Soerser Tal Aachen/DE
This wind object consists of four rectangles, each two are arranged parallel vertical and one those packet is fixed opposit to the other and rotated 90 degree. They can rotate on an horizontal and on a vertical axis. If a vertical plane catches the wind, it is turned back. Thus the horizontal plane is moved into the wind. It is turned back on the horizontal axis. By this the vertical plane again is brought to the wind. The circulation starts.