physics engines

I think I may finally have an idea of where I want to try my hand at writing a physics engine where I don't have to write the rest of the code to display graphics. Open Simulator appears to be modular enough to allow one to swap things in and out to fit one's needs. Mine aren't about the pretty graphics that dominate places like Second Life. I'm curious about the way Clados would work as a physics platform. That means I should take a peek at how the current physics engines support the simulators. Obviously, I'd have to wrap anything I write so as not to change the interface to simulators, but the simulator's expectations would speak to what the engine has to do.

I also know two basic problems I'd start with to look for engine consistency. The first involves bouyancy in the presence of environmental forces. The second involves gravitation on a solar system scale. Airships first, of course, as I'd have to look into how land is represented for the second.