An airplane engine is a type of propulsion system used to generate thrust for an aircraft. Two common types of engines are the fanjet and the ramjet. A fanjet is a type of jet engine that uses a fan to compress air before it enters the combustion chamber, while a ramjet is a type of jet engine that relies on the forward motion of the aircraft to compress air before it enters the combustion chamber. Both fanjets and ramjets are used in modern aircraft to provide thrust.