Topic summary
Rocket Engines
Extracted from the Wikipedia article Rocket engine.
Principle of operation
Rocket engines produce thrust by the expulsion of gas that has been accelerated to high speed through a nozzle. The fluid is usually a gas created by high pressure (150-to-4,350-pound-per-square-inch (10 to 300 bar)) combustion of solid or liquid propellants, consisting of fuel and oxidizer components, within a combustion chamber. As the gases expand through the nozzle, they are accelerated to supersonic speed, and by Newton's third law generates thrust opposite to the direction of the gas. Combustion is most frequently used for bi propellant and solid rockets, as the laws of thermodynamics (more specifically Carnot's theorem) dictate that high temperatures and pressures are desirable for the best thermal efficiency.