A morphing aerofoil with highly controllable aerodynamic performance

In this paper, a morphing carbon fibre composite aerofoil concept with an active trailing edge is proposed. This aerofoil features of camber morphing with multiple degrees of freedom. The shape morphing is enabled by an innovative structure driven by an electrical actuation system that uses linear ultrasonic motors (LUSM) with compliant runners, enabling full control of multiple degrees of freedom. The compliant runners also serve as structural components that carry the aerodynamic load and maintain a smooth skin curvature. The morphing structure with compliant truss is shown to exhibit a satisfactory flexibility and loading capacity in both numerical simulations and static loading tests. This design is capable of providing a pitching moment control independent of lift and higher L/D ratios within a wider angle-of-attack range. Such multiple morphing configurations could expand the flight envelope of future unmanned aerial vehicles. A small prototype is built to illustrate the concept, but as no off-the-shelf LUSMs can be integrated into this benchtop model, two servos are employed as actuators, providing two controlled degrees of freedom. This paper received a Written Paper Prize - Bronze Award from the Royal Aeronautical Society in 2018.