Physics-Based Modeling of Asymmetric Control Response for Level-D Helicopter Simulation

This paper presents an improved strategy for development and validation of physics-based flight dynamics models for Level-D helicopter training simulation. State-space model identification is used to prescribe physics-based model parameters from flight-identified stability and control derivatives. This is in contrast with traditional development methods focused on iterative cycles of model design, validation and tuning. The application of a state-space model to nonlinear problems is accomplisehd by isolating the predominantly linear main rotor forces and moments from nonlinear airframe contributions, and by expressing nonlinear response in a piecewise-linear fashion. This is demonstrated through the identification of a model for main rotor wake interference on the fuselage and horizontal stabilizer for the AW139 helicopter in a one-shot solution. The minimum level of model complexity and robustness required to capture nonlinear response accurately for Level-D simulation is discussed.