Boron-fuel-rich propellant compositions

Abstract

Fuel-rich propellant compositions, for use in air-augmented rocket propulsion, containing a high-energy fuel component in the form of finely-divided boron, wherein the boron is present in large excess of the amount oxidizable during combustion of the propellant. A major portion of the boron is ejected, largely as free boron particles, together with the combustion products of the propellant and is burned downstream of the propellant by ram air injected into an afterburner combustion zone. The propellant additionally comprises an organic fuel binder comprising an organic polymer, and an inorganic oxidizer salt, preferably ammonium perchlorate, in an amount at least sufficient to maintain stable combustion of the propellant at desired combustion chamber pressures. The propellant compositions may additionally contain small amounts of Mg, Al, or Zr metal as ballistic or afterburner combustion modifiers. Ejection of the boron is substantially improved by incorporating at least a portion of the boron in the propellant composition in the form of agglomerate masses or particles. Preferably the agglomerate particles are spheroidal and the finely-divided boron in the agglomerate particles is bonded together by a matrix of an organic polymer. From 0 to 100% of the oxidizer salt is admixed with the boron in the agglomerate particles. Inclusion of the oxidizer with the metallic fuel in the agglomerate particles provides a substantial increase in propellant pressure exponent, which is highly desirable in certain applications. The Mg, Al, or Zr metal modifiers when present, may be incorporated wholly in the organic fuel binder, wholly in the agglomerate particles, or distributed therebetween.

Dependencies are inferred from the claim text.