thumb|Mockup of a prototype [[General Electric GE36|GE36 at the Musée aéronautique et spatial Safran]]

thumb|A closeup of the PW–Allison 578-DX propfan demonstrator installed on the port side of a [[McDonnell Douglas MD-80 testbed]]

A propfan, also called a propjet, an open rotor engine, or an open fan engine, is an aircraft engine combining features of turbofans and turboprops. It uses advanced, curved propeller blades without a duct. Propfans first started prototype testing in the 1970s, aiming to combine the speed capability of turbofans with the fuel efficiency of turboprops, especially at high subsonic speeds. However, they have never proceeded beyond testing, never going into commercial use. Over the decades, different efforts to perfect the concept have used names like "open rotor" and "ultra-high-bypass (UHB) turbofan".

Definition

thumb|Propulsive efficiency comparison for various gas turbine engine configurations

In the 1970s, Hamilton Standard described its propfan as "a small diameter, highly loaded multiple bladed variable pitch propulsor having swept blades with thin advanced airfoil sections, integrated with a nacelle contoured to retard the airflow through the blades thereby reducing compressibility losses and designed to operate with a turbine engine and using a single stage reduction gear resulting in high performance". CFM planned for an aerodynamically three-dimensional rotor with 12 woven carbon-fiber composite blades. Aided by a smaller engine core, the CFM RISE engine would have a bypass ratio of 75.

  • McDonnell Douglas MD-94X
  • MPC 75
  • Yakovlev Yak-44
  • Yakovlev Yak-46

See also

  • Contra-rotating propellers
  • Ducted fan
  • Geared turbofan

References

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General resources

  • Prop fan propulsion concepts: Technology Review, Design Methodology, State-of-the-art designs and future outlook. Raymond Scott Ciszek. University of Virginia Department of Mechanical and Aerospace Engineering. Senior Thesis Project. March 25, 2002

Bibliography

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  • [https://www.youtube.com/watch?v=APzO7OVGakw]
  • [https://www.youtube.com/watch?v=W1y5c1lnDVs]

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