Hybrid Rocket Theory and Design

A hybrid rocket is so named because one of the propellant components is liquid and the other solid. Normally the oxidizer is liquid and the fuel is solid. In a typical design (Fig. 7-1), the oxidizer is sprayed in at the head end of a solid cylindrical fuel grain. It is apparent that once the liquid oxidizer is injected, the combustion process proceeds according to natural law and the geometric constraints designed into the grain and is not subject to external control. It is very important, therefore, to understand the details of the combustion if it is to occur in the manner desired by the designer.