Atelier
It`s a bit difficult to describe the tric that makes possible this inventiv movement: If wind touches the paddles they start an oscillatory movement, that is guided by two axes which form an angle of 45. The paddle which is touched by the wind is oscilllating with its utmost wind stability. That speeds up. Reaching the turning point the one paddle rotates a quater of a circle and cuts the wind. The two paddles alternate. If one cuts the wind the other is pressed back.