Advanced Anti-Torque Concepts Study
LOCKHEED-CALIFORNIA CO BURBANK
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A design study has been conducted by the Lockheed-California Company on advanced antitorque concepts intended to replace tail rotors on conventional single-main-rotortail-rotor helicopters. The principal design objectives were to reduce hazard to ground personnel and to reduce vulnerability of helicopters to terrain-contact damage. Secondary objectives were reduced vulnerability to small-arms fire and improvements in dynamic, reliability, maintainability and noise characteristics. Two systems were selected from a broad literature search and subsequent design studies. The first concept is based on a main-rotor- driven axial flow fan internally mounted in the aft fuselage delivering air under pressure to a variable geometry louvered exit for antitorque andor forward-flight propulsion thrust. The second concept employs a main-rotor-driven ducted fan installed in a central pylon supporting a twin-fin empennage. Results of preliminary design studies applying these concepts to an existing Lockheed Model 286 helicopter are presented in this report, including performance and weight data. Improvements over the research vehicle that could result from applying these concepts to a totally new vehicle, using current state-of-the-art design technology, are also discussed.