Aeroelastic scaling of a high aspect ratio wing incorporating semi aeroelastic hinge

There has been a growing interest in utilizing flared folding wingtips as an in-flight load alleviation device to enable increased wing spans that meet airport gate limits but with little increase in wing weight. The semi-aeroelastic hinge (SAH) concept is implemented in high aspect ratio wings to enable wingtips to be released during severe load cases such as manoeuvres and gusts to alleviate the bending moments whilst maintaining optimum aerodynamic shape for the rest of the flight. In this paper, scaling methods for wings incorporating the SAH are explored, allowing for the development of equivalent scaled Unmanned Aerial vehicles (UAVs) or wind tunnel models with similar aeroelastic behaviour as full-size aircraft. Three scaling approaches are considered in this study, namely Iso-Froude, Iso-Frequency and Iso-Strain, where a set of governing non-dimensional quantities and scaling factors are determined. Despite the significant non-linearities resulting from large wingtip fold angles, it is shown that a linear scaling approach can be appropriate for such a wing configuration. Furthermore, the aeroelastic properties of each scaled model are compared to that of the full scale model and a reasonably good agreement is obtained.