Study of Morphing Winglet Concepts Aimed at Improving Load Control and the Aeroelastic Behavior of Civil Transport Aircraft


C. Liauzun, D. Le Bihan, J.-M. David, D. Joly, B. Paluch (ONERA)

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Morphing is today widely studied in order to improve aircraft performance and thereby decrease their environmental footprint. This paper deals with the preliminary study of several morphing winglet concepts aimed at improving load control and aeroelastic behavior. The first step consisted in building and validating low-CPU-time-consuming but accurate aeroelastic models able to take into account aerodynamics, structural dynamics and flight mechanics, in order to handle free flexible aircraft. Aeroelastic state- space models have therefore been built from a structural modal reduction and from a rational function approximation of the aerodynamic forces based on the Roger formulation. They have been validated through comparisons with high-fidelity fluid-structure (CFD-CSM) coupling simulations. The flight mechanics has been taken into account by coupling these models with the AVL software. The second step consisted in designing a realistic reference wing equipped with a conventional winglet.
Then, four morphing winglet concepts were assessed: a flapping winglet, a winglet whose deformation in torsion is controllable, a winglet able to rotate around an axis along its span and a winglet equipped with a trailing edge flap. The latter concept was found to be the most promising in terms of load control, in particular when used in conjunction with the aileron. Finally, a technological study was performed in order to ensure the feasibility of the concepts. This study was pursued up to the drawing phase, but stopped before a demonstrator was manufactured. Nevertheless, it demonstrated the feasibility of a winglet equipped with a trailing edge flap, at both the demonstrator and real aircraft scales.