1,045,555. Underwater missiles. MITSUBISHI SHIPBUILDING & ENGINEERING CO. Ltd. Feb. 28, 1964 [March 1, 1963], No. 8484/64. Heading B7A. In an underwater self-propelling missile an engine 21 is driven by a high temperature and pressure combustion gas produced by mixing a fuel, e.g. alcohol and an oxidizer, e.g. nitric acid in combustion chamber 16 and in which means are provided for introducing sea water mixed with a salt separation preventative agent, e.g. zinc chloride into combustion chamber 16 for cooling purposes. As shown, when rod 6 is raised compressed-air from chamber 1 passes through reducing valve 11 and then flows into fuel chamber 2, oxidizer chamber 3, chamber 4 containing a salt separation preventative agent and auxiliary water tank 37. The fuel and the oxidizer are forced by the air through nozzles 17 and 18 respectively into combustion chamber 16. Similarly, fresh water from tank 37 and agent from chamber 4 are mixed in mixing device 56 after which they are led into water passage 20 of combustion chamber 16. Combustion gas is led from the chamber 16 into engine 21, e.g. a turbine, which besides driving the missile via a propeller (not shown), also drives a gear pump 34 through shafting and gears 28, 31, 25, 26, 29, 30 and 32. The fresh water in tank 37 is then replaced by sea water sucked in from port 35 in pump 34.