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The Chinese Windmill



From Persia bandied the tidings of the wind that does the work of bullocks at the grinding or pumping of water towards China. There they worked meticulously further and they found an improvement: when you put the axle for the panels not in the middle of the windmill but outside and let the axles turn around another axle in the middle the windmill becomes independent of the direction of the wind. And because there is much bamboo in China they took bamboo and forewent to the brickwork.

Chinese Windmill
(schematic)
Bild "Home:chinesische.GIF"
(top view) the wind comes from left

The sails move over two axles that are parallel to each other. The main axle is in the middle and the sails are mounted like doors on a second axle that turns round the main axle. There are stoppers (in the drawing in blue) that hinder the sails to go through. So on this side the Chinese Windmill works like the Persian Windmill. But on the other side, the sails can open freely. When the direction of the wind changes, the system relocates automatically by itself. To hinder the mill to open more than 180° there are some ropes.

As shown in the picture above the Chinese Windmill is more a resistance runner. By trial the Chinese found out, that they could exalt the efficiency very much, if they reduce the range of the angles the sails can flap. Opening and closing of the sails take some time and therefore cost energy. By reducing the range the Chinese Windmill also becomes a buoyancy runner.

Chinese Windmill
(optimized)
Bild "New Windmills:anigif_chinWindmill.gif"
animated drawing

The arrows show the virtual wind on the ends of the sails. (Whirls caused by the sails on the luv side are not allowed for.) The sails are dragged over their axle. This brakes the windmill and reduces the velocity of the turning and makes the windmill easier to handle.

The main use for the Chinese Windmill was the pumping of water. The rice fields were irrigated that way.

A disadvantage of the Chinese Windmill is, that the upper point of the middle-axle must be holded, otherwise the farmers would be in some surprise. A second disadvantage is the huge need of place of the windmill.

(I was tasked by the question what would happen if the range of the angles is 0° and when the sails are so narrow, that the air in the middle could not get out easily. So I reinvented the Tirajator.)