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In aeronautics, a ducted fan is a thrust-generating mechanical fan or propeller mounted within a cylindrical duct or shroud. Other terms include ducted propeller or shrouded propeller . [ 1 ] When used in vertical takeoff and landing ( VTOL ) applications it is also known as a shrouded rotor .
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.
Turbofan, gasses travel through a ducted fan; Turboprop, gasses travel through an unducted propeller, usually with variable pitch; Turboshaft, a gas turbine optimised for producing mechanical torque instead of thrust
All practical airbreathing jet engines heat the air by burning fuel. [1] Alternatively a heat exchanger may be used, as in a nuclear-powered jet engine. [6] Most modern jet engines are turbofans, which are more fuel efficient than turbojets because the thrust supplied by the gas turbine is augmented by bypass air passing through a ducted fan. [4]
The propulsive efficiency is always less than one, because conservation of momentum requires that the exhaust have some of the kinetic energy, and the propulsive mechanism (whether propeller, jet exhaust, or ducted fan) is never perfectly efficient. It is greatly dependent on exhaust expulsion velocity and airspeed.
A ducted propeller, also known as a Kort nozzle, is a marine propeller fitted with a non-rotating nozzle. It is used to improve the efficiency of the propeller and is especially used on heavily loaded propellers or propellers with limited diameter. It was developed first by Luigi Stipa (1931) and later by Ludwig Kort (1934). The Kort nozzle is ...
The Fenestron's disadvantages are those common to all ducted fans when compared to propellers. They include: Greater weight, [23] power requirement, [24] and air resistance brought by the enclosure; Higher construction and purchasing cost. [19] Increase in power required during the hover phase of flight. [19]
1871 Planophore A Farman MF.11, showing the classic Farman configuration with engine between tail booms Buhl A-1 Autogyro, the first pusher autogyro The post-WWII Convair B-36 was unusual in its size, era, number of engines, and combining both propeller and jet propulsion, with six radial piston and four jet engines Typical of many UAVs, the General Atomics MQ-9 Reaper has a propeller at the ...