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.

This article presents some application of the morphing technology for aerodynamic performance improvement of turboprop regional aircraft. It summarizes the results obtained in the framework of the Clean Sky 2 AIRGREEN2 program for the development and application of dedicated morphing devices for take-off and landing, and their uses in off design conditions. The wing of the reference aircraft configuration considers Natural Laminar Flow (NLF) characteristics. A deformable leading edge morphing device (“droop nose”) and a multi-functional segmented flap system have been considered. For the droop nose, the use of the deformable compliant structure was considered, as it allows a “clean” leading edge when not used, which is mandatory to keep natural laminar flow (NLF) properties at cruise. The use of a segmented flap makes it possible to avoid external flap track fairings, which will lead to performance improvement at cruise. An integrated tracking mechanism is used to set the flap at its take-off optimum setting, and, then, morphing is applied in order to obtain a high-performance level for landing. Lastly, some performance improvements can be obtained in climb conditions by using the last segment of the flap system to modify the load distribution on the wing in order to recover some extended laminar flow on the wing upper surface.

Modern transport aircraft wings have reached near-peak levels of energy-efficiency and there is still margin for further relevant improvements. A promising strategy for improving aircraft efficiency is to change the shape of the aircraft wing in flight in order to maximize its aerodynamic performance under all operative conditions. In the present work, this has been developed in the framework of the Clean Sky 2 (REG-IADP) European research project, where the authors focused on the design of a multifunctional twistable trailing-edge for a Natural Laminar Flow (NLF) wing. A multifunctional wing trailing-edge is used to improve aircraft performance during climb and off-design cruise conditions in response to variations in speed, altitude and other flight parameters. The investigation domain of the novel full-scale device covers 5.15 m along the wing span and the 10% of the local wing chord. Concerning the wing trailing-edge, the preliminary structural and kinematic design process of the actuation system is completely addressed: three rotary brushless motors (placed in root, central and tip sections) are required to activate the inner mechanisms enabling different trailing-edge morphing modes. The structural layout of the thin-walled closed-section composite trailing-edge represents a promising concept, meeting both the conflicting requirements of load-carrying capability and shape adaptivity. Actuation system performances and aeroelastic deformations, considering both operative aerodynamic and limit load conditions, prove the potential of the proposed structural concept to be energy efficient and lightweight for real aircraft implementation. Finally, the performance assessment of the outer natural laminar flow (NLF) wing retrofitted with the multifunctional trailing-edge is performed by high-fidelity aerodynamic analyses. For such an NLF wing, this device can improve airplane aerodynamic efficiency during high speed climb conditions.

A multidisciplinary design analysis and optimization process is developed at ONERA for the design of tube and wing and blended wing–body aircraft configurations. This process is composed of different disciplinary modules (geometry, propulsion, aerodynamics, structure, handling qualities and flight mission), and the overall process considers different fidelity levels for these modules at each step of the design process. This article describes the low-fidelity aerodynamic module used during the preliminary design optimization process. Analytical formulations retained for lift and drag components are presented in the first part. Then, the performances estimated by the aerodynamic module on some reference configurations are compared with both numerical and experimental data, showing a quite good agreement for both tube and wing and blended wing–body configurations not only for global performance but also for individual drag components.

The improvement of slatless high-lift configurations is of high importance for future aircraft. This statement is valid for turbulent wing as well as wing integrating laminar flow technologies. Such performance improvement can be obtained by using active flow control at the main wing leading edge, or by the use of passive devices (vortex generators) or active devices (blowing slot) located on the flap, in order to suppress the flow separation that generally exists at the flap trailing edge for lift-optimized landing configurations. This paper presents the numerical optimization of a flap system equipped, or not equipped, with mechanical vortex generators, including the flap settings and the vortex generator characteristics. The flap settings (gap, overlap, and angle) and the mechanical vortex generator parameters (location, height, skew angle, spacing and length), are optimized at the same time.