I'm not working with bullet for a long time yet, so I probably don't know if I just have done something stupid in the setup of the engine.
To get you a better overview of the situation I made a little picture for you:
Most of the time the ship will just crash through the border marked with the red arrow when I am "fast" enough. This will also happen if I jump off a ramp and do a hard landing afterwards. I will just smash through the ground.
Someone may point me into the right direction?