
A hybrid propellant is a form of chemical rocket propellant wherein the fuel and oxidizer are in different physical states. One of the substances is solid, usually the fuel, while the other, usually the oxidizer, is liquid. The liquid is injected into the solid, whose fuel reservoir also serves as the combustion chamber. Hybrid rocket propellants are environmentally safer than solid rocket fuels, as some solid rocket propellants contain chlorine. The products of combustion are environmentally viable. This is one of the major advantages of hybrid propellants compared to solid and liquid propellants. Hybrids combine some of the advantages of liquids and solids and also exhibit unique advantages. The most important is the inherent safety associated with storing the fuel in the solid phase. Hybrid propellants offer many advantages. They are cheaper, can be shut down easily, throttle control, and are much safer to handle. Fuel used in hybrid propellants can be fabricated at any conventional commercial site with no danger of explosion. Thus, significant cost saving can be achieved in the manufacture and launch operations.