Aeroelastic Behaviour of Forward-Swept Wings with Flared FoldingWingtips

The forward-swept wing (FSW) has been a topic of interest in the field of natural laminar flow for over forty years, yet its application to aircraft design has been limited by the inherent adverse aeroelastic behaviour. Furthermore, a recent consideration in aircraft design has been the implementation of Flared Folding Wingtips (FFWTs) for reducing in-flight loads and improving roll behavior. This work investigates whether such devices may mitigate the aeroelastic instabilities associated with FSWs. A semi-span wing model is developed in MSC Nastran and it is found that employing a FFWT increases the divergence speed to close to that if the wing tip’s were removed. To further investigate the benefits associated with FFWTs on divergence behaviour, a case study is carried out on a medium-sized civil aircraft model, showing that FFWTs provide a significant increase in divergence speed for a FSW. However, these benefits are limited due to the occurrence of flutter, which becomes the critical instability when the wingtips are free-floating for these design cases.