Chemical Rocket Engine

a rocket engine in which the chemical energy of a propellant is used to produce thrust. It is the principal type of rocket engine.

The propellant may be liquid, solid, or hybrid. Accordingly, chemical rocket engines are classified as liquid-propellant, solid-propellant, or hybrid. For auxiliary spacecraft systems, chemical engines have also been developed that use the vapor of a liquid propellant, the gases liberated in the electrolysis of water, or a gaseous monopropellant.

Propulsion systems incorporating chemical rocket engines have thrusts that range from fractions of a newton to tens of meganewtons. The specific impulse may be as high as 5 kilonewton-seconds per kilogram (kN · sec/kg), a value obtained with experimental engines that burn fluorine/lithium/hydrogen propellant. The development of propellants based on free atoms and radicals or on excited atoms and molecules should increase the specific impulse of chemical rocket engines to 10–20 kN · sec/kg.