Method based on Chebyshev Polynomials Theories for Aeroservoelastic Interactions Studies on a F/A-18 Aircraft

R.M. Botez, A.D. Dinu, and I. Cotoi (Canada)


aeroelasticity, aeroservoelasticity, control laws, aerodynamics, flexible aircraft.


A significant aspect of aeroservoelasticity is the conversion of unsteady aerodynamic forces from the frequency domain into the Laplace domain. Until now, the most popular methods used for these studies have been the Minimum State and the Least Square methods. The classical method is the Least Square method based on Padé polynomials approximations. We present a new method for these studies, based on Chebyshev polynomials and their orthogonality properties. Results obtained by this method are compared to results obtained by the Padé method. Two sets of results are presented for this comparison. The first shows the values of the aerodynamic forces in the Laplace domain and the second shows the flutter speeds and frequencies. In both cases, different approximation orders were used for comparison. The new method presented here shows very good results versus those obtained with the Padé method on the F/A 18 aircraft.

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