Several critical load cases during the aircraft design process are defined due to atmospheric turbulence. Thus, rapidly performable and highly accurate dynamic response simulations are required to analyse a wide range of parameters. In this paper a method is proposed to predict dynamic loads on an elastically trimmed, large civil aircraft using computational fluid dynamics in conjunction with model reduction. A small sized modal basis is computed by sampling the aerodynamic response at discrete frequencies and applying proper orthogonal decomposition. The linearised Reynolds-averaged Navier-Stokes equations are then projected on the subspace spanned by this basis. The resulting reduced system is solved at an arbitrary number of frequencies to analyse responses to 1-cos gusts very efficiently. Lift coefficients and surface pressure distributions are compared with full order, non-linear, unsteady timemarching simulations to verify the method. Overall, the reduced order model predicts highly accurate global coefficients and surface loads at a fraction of the computational cost.
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