Jet Engine

A jet engine is a heat engine that is propelled in a forward direction as the result of the escape of hot gases from the rear of the engine. Two general types of jet engines exist: the air-breathing jet engine and the rocket. In an air-breathing jet engine, air entering the front of the engine is used to burn a fuel within the engine, producing the hot gases needed for propulsion. In a rocket, air is not needed for propulsion. Instead, some type of chemical, nuclear, or electrical reaction takes place within the rocket engine. Hot gases formed as a result of that reaction exit the engine from the rear, providing the engine with its thrust, or forward momentum. Some authorities reserve the term jet engine for the first of these two types, the air-breathing jet engine. Air-breathing jet engines are used for the fastest commercial and military aircraft now available.