Compliant structures for morphing aircraft

Morphing aircraft are flight vehicles that change their shape to effect both a change in the mission of the aircraft and to perform flight control without the use of conventional control surfaces. The key to morphing aircraft is the full integration of the shape control into the wing structure, and this is most easily achieved using composite structures. The design of these vehicles must take full account of the aerodynamic loads and must carefully consider the power requirements for shape control to ensure an overall performance benefit. This paper overviews three possible methods to achieve the required structural compliance that are under investigation at Bristol. The first is the design of the internal structure to produce a compliant mechanism that achieves the required aerofoil deformation using a small number of actuators. The second is the use of stiffness tailoring, incorporating the performance objectives, together with material constraints such as buckling and manufacturing requirements. The final approach is the use of multi-stable structures to perform large shape changes. For these structures, no force is required to maintain their stable configurations. The general features of these approaches will be described and illustrated using simulated and experimental results.