Patent GB-627727-A (GB)
Title: Improvements in or relating to power-gas generating devices
IPC: C06D5/00
Filed: 1946-11-29
Abstract: 627,727. Self-combustible charges for generating gases under pressure; propellants. TAYLOR, J., HUTCHISON, A. C., FAGELSTON, I., and IMPERIAL CHEMICAL INDUSTRIES, Ltd. Nov. 29, 1946, No. 35435. [Classes 9 (i) and 9 (ii)] A charge or cartridge for generating gas pressure suitable for actuating reciprocating or turbine engines or for the propulsion of jet apparatus or projectiles comprises a compressed columnar charge of a powder mixture including at least one nitrogen base nitrate or nitro derivative and a sensitizer to produce selfsustained thermal decomposition, the longitudinal surface of the charge closely contacting a surrounding structure so that along the longitudinal surface decomposition is not faster than that of the exposed transverse surface. When the powder mixture is an ammonium nitrate composition a compound inhibiting change of volume at 32  C. is included. This compound may be potassium nitrate which also acts as a sensitizer for the thermal decomposition of the ammonium nitrate. A fuel such as anhydrous ammonium oxalate may be ' included in the mixture. Inert ingredients such as china clay may be included in the mixture. The compressed powder charge may have a central bore when used as a jet-propulsion unit. A device according to the invention for actuating a 4-cylinder reciprocating engine comprises a steel tube closed at one end and lined with a rubber-bonded asbestos sheet material into which 15 lbs. of a powder mixture is filled. The tube has an external diameter of 5 inches and is 0.15 inches thick. The mixture comprises the following parts by weight: ammonium nitrate 78.5 parts, potassium nitrate 9.0 parts, anhydrous ammonium oxalate 6.9 parts, ammonium bichromate 5.6 parts, and china clay 0.7 parts. The filling is carried out in steps, a pressure of 5,550 lbs. per sq. inch being applied at each step. A device containing 149 lbs. of a powder mixture in a 17 inch diameter iron pot was filled in six steps, the base of the pot being covered with 8 lbs. of china clay placed over a layer of asbestos lining material. A similar device was filled by placing a thin metal cylinder coaxially in the pot after introducing the base layer of clay. A measured quantity of sensitized powder mixture was placed in the metal cylinder. Between the cylinder and the lining material an equal depth of a mixture comprising potassium nitrate, ammonium nitrate and china clay was inserted. The cylinder was withdrawn and pressure applied to the layer. The cylinder was then replaced and a second layer built up, the process being repeated until the filling was completed. A device containing 8 lbs. of a powder mixture in a 3¢ inch internal diameter steel tube had a 1 inch axial hole bored through the powder mixture to the china clay layer. A similar device was provided with a top layer of inert material. Methods of testing the charges are given, together with the results obtained. Specifications 489,279, 521,890, 583,986 and 627,724 are referred to. Specifications 454,091 and 570,075 are referred to in the Provisional Specification.