Afterburner A device added to a turbojet to increase its thrust. Inside the afterburner, additional fuel is burned to use up any unburned oxygen left in the gases that leave the jet’s exhaust.

Air intake The part of a jet engine through which air is drawn. Jet engines do not work in space where there is no oxygen.

Bypass duct The part of a turbofan through which air flows, bypassing the core of the engine to join the exhaust gases at the engine’s rear.

Combustion chamber The part of a jet engine in which air is mixed with kerosene fuel and ignited. Temperatures inside the combustor can reach 2700°C (4900°F). Most combustors are lined with ceramic coating to make them heat-resistant.

Compressor A device in a jet engine that compresses air. It consists of spinning blades that squeeze air into increasingly smaller spaces. The compressor then feeds air to the combustion chamber.

Cowling The pod covering an aeroplane’s jet engine. Cowling is also known as cowl. It is light and streamlined and is usually made out of aluminium.

Exhaust Waste gases ejected from an engine. The expulsion of hot exhaust from the back of a jet engine provides its forward thrust.

Jet engine In a jet engine, air enters a fan at its front end. The air is compressed by the spinning blades, mixed with fuel and the air-fuel mixture is burned in a combustion chamber. The hot exhaust gas escapes at speed through the rear engine, turning a turbine. The movement of gases through the engine provides forward thrust, just like a balloon shoots forward if the air inside it is suddenly released. There are several kinds of jet engine, including turbojets, turboprops and turboshafts. Airliners, military planes, missiles and some speed boats are powered by jet engines.

Kerosene A colourless, highly flammable oil that is used as fuel for jet engines.

Pulse-jet engine A simple jet engine that uses intermittent or “pulsing” combustion. Air enters the engine through valves that shut behind it. As the exhaust leaves, the pressure inside the engine drops, and the valves open to let more air in. Pulse-jet engines are used for pilotless vehicles. They were used for the V-1 flying bombs, or “doodlebugs”, during World War II.

Ramjet A simple jet engine with no rotating parts. It uses forward motion to compress or “ram” air into its engine. Ramjets need to be launched by another aircraft, as they can only operate at speeds of 320 km/h (200 mph) or more. They are mainly used for missiles.

Turbine A machine that is caused to rotate by a fluid (a liquids or a gas). The turbine in a jet engine is turned by the jet exhaust. Its motion drives the compressor.

Turbofan A jet engine in which some cold incoming air is ducted to bypass the combustion chamber and turbine. This makes the engine cooler, quieter, more powerful and more fuel efficient than other engines. Turbofans are used in most commercial airliners and military aircraft.

Turbojet A jet engine in which hot gases escape through the rear at high speed. In a turbojet, all the air drawn into the engine goes through the combustion chamber. Turbojet engines cannot start on their own—their rotory motion must be started by an external motor.

Turboprop A jet engine that drives a propeller via a shaft. The shaft is turned by the rotary movement of the turbine. Some small airliners and transport aircraft are powered by turboprops.

Turboshaft A jet engine in which an additional turbine is used to turn a shaft, for example to power the rotors on a helicopter. The speed of the helicopter rotor is driven through a gearbox from the engine.

Von Ohain, Hans (1911–1998) German-American engineer who developed an early jet engine and worked on the first aircraft to be powered by jet propulsion.

Whittle, Sir Frank (1907–1996) British pilot and engineer, who designed and patented the first turbojet engine in 1930. The Whittle jet engine made its first successful flight in 1941.

Consultant: Chris Oxlade