Multiple flight regimes during typical aircraft missions mean that a single unique optimized configuration, that maximizes aerodynamic efficiency and maneuverability, cannot be defined. Discrete components such as ailerons and flaps provide some adaptability, although they are far from optimal. Wing morphing can significantly improve the performance of future aircraft, by adapting the wing shape to the specific flight regime requirements, but also represents a challenging problem: the structure has to be stiff to maintain its shape under loads, and yet be flexible to deform without collapse. One solution is to adopt structural elements made of smart materials; Shape Memory Alloys (SMAs) have demonstrated their suitability for many static applications due to their high structural integration potential and remarkable actuation capabilities. In this work, the airfoil camber at the wing trailing edge on a full scale wing of a civil regional transportation aircraft is controlled by substituting a traditional split flap with a hingeless, smooth morphed flap. Firstly, the development and testing of an actuator device based on a SMA ribbon, capable of a net rotation of 5 deg, is presented. Then, a flap bay is designed and experimentally tested in presence of static loads, based on a compliant rib built as a series repetition of the proposed actuator. An aero-thermo-mechanical simulation within a FE approach was adopted to estimate the behavior and performance of the compliant rib, integrating both aerodynamic loads, by means of a Vortex Lattice Method (VLM) code, and SMA phenomenology, implementing Liang and Rogers’ constitutive model. The prototype showed good actuation performance even in presence of external loads. Very good numerical-experimental correlation is found for the unloaded case, while some fatigue issues emerged in presence of static loads.

Several flight regimes occurring during a typical aircraft mission make it impossible to define a unique optimized wing configuration able to maximize aerodynamic efficiency, maneuverability, and stability in every flight condition. Components like ailerons and flaps, in some way, guarantee a certain level of adaptability, being far from optimal. Wing morphing can strongly improve the aerodynamic efficiency of future aircraft by assuring an optimal adaptive behavior which best fits the specific flight regime requirements. Such an approach, in spite of related benefits, presents a challenging problem: the same structure rigid enough to keep its shape under the aerodynamic loads has to largely deform itself without undergoing structural collapses. In the frame of a research project funded by Alenia Aeronautica S.p.A., the authors came to the definition of a novel morphing architecture acting as high-lift device. In this study, the design assessment of an innovative flap architecture for a variable-camber trailing edge is illustrated. The reference geometry is based on a full-scale wing of a reference civil regional transportation aircraft, where the conventional flap component has been substituted by a morphing trailing edge based on compliant ribs. The presented architecture moves toward the direction of assuring high deformability while keeping good load-sustaining capabilities: each rib is composed of multiple, suitably shaped rigid elements connected by means of hinges and linking rods. The rib’s shape changes upon the activation of a smart actuator based on shape memory alloy technology. Design process of the morphing rib and integrated actuator structure has been widely discussed as well as the functional tests performed on a technological demonstrator manufactured in order to prove the goodness of chosen design strategies and adopted numerical models.

Based on numerical and experimental analyses, this article proposes an application of the smart structure concept aimed at realizing a bump on an airfoil profile, finalized to reduce transonic drag, through the use of shape memory alloys (SMAs). The ability of morphing the wing profile is functional to maximize the aerodynamic efficiency in different mission conditions. The use of the so-called smart materials allows a favorable actuation performance per weight ratio, also leading to simple and integrated devices. Currently, to model their mechanical behavior is still an open issue and this work presents some original ideas about this. Numerical results and experimental tests herein presented, demonstrate the efficacy of the developed concept device, calling for further studies on real structures; their correlation also validate the implemented simulation procedure.

A new wing-tip concept with morphing upper surface and interchangeable conventional and morphing ailerons was designed, manufactured, bench and wind-tunnel tested. The development of this wing-tip model was performed in the frame of an international CRIAQ project, and the purpose was to demonstrate the wing upper surface and aileron morphing capabilities in improving the wing-tip aerodynamic performances. During numerical optimisation with ‘in-house’ genetic algorithm software, and during wind-tunnel experimental tests, it was demonstrated that the air-flow laminarity over the wing skin was promoted, and the laminar flow was extended with up to 9% of the chord. Drag coefficient reduction of up to 9% was obtained when the morphing aileron was introduced.