The invention provides a wing structure for an aircraft, including a top skin and a bottom skin defining a primary wing surface, the surface having a width, a length, a leading edge and a trailing edge; a flap having a width smaller than the width of the wing surface and a length extending over a major portion of the wing length, the flap being hingedly joined adjacent to the trailing edge of the wing, wherein the flap is capable of assuming two limit dispositions, a first disposition in which the flap extends substantially parallel to the bottom skin, and a second disposition extending towards the trailing edge of the wing, at an obtuse angle. A method for slowing down the speed of flight of an aircraft is also provided.