Keywords: Lynx-XZ170 helicopter, Performance, Rotor load
Abstract: Results from two rotorcraft codes were correlated with flight-test data obtained from the Lynx-XZ170 helicopter. The LYNX-XZ170 features a hingeless rotor system with four blades having rectangular tip planforms. The flight-test data base includes steady, level flight conditions at different thrust levels and advance ratios up to and beyond the rotor stall boundary. Rotor performance, control inputs, blade and control loads were compared with results from the Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics developed by Johnson Aeronautics (CAMRAD/JA) and the R150 rotor analysis developed by Westland Helicopters Limited (WHL) and the Defense Research Agency. Effects on blade loads correlation are examined by varying CAMRAD/JA modeling parameters such as lag-damper model, stall model, and wake model. In addition, effects of rotor trim condition on blade structural loads and methods of calculating the loads are investigated. The influence of the fuselage on rotor loads is presented using the R150 analysis. CAMRAD/JA calculations for the flatwise bending moments at the outboard stations compare reasonably well with the flight-test data. Near the hub, CAMRAD/JA flatwise moment calculations compare well with the data at low speeds but fairly at high speeds. R150 correlations of the flatwise bending moments are very good near the hub and at the outboard station, but only fair at the inboard station. For the edgewise bending moments, both the CAMRAD/JA and R150 comparisons with data are good near the hub and fair at the outboard stations. Except for a phase difference, the CAMRAD/JA correlation of the lag-damper load is reasonably good using the nonlinear lag-damper model. Although the general trends of the vibratory pitch-link load data are captured by both analytical codes, the details of the waveform are not.
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