Oxidizers, propellant gelled

Thixotropic gels are also useful as propellants for rocket applications. These are commonly called thixotropes or gels. Normal fuels and oxidizers are converted into thioxotropes by the addition of a small quantity of a gelling agent in order to ensure uniform suspension of solid additives (usually metal additives) during storage. It is reported that if very finely pulverized particles of beryllium or aluminum are suspended in the liquid fuel, it is possible to increase the specific impulse substantially. 

Figure IV. B. 1. concentrates on the storable propellant systems. The morphology obviously can be extended to include the cryogenics. Again, the method by which the metal particles are introduced determines the approach. Both the hybrid and the gelling procedure would be considered. The only perturbation would be in the case of the hybrid in which both fuel and oxidizer are injected as liquids and the binder is used simply as a vehicle to carry the metal particles.

Liquid propellants can be categorized by their type of storage (cryogenic propellants vs. storable propellants) or by their function in the chemical propulsion system (oxidizers, fuels, or monopropellants). The functional categorization is used here for discussion of the liquid propellants. In addition, liquid propellants, either oxidizer or fuel, can be gelled as a neat material or as a heterogeneous gel mixture containing suspended solid material such as aluminum powder. 

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