Integration of Rigid and Aeroelastic Aircraft Models using the Residualised Model Method

This article describes a procedure for development of an integrated model of a flexible aircraft by combining available flight dynamics and aeroelastic models. Both types of models mostly complement each other. However, two overlaps are typically present that should be properly taken care of. In the first place, rigid aircraft flight dynamics models usually already take the deformation of the airframe quasi-statically into account in the aerodynamics computation. Second, aeroelastic models also contain so-called rigid-body modes that correspond with the flight dynamics degrees of freedom. The adopted solution is to leave the flight dynamics model unchanged, and to remove rigid modes and the quasi-static influence on the flight dynamics from the aeroelastic model. This article presents an extension to previously published work, introducing a method for properly handling of so-called unsteady aerodynamic lag states. As a spin-off result, it will be shown how the proposed procedure can be used to correct rigid body dynamics in an aeroelastic state space model