English: Free body diagrams illustrating the pendulum rocket fallacy. On the left are typical rockets with thrust applied at the base; on the right, thrust is applied at the nose of the rocket. The upper row shows the actual set of forces on each rocket (weight W, drag D, and thrust T), with the thrust vector passing through the center of mass of the rocket. The lower row shows the fallacy in which the thrust vector is assumed to point upward at all times, and acts as a destabilizing or stabilizing force depending on where it is applied.