A Schleicher motor glider
A Hercules W-2000 bike
They’ve something in common.
A rotary thing, to be specific a 294 cc single rotor Wankel engine. Not exactly the same one it must be said, but the modern airborne one is derived from its terrestrial predecessor.
Yes, the glider looks weird under power. When you actually want to glide the prop folds away out of sight.