Performance Assessments of a Boron Containing Gel Fuel Ramjet

Abstract

A ramjet engine is an attractive means of propulsion because of its high efficiency and simplicity. In this work an attempt was made to combine the merits of a ramjet engine with the high energy potential of boron, an extremely energetic metal fuel additive. The use of boron poses two problems. The first, common to all solid additives to liquid fuels, is particle sedimentation and poor dispersion. This problem is solved through the use of a gel fuel. The second problem, which is specific to boron, is the extremely difficult realization of its full energetic potential. This problem can be eliminated by means of an aft-combustion chamber, where fuel rich combustion gases are mixed with cold bypass air. Cooling causes the gaseous boron oxide to condense and release the latent heat of evaporation held in the gaseous oxide. The design took the form of an air-to-surface missile, of relatively small size, capable of delivering a large payload over a distance of about 1000 km. This paper deals with the preliminary design of a missile powered by a ramjet using a gel fuel loaded with boron. It deals with the thermochemical aspects of the two stage combustion of such a fuel, and it makes a comparison with a missile powered by a solid rocket motor and launched under the same conditions as the ramjet powered missile.