/sci/ - Science & Math

You should think about the vector rather than just the point of thrust. In general a thrust will cause both rotation and linear motion. The rotation is around the centre of mass, and the linear motion is in the direction given by the point of thrust thtough the centre of mass. Only a rotation or only a linear motion can be achieved by thrusting either through the line from point of thrust to centre of mass, or perpindicular to it as necessary. 5 mins in photoshop gave the attached image, where I've drawn these three cases.

If you think about the us shuttle, it is asymmeytric, and has angled engines on the orbiter, so that it doesn't rotate and only moves forwards. Despite what you expect, the shuttle with the external tank moves diagonally, not along the direction it's pointing.

Any asymettric craft will do the same, and end up moving linearly in a different direction to that which you might expect.