Abstract: A variable area convergent-divergent nozzle for use as an attitude control thruster on a VTOL aircraft is formed by a curved wall forming a chamber a convergent section a throat section and a divergent section and a pair of parallel side plates, one of the side plates being movable to alter the area of the nozzle.

Abstract: A reaction jet control system for a flying vehicle, the system comprising pairs (3, 4 and 5, 6) of jet reaction nozzles with associated gas flow supply ducts, the duct between two nozzles (3, 4) of any one pair including a first gas diverter valve (11B) and the duct between the pairs of nozzles including a second gas diverter valve (11A). This arrangement ensures accurate balancing of the gas flows between the nozzles and gives economy in use of the fuel supply.

Abstract: An emergency fuel control system for an aircraft engine, which emergency fuel control system comprises means for supplying emergency fuel to the engine such that the fuel supplied to the engine is proportional to engine speed and pressure, first fluidic means which is controlled by a pilot's throttle lever giving a throttle demand and which includes fluidic sensor inputs for limiting engine performance, second fluidic means which has an acceleration control for generating a signal pressure as a particular function of engine compressor ratio, a fluidic mixer for mixing an acceleration control signal and a pilot's control signal such that the pilot cannot demand more fuel than it is safe for the engine to accept, and a fluidic output device which receives signals from the fluidic mixer and which generates a signal which has substantially the same shape as the acceleration control signal but which is at a lower level and which is used to define the minimum amount of fuel that is safely required by the engine in