Assessment of a state-space aeroelastic rotor model for rotorcraft flight dynamics

The aim of the paper is the assessment of a methodology for the identification of a helicopter rotor aeroelastic operator in state-space form relating airframe motion and blade controls perturbations to corresponding hub loads, as extracted from a high-fidelity rotor aeroelastic solver. It is suited for helicopter flight dynamics stability and real-time commands response analyses, as well as for control laws synthesis.The identification method consists of a three-step process, starting with evaluation of responses to small perturbation harmonic inputs, followed by their spectral analysis and rational form approximation of corresponding transfer functions. Considering a Bo-105-type helicopter, numerical investigation is focused on: analysis of critical parameters affecting accuracy and efficiency of transfer functions identification, interpretation of the additional states introduced by rational approximation, validation of rotor finite-state aeroelastic representation.