Patent GB-838642-A (GB)
Title: Improvements in or relating to liquid propellant rocket
IPC: F02K9/95
Filed: 1956-09-10
Abstract: 838,642. Jet-propulslon plant. NORTH AMERICAN AVIATION Inc. Sept. 10, 1956, No. 27666/56. Class 110 (3). A liquid fuel rocket comprises a main liquid propellant tank having a rigid structural wall, a second liquid propellant tank having flexible walls located within the main tank and means for pressuring one or other of the tanks so as to force the propellants in the tanks into the rocket motor. A rocket motor has a combustion chamber 2 into which propellants contained in a cylindrical tank 4 and a flexible bag 5 are injected by orifices 3. The propellants may be white fuming nitric acid and turpentine. The propellants may be hypergolic or require separate ignition means. Bursting diaphragms 6, 7 separate the contents of the tank 4 and bag 5 from the orifices 3. The bag 5 may be of any flexible material and may be made of polytrifluoromonochloroethylene if it contains white fuming nitric acid. A bulkhead 8 separates the warhead 9 from the tank 4. A cylindrical chamber 10 containing a piston 11 and liquid 12, hypergolic with one of the propellants, is situated aft of the bulkhead. The chamber 10 is connected to the interior of the tank 4 by a conduit 13 terminating in an injector 14. Piston 11 is integral with a piston 16 which is free to slide in an annular chamber 17 vented to atmosphere through a port 18. The piston 11 includes a small open-ended chamber 20a, Fig. 3, separated from the contents of the tank 4 by a bursting diaphragm 21 and a powder charge 20. A spring-loaded pressure regulator 22 limits the pressure in the chamber 20a. In operation, the charge 20 is ignited by the heating element 25. This causes the piston 11 to move to the left and displace fluid 12 into the conduit 13. The bursting diaphragm 28 is then broken and the contact of the fluid 12 with the propellant in tank causes rapid generation of gas. The tank 4 is therefore pressurized which pressure is also transmitted through the flexible walls of the bag 5 to its contents. This causes the diaphragms 6, 7 to rupture and the propellants to be supplied to the rocket motor combustion chamber 2. The combustion chamber may be fired either by spontaneous combustion of the propellants or by a separate firing device. The diaphragm 21 is broken at the same time as the diaphragms 6, 7 so that the pressure in the tank 4 is transmitted through chamber 20a to the forward face of the piston 11 so that more fluid is expelled from the chamber 10 into the tank 4 thereby increasing its pressure. In a modification. Fig. 7 (not shown), the initial injection of the fluid 12 into the tank 4 is obtained by allowing a compressed spring to act on the piston 11. This spring may be held in the compressed condition either by a firing pin or by a rod which may be broken by firing a small charge located around it. In another modification, Fig. 8 (not shown), a small combustion chamber contains a powder charge which when fired causes a piston to move and displace fluids from two chambers into the small combustion chamber where they are burnt to cause further movement of the piston. The ignition of the powder charge also bursts a diaphragm in a conduit connecting the combustion chamber to the tank 4 so that the rocket propellants are pressurized as described above. In a further modification, Fig. 9 (not shown), the warhead is adapted to move relative to the rocket motor under the action of a spring and in so doing causes a piston to force a small quantity of fluid hypergolic with one of the propellants into the tank 4. The resulting pressure in the tank 4 causes further movement of the warhead relative to the rocket and the injection of more fluid into the tank 4. In another modification, Fig. 10 (not shown), a plate carrying the injection orifices 3 moves under the action of a spring, relative to the rocket combustion chamber. This plate is connected to a piston working in an annular cylinder which contains a small quantity of fluid hypergolic with one of the propellants. This fluid is injected into the tank 4 and the resulting rise in pressure is used to move the plate further into the combustion chamber. In any of these embodiments the pressure may, if desired, be applied to the bag 5 which expands and pressurizes the outer tank.