I'm making a hybrid car which uses an ICE in tandem with compressed air. I have modelled two tanks on the sides with a default pressure of 30 psi and completely closed them in with coltris. Or so I think -- when I spawn the monocoque with the tanks, it starts to slide backwards like an untied balloon. All of the coltris that make up the tanks have normals facing outwards. Being a JBeam rookie, I have absolutely no idea why this happens, and would be grateful for any help.