GB743366A - Improvements in or relating to igniter cartridges - Google Patents

Abstract

743,366. Cartridges for igniting fuels. OLIN MATHIESON CHEMICAL CORPORATION. Aug. 6, 1953 [Aug. 20, 1952], No. 21728/53. Class 9(1) An igniter cartridge 20 for igniting the fuel in the combustion chamber 42 of a jet engine has a casing 22 of paper, cardboard or metal, with a brass base 34 housing a primer 24 as in a shot-cartridge. At the forward end of the casing is an ignition charge 26 adapted to be ignited by flash from the primer 24 through a flash tube 30, which is surrounded by the main gas-producing charge 28. The main charge extends from base wads 35 to the ignition charge over which is a, closure wad 36 on to which the casing is crimped. The flash tube, which has a press-fit in the base 34, has an enlarged end to receive the primer 24. Fuel is injected into the combustion chamber 42 through a nozzle 44 where it mixes with compressed air entering through the inlet 46 to form a combustible mixture. On actuation, by remote control, of a trigger 52, a percussion pin 50 fires the cartridge 20 in a mounting 48-on the engine and a, stream of hot gases and molten metal is projected into the chamber 42 to ignite the fuel-air mixture. The main charge 28 may be made up of a slow-burning base charge 56 and a faster burning intermediate charge 58 which is a blend of the base charge and the ignition charge compositions. The base charge may be about 25 per cent by weight of powdered magnesium, 60 per cent by weight of a pulverulent oxidizing agent such as alkaline earth peroxide or nitrate with small quantities of fuels such as oxalates and binders such as metal soaps, e.g., calcium resinate. The ignition mixture may consist of 15 per cent by weight of powdered magnesium and about 85 per cent by weight of an alkaline earth peroxide with small amounts of insoluble metal soap. The intermediate charge is preferably a blend of 80 per cent of the base charge composition and 20 per cent of the ignition mixture, while the ignition charge is 80 per cent by weight of the igniter mixture and 20 per cent of the base charge. The flash tube 30 is made of a combustible metal such as aluminium, magnesium, zinc or alloys thereof. Before firing, the forward end of the tube is closed by pressing equal portions 64 of the wall inwardly to form radial fins 66, Fig. 9. On firing, flash from the primer forces the fins apart. These fins may be sealed by dipping in lacquer.