Windmills are powered by their sails. A windmill is a machine that is powered by the energy of the wind These sails are found in different designs, from the primitive Common Sails to the advanced Patent sails.
Contents |
Jib sails
The Jib Sail is found in Mediterranean countries, consisting of a simple triangle of cloth wound around a spar. The mill needs to be stopped in order to adjust the reefing of the sail.
 Jib sails |
 more fully spread |
Common sails
The simplest form of sail. In medieval mills the sailcloth was wound in and out of a ladder type arrangement of sails. Medieval sails could be with or without- outer sailbars. Post-medieval mill sails have a lattice framework that the sailcloth is spread over. There are various "reefs" for the different spread of sails. These are full reef, dagger point, sword point and first reef. The mill needs to be stopped in order to adjust the reefing of the sail. [1]
 Furled |
 First Reef (Medieval style sail) |
 Sword point |
 Dagger point |
.jpg/120px-Cassel_Nord_(moulin).jpg) Full reef |
 Full reef {Medieval style sail) |
Dutch sail types
In the Netherlands, the Common Sail predominates. The Netherlands ( Dutch:, ˈnedərlɑnt is the European part of the Kingdom of the Netherlands, which consists of the Netherlands the Netherlands During the nineteenth and twentieth centuries, Dutch millwrights developed the windmill sail to make it more efficient aerodynamically. The trade of millwright is concerned with the construction and maintenance of machinery
- Dekker / Van Bussel system
The Dutch millwright A J Dekker improved on the design of the Common sail by streamlining the leading edge. Dekkerised sails can work the mill with no sailcloth spread if the wind is strong enough. They are not adjustable except by adding more sailcloth as with a Common Sail. The millwright Van Bussel of Weert produced a similar system, with an airfoil on the leading edge. This is about the city in the Netherlands For other uses see Weert (disambiguation. An airfoil (in American English) or aerofoil (in British English) is the shape of a Wing or blade (of a Propeller, rotor [1]
- Ten Have / Van Riet system
Invented by Dutch millwright Ten Have[2] of Vorden, Ten Have sails have a number of longitudinal shutters, operated in a similar method to Patent sails. The town of Vorden The name 'Vorden' occurred for the first time in documents from 1121 AD The sail can be adjusted without stopping the mill. A similar system was invented by a millwright by the name of Van Riet of Goes. Goes ( is a Municipality and a City in the southwestern Netherlands, in Zuid-Beveland. [1]
 Ten Have sail open, Dekkerised Common sails. |
 Ten Have sail closed. |
 Van Bussel system on leading edge. |
Spring sails
Spring sails were invented by the Scottish millwright Andrew Meikle in 1772. Andrew Meikle (1719 &ndash 27 November 1811) was an early Mechanical engineer credited with in about 1786 inventing (though some say he only improved The sail is divided into a number of bays with each bay having a number of shutters in it. All of the shutters are joined together by the shutter bar, and the force required for the wind to open the shutters is adjusted by a separate spring on each individual sail. A spring is a flexible elastic object used to store mechanical Energy. Although automatic in operation, the mill needs to be stopped in order to adjust the reefing of the sail. [1]
 Open |
Roller Reefing sails
Roller Reefing sails were invented by Stephen Hooper in 1789. As with Spring Sails, the sail is divided into a number of bays. Each bay has a number of spars, with cloth wound around it. The cloth is extended or retracted by a rod and lever system, and connected with a shutter bar on each sail. Adjustment of the roller reefing sail can be made without stopping the mill. This type of sail was popular in Yorkshire, although the only remaining mill with Roller Reefing sails intact is Ballycopeland Windmill in Northern Ireland. Yorkshire is a historic county of Northern England and the largest in Great Britain. Ballycopeland Windmill (Muileann gaoithe Bhaile Chóplainn is a functioning windmill near Millisle, County Down. Northern Ireland (Tuaisceart Éireann Ulster Scots: Norlin Airlann) is a Country within the United Kingdom, lying in the northeast of
 Furled |
Patent sails
Patent sails were invented by William Cubitt in 1813. } Sir William Cubitt (1785-1861 was an eminent English Civil engineer and Millwright. They combine the shutters of the spring sail with the automatic adjustment of the roller reefing sail. Their construction is similar to that of the spring sail. Adjustment of patent sails can be made without stopping the mill. [1]
- Air brakes
In 1860, the English millwright Catchpole fitted an automatic air brake to the end patent sails. These were longitudinal shutters at the tip of each sail, which opened up if the wind got too strong, thus slowing the sail. [1]
 Open |
 Closed |
French System
In France some mills have a system with longitudinal shutters running the length of the sail. This article is about the country For a topic outline on this subject see List of basic France topics. These sails can be adjusted without stopping the mill.
 Closed |
 Open |
Annular Sails
A few mills had Annular sails, forming a circle. These sails utilised the patent system, enabling adjustment to be made without stopping the mill. One example of a mill with annular sails was at Feltwell, Norfolk. Feltwell is a village 10 miles west of Thetford, Norfolk, England and is in the borough of King's Lynn and West Norfolk. Norfolk (ˈnɔrfək is a low-lying county in East Anglia, England, United Kingdom. [3] Others are known to have existed at Haverhill, Suffolk,[4] Boxford, Suffolk and Roxwell, Essex. Haverhill is the name of a number of different places in the world Haverhill Suffolk, in England Haverhill Florida, USA Suffolk (ˈsʌfək is a non-metropolitan county of historic origin in East Anglia, England. Boxford may refer to Boxford Berkshire, England Boxford Suffolk, England Boxford Massachusetts, United States Suffolk (ˈsʌfək is a non-metropolitan county of historic origin in East Anglia, England. Essex is a county in the East of England. The County town is Chelmsford, and the highest point of the county is Chrishall Common [5]
Spring Patent sails
Spring Patent sails have a spring to enable each sail to be adjusted individually, with the patent sail system allowing all sails to be adjusted without stopping the mill. The system was not a common one.
References
- ^ a b c d e f The important exterior features of a windmill. Odur. net. Retrieved on 2008-04-30. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 313 - Roman emperor Licinius unifies the entire Eastern Roman Empire under his rule
- ^ Pronounced "Ten Halve"
- ^ Feltwell Wilton Road postmill. Norfolk mills. Retrieved on 2008-04-30. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 313 - Roman emperor Licinius unifies the entire Eastern Roman Empire under his rule
- ^ The Old Windmills of Haverhill. Haverhill website. Retrieved on 2008-04-30. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 313 - Roman emperor Licinius unifies the entire Eastern Roman Empire under his rule
- ^ Farries, Kenneth G (1985). Essex Windmills, Millers and Millwrights; Volume Four - A Review by Parishes, F - R. Cheddar: Charles Skilton Ltd, p126-128. ISBN 0 284 98647 X.
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