Improvements in or relating to jet propulsion devices, particularly for model aircraft and toys

摘要

836,139. Jet propulsion nozzles. V-MAX Ltd. April 3, 1957, No. 10919/5 Class 110 (3). A jet propulsion engine comprises a nozzle unit and a casing for a solid fuel charge or charges, the nozzle unit having a discharge nozzle the wall of which is movable to increase the cross-sectional area of the discharge nozzle. A jet propulsion cartridge unit has a casing 10 to which a nozzle unit 17 is clamped by a cap member 14. The nozzle consists of a metal pressing or stamping having a central portion 21 which acts as the discharge nozzle. The portion 21 has scores or grooves 23 forming lines of weakness along which the portion 21 splits if the internal pressure in the casing 10 becomes excessive. The casing 10 contains two or three solid fuel pellets ignited by a wick passed through the opening 22. The unit 17 may be of conical construction throughout its length with the grooves 23 formed adjacent the opening 22. The casing 10 may have cooling fins and the cap member 14 may be attached to the casing by a bayonet-type fixing or by a wire yoke or clip. The casing 10 has a diameter preferably of the order of 0.6 inch with a length of about one inch to 1.45 inches. The thickness of the unit 17 is preferably about 15 to 25 thousandths of an inch and the diameter of the opening 22 about 34 to 45 thousandths of an inch. The wall at the outlet end of the nozzle may be formed of sections which overlap initially so as to maintain a continuous circumferential wall even after substantial enlargement has taken place. Specification 796,154 is referred to.