Liquid propellants are nothing but rocket propulsion fuels in liquid state.
They are made up of 2 parts
Both the oxidizer and fuel are in liquid form.
Liquid propellants are more difficult to handle than solid propellants and they require separate oxidizer and fuel tanks. Lightweight pumps and injectors are used to spray the propellants into the combustion chamber.
The combustion of liquid propellants can be controlled easily by controlling the rate at which the pumps spray the liquid into the combustion chamber. Shutting off the pumps completely can easily stop the combustion. Thus controlling, stopping and starting the combustion is very easy when liquid propellants are used.
In order to start the combustion process spark plugs, igniters, explosives are used.
Liquid propellants used in launch vehicles can be classified into:
We will now see each of these propellants in detail