GB753844A - Improvements in or relating to charges for the generation of power gases - Google Patents

Abstract

753,844. Engine-starter cartridges. IMPERIAL CHEMICAL INDUSTRIES, Ltd. Oct. 25, 1954 [Jan. 6, 1954], No. 360/54. Class 9(1) A charge for an engine-starter cartridge which is adapted to burn at a predetermined constant pressure for a predetermined time, comprises a main charge of slow burning colloided nitrocellulose composition having at least two narrow bores, the burning surface of the charge being such that it increases with time, and a 'smaller compensating charge of the same composition having a burning surface which decreases with time, The main charge is free to burn along its outer curved surface, the inner bores, one end surface and at least part of the other end surface, while the compensating charge may be annular, the thickness and length of the annulus being substantially the same. Alternatively, the compensating charge may be a solid cylinder with length at least equal to its. diameter when it is not attached to the main charge, and if attached the length is at least equal to the radius. The cartridge case 1, Fig. 1, encloses a main charge 2 trilobed in cross-section and with three equidistant parallel longitudinal bores C, Fig. 2. Spacers 4 separating the main charge from the compensating charge 3 surround a muslin bag 5, containing a kindling composition, below which is a primer 6. Resting on the top of the charge 2 is a grid 7 over which is a cellulose acetate cup 8 held in position by the turned-over edge 9 of the case, which is secured to the cup 8 by . a sealing cement. The spacers may be of inert material or a nitrocellulose composition with a faster burning rate than either of the charges 2, 3. The primer 6 is fired electrically to initiate the composition in the bag 5, whereby the charges 2, 3 are ignited and the cup 8 is shattered to release the combustion gases. A preferred nitrocellulose composition is nitroglycerine 43.9 parts, nitrocellulose 27.8 parts, diethyl diphenyl urea 0.9 parts, cellulose diacetate 26.3 parts, potassium nitrate 0.9 parts, mineral jelly 0.2 parts, all parts being by weight.