Whatever amount of downward thrust pushes against the vanes cancels out an equal amount of the thrust's upward push inside the rocket. The solution developed for large rockets and space boosters was to gimbal the nozzle. A gimbal is a pivot device that allows the entire nozzle, and the flow of exhaust gases, to be swiveled in any desired direction. The rocket's course then veers in the opposite direction. Rockets can be guided by radio signals from the ground or by equipment and prerecorded instructions that have been placed on board.
Inertial guidance is a common form of on-board control.
It is an automatic navigation system that senses, through gyroscopic devices and acceleration measuring devices, the vehicle's position and speed, compares them with the planned flight path, then gives orders for any necessary adjustments. A number of missile and space programs use inertial guidance. Inertial guidance signals cannot be detected outside the vehicle or disrupted by radio commands. Stability in flight is another concern of engineers. There are three distinct motions to be controlled and corrected quickly before the vehicle begins undesirable tumbling.