Time Efficient Methodology for the Evaluation of Aerodynamics and Flight Mechanics of the RACER Compound Helicopter in Hover under Cross Wind Conditions

This paper describes a new mid-fidelity, steady RANS based, method to predict the aerodynamic interactions between rotating and fixed parts of the compound rotorcraft RACER of Airbus Helicopters. The method models main rotor and side propellers with source terms, hence avoiding near-body grids and unsteady overset grid techniques. The method is then applied to the analysis of the flight mechanics of the RACER in hover flight under cross-wind conditions, as part of the de-risking of the coming flight testing. The method is validated by comparison with higher-fidelity, URANS based, results taken from the literature. Trends on aircraft controls and pitch and roll attitudes are found to be consistent. The new mid-fidelity methodology provides physical insight on how the aerodynamic interactions between main rotor, fuselage, wings, rear parts, side propellers and cross wind impact aircraft controls and attitude to maintain a stabilized hover under cross-wind.