Sensitivities and Approximations for Aeroservoelastic Shape Optimization with Gust Response Constraints

Analytic sensitivities with respect to configuration shape design variables are derived for state-space models of aeroservoelastic systems excited by gust inputs. Minimum-State rational function approximations are used to transform aerodynamic load expressions from the frequency domain to the time domain, and sensitivities of such approximations are extended from terms associated with structural motions to terms associated with the downwash due to gusts. Sensitivity-based approximations of the resulting gust response behavior, including Taylor-Series based direct approximations of the RMS of the response, or Lyapunov equation solutions using Taylor-Series based approximate system matrices are compared. The paper contributes to the development of design-oriented analysis techniques for multidisciplinary design optimization of flight vehicles.