Linear Inflow Model Extraction from High-Fidelity Aerodynamic Models for Flight Dynamics Applications

Modern aerodynamic analysis tools such as free wake models and CFD-based techniques, include fewer theoretical limitations and approximations than classical-simplified schemes, and represent the state-of-the-art in rotorcraft aerodynamic modeling. However, they are impractical or impossible to apply to many flight dynamics problems because they are not formulated in state-space form and are often computationally intensive. Inflow models that couple the accuracy of free wake or CFD and the simplicity and state-space form of dynamic inflow-type theory would be an important contribution to the field of flight dynamics and control. The objective of this paper is to present two different methods for the extraction of state-space linearized models from computed inflow data acquired from detailed aerodynamic free wake models. These methods are very general and applicable to any aerodynamic model, and are demonstrated with two different vortex wake models in hover for a rotor that is broadly representative of the UH-60.