A Fantail is a small windmill mounted at right angle

Right angle

In geometry and trigonometry, a right angle is an angle that bisects the angle formed by two halves of a straight line. More precisely, if a ray is placed so that its endpoint is on a line and the adjacent angles are equal, then they are right angles...

s to the sails, at the rear of the windmill

Windmill

A windmill is a machine which converts the energy of wind into rotational energy by means of vanes called sails or blades. Originally windmills were developed for milling grain for food production. In the course of history the windmill was adapted to many other industrial uses. An important...

, and which turns 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

Wigan

Wigan is a town in Greater Manchester, England. It stands on the River Douglas, south-west of Bolton, north of Warrington and west-northwest of Manchester. Wigan is the largest settlement in the Metropolitan Borough of Wigan and is its administrative centre. The town of Wigan had a total...

, England, and perfected on mills around Leeds

Leeds

Leeds is a city and metropolitan borough in West Yorkshire, England. In 2001 Leeds' main urban subdivision had a population of 443,247, while the entire city has a population of 798,800 , making it the 30th-most populous city in the European Union.Leeds is the cultural, financial and commercial...

 and Hull

Kingston upon Hull

Kingston upon Hull , usually referred to as Hull, is a city and unitary authority area in the ceremonial county of the East Riding of Yorkshire, England. It stands on the River Hull at its junction with the Humber estuary, 25 miles inland from the North Sea. Hull has a resident population of...

 towards the end of the 18th 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 the windmill via a system of gear

Gear

A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine....

ing to a toothed rack

Rack and pinion

A rack and pinion is a type of linear actuator that comprises a pair of gears which convert rotational motion into linear motion. A circular gear called "the pinion" engages teeth on a linear "gear" bar called "the rack"; rotational motion applied to the pinion causes the rack to move, thereby...

 around the top of the mill tower, or to wheels running on the ground in the case of a post mill

Post mill

The post mill is the earliest type of European windmill. The defining feature is that the whole body of the mill that houses the machinery is mounted on a single vertical post, around which it can be turned to bring the sails into the wind. The earliest post mills in England are thought to have...

. It does so until the fantail sails are oriented parallel to the wind, as in this case the wind can no longer move them. When the fantail is oriented parallel to the wind, the main sails are in the optimal perpendicular orientation and produce maximum power.

External links

• Shipley Windmill, West Sussex.