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SARISTU was a big cooperation project granted by the European Commission, 7th Framework Programme, carried out between 2011 and 2015. It dealt with smart aeronautic structures, both morphing and sensored; its main target was to demonstrate the feasibility of designing, manufacturing and operating in representative environment, instrumented structures. Till now, it represents the major effort carried out within the European Union on the development of adaptive architectures for air systems. Inside that big activity, the realization of an Adaptive Trailing Edge Device (ATED) for wing camber adaptations aimed at compensating the weight reduction following the fuel consumption during cruise was addressed. It made the core of investigations target variable geometry aircraft components together with two other analyses concerning the development of shape-changing winglet and droop nose. ATED activities were conducted by the Italian Aerospace Research Centre (CIRA) in tight cooperation with the University of Napoli, “Federico II”, who coordinated a group of 12 different partners from 8 different nations (France, Germany, Greece, the Netherlands, Israel, Spain, Turkey, and Italy). In this paper, an integral synthesis of that work is reported, with a focus on the definition and realization of the components of the presented device. The publication is in fact meant as the first part of a series that is aimed at overviewing the whole adaptive trailing edge development, till wind tunnel tests execution. Such a concise report is a critical and harmonized review of what have been performed by many colleagues spread all over Europe, all of which are duly recalled in the reported bibliography where the reader may access more detailed information and descriptions. In detail, the paper starts with a general introduction of the concept and its aims, to move to the specs definition immediately after. Then, it deals with a short but comprehensive description of the main ATED components: structural skeleton, skin, actuation and sensing systems. It is worth remarking that the paragraph dedicated to the body frame includes some discussion about aeroelastic assessment and manufacture, seen as complementation for a complete assessment of the design constraints.

This paper deals with the actuation system design of a full-scale morphing aileron for regional aircraft. The aileron is allowed to smoothly change its geometrical configuration and perform the in-flight transition from a baseline shape to a set of optimal morphed ones pre-defined on the basis of aerodynamic requirements. The design of such innovative aileron is aimed not only at substituting the conventional aileron installed on a real aircraft but also to provide additional functionality. The aileron is free to rotate around its main hinge axis and it is also allowed to smoothly modify camber with two independent actuation systems. In such manner it can be used also during cruise with a symmetric deflection between the two half wings in order to reduce drag in off design condition. To accomplish variable aileron shape, a rigid-body mechanism was designed. The proposed aileron architecture is characterised by segmented adaptive ribs rigidly linked each other with spanwise reinforcements such as spars and stringers in a multi-box arrangement. Each rib is split into two movable plates connected by means of rotational hinges in a finger-like mechanism. The mechanism is driven by a load-bearing actuator by means of a kinematic chain opportunely tied based on the structural requirements in terms of shape to be matched and load to be withstood. The proposed device is an innovative arrangement of the quick-return mechanism composed of a beam leverage, commercial linear guides and a crank. The actuator shaft is directly inserted in the crank, which transmits the rotation to the linear guide that slide along a rail moving upward or downward the beam thus resulting in a camber variation. The entire aileron is moved by three leverages internally contained and distributed along the first two bays while the most external ribs are considered passive and their movement slaved. Two actuation layouts are analytically and numerically studied, the analytical theory is presented and validated by means of a multi-body simulation. Moreover, a linear static analysis was carried out under the hypothesis of glued contact between linear guides components simulating a jamming condition. This assumption has been formulated because it represents the most severe condition that envelop all the operative loads to which the actuation system is subjected. The analyses conducted are preliminarily aimed to verify that no failure occur under the imposed loads. In this first design loop, the vertical static force acting on the linear carriage exceeded allowable value and then a new configuration with double-sided linear guides was then investigated.

International audience; Aircraft winglets are well-established devices that improve aircraft fuel efficiency by enabling a higher lift over drag ratios and lower induced drag. Retrofitting winglets to existing aircraft also increases aircraft payload/range by the same order of the fuel burn savings, although the additional loads and moments imparted to the wing may impact structural interfaces, adding more weight to the wing. Winglet installation on aircraft wing influences numerous design parameters and requires a proper balance between aerodynamics and weight efficiency. Advanced dynamic aeroelastic analyses of the wing/winglet structure are also crucial for this assessment. Within the scope of the Clean Sky 2 REG IADP Airgreen 2 project, targeting novel technologies for next-generation regional aircraft, this paper deals with the integrated design of a full-scale morphing winglet for the purpose of improving aircraft aerodynamic efficiency in off-design flight conditions, lowering wing-bending moments due to maneuvers and increasing aircraft flight stability through morphing technology. A fault-tolerant morphing winglet architecture, based on two independent and asynchronous control surfaces with variable camber and differential settings, is presented. The system is designed to face different flight situations by a proper action on the movable control tabs. The potential for reducing wing and winglet loads by means of the winglet control surfaces is numerically assessed, along with the expected aerodynamic performance and the actuation systems' integration in the winglet surface geometry. Such a device was designed by CIRA for regional aircraft installation, whereas the aerodynamic benefits and performance were estimated by ONERA on the natural laminar flow wing. An active load controller was developed by PoliMI and UniNA performed aeroelastic trade-offs and flutter calculations due to the coupling of winglet movable harmonics and aircraft wing bending and torsion.

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.

Airfoil camber adaptation may be the key for the performance improvement of wings for many specific applications, including shorter take-off distance, compensation of weight variation and so on. Following the successful experiences gained in SARISTU, where an adaptive trailing edge device was developed for medium to large size commercial aircraft, the authors propose to exploit the developed architecture to a small aircraft wing. The basic reasons behind that mainly rely on the associated possibility to access easier implementation onto a real aircraft instead of referring to wing segments for wind tunnel or ground tests. In this way, many operative problems are faced, that would be otherwise neglected in usual lab experimentation. First of all, the integration of the proposed device onto a flying machine, that in turn pose the problem of facing the interface with the existing systems. Secondly, the necessity of including the device into the flap while fully preserving its current functionality. Furthermore, the necessity of developing a robust design process that allows having the release of the permit-to-fly. Each of the above steps, non-exhaustive in illustrating the difficulty of the addressed challenge, is structured in many other sub-segments, ranging from a suitable FHA analysis to a full re-design of the existing high lift systems or the adaptation of the architecture of the reference morphing trailing edge itself. This last item poses the classical challenge of the scaling issues, requiring the structural and the actuation subsystems to entirely fit into the new geometry. The objective of the present research is then to verify the feasibility of applying a certain architectural morphing philosophy onto a real aircraft, taking into account all the operational difficulties related to such an operation. This paper reports the activities related to the exploitation of the reference adaptive structural architecture, to the geometry of a flap of a small aircraft. In detail, the system layout is presented, followed by a FE analysis of the structural system under the operational loads and an estimation of the weight penalty associated to this transformation. Interfaces of the flap system with the main aircraft body are considered as constraints to the design development, so that the only flap is affected.

The common challenge of all aerospace advancements is greening the air transport. This led the recent research programs towards the study of “metamorphic” wing structures, capable of adapting their geometry to the different conditions of flight. The development of morphing structures allows the reduction of drag and the increase of range, together with the growth of load control effectiveness. In this context, the European research project SARISTU addressed the physical integration of smart and morphing structural concepts, by implementing them on a true scale outer wing belonging to a CS-25 category aircraft finally tested in a large Wind Tunnel. In the framework of SARISTU project, the design of an Adaptive Trailing Edge Device was developed. The morphing skin concept consisted of a segmented skin, with aluminum and silicone foam strips covered by a protective silicone top-layer. A two-bay demonstrator was tested inside the Wind Tunnel at the Department of Industrial Engineering of the University of Naples “Federico II”; experimental analyses were performed in order to verify whether the silicone parts could show out of plane bumps induced by the aerodynamic loads occurring during the Wind Tunnel test campaign. A photogrammetric optic approach was adopted, in order to reach the aforementioned targets in a non-invasive way; such methodology was selected due the high resolution assured at a very low implementation costs. Obtained results allowed to confirm the demonstrator well done design and opened the doors to the next experimental test campaign performed in TsAGI Russian Wind Tunnel, on the outer wing equipped with a five-bay demonstrator of the Adaptive Trailing Edge Device.

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 was done in the frame of an international CRIAQ project, and the purpose was to demonstrate the upper surface morphing and aileron morphing capabilities in improving the wing tip aerodynamic performances. During numerical optimization with ‘in-house’ genetic algorithm software, and during wind tunnel experimental tests, it was demonstrated that the air flow laminar state was extended and drag coefficient reduction were obtained., 55th AIAA Aerospace Sciences Meeting, 9-13 January 2017, Grapevine, Texas, USA

Aircraft wings are usually optimized for a specific design point. However, since they operate in a wide variety of flight regimes, some of these have conflicting impacts on aircraft design, as an aerodynamically efficient configuration in one instance may perform poorly in others. Conventional wing structures preclude any significant adaptation to changing conditions; movable surfaces, such as flaps or slats, lead to limited changes of the overall shape with narrow benefits compared with those that could be obtained from a wing structure that is inherently deformable and adaptable. An adaptive trailing edge concept conceived to enhance wing aerodynamic performance in cruise condition is outlined. The camber of the trailing edge is controlled during flight to compensate the weight reduction following the fuel burning. In this way, the trimmed configuration remains optimal in terms of efficiency (lift to drag ratio) or minimal drag with positive fallouts on aircraft fuel consumption per flight. The main steps concerning the design of the device are reported, with a special focus on each of its relevant architectural elements. In detail, the skin, the structural skeleton, the actuator, sensor, and control systems are dealt with. Some attention is devoted to aspects that are necessary to come to a finalized product of industrial relevance: namely, the aeroelastic and the safety analyses. The former assumes a main relevance because the system has augmented degrees of freedom with respect to a standard layout and then, a more complex dynamic response and a higher risk of instability. The latter is necessary to envisage a future certification process of this kind of device that requires the development of a dedicated path.

“Inspiration from nature” is the key words that lies behind the morphing idea. Just as bird helped to inspire the design of the warping mechanism of the Wright Flyer, nature offers a philosophy inspiration for morphing wing design. Since aviation origin, a connection between bio-inspiration and aeronautical engineering can be found which has led through years at the current idea of a morphing wing as a mechanism capable to adapt its shape as well as the flight conditions change. Design of morphing wings at increasing TRL is common to several research programs worldwide, especially aimed at improving their associated benefits (optimize aerodynamic efficiency, fuel consumption reduction, decrease of COx and NOx emission, etc.) and overcoming classical limits (increasing system complexity, certification, reliability and so on). In this framework, the CRIAQ MD0505 project was launched; a joint research program between Canadian and Italian academies, research centers and leading industries. The target of this research cooperation is the development of combined smart structures systems on a full scale wing tip of a next generation regional aircraft. The complex device combines a modifiable airfoil thickness with a camber morphing aileron. This paper focuses on the preliminary design and the numerical modeling of the aileron architecture. The structural layout consists of a number of deformable ribs, each made of three consecutive blocks connected each other by hinges. Further cross connections between pair of elements, make the system a SDOF finger-like mechanism. The aileron is moved by servo rotary load bearing actuators which drive a kinematic chain and sustain the external aerodynamic pressure distribution. A FE model of the entire architecture was released to verify the structural integrity under prescribed operational conditions.

Aircraft wings are usually optimized for a specific design point. However, since they operate in a wide variety of flight regimes, some of these have conflicting impacts on aircraft design process, as a single configuration may be efficient in one instance but perform poorly in others. In principle, stiff, hardly deformable aircraft structures preclude any adaptation to changing conditions. Alternatively, morphing wings could provide adaptive capabilities to maximize aircraft performance in any flight operation. Inside SARISTU, specific research activities were carried out on the technological development of an Adaptive Trailing Edge Device (ATED) implementing airfoil camber morphing for the maximization of the wing aerodynamic performance during cruise, with the ultimate goal to reduce fuel consumption. Wing shape is changed to compensate weight losses following fuel burning, to keep L/D ratio (or simply drag, D) to its optimal value. ATED camber adaptations are predicted to lead to significant benefits in fuel consumption, estimated from 3 to 5%, depending on a number of initial and boundary conditions. This paper is focused on the design process adopted for the definition and verification of ATED primary structure; fast and reliable elementary methods combined with rational design criteria and advanced FE analyses were adopted to assess the architectural concept and the embedded actuation mechanisms. Structural design was carried out in compliance with the very demanding requirements posed by the implementation of the device on large Aeroplanes (EASA CS25 category).