Abstract: An aircraft wing has a winglet extending from the tip to reduce drag and thereby improve the efficiency of the aircraft. Hitherto such winglets, although they have succeeded in reducing drag, they have also increased the wing bending moment at high coefficients of lift sufficient to require a strengthened and therefore heavier wing. Moreover, they have suffered flow break-away at such high coefficients of lift and have therefore incurred aircraft control problems. A winglet according to the present invention, is of high sweep back and low Aspect Ratio. Its resulting increase in the bending moment on the wing is relatively low even at high lift coefficients and since it changes from conventional attached flow to vortex flow and therefore does not experience random flow break-away at high lift coefficients, it does not harm aircraft control.