Windmill fantail

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Fantail – a little windmill mounted at right angles to the sails, at the rear of the windmill, and which turned the cap automatically to bring it into the wind. The fantail was patented in 1745 by Edmund Lee, a blacksmith working at Brockmill Forge near Wigan, England, and perfected on mills around Leeds and Hull towards the end of the eighteenth century. Fantails are found on all types of traditional windmills. They are more common in England, Denmark and Germany than in other parts of Europe, and are little-known on windmills elsewhere except where English millwrighting traditions were in evidence.

The rotating fantail turns the cap of windmill via a system of gearing to a toothed rack around the top of the mill tower, or to wheels running on the ground in the case of a post mill. It does so until the fantail sails are oriented parallel to the wind, as in this case the wind cannot longer move them. If the fantail is oriented parallel to the wind, this means that the main sails are in the optimal perpendicular orientation, producing maximum power [1].

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