground.


All the best,


David