A jet engine is a type of reaction engine, discharging a fast-moving jet of heated gas that generates thrust by jet propulsion. While this broad definition may include rocket, water jet, and hybrid propulsion, the term jet engine typically refers to an internal combustion air-breathing jet engine such as a turbojet, turbofan, ramjet, or pulse jet. In general, jet engines are internal combustion engines.
A turboprop is a turbine engine that drives an aircraft propeller.
A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part and are, in the direction of flow:
An auxiliary power unit (APU) is a device on a vehicle that provides energy for functions other than propulsion. They are commonly found on large aircraft and naval ships as well as some large land vehicles. Aircraft APUs generally produce 115 V AC voltage at 400 Hz, to run the electrical systems of the aircraft; others can produce 28 V DC voltage. APUs can provide power through single or three-phase systems.
The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft propulsion. The word "turbofan" is a combination of the preceding generation engine technology of the turbojet, and a reference to the additional fan stage added. It consists of a gas turbine engine which achieves mechanical energy from combustion, and a ducted fan that uses the mechanical energy from the gas turbine to force air rearwards. Thus, whereas all the air taken in by a turbojet passes through the combustion chamber and turbines, in a turbofan some of that air bypasses these components. A turbofan thus can be thought of as a turbojet being used to drive a ducted fan, with both of these contributing to the thrust.
An aircraft engine, often referred to as an aero engine, is the power component of an aircraft propulsion system. Aircraft using power components are referred to as powered flight. Most aircraft engines are either piston engines or gas turbines, although a few have been rocket powered and in recent years many small UAVs have used electric motors.
The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and a turbine. The compressed air from the compressor is heated by burning fuel in the combustion chamber and then allowed to expand through the turbine. The turbine exhaust is then expanded in the propelling nozzle where it is accelerated to high speed to provide thrust. Two engineers, Frank Whittle in the United Kingdom and Hans von Ohain in Germany, developed the concept independently into practical engines during the late 1930s.
The bypass ratio (BPR) of a turbofan engine is the ratio between the mass flow rate of the bypass stream to the mass flow rate entering the core. A 10:1 bypass ratio, for example, means that 10 kg of air passes through the bypass duct for every 1 kg of air passing through the core.
The Rolls-Royce T406 is a turboshaft engine that powers the Bell Boeing V-22 Osprey tiltrotor. The engine delivers 6,000 shp (4,470 kW).
Bristol Siddeley Engines Ltd (BSEL) was a British aero engine manufacturer. The company was formed in 1959 by a merger of Bristol Aero-Engines Limited and Armstrong Siddeley Motors Limited. In 1961 the company was expanded by the purchase of the de Havilland Engine Company and the engine division of Blackburn Aircraft. Bristol Siddeley was purchased by Rolls-Royce Limited in 1966.
The Bristol Siddeley Nimbus, later known as the Rolls-Royce Nimbus, was a British turboshaft engine developed under license by Blackburn Aircraft Ltd. from the Turbomeca Turmo in the late 1950s. It was used on the Westland Scout and Westland Wasp helicopters.
The Turbomeca Turmo is a family of French turboshaft engines manufacturered for helicopter use. Developed from the earlier Turbomeca Artouste, later versions delivered up to 1,300 kW (1,700 shp). A turboprop version was developed for use with the Bréguet 941 transport aircraft.
The Pratt & Whitney T73 is a turboshaft engine. Based on the JT12A, the T73 powered the Sikorsky CH-54 Tarhe and its civil counterpart Sikorsky S-64 Skycrane flying crane heavy-lift helicopters. Turboshaft versions for naval use are known as the FT12.
The General Electric T64 is a free-turbine turboshaft engine that was originally developed for use on helicopters, but which was later used on fixed-wing aircraft as well. General Electric introduced the engine in 1964. The original engine design included technical innovations such as corrosion resistant and high-temperature coatings. The engine features a high overall pressure ratio, yielding a low specific fuel consumption for its time. Although the compressor is all-axial, like the earlier General Electric T58, the power turbine shaft is coaxial with the HP shaft and delivers power to the front of the engine, not rearwards. Fourteen compressor stages are required to deliver the required overall pressure ratio. Compressor handling is facilitated by 4 rows of variable stators. Unlike the T58, the power turbine has 2 stages.
The Boeing T50 was a small turboshaft engine produced by Boeing. It was the first turboshaft engine to ever power a helicopter: a modified Kaman K-225 in 1951. Based on Boeing's earlier Model 500 gas generator, the T50's main application was in the QH-50 DASH helicopter drone of the 1950s. An up-rated version designated Model 550 was developed to power the QH-50D and was given the military designation T50-BO-12.
The Turbomeca Astafan is a single-spool, variable-pitch turbofan engine developed from the Turbomeca Astazou. Despite successful flight-testing, an efficient, quiet and clean design and some commercial interest, the Astafan never entered series production. The engines were only flown on the Fouga 90 prototype and Turbomeca's two test aircraft.
An airbreathing jet engine is a jet engine in which the exhaust gas which supplies jet propulsion is atmospheric air, which is taken in, compressed, heated, and expanded back to atmospheric pressure through a propelling nozzle. Compression may be provided by a gas turbine, as in the original turbojet and newer turbofan, or arise solely from the ram pressure of the vehicle's velocity, as with the ramjet and pulsejet.
The Turbomeca Orédon was a small French turbo-shaft / Auxiliary Power Unit (APU) engine produced by Turbomeca in the late 1940s.
Many variations of aircraft engine starting have been used since the Wright brothers made their first powered flight in 1903. The methods used have been designed for weight saving, simplicity of operation and reliability. Early piston engines were started by hand. Geared hand starting, electrical and cartridge-operated systems for larger engines were developed between the First and Second World Wars.
A free-turbine turboshaft is a form of turboshaft or turboprop gas turbine engine where the power is extracted from the exhaust stream of a gas turbine by an independent turbine, downstream of the gas turbine. The power turbine is not mechanically connected to the turbines that drive the compressors, hence the term "free", referring to the independence of the power output shaft. This is opposed to the power being extracted from the turbine/compressor shaft via a gearbox.
