898,276. Generating combustion products under pressure. UNITED AIRCRAFT CORPORATION. Nov. 15, 1960, No. 39168/60. Class 51 (1). [Also in Groups XXVI and XXIX] A rocket motor assembly comprises at least one combustion chamber and thrust nozzle, a fuel supply tank and an oxidiser supply tank, conduits connecting each of the tanks to the combustion chamber and a valve in each conduit, an actuator for each of the valves and means for pressurising the fuel supply and the oxidiser supply, the pressurising means being regulated by means responsive to the pressure in at least one of the supply conduits. The assembly shown in Fig. 1 comprises a tank 10 divided by a partition 12 into a fuel compartment 14 and an oxidiser compartment 16, also four thrust chambers 26 each comprising a combustion chamber 28 and a thrust nozzle 30. A fuel conduit 18 having an initially closed valve 38 connects the compartment 14 to the fuel distribution conduit 20 from which branch pipes 22 lead to jacket spaces 24 around the thrust chambers, the fuel entering the combustion chambers through nozzles 34. An oxidiser supply conduit 42 having an initially closed valve 52 connects the compartment 16 to the oxidiser distribution conduit 44 from which branch pipes 46 lead to the combustion chambers 28. The fuel may be hydrazine and the oxidiser nitrogen tetroxide. The system also comprises a high pressure helium tank 56, a starting squib valve 64, a helium pressure regulator 80, a stop squib valve 116, an actuating means 148 for the propellant supply valves 38 and 52, also an auxiliary oxidiser tank 60 and an auxiliary fuel tank 62, these two tanks being connected to combustion gas generators 170, 172 from which gases pass to the fuel and oxidiser compartments 14, 16 to pressurise them. The start valve 64, Fig. 2, comprises a casing containing a solid combustible charge 68 and a valve 74 which normally is in the position shown in which it closes the duct 58 from the helium tank 56. At starting, the charge 68 is fired, the resulting gases forcing the valve 74 downwardly, whereupon helium flows from the tank 56 through the regulator 80 and stop valve 116 to the actuator 148, also to pressurise the auxiliary oxidiser tank 60 and auxiliary fuel tank 62 after rupturing the bursting discs at 162, 164. The actuator 148 comprises a piston 150 which is urged to the right, the operating rod 154 causing the valves 52 and 38 to open. These valves each comprise a diaphragm which is secured to the valve disc whereby the valve is initially sealed, the diaphragm bursting upon initial movement of the valve disc. Pressurising of the tanks 60, 62 by the helium causes fuel and oxidiser to flow to the two combustion gas generators 170, 172, gases from the generator 170 which are oxidiser-rich passing through the duct 190 so as to pressurise the oxidiser compartment 16, and gases from the generator 172 which are fuel-rich passing through the duct 196 so as to pressurise the fuel compartment 14. Fuel and oxidiser thereupon flow through the ducts 18 and 42 and the open valves 38 and 52 respectively to the combustion chambers 28. To stop the operation, the charge 118 in the stop squib valve 116, Fig. 4, is fired, the resulting gases forcing the valve member 126 downwardly thereby closing the helium supply duct 58, but permitting helium under pressure to flow through ducts 142 and 132 to the righthand side of the piston 150 which thereby acts to close the valves 38 and 52. Helium also flows through the ducts 256, 254 into the propellant supply ducts 18, 42 downstream of the valves 38, 52 to purge them. The combustion gas generators 170, 172 are as shown in Fig. 5 and comprise two supply conduits 182, 184, the conduit 182 having a restriction 186 which meters the fuel or oxidiser as the case may be, the excess fuel or oxidiser passing through duct 188 to enter the combustion chamber at a downstream point. In the case of the gas generator 170 which operates oxidiser-rich and serves to pressurise the oxidiser tank 16, the supply of fuel thereto is controlled by means of a regulator 204 which is shown in detail in Fig. 6, the regulator being connected by means of ducts 222, 224 to the main oxidiser conduit 42 downstream of the valve 52. In the case of the gas generator 172 which operates fuel-rich and serves to pressurise the fuel compartment 14, the supply of oxidiser thereto is controlled by means of a regulator similar to that shown in Fig. 6 except that this regulator is connected by means of a conduit 234 to the main fuel conduit 18 downstream of the valve 38, as well as to the main oxidiser conduit 42 by means of conduit 222. The regulator 204 comprises a casing containing opposed bellows 212, 214 connected by a bar 216 having a port 218 therein the port controlling flow of auxiliary fuel from tank 62 and lines 174, 176 through nozzle 210, the fuel discharging through outlet 220 to gas generator 170. The bellows 212 is vented while bellows 214 is subjected to pressure of the oxidiser in duct 42 downstream of valve 52 by means of ducts 222, 224. Each bellows is spring-loaded, the spring within bellows 212 being adjustable. The regulator 232 is similar to regulator 204 except that auxiliary oxidiser is supplied to the nozzle 210 instead of auxiliary fuel ; also the bellows 212 is subjected to pressure of fuel in conduit 18 downstream of valve 38 by means of duct 234 instead of being vented. Burst diaphragms 236, 238 are disposed in the auxiliary ozidiser ducts supplying the gas generators and burst diaphrams 240 242 are disposed in the auxiliary fuel ducts. A further burst diaphragm 244 is disposed adjacent the diaphragm 240 and a slug of fuel hypergolic with the auxiliary oxidiser is disposed in the duct between the two diaphragms, the slug passing to the gas generator in advance of the auxiliary fuel at starting and so initiating combustion in the gas generator. Similarly, a burst diaphragm 246 is disposed adjacent the diaphragm 242 and a slug of fuel hypergolic with the auxiliary oxidiser is disposed between these two diaphragms to initiate combustion in gas generator 172. The helium pressure regulator 80 is shown in Fig. 3 and comprises a casing having a double-seated valve 84 therein; the valve being loaded in a downward direction by spring 94 and in an upward direction by spring 104 which is disposed within bellows 98, the spring 104 being adjustable. The interior of bellows 98 is vented. Helium is admitted to the regulator at 58 and passes through the two valves 86, 88 to the space 100 and then issues through outlet 58 at constant pressure. Pressure relief valves 200 and 202 are provided for the oxidiser and fuel compartments, respectively. In a second embodiment, Fig. 7, at starting, an electric signal is sent to squib valve 282, 284, 286 and to solid fuel gas generator 288. Actuation of squib valve 282 allows helium to pass through duct 290 to actuators 292, 298 which open diaphragm sealed valves 294, 300 in the fuel and oxidiser conduits 296, 302 respectively. Gases from the gas generator 288 pass through duct 304 and through the heat exchanger coil 306 disposed in the oxidiser compartment 272, then back through duct 308 to the fuel pressurising control 310 which is similar to the regulator shown in Fig. 6. The gases then flow through the squib valve 286 to pressurise the fuel compartment 274. The control 310 operates in dependence on the pressure of fuel in the space 312 which is communicated via the duct 314. The oxidiser compartment 272 is pressurised by causing a small quantity of fuel to flow through duct 322, oxidiser pressurising control 324, duct 330, squib valve 284 and nozzle 332 into the oxidiser, the resulting combustion products pressurising the. compartment. The control 324 is also similar to the regulator shown in Fig. 6 and regulates the fuel flow in accordance with the pressure of the oxidiser in space 326 adjacent the combustion chamber, the pressure being communicated via the duct 328.