Endothermic gas generator for use in a device propulsion

Abstract

An enclosure has stationary walls and a ram dividing the enclosure into first and second sections and movable in a particular direction to enlarge the first section and reduce the second section. A device (e.g. a projectile) is disposed in the second section for expulsion by the ram from the enclosure. Exothermic material, preferably on a hollow stationary support within the first section, is combustible to produce solids not deleterious to the enclosure walls and gases expansible to move the ram in the particular direction. Such material may include an oxidizer (e.g. perchlorate, preferably ammonium perchlorate), a binder-reducing agent, preferably organic (e.g. hydroxy-terminated or carboxy-terminated polybutadiene), an additive (e.g. powdered aluminum) to increase the combustion energy, an additive (e.g. iron oxide) to increase the combustion rate and an additive (e.g. potassium perchlorate) to modify the burning rate slope. Their relative weights may be: NH.sub.4 ClO.sub.4 -74.2, polybutadiene-15.3, Al-1.5, FeO-2.0, KClO.sub.4 -7.0. Endothermic material (e.g. a metal hydrate or hydroxide) preferably lining the ram interior periphery protects the ram. Such material, preferably aluminum trihydrate (Al(OH).sub.3), decomposes at the combustion temperature of the exothermic material to limit the enclosure temperature. Half of the Al(OH).sub.3 may be mixed with an epoxy and the other half with a polyamide resin. The two (2) halves may be mixed and then applied to the ram inner periphery. The decomposition products from the endothermic material and the combustion products from the exothermic material react to produce gases which are soluble in water or non-reactive in air if not soluble in water.