611:
256:
441:
453:
378:, 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.
465:
477:
71:
83:
535:
429:
489:
176:
47:
140:
188:
551:
523:
316:
128:
221:
268:
152:
59:
304:
164:
412:
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
399:
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
104:
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
361:
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
625:
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
236:
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.
287:
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.
296:
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.
394:
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
209:
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
348:
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.
417:
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
331:
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.
558:
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
610:
654:, 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
513:
749:
428:
36:
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
452:
40:
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).
440:
366:
to invent a similar system, though with just a more rounded airfoil replacing the leading boards and not covering the stock itself.
464:
476:
757:
508:
some mills have a system of longitudinal shutters running the length of the sail. The system, invented in 1842, is called
914:
898:
724:
214:
on each sail. Although automatic in operation, the mill must be stopped in order to adjust the reefing of the sail.
70:
488:
255:
237:
Adjustment of the roller reefing sail can be made without stopping the mill. This type of sail was popular in
139:
627:
618:
187:
82:
868:
847:
631:
534:
357:
The Dutch millwright A. J. Dekker improved on the efficiency of the common sail. The stock is given an
822:
595:
522:
26:. Sails are found in different forms, from primitive common sails to the advanced patent sails.
242:
753:
46:
8:
614:
434:
Ten Have sails open on one stock, common sails on the other, both with van Bussel system.
175:
947:
567:
315:
894:
779:
720:
685:
396:
344:, the common sail predominates. During the nineteenth and twentieth centuries, Dutch
58:
835:
Le
Saumurois des moulins & des meuniers: heurs et malheurs de la meunerie Ă vent
891:
Essex
Windmills, Millers and Millwrights; Volume Four - A Review by Parishes, F - R
591:
575:
246:
267:
127:
413:
airbrake disturbs the airfoil shape thereby slowing the mill. It was invented by
211:
151:
220:
422:
where the leading edge and the airbrake together form a more complete airfoil.
391:
284:
163:
941:
801:
206:
550:
303:
341:
345:
241:, although the only remaining mill with roller reefing sails intact is
121:. The mill must be stopped in order to adjust the reefing of the sail.
590:. Annular sails were also employed on large wind engines, such as the
915:"In somber ceremony, Dutch receive the first remains of MH17 victims"
599:
386:
The Fok system, invented by engineer P.L. Fauël, was inspired by the
238:
559:
101:
19:
583:
579:
571:
563:
414:
358:
37:
651:
505:
375:
587:
458:
Ten Have sail closed with Van Bussel streamline leading edge.
363:
647:
630:
and during the day of national mourning for victims of the
419:
919:
516:. These sails can be adjusted without stopping the mill.
387:
626:
mourning at national events, for example the death of
617:
windmill in mourning position following the death of
719:. Deventer-Antwerpen: Kluwer Technische Boeken B.V.
16:
Aerofoil for converting wind energy to rotary motion
893:. Cheddar: Charles Skilton Ltd. pp. 126–128.
205:Spring sails were invented by Scottish millwright
446:Dekkerised sails with air brake and patent system
100:The common sail is the simplest form of sail. In
939:
780:"The important exterior features of a windmill"
686:"The important exterior features of a windmill"
717:Wieksystemen voor polder- en industriemolens
482:Close-up of Fok system with spread sailcloth
362:Dekker system led millwright Van Bussel of
861:
750:"Braamtse Molen te Braamt, Over de Molen"
374:Invented by Dutch millwright Ten Have of
609:
549:
888:
840:
231:
940:
816:
710:
708:
706:
704:
702:
680:
678:
676:
674:
672:
670:
566:. Others are known to have existed at
326:
742:
470:Close-up of Fok system with air brake
882:
794:
772:
714:
699:
667:
619:Queen Wilhelmina of the Netherlands
335:
13:
823:de:WindmĂĽhle#Bilausche Ventikanten
733:
14:
959:
408:Bilau Ventisails/ Van Riet system
869:"The Old Windmills of Haverhill"
642:Sails are colloquially known as
605:
545:
533:
521:
512:, commemorating their inventor,
487:
475:
463:
451:
439:
427:
390:on a sailing boat ('fok' is the
314:
302:
266:
254:
219:
186:
174:
162:
150:
145:First reef (Medieval style sail)
138:
126:
81:
69:
57:
45:
907:
848:"Feltwell Wilton Road postmill"
499:
278:
200:
193:Full sail (Medieval style sail)
95:
827:
494:Mill equipped with Bilau sails
283:Patent sails were invented by
1:
661:
31:
7:
889:Farries, Kenneth G (1985).
632:Malaysia Airlines Flight 17
10:
964:
353:Dekker / Van Bussel system
76:St Mary's, Isles of Scilly
88:Cann Mills, Melbury Abbas
637:
833:Nicolas Jolivot, 1994.
554:Crux Easton wind engine
514:Pierre-Théophile Berton
739:Pronounced "Ten Halve"
622:
555:
243:Ballycopeland Windmill
613:
553:
22:are powered by their
802:"Pride and Priority"
754:De Hollandsche Molen
715:Pouw, G. J. (1982).
232:Roller reefing sails
871:. Haverhill website
528:Berton sails closed
382:Fauël or Fok system
327:Spring patent sails
760:on 29 October 2014
623:
556:
370:Ten Have / Beckers
782:. odur.let.rug.nl
540:Berton sails open
397:leading edge slot
64:More fully spread
955:
933:
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814:
813:
811:
809:
798:
792:
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789:
787:
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769:
767:
765:
756:. Archived from
746:
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731:
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712:
697:
696:
694:
693:
682:
537:
525:
491:
479:
467:
455:
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336:Dutch sail types
318:
306:
270:
258:
247:Northern Ireland
223:
190:
178:
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142:
130:
85:
73:
61:
49:
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924:
913:
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887:
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874:
872:
867:
866:
862:
853:
851:
850:. Norfolk mills
846:
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832:
828:
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548:
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134:
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98:
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77:
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65:
62:
53:
50:
34:
17:
12:
11:
5:
961:
951:
950:
935:
934:
923:. 23 July 2014
906:
899:
881:
860:
839:
826:
815:
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771:
741:
732:
725:
698:
665:
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337:
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328:
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294:
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285:William Cubitt
280:
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68:
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56:
54:
51:
44:
33:
30:
15:
9:
6:
4:
3:
2:
960:
949:
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916:
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900:0-284-98647-X
896:
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797:
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728:
726:90-201-1479-4
722:
718:
711:
709:
707:
705:
703:
687:
681:
679:
677:
675:
673:
671:
666:
659:
657:
656:patent sweeps
653:
649:
645:
635:
633:
629:
620:
616:
612:
606:Communication
603:
601:
597:
593:
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569:
565:
561:
552:
546:Annular sails
536:
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207:Andrew Meikle
198:
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84:
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60:
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48:
43:
42:
41:
39:
29:
27:
25:
21:
925:. Retrieved
918:
909:
890:
884:
873:. Retrieved
863:
852:. Retrieved
842:
834:
829:
818:
806:. Retrieved
796:
786:29 September
784:. Retrieved
774:
762:. Retrieved
758:the original
752:(in Dutch).
744:
735:
716:
690:. Retrieved
655:
643:
641:
628:Prince Friso
624:
557:
510:Ailes Berton
509:
503:
500:Berton sails
411:
401:
385:
373:
356:
339:
330:
295:
282:
279:Patent sails
235:
204:
201:Spring sails
197:
169:Dagger point
118:
114:
111:dagger point
110:
106:
99:
96:Common sails
92:
35:
28:
23:
18:
596:Crux Easton
346:millwrights
342:Netherlands
157:Sword point
115:sword point
875:2008-04-30
854:2008-04-30
764:29 October
692:2008-04-30
688:. Odur.net
662:References
594:engine at
292:Air brakes
119:first reef
948:Windmills
808:16 August
600:Hampshire
568:Haverhill
402:see photo
239:Yorkshire
181:Full sail
107:full sail
52:Jib sails
32:Jib sails
20:Windmills
942:Category
837:pp 68ff.
804:. Musker
560:Feltwell
273:Unfurled
102:medieval
927:24 July
621:in 1962
615:De Valk
584:Roxwell
580:Suffolk
576:Boxford
572:Suffolk
564:Norfolk
359:airfoil
340:In the
38:reefing
897:
723:
652:Sussex
644:sweeps
506:France
415:German
376:Vorden
321:Closed
261:Furled
212:spring
133:Furled
638:Notes
588:Essex
392:Dutch
364:Weert
24:sails
929:2014
895:ISBN
810:2009
788:2009
766:2014
721:ISBN
650:and
648:Kent
592:Titt
582:and
420:Goes
309:Open
226:Open
117:and
105:are
920:CNN
646:in
504:In
404:).
388:jib
245:in
944::
917:.
701:^
669:^
658:.
634:.
602:.
598:,
586:,
578:,
574:,
570:,
562:,
249:.
113:,
109:,
931:.
903:.
878:.
857:.
812:.
790:.
768:.
729:.
695:.
400:(
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
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