Abstract: Direction of rotation of a device is sensed by means of a rotor which is coupled to the device and which carries at least two permanent magnets which are angularly spaced and present opposite magnetic poles to two sensors. One of the sensors is responsive to one only of the magnetic polarities to produce a voltage signal and the other sensor produces a voltage signal whose polarity is dependent on the polarity and direction of rotation of the magnet which induces that signal. The two detector voltage are compared and their correspondence or otherwise indicates the direction of rotation.

Abstract: A missile flight control system includes a plurality of fins movable by actuators and a corresponding plurality of valves each of which regulates gas flow through a pair of outlets which are oppositely directed perpendicularly of the missile axis, the valve being operated by respective ones of the actuators.