a liquid rocket fuel used to initiate combustion in the combustion chamber of a rocket engine operating on a propellant (oxidizer and fuel) that is not hypergolic (self-igniting) at operating temperatures. Piping is used to feed the fuel component to the combustion chamber; in order to initiate combustion, a section of the piping immediately adjacent to the rocket engine is filled with the igniter fuel. When the rocket is to be launched, the igniter fuel is ejected by the principal fuel component and is fed first into the engine. When the igniter fuel comes into contact with the propellant oxidizer, spontaneous combustion occurs and the principal fuel component is ignited.
Igniter fuels must be capable of spontaneous combustion, and they must be safe, stable, and compatible with the rocket’s structural materials. An igniter fuel was first used in 1933 at the Gas Dynamics Laboratory.