Re: Biomechanics of simple throwing
This horse is in pretty sorry shape, but just to take a last swipe at it:
I'm not opposed to physical models, I'm just opposed to believing in them. :-) Let me give you an example: if you're going to push a car everyone, from grandma to the local strongman pushing a Mac truck, will use bent arms. Yet any force/vector model would surely show that this is inefficient--that you ought to keep your arms straight, arm bones lined up with the force you're applying to the car.
Anyone want to disagree? Give me a model where that's not so? Claim that it's actually better to push with absolutely straight arms?
Okay. So if the force/vector model fails so completely in such a simple case, what hope does it have of modeling a real confrontation? Instead, y'all will go teach your students to do the equivalent of pushing with straight arms and because we're all martial artists and have checked our common sense at the door, your students will actually go out and try to do it.
So yeah, play with physical models, but when they contradict experience--your own, or as captured by hundreds of years of tradition--get very suspicious of the model, not the experience.
Jon--Fascinating insight. I've never done enough Judo to understand their approach to kuzushi. Joe C suggested in the Takahashi thread that Judo-style understanding of kuzushi was what was missing from Aikido... I'd love to hear more about that. (Or play with it tonight!)