Fuselage Vibration Reduction Of Lift-Offset Coaxial Rotor Vehicles With Auxiliary Propulsion Via Individual Blade Pitch Control (Ibc)

Abstract

The present study investigates the fuselage vibration reduction potential for a lift-offset coaxial rotor vehicle with auxiliary propulsion using open-loop individual blade pitch control (IBC) applied to the main rotor. The comprehensive aeroelastic software, Rotorcraft Comprehensive Analysis System (RCAS), was utilized to implement the XH-59A elastic-line fuselage model and create a comprehensive coupled rotor-fuselage model for analysis. An open-loop IBC phase sweep was applied to the main rotor at 200 knots and reduced the 3/rev and 6/rev hub loads and cockpit vibrations. For a 3/rev, 1° IBC amplitude at 270° phase, the reductions in the 3/rev hub loads for this input were 89% in ??!, 48% in ??", and 79% in ??#. Additionally, the cockpit vibrations decreased by 81% in the longitudinal direction and 76% in the vertical direction for the 3P/1°/270° IBC input. The 6/rev hub loads and cockpit vibrations were also reduced with various open-loop IBC inputs.