JYL, you brilliantly solved a stunt man physics question for me a few years back. Here:
http://forums.pelicanparts.com/off-topic-discussions/574805-stuntman-physics-question.html
I'm a dumbass but I "think" what you're asking is akin to why can an Olympic diver do flips and such once he leaves the high board, he has no external forces applied to allow him to do those flips. The answer is he is changing his arc and thus gravity allows for rotation.