Aerodynamic and Structural Behaviour of a Wing Equipped with a Winglet at Cruise

At transonic cruise the addition of a winglet to a wing does not simply consist in enhancing the induced drag. In this paper we analyse in details the performance of the wing plus winglet assembly including the wing deformation through aeroelastic computations. The method allows comparing thoroughly drag and its physical breakdown (wave drag, viscous drag and induced drag) for different devices. The large sensitivity of drag and wing root bending moment to twist is underlined for configurations with a large device in comparison to the clean wing. The case of a real aircraft equipped with two different winglets over its cruise range is tackled (weight and altitude evolutions) and compared to flight tests. Accurate predictions of the wing deformations and performance are achieved even if some discrepancy remains in the aerodynamic simulation of the tip of the wing.