Gun launch rocket propellant support filler

Abstract

A gun launched rocket motor is provided with a filler material to fill all f the free volume in the rocket with a void-free incompressible 'filler'. The described filler material is selected from a solid, semi-solid, or liquid having many properties closely comparable to the rocket propellant, especially match the density, chemical compatibility, coefficient of thermal expansion, and thermal stability. The filler material functions to provide the required physical support to various propellants to survive gun launch. A preferred filler material is a completely fluorinated organic material which is a liquid which is compatible with various solid rocket propellants and can readily be ejected from the chamber by pressurization from conventional igniters or combustible cords such as Rapid Deflagrating Cord, RDC. These completely fluorinated perfluoro compounds, which are designated as C5-18 compounds, are marketed as Fluorinert Brand Electronic Liquids by 3M Corporation, St. Paul, Minn. More specifically, the Fluorinert liquid compound, which is designated as FC-77, has a density of 1.78 g/ml which matches highly aluminized composite rocket propellants. FC-77 has a desirably high boiling point (97.degree. C.), low temperature pour point (-110.degree. C.), and a coefficient of thermal expansion of 0.0014 ml/ml.degree. C. which is lower than many organic liquids and comparable to solid propellants. The family of Fluorinert compounds available from 3M Corporation have properties that cover a wide area providing matching properties such as densities of solid propellants for most, if not all gun boosted applications.