1,047,230. Rocket engines. ROLLS-ROYCE Ltd. March 7, 1960 [March 11, 1959], No. 8500/59. Heading F1J. In a rocket propulsion motor, a fail safe system is provided such that when a fault occurs the valves controlling the flow of fuel and oxygen to the thrust chamber are closed, if the rocket is on the ground, and are maintained open once the rocket has left the launching area. In addition, the fuel and oxygen feed to a gas generator, within the rocket, supplying the fuel and oxygen pump turbine, is similarly controlled. Both systems may be shut down during flight by the remote firing of cartridges to effect valve closure. The motor thrust chamber is supplied with liquid oxygen and fuel, the latter first cooling the chamber before entering through spray nozzles. The chamber is shaped in throat form and, has a pyrotechnic igniter. To limit the rocket acceleration, as the mass is reduced by the consumption of fuel, the flow of oxygen is automatically controlled by a valve having an acceleration sensitive member. The motor is started from fuel and liquid oxygen tanks of the ground installation, pressurised with nitrogen, and after the commencement of combustion in the chamber, fuel and oxygen at low pressure flow from the rocket tanks into the chamber. An ignition detector in the chamber causes fuel and oxygen to be directed to the gas generator from the ground tanks where they are ignited to drive the rocket fuel and oxygen pumps which raise oxygen and fuel supply pressure to the thrust chambers to full value. At 80% full pressure the ground tanks are de-pressurised and the rocket released. To maintain accuracy in the flight path, the liquid levels in the fuel and oxygen tanks are sensed and the fuel flow throttled to maintain the required fuel-oxygen flow. The oxygen control valve 163, Fig. 11, compress the plate 164 and is controlled by the piston 172. Nitrogen from the ground installation urges 172 against spring 185, to open 164. If the valve fails during flight, it remains open due to the locking of fingers 174, behind shoulder 175. To interrupt the oxygen supply during flight, a remotely fired cartridge generates gases which are applied, through pipe 181 to the opposite side of 173. Member 177 is lifted, fingers 174 are freed and piston 172 forced downwards to close 164. A "fail safe" on the ground is effected by the introduction of nitrogen into the space above 172 by ground fault detector equipment. The fuel control valve, (Fig. 12, not shown) operates in a similar manner and in addition incorporates a fuel throttling system operated by an electrically adjusted valve energised in dependence upon signals representing the relative levels in the fuel and oxygen tanks.