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Turbofan on the wing of a Boeing 777-200
Afterburner on the tail of a F16
Thrus reverser (red) on the tail of a Cessna Citation Bravo
Propeller on the wing of a Cessna C310

An aircraft engine (know as the powerplant) is a propulsion system for an aircraft. Aircraft engines are almost always either lightweight piston engines or gas turbines. This article is an overview of the basic types of aircraft engines and the design concepts employed in engine development for aircraft.





While military fighters require very high speeds, many civil airplanes do not. Yet, civil aircraft designers wanted to benefit from the high power and low maintenance that a gas turbine engine offered. Thus was born the idea to mate a turbine engine to a traditional propeller. Because gas turbines optimally spin at high speed, a turboprop features a gearbox to lower the speed of the shaft so that the propeller tips don't reach supersonic speeds. Often the turbines which drive the propeller are separate from the rest of the rotating components so that they are free to rotate at their own best speed (referred to as a free-turbine engine). A turboprop is very efficient when operated within the realm of cruise speeds it was designed for, which is typically 200 to 400 mph (640 km/h).




A turbofan is a type of jet engine, similar to a turbojet. It essentially consists of a ducted fan with a smaller diameter turbojet engine mounted behind it that powers the fan. Part of the airstream from the ducted fan passes through the turbojet where it is burnt to power the fan, but the majority of the flow bypasses it, and very often produces most of the thrust.


An afterburner is an additional component added to some jet engines, primarily those on supersonic aircraft. Its purpose is to provide a temporary increase in thrust, both for supersonic flight and for takeoff (as the high wing loading typical of supersonic aircraft designs means that take-off speed is very high). On military aircraft the extra thrust is also useful for combat situations. This is achieved by injecting additional fuel into the jet pipe downstream of (i.e. after) the turbine. This fuel is ignited by the hot exhaust gases and adds greatly to the thrust of the engine. The advantage of afterburning is significantly increased thrust; the disadvantage of afterburning is its very high fuel consumption and inefficiency but this is acceptable for the short periods in which it is usually used.

Thrust reversal

Thrust reversal, also called reverse thrust, is the temporary diversion of an aircraft engine's output so that the thrust produced is directed forward, rather than aft. This acts against the forward travel of the aircraft, providing deceleration. Thrust reversers are used by many jet aircraft to help slow down just after touch-down, reducing wear on the brakes and enabling shorter landing distances. It is also available on many propeller aircraft through reversing the controllable pitch propellers to a negative angle.



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