Some tests seem to show that the drag of a torus or ballute during rotation is prohibitive. Perhaps it would be better to replace it with a central inflatable disc to reduce drag, but it is not sure because even a thin throwing ring significantly slows down the rotation, all the more for a disk. Airborne solar wind energy systems (ASWES) - Lounge - AWESystems Forum
I just noticed that the rotary ballute-based kite has already been made, with flexible kite blades (video below).
