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Mast Head T Foil?
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Rupert View Drop Down
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    Posted: 30 Oct 14 at 10:42am
That 2nd one has it filled with lighter than air gas, too, which I suspect sums up the whole project.
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Posts: 107 		Post Options Post Options   Quote hobbiteater Quote  Post ReplyReply Direct Link To This Post Posted: 30 Oct 14 at 11:26am
Originally posted by Medway Maniac

None of which appears to explain why winglets are used on competition-winning gliders, and we are more interested in pressure coefficients and moments than they are.

most gliders are span limited, by class (15m, 18m, 20m) or by structural considerations (a 0.3m winglet gives an equivalent span increase of 1m so is much lighter). 

there are also handling benefits not applicable to sails.

they dont fly inverted (which sails do - port or stbd tack)
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Medway Maniac View Drop Down
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Posts: 2788 		Post Options Post Options   Quote Medway Maniac Quote  Post ReplyReply Direct Link To This Post Posted: 30 Oct 14 at 12:38pm
We're span-limited too - most class rules limit the mast length.

I like the idea of a 0.3m winglet (or pair thereof) instead of a 1m longer mast which would add about a kilo of mast higher up (alu. rig). Lower c.of.e. too.
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Posts: 6662 		Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 30 Oct 14 at 12:46pm
We have to be symmetrical though, so need an identical structure each side which increases the weight and hugely complicates the aerodynamics compared to the glider.
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Medway Maniac View Drop Down
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Posts: 2788 		Post Options Post Options   Quote Medway Maniac Quote  Post ReplyReply Direct Link To This Post Posted: 30 Oct 14 at 1:52pm
Airbus winglet. Not quite symmetrical, but shows that pressure side fences are not without benefits:

http://commons.wikimedia.org/wiki/File:Winglet_Airbus_A319-132.jpg
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Posts: 2143 		Post Options Post Options   Quote getafix Quote  Post ReplyReply Direct Link To This Post Posted: 30 Oct 14 at 6:38pm
Interesting stuff, would a winglet at the mast head that could be spun around be the answer? this as an effort to overcome the symetrical 'issue' which would result in a t-foil type structure, I'm thinking more "L" than "T", just t'other way up with a kind of mast-spanner or wheel effort (with pulley arrangement) at the mast base to provide the spin. Even better, a system allowing the <wing> mast's rotation to govern the winglets' angle via an off-set pulley system connected to 'arms' off the base of the mast


Edited by getafix - 30 Oct 14 at 6:41pm
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Medway Maniac View Drop Down
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Posts: 2788 		Post Options Post Options   Quote Medway Maniac Quote  Post ReplyReply Direct Link To This Post Posted: 30 Oct 14 at 7:50pm
Winglets seem to work best near the trailing edge where the vortex is building to its maximum energy, so the foil would really need to be near the leech of a square top sail for best effect - tricky to arrange.
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mole View Drop Down
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Posts: 43 		Post Options Post Options   Quote mole Quote  Post ReplyReply Direct Link To This Post Posted: 30 Oct 14 at 8:48pm
These model yacht guys have been doing it for some time.

http://www.users.on.net/~malcolmandjane/750/750picsJ.html

Edited by MerlinMags - 03 Nov 14 at 7:48am
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Posts: 107 		Post Options Post Options   Quote hobbiteater Quote  Post ReplyReply Direct Link To This Post Posted: 31 Oct 14 at 9:22am
Originally posted by Medway Maniac

Airbus winglet. Not quite symmetrical, but shows that pressure side fences are not without benefits:

http://commons.wikimedia.org/wiki/File:Winglet_Airbus_A319-132.jpg

unfortunately not even close to being aerodynamically symmetrical even if it looks similar geometrically.
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Posts: 1005 		Post Options Post Options   Quote fab100 Quote  Post ReplyReply Direct Link To This Post Posted: 31 Oct 14 at 11:36pm
Will the winglet need a winglet?
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