The Rolls-Royce Spey is a low-bypass turbofan engine originally designed and manufactured by Rolls-Royce that has been in widespread service for over 40 years. A co-development version of the Spey between Rolls-Royce and Allison in the 1960s is the Allison TF41.
Rolls-Royce Spey
Afterburner section of an RB.168
Rolls-Royce Spey RB.163 Mk.505-5 for the Trident in RAF Museum Cosford
Rolls-Royce Spey Mk 202 at the RAF Museum in London
A 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.
Chevrons on an Air India Boeing 787 GE GEnx engine
Rolls-Royce Conway low-bypass turbofan from a Boeing 707. The bypass air exits from the fins, while the exhaust from the core exits from the central nozzle. This fluted jetpipe design is a noise-reducing method devised by Frederick Greatorex at Rolls-Royce
General Electric GEnx-2B turbofan engine as used on a Boeing 747–8. View into the bypass duct looking forward from the bypass nozzle and showing fan exit stators/fan blades
The widely produced Pratt & Whitney JT8D used on many early narrowbody jetliners. The fan is located behind the inlet guide vanes.
