GetForce function?

I'm trying to write up some asteroids type player code (birds eye view, go in a constant momentum in the direction you last moved to, etc.) and I can't seem to find a function that gets the current Impulse Force (or speed of force). I'm looking for it because I want to give the player a max speed that it can't go over. Is there a function that does this?

By the way, I did look at the included behavior code, but it seems the max speed limitation is achieved simply by applying damping, which isn't something I want to do.