622:
389:, Ten Have sails have a small number of wide longitudinal shutters, operating by centrifugal weights and often also by the miller at the tail of the mill similar to patent sails. This way the sail can be adjusted without stopping the mill. The leading edge is commonly streamlined by the Van Bussel system. Ten Have shutters are normally only used on one stock as the wide Ten Have shutters standing open on a vertical stock would leave this stock vulnerable to side winds during a storm. Beckers sails are an alternative to Ten Have sails. Only two mills in the Netherlands were fitted with them.
267:
452:
464:
476:
488:
82:
94:
546:
440:
500:
187:
58:
151:
199:
562:
534:
327:
139:
232:
279:
163:
70:
315:
175:
423:
The Bilau system uses sails with a streamline covering of the stock, coupled with a full length air brake on the trailing edge, together forming an airfoil. The airbrake is opened by centrifugal weights in the sails but can also be operated by the miller similar to the patent system. When opening the
410:
on an aircraft wing. It enables the mill to work in a lower windspeed but in variable windspeeds tends to make it difficult to have the mill run at a steady pace. For this reason it is often equipped with air brakes operating by centrifugal force. The Fauël system is used in addition to common sails
115:
mills, the sailcloth was wound in and out of a ladder-type arrangement of sails. Medieval sails could be constructed with or without outer sailbars. Post-medieval mill sails have a lattice framework over which the sailcloth is spread. There are various "reefs" for the different spread of sails; these
372:
shape by completely covering it with galvanised steel plates. Dekkerised sails provide enough surface area to be able to work the mill with no sailcloth spread if the wind is strong enough. As with the common sail, they are not adjustable except by adding more sailcloth. Some disadvantages of the
636:
In the
Netherlands the position of the sails can be used as a means of communication to display joy or mourning. These sail positions are generally used by the miller to show for example a birth, marriage or death within his family or circle of friends but may occasionally also be used to show
247:
Roller reefing sails were invented by
Stephen Hooper in 1789. As with spring sails, the sail is divided into a number of bays, each with a number of spars with cloth wound around them. The cloth is extended or retracted by a rod and lever system, and connected with a shutter bar on each sail.
298:
in 1807. They combine the shutters of the spring sail with 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.
621:
307:
In 1860, the
English millwright Catchpole fitted an automatic air brake to the ends of 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.
405:
word for jib). In this design the leading boards are replaced by a rounded profile of wooden slats in the form of a foresail leaving a small slot between this profile and the stock. Its working principle can be compared to a
220:
in 1772. The sail is divided into a number of bays, each having a number of shutters. All the shutters are joined together by a shutter bar, and the force required for the wind to open the shutters is adjusted by a separate
359:
developed the windmill sail to make it more efficient aerodynamically and operation easier in an effort to keep the traditional windmill economically viable in competition with factories and electric pumping stations.
428:
airplane engineer Kurt Bilau early in the twentieth century and became quite popular in
Germany where it was fitted to over 140 mills. A similar system was invented by a millwright by the name of Van Riet of
342:
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.
569:
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
665:, primarily due to the physical movement they perform and also that their construction does not necessarily involve sailcloth or canvas. Hence, patent sails are referred to as
439:
463:
760:
451:
47:
The jib sail is found in
Mediterranean countries and consists of a simple triangle of cloth wound round a spar. The mill must be stopped in order to adjust the
51:
of the sail. Though rare in the UK, at least two windmills are known to have had jib sails (St Mary's, Isle of Scilly and Cann Mills, Melbury Abbas).
475:
487:
266:
909:
735:
377:
to invent a similar system, though with just a more rounded airfoil replacing the leading boards and not covering the stock itself.
81:
499:
768:
93:
150:
638:
629:
519:
some mills have a system of longitudinal shutters running the length of the sail. The system, invented in 1842, is called
198:
925:
642:
545:
225:
on each sail. Although automatic in operation, the mill must be stopped in order to adjust the reefing of the sail.
533:
248:
Adjustment of the roller reefing sail can be made without stopping the mill. This type of sail was popular in
524:
606:
879:
858:
253:
57:
368:
The Dutch millwright A. J. Dekker improved on the efficiency of the common sail. The stock is given an
833:
186:
764:
326:
958:
578:
37:. Sails are found in different forms, from primitive common sails to the advanced patent sails.
905:
731:
407:
138:
69:
278:
602:
586:
257:
231:
162:
222:
625:
445:
Ten Have sails open on one stock, common sails on the other, both with van Bussel system.
561:
402:
295:
174:
952:
790:
696:
355:, the common sail predominates. During the nineteenth and twentieth centuries, Dutch
217:
846:
Le
Saumurois des moulins & des meuniers: heurs et malheurs de la meunerie Ă vent
314:
902:
Essex
Windmills, Millers and Millwrights; Volume Four - A Review by Parishes, F - R
424:
airbrake disturbs the airfoil shape thereby slowing the mill. It was invented by
352:
433:
where the leading edge and the airbrake together form a more complete airfoil.
356:
812:
610:
249:
17:
570:
112:
30:
594:
590:
582:
574:
425:
369:
252:, although the only remaining mill with roller reefing sails intact is
132:. The mill must be stopped in order to adjust the reefing of the sail.
48:
601:. Annular sails were also employed on large wind engines, such as the
926:"In somber ceremony, Dutch receive the first remains of MH17 victims"
662:
516:
397:
The Fok system, invented by engineer P.L. Fauël, was inspired by the
386:
620:
598:
560:
374:
658:
430:
930:
398:
469:
Ten Have sail closed with Van Bussel streamline leading edge.
641:
and during the day of national mourning for victims of the
527:. These sails can be adjusted without stopping the mill.
637:
mourning at national events, for example the death of
628:
windmill in mourning position following the death of
730:. Deventer-Antwerpen: Kluwer Technische Boeken B.V.
27:
Aerofoil for converting wind energy to rotary motion
904:. Cheddar: Charles Skilton Ltd. pp. 126–128.
216:Spring sails were invented by Scottish millwright
457:Dekkerised sails with air brake and patent system
111:The common sail is the simplest form of sail. In
791:"The important exterior features of a windmill"
697:"The important exterior features of a windmill"
8:
728:Wieksystemen voor polder- en industriemolens
493:Close-up of Fok system with spread sailcloth
373:Dekker system led millwright Van Bussel of
761:"Braamtse Molen te Braamt, Over de Molen"
385:Invented by Dutch millwright Ten Have of
677:
529:
435:
310:
262:
227:
134:
53:
721:
719:
717:
715:
713:
691:
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683:
681:
577:. Others are known to have existed at
481:Close-up of Fok system with air brake
7:
630:Queen Wilhelmina of the Netherlands
834:de:WindmĂĽhle#Bilausche Ventikanten
25:
419:Bilau Ventisails/ Van Riet system
880:"The Old Windmills of Haverhill"
653:Sails are colloquially known as
544:
532:
523:, commemorating their inventor,
498:
486:
474:
462:
450:
438:
401:on a sailing boat ('fok' is the
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313:
277:
265:
230:
197:
185:
173:
161:
156:First reef (Medieval style sail)
149:
137:
92:
80:
68:
56:
859:"Feltwell Wilton Road postmill"
204:Full sail (Medieval style sail)
505:Mill equipped with Bilau sails
294:Patent sails were invented by
1:
900:Farries, Kenneth G (1985).
643:Malaysia Airlines Flight 17
975:
364:Dekker / Van Bussel system
87:St Mary's, Isles of Scilly
99:Cann Mills, Melbury Abbas
844:Nicolas Jolivot, 1994.
565:Crux Easton wind engine
525:Pierre-Théophile Berton
750:Pronounced "Ten Halve"
633:
566:
254:Ballycopeland Windmill
624:
564:
33:are powered by their
813:"Pride and Priority"
765:De Hollandsche Molen
726:Pouw, G. J. (1982).
243:Roller reefing sails
882:. Haverhill website
539:Berton sails closed
393:Fauël or Fok system
338:Spring patent sails
771:on 29 October 2014
634:
567:
381:Ten Have / Beckers
793:. odur.let.rug.nl
551:Berton sails open
408:leading edge slot
75:More fully spread
16:(Redirected from
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767:. Archived from
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708:
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347:Dutch sail types
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258:Northern Ireland
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861:. Norfolk mills
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934:. 23 July 2014
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296:William Cubitt
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911:0-284-98647-X
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737:90-201-1479-4
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672:
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668:
667:patent sweeps
664:
660:
656:
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617:Communication
616:
614:
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557:Annular sails
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218:Andrew Meikle
211:
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59:
54:
52:
50:
42:
40:
38:
36:
32:
19:
936:. Retrieved
929:
920:
901:
895:
884:. Retrieved
874:
863:. Retrieved
853:
845:
840:
829:
817:. Retrieved
807:
797:29 September
795:. Retrieved
785:
773:. Retrieved
769:the original
763:(in Dutch).
755:
746:
727:
701:. Retrieved
666:
654:
652:
639:Prince Friso
635:
568:
521:Ailes Berton
520:
514:
511:Berton sails
422:
412:
396:
384:
367:
350:
341:
306:
293:
290:Patent sails
246:
215:
212:Spring sails
208:
180:Dagger point
129:
125:
122:dagger point
121:
117:
110:
107:Common sails
103:
46:
39:
34:
29:
18:Patent sails
607:Crux Easton
357:millwrights
353:Netherlands
168:Sword point
126:sword point
886:2008-04-30
865:2008-04-30
775:29 October
703:2008-04-30
699:. Odur.net
673:References
605:engine at
303:Air brakes
130:first reef
959:Windmills
819:16 August
611:Hampshire
579:Haverhill
413:see photo
250:Yorkshire
192:Full sail
118:full sail
63:Jib sails
43:Jib sails
31:Windmills
953:Category
848:pp 68ff.
815:. Musker
571:Feltwell
284:Unfurled
113:medieval
938:24 July
632:in 1962
626:De Valk
595:Roxwell
591:Suffolk
587:Boxford
583:Suffolk
575:Norfolk
370:airfoil
351:In the
49:reefing
908:
734:
663:Sussex
655:sweeps
517:France
426:German
387:Vorden
332:Closed
272:Furled
223:spring
144:Furled
649:Notes
599:Essex
403:Dutch
375:Weert
35:sails
940:2014
906:ISBN
821:2009
799:2009
777:2014
732:ISBN
661:and
659:Kent
603:Titt
593:and
431:Goes
320:Open
237:Open
128:and
116:are
931:CNN
657:in
515:In
415:).
399:jib
256:in
955::
928:.
712:^
680:^
669:.
645:.
613:.
609:,
597:,
589:,
585:,
581:,
573:,
260:.
124:,
120:,
942:.
914:.
889:.
868:.
823:.
801:.
779:.
740:.
706:.
411:(
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
