Time domain gust response analysis based on large-order nonlinear aeroelastic models is computationally expensive. An approach to the reduction of nonlinear models for gust loads prediction is presented in this paper. The method uses information on the eigenspectrum of the coupled system Jacobian matrix and projects the full order model through a series expansion onto a small basis of eigenvectors which is capable of representing the full order model dynamics. Linear and nonlinear reduced models derived from computational fluid dynamics and linear/nonlinear structural models are generated in this way. The novelty in the paper concerns the representation of the gust term in the reduced model in a manner consistent with standard synthetic gust definitions, allowing a systematic investigation of the influence of a large number of gusts without regenerating the reduced model. The methodology is illustrated by results for an aerofoil, with a combination of linear and nonlinear structural and aerodynamic models used, and a wing model with modal structural model.
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