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Future transportation aircraft requirements focused on energy efficiency and environmental impact are leading to design concepts with very high-aspect-ratio wings. These slender wings aim to maximize efficiency by reducing drag and lowering structural weight, but can lead to larger structural deformations under aerodynamic loading and tighter coupling between the aeroelastic response and flight dynamics of the vehicle. Current engineering practice is to use wind tunnel testing to predict the stability and performance characteristics of the vehicle. However, the flutter boundary and mode maybe very different for a flexible vehicle in free flight compared to the cantilevered wing model alone. The coupled aeroelastic and flight dynamic response of an aircraft concept with a flexible high-aspect-ratio wing is investigated to better understand the nonlinear aeroelastic implications of these future design trends. This paper reports the impact of the aeroelastic and rigid body interaction on the free flight flutter boundary and vehicle response. i Autoregressive model time index i Point mass index k Step response time index, 1...n x, y, z Body coordinate frame 1, 2, 3 Beam axis

This paper describes the development of an aeroelastic simulation tool designed to aid the optimization process for anisotropic wings in low subsonic flow and subsequent aeroelastic tailoring of a sailplane wing to maximize its cross-country speed. To this end a nonlinear, quasi-three dimensional structural beam solver is coupled with a three dimensional panel code. The code is then verified using a published, theoretical configuration. Simulation results closely correspond to the reference values and show very fast convergence. Using the cross-section flexibility matrices as design variables, the deflections of a conceptual sailplane wing are optimized for multiple operating points according to crosscountry theory. The final configuration features a significant improvement in cross country speed compared to the rigid wing and an incremental improvement when compared to the flexible base configuration.

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