Linearized Rotorcraft Wake Model for Advanced Configurations

Linearized inflow models have been used to represent dynamic wake effects with great success for aiding control law development and flight dynamics investigations on conventional single-main rotor / tail rotor rotorcraft, but are difficult to extend to alternate configurations such as coaxial rotors or tiltrotors having significant interacting wake effects. By contrast, state of the art real-time free wake analyses can support manned flight simulation on all rotorcraft types, but are not readily used within control law development, as they are not formulated in a state-space representation as ordinary differential equations. The proposed investigation will leverage CDIs CHARM free wake analysis to evaluate methods for extracting a linearized model of the aerodynamics for a wide range of rotorcraft, to help support stability analysis and control system design activities. Since the underlying vortex-based model can compute far-field induced flow effects, this same linearization process will be extended to model interference effects on other aircraft components. The resulting tool will provide both enhanced fidelity for linearized aerodynamic representations of alternate rotorcraft configurations, as well as provide a consistent transition path for analysis of nonlinear response behavior using the full CHARM analysis in simulation settings.