Handling-Qualities Investigation of Conventional Helicopter Directional Control Characteristics,
NATIONAL AERONUATICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER
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A piloted simulation was conducted to investigate the directional-axis handling qualities of a conventional single-main-rotortail-rotor helicopter during the performance of low-speed or 40 knots tasks. The objectives of the experiment were to attempt to model the first-order effects that contribute to the loss of tail-rotor control that has been experienced by pilots of the OH-58 series aircraft, and to investigate handling-qualities parameters that reduce or eliminate tail-rotor-control problems in the context of the given test conditions. The aircraft configuration variables investigated were yaw damping, tail-rotor sensitivity, and directional, or weathercock, stability. Two types of yaw stability and control augmentation systems were implemented, and an engine model was included to capture the effects of rotor angular speed variations on the total yawing moment, heave-axis force, and tail-rotor thrust capability. Five pilots evaluated 10 generic tail-rotor configurations in varied wind conditions while maneuvering through a nap-of-the-Earth NOE corrider terminating in a confined area to a hover. Keywords experimental design charts.