Electromechanical actuation for morphing winglets

As a key enabler for future aviation technology, the use of servo electromechanical actuation offers new opportunities to transition innovative structural concepts, such as biomimicry morphing structures, from basic research to new commercial aircraft applications. In this paper, the authors address actuator integration aspects of a wing shape-changing flight surface capable of adaptively enhancing aircraft aerodynamic performance and reducing critical wing structural loads. The research was collocated within the Clean Sky 2 Regional Aircraft Demonstration Platform (IADP) and aimed at developing an adaptive winglet concept for green regional aircraft. Finite Element-based tools were employed for the structural design of the adaptive device characterized by two independent movable tabs completely integrated with a linear direct-drive actuation. The structural design process was addressed in compliance with the airworthiness needs posed by the implementation of regional airplanes. Such a load control system requires very demanding actuation performance and sufficient operational reliability to operate on the applicable flight load envelope. These requirements were met by a very compact direct-drive actuator design in which the ball recirculation device was integrated within the screw shaft. Focus was also given to the power-off electric brake necessary to block the structure in a certain position and dynamically brake the moveable surface to follow a certain command position during operation. Both the winglet layout static and dynamic robustness were verified by means of linear stress computations at the most critical conditions and normal mode analyses, respectively, with and without including the integrated actuator system.