This paper is focused on numerical investigations that analyze the advantages obtained from high-aspect-ratio wings with unconventional roll control strategies based on wing twist morphing. A sailplane, the G103-B, produced by the GROB Werke company, was chosen as the reference aircraft for the analyses. For confidentiality reasons, the data disclosed by the builder covered only general properties such as the main dimensions, the lifting surface airfoils and attitudes, the characteristic speeds and a rough mass budget. As a consequence of this, “reverse-engineering” was considered necessary to define a reasonable wing structural layout that enabled the analysis of the elastic-aircraft roll dynamics. A preliminary sizing of the wing structure was addressed using CS-22 airworthiness requirements and by adopting fast, elementary approaches that are well known in the literature. The estimated structural arrangement, which was verified using a finite element analysis, was then used to generate the aircraft dynamic model. The elastic-aircraft roll dynamics were first investigated with regard to conventional aileron-based control. Extra modes simulating controlled twist distributions along the wing span were added into the aircraft modal base and their effects on the aircraft roll dynamics were analyzed. The conventional (aileron-based) and the unconventional (wing twist morphing) roll control strategies were compared from the aerodynamic and the aeroelastic standpoints, and the benefits achieved with the unconventional strategy are summarized

Nature teaches that the flight of the birds succeeds perfectly since they are able to change the shape of their wings in a continuous manner. The careful observation of this phenomenon has re-introduced in the recent research topics the study of "metamorphic" wing structures; these innovative architectures allow for the controlled wing shape adaptation to different flight conditions with the ultimate goal of getting desirable improvements such as the increase of aerodynamic efficiency or load control effectiveness. In this framework, the European research project SARISTU aimed at combining morphing and smart ideas to the leading edge, the trailing edge and the winglet of a large commercial airplane (EASA CS25 category) while assessing integrated technologies validation through high-speed wind tunnel test on a true scale outer wing segment. The design process of the adaptive trailing edge (ATED) addressed by SARISTU is here outlined, from the conceptual definition of the camber-morphing architecture up to the assessment of the device executive layout. Rational design criteria were implemented in order to preliminarily define ATED structural layout and the general configuration of the embedded mechanisms enabling morphing under the action of aerodynamic loads. Advanced FE analyses were then carried out and the robustness of adopted structural arrangements was proven in compliance with applicable airworthiness requirements.

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Design of morphing wings at increasing TRL is common to several research programs worldwide. They are focused on the improvement of their performance that can be expressed in several ways, indeed: aerodynamic efficiency optimization, fuel consumption reduction, COx and NOx emission reduction and so on, or targeted to overcome the classical drawbacks related to the introduction of a novel technology such as system complexity increase and management of certification aspects. The Consortium for Research and Innovation in Aerospace in Quebec (CRIAQ) lunched project MD0505 that can be inserted in this crowded frame. The target of this cooperation, involving Canadian and Italian academies and a research centre, is the development of a camber "morphing aileron" integrated on an innovative full scale wing tip of the next generation regional aircraft. This paper focuses on the preliminary design and the numerical modeling of its architecture. The structural layout is, at the beginning, described in detail and furthermore, a finite element (FE) model of the entire aileron architecture is assessed and used to verify the structural integrity under prescribed operational conditions.

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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.

The development of adaptive morphing wings has been individuated as one of the crucial topics in the greening of the next generation air transport. Research programs are currently running worldwide to exploit the potentiality of morphing concepts in the optimisation of aircraft efficiency and in the consequent reduction of fuel burn. Among these, SARISTU represents the largest European funded research project which ambitiously addresses the challenges posed by the physical integration of smart concepts in real aircraft structures; for the first time ever, SARISTU will experimentally demonstrate the structural feasibility of individual morphing concepts concerning the leading edge, the trailing edge and the winglet on a full-size outer wing belonging to a CS-25 category aircraft. In such framework, the authors intensively worked on the definition of aeroelastically stable configurations for a morphing wing trailing edge driven by conventional electromechanical actuators. Trade off aeroelastic analyses were performed in compliance with CS-25 airworthiness requirements (paragraph 25.629, parts (a) and (b)-(1)) in order to define safety ranges for trailing-edge inertial and stiffness distributions as well as for its control harmonics. Rational approaches were implemented in order to simulate the effects induced by variations of trailing-edge actuators' stiffness on the aeroelastic behaviour of the wing also in correspondence of different dynamic properties of the trailing-edge component. Reliable aeroelastic models and advanced computational strategies were properly implemented to enable fast flutter analyses covering several configuration cases in terms of structural system parameters. Already available finite elements models were processed in MSC-NASTRAN ® environment to evaluate stiffness and inertial distributions suitable for the stick-equivalent idealisation of the reference structure. A parametric stick-equivalent model of the reference structure was then generated in SANDY3.0, an in-house developed code, that was used for the definition of the coupled aero-structural model as well as for the solution of aeroelastic stability equations by means of theoretical modes association in frequency domain.Obtained results were finally arranged in stability carpet plots efficiently conceived to provide guidelines for the preliminary design of the morphing trailing-edge structure and therein embedded actuators.

Noise from contra-rotating open rotors is a major obstacle to the adoption of this fuel efficient technology as a viable aircraft propulsion system. A better understanding of both contra-rotating open rotor noise generation and reduction has been achieved due to ongoing extensive research. One of the most recent research activities is the WENEMOR (wind tunnel tests for the evaluation of the installation effects of Noise EMissions of an open rotor advanced regional aircraft) project, which has been developed in response to the requirements described in the Clean SkyIntegrated Technology Demonstrators under the heading of Green Regional Aircraft. The project investigates the airframe installation effects of a 1=7th scale model of a regional aircraft equipped with two contra-rotating open rotors of the same rotor diameter, the same rotational speed and equal blade number. For this case, the blade passing frequency of rotor-alone tones and the frequency of relevant interaction tones cannot be distinguished due to the equal blade count of the two rotors. This study presents the tone directivity plots up to 4 Â blade passing frequency of the isolated WENEMOR single pylon contra-rotating open rotor engine in both pusher and tractor configurations at various angles of incidence and flow velocities. A linear array of 13 microphones is deployed for the far field sound measurements. The tone directivity trends show the efficient on-axis acoustic radiation at all blade passing frequency tones with the contra-rotating open rotor tone at 2 Â blade passing frequency dominating in the vast majority of the tests. The main objective is to compare the acoustic emission of pusher and tractor configurations tested under the same flow velocities and angles of incidence. The results suggest that the pusher configuration of the isolated contra-rotating open rotor tends to be slightly louder than the tractor at 2 Â blade passing frequency. However, it is shown that the acoustic performance of the isolated contra-rotating open rotor is complicated and sensitive to any change in the flow velocity and the angle of incidence. The increasing flow velocity and the increasing angle of incidence show limited consistency in proportional trends in the directivity plots of sound pressure levels. It is anticipated that the findings will be different for a more realistic case of installedon-model contra-rotating open rotor.