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Like turboprop engines, propfans generate most of their thrust from the propeller and not the exhaust jet. The primary difference between turboprop and propfan design is that the propeller blades on a propfan are highly swept to allow them to operate at speeds around Mach 0.8, which is
A propfan, also called an open rotor engine, open fan engine [1] [2] or unducted fan (as opposed to a ducted fan), is a type of aircraft engine related in concept to both the turboprop and turbofan, but distinct from both. The design is intended to offer the speed and performance of a turbofan, with the fuel economy of a turboprop.
A turboprop is a gas turbine engine that drives an aircraft propeller. [1] A turboprop consists of an intake, reduction gearbox, compressor, combustor, turbine, and a propelling nozzle. [2] Air enters the intake and is compressed by the compressor. Fuel is then added to the compressed air in the combustor, where the fuel-air mixture then ...
The turboprop at its best flight speed gives significant fuel savings over a turbojet even though an extra turbine, a gearbox and a propeller are added to the turbojet's low-loss propelling nozzle. [24] The turbofan has additional losses from its greater number of compressor stages/blades, fan and bypass duct. [clarification needed]
While a turbojet engine uses all of the engine's output to produce thrust in the form of a hot high-velocity exhaust gas jet, a turbofan's cool low-velocity bypass air yields between 30% and 70% of the total thrust produced by a turbofan system. [80] The net thrust (F N) generated by a turbofan can also be expanded as: [81]
Low pressure (40–70 psi or 280–480 kPa), high volume air from the compressor section of the APU is bled off through a system of pipes to the engines where it is directed into the starting system. This bleed air is directed into a mechanism to start the engine turning and begin pulling in air. The starter is usually an air turbine type ...
A turboshaft engine is similar to a turboprop in principle, but in a turboprop the propeller is supported by the engine and the engine is bolted to the airframe: in a turboshaft, the engine does not provide any direct physical support to the helicopter's rotors. The rotor is connected to a transmission which is bolted to the airframe, and the ...
The General Electric F404 and F412 are a family of afterburning turbofan engines in the 10,500–19,000 lbf (47–85 kN) class (static thrust). The series is produced by GE Aerospace. Partners include Volvo Aero, which builds the RM12 variant. The F404 was developed into the larger F414 turbofan, as well as the experimental GE36 civil propfan.