Spin and flat spin

The pieces of yarn...

Here are the images of an attempted "scientific" experiment. I simultaneously filmed from the ground and with an on-board camera a classical spin, and a flat spin.

The wings are equipped with pieces of yarn in order to see the flow of air during the 2 tricks.

The flat spin was rotated with the madstab not too raised: this accelerates the speed of rotation and I hoped to clarify the flow as much as possible.

I must admit that I expected a more straightforward result. The pieces of yarn of the classical spin come off quite regularly from the airfoil. Those of the flat spin remain fairly flat, but in a centrifugal direction, whereas I was hoping for a back-to-front direction.

The images are therefore subject to your interpretation, they simply have the merit of existing at least once here, because it requires combining several things:

I'm interested in any other similar experience!