The lift/cruise fan represents one of several aircraft design approaches being considered to achieve vertical takeoff and landing (VTOL) but also high subsonic cruise with a payload approaching what operational airplanes now yield. The concept calls for a high-bypass-ratio fan propulsion system to augment thrust for hovering flight and to give efficient thrust for hovering flight and to give efficient cruise. Two types of lift-fan propulsion system have been studied for operational VTOL aircraft: gas-coupled and mechanically coupled engines and fans. The gas-coupled system uses the hot gas from a gas generator to drive the fans through tip turbines on them. Fan speed controls thrust, and valving hot gas to the tip turbines controls fan speed. The mechanically coupled system interconnects fans and engines with high-speed shafting and gear boxes. It operates at constant fan speed, thrust being controlled by variable-pitch fan blades. A lift/cruise fan VTOL aircraft must use deflection to direct thrust for the various modes of flight, from hover to cruise. Two basic arrangements for deflecting thrust have been tested: fixed fan with thrust-deflecting nozzles, and tilting nacelle for completely rotating the fan. Both have been applied to VTOL design concepts.

  • Corporate Authors:

    American Institute of Aeronautics and Astronautics

    1290 Avenue of the Americas
    New York, NY  United States  10019
  • Authors:
    • Quigley, H C
  • Publication Date: 1977-12

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00174325
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Files: TRIS
  • Created Date: Jun 28 1978 12:00AM