Like what you may have done with Hot Wheels. Or like numerous video games. I once saw a car do a barrel roll fron one curved ramp onto another curved ramp, but never a genuine loop on a course. I have never even seen a loop setup to perform such a course.
I have never really even seen a motorcycle do this stunt, except maybe in a circus cage. Never “Robbie Kneival picking up speed into a loop” type of stunt.
Certainly this is possible, although the amount of preparation into the vehicle or the course is prohibitive.
Have I just never seen it, or has it never been done and why?