GB838490A - Improvements relating to the ignition of gas-generating charges in small reaction motors - Google Patents

Abstract

838,490. Rocket motors for model aircraft and other jet-propelled devices. WILMOT MANSOUR & CO. Ltd. June 22, 1956 [March 23, 1955], No. 27552/54. Class 9(2) A rocket motor comprises a casing 1 on to which is screwed a cap 3 having a jet orifice 4, the gas-producing charge 5 being ignited by a coiled fuze 8 when the fuze 8 is ignited by heat transmitted through the wall of the casing 1. The free end of the fuze 8 is led through a gauze disc 9 into a hollow [projection 10 closed by a thin disc 11 held by a collar 12, which with a packing ring 13 forms a gas-tight seal. A stay 14 holds the fuze 8 against the disc 11 which is in contact with an external fuze 15 extending out of a tube 16 fitted over the collar 12. A spring clip 17 having frictional engagement in the tube 16 holds the fuze 15 against the disc, which is of high thermal conductivity, e.g. nickel chromium alloy. The gases are filtered by a gauze disc 6 between the charge and the orifice 4. Fuze 8 may be copper wire with a highly inflammable plastic coating. Fig. 3 shows a motor having two jet orifices 19, 20 in caps screwed on exhaust pipes 23, 24 leading from the combustion chamber 25. The coiled fuze 28 held in place by gauze disc 29 extends through the disc 29 and a compression spring 34 holding the fuze in contact with a heat-transmitting disc 31 against the outer face of which a fuze 35 is packed. In another modification the jet orifice is placed eccentrically in an end cap which has a portion of reduced thickness providing the heat-transmitting means for the fuze. The heat-transmitting discs also provide a safety device, which can rupture if excessive pressure occurs in the motor. In Fig. 5, a collar 45 holds in position an end plate 50 with an eccentric orifice 53 aligned with a hollow boss 52 surmounted by a fine gauge filter 55. A tube 61 of high thermal conductivity and thermally insulated is mounted in the plate 50, the coiled fuze 48 having an end 49 packed into the tube 61. The external fuze 65 is wound around the tube 61 and secured by a gauze sleeve 66 and a rupture disc 67 closes the tube 61. Specifications 642,689, 688,838 and 712,551 are referred to.