Flutter Clearance Investigation of Camber-Morphing Aileron Tailored for a Regional Aircraft

When dealing with adaptive lifting surfaces, the level of complexity of the structural design naturally increases as a consequence of the augmented functionality of the resulting system. Specifically, an adaptive structure ensures a controlled and fully reversible transition from a baseline shape to a set of different configurations, each one characterized by different external loads and transmission paths of the internal stresses. The Consortium de recherche et d'innovation en aérospatiale au Québec (CRIAQ) MD0-505 research project, born from an efficient transatlantic cooperation among Italian and Canadian academic departments, research centers, and leading companies, suggests a possible solution to more stringent government requirements on emissions and safety: an innovative morphing aileron implemented to increase both structural stability and the in-cruise load control, was designed, manufactured, and tested. The aim of this article is to predict the aero-servo-elastic impact of a true-scale prototype on a regional aircraft, following an experimental test campaign and the development of a well-correlated finite-element model of the device. A detailed trade-off flutter analysis was performed by means of SANDY, an in-house code, in compliance with European Aviation Safety Agency (EASA) CS-25 airworthiness requirements and referring - initially - to nominal aileron functioning. Furthermore, a sensitivity investigation was carried out to assess the dynamic stability of the adaptive aileron, verifying the flutter clearance in the presence of critical scenarios related to malfunctions of the actuation system. Safety values for the aileron control harmonic were investigated looking at potential certification and industrialization issues.