Design and Assessment of Subscale Flexible High Aspect Ratio Cantilever Wings

High aspect ratio wings have been the focus of several recent studies for efficiency improvements in modern aircraft. Many numerical studies can be found in literature with some experimental validations. The work presented here describes the design, manufacture, and the ground testing of three wings with a half-span of 0.85 m and full-span aspect ratio of 19 aimed for the future wind tunnel studies of nonlinear geometric effects on static and dynamic behaviour. Comparisons with a numerical model featuring geometric nonlinearity is made. The wing design approach used here is unique in the sense that the wings are designed simultaneously such that each will have a different level of flexibility, with other parameters such as mass distribution remaining constant. These wings will be used in future experiments aimed at investigating the effects of geometric nonlinearity and flexibility on the overall flight dynamics of an aircraft model on a multi-degree-of-freedom manoeuvre rig. The design considerations and interdependent constraints are discussed. The designed wings were manufactured and assembled to identical mass distributions and in good agreement with numerical models in terms of stiffness and frequency response. The design process, challenges, and learned lessons are presented.