If you use the "tinker parts" menu to set your crafts mass to 0 kg, it makes weird things happen. In normal sandboxes, your craft seems to be almost stuck to the ground, but then if you try to gimbal or rotate, the craft spins rapidly around the front of the craft (a screenshot does not do this movement justice). I also did it in a challenge (maxumum speed), and there it just exploded between the runway, then after going back to the editor and comeing back to the challenge, the explosen was in space. I am not sure what was happening there, and even thou the tinker panel is experemental, this may be something to look at. thank you for readning my paragraph.
Sorry for spelling.
Thanks for the bug report. I don't know that there's much we can do with a 0kg craft. All bets are off with the physics engine at that point, but that's why it's fun!