Hybrid propellants are those propellants, which are a mixture of solid and liquid propellants. In these propellants, one of the two components (oxidizer and fuel) is solid (usually fuel) whereas the other is liquid (usually oxidizer).
In a hybrid propellant rocket engine, the liquid part is injected into the solid part. Thus the storage chamber of the solid part acts as the combustion chamber.
In a hybrid rocket the oxidizer flows down the perforation (see solid propellants) in the solid fuel grain and reacts with the solid fuel. This produces the hot exhaust gases required to produce thrust. This process can be seen in the following image:
In many hybrid motor designs, the oxidizer is pressurized liquefied nitrous oxide (N2O) while the fuel is cellulose (C6H10O5 ).
The cost per flight is remarkably less than that of solid propellant engines.
These engines have high performance and the combustion process can be stopped or slowed down anytime.
The next section is the different types of propulsion techniques…