Wing-drive

Discussion in 'Sailboats' started by Kjell Dahlberg, Feb 27, 2005.

  1. Sailing4Fun
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    Sailing4Fun New Member

    Ugly?

    Not sure if this has been mentioned .... but beyond the arguments on efficiency and performance .... let look at one of the real selling points of sail boats ... THEY ARE VISUALLY APPEALING ... this design is ... well ... in my opinion ... ULGY

    Nothing worse then an ugly boat
     
  2. kjell
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    kjell Senior Member

    Thanks for your opinion.
     

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  3. RHough
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    RHough Retro Dude

    Yes. To be very clear:

    A combination of main and jib that total X ft^2 can operate at CL = 2.0+

    A single foil operates in the 1.2-1.5 CL range.

    So yes, a traditional Main and Jib (a multi-element foil system) will have more lift than a single element foil.

    The AOA for maximum lift is something like 15-16 degrees greater than the zero lift AOA. For a symmetrical foil the zero lift AOA is 0 and maximum lift is about AOA = 15 degrees (IIRC).

    In any case, the the CL vs AOA relationship is linear. The theoretical relationship for a 2D foil is 0.1097 CL per degree, at 15 degrees that gives CL=1.6449

    The 2D lift line is for a foil of infinite span. A 3D foil has a lift line slope that is lower than the 2D theory depending on Aspect Ratio and the Oswald efficiency factor (in aircraft the interference of a fuselage or gap in the span).

    The apparent lift curve slope of a 3D planform is closer to:

    a = a0 / (1 + a0 * 57.3 / (pi * AR * e))

    a = 3D lift curve slope, per deg
    a0 = 2D lift curve slope, per deg
    AR = aspect ratio
    e = Oswald efficiency factor

    The profile of the section is not considered, since profile has no effect on the lift line slope. The camber of the foil effects the zero lift angle compared to the geometric chord line, but does not effect the slope of the lift line.
     
  4. CT 249
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    CT 249 Senior Member

    But to some extent, beauty is what you are used to isn't it? Many boats that we currently think are beautiful or at least attractive were thought ugly in earlier days and vice versa. The classic example is the magnificent royal yacht Brittania (the classic 130' English cutter). Her own designer Watson wrote about the fact that while he had been able to get used to the "ugly" clipper bow (a shape we now love) he didn't think ANYONE would ever love the "spoon bow" of Brittania.

    Of course, today we revere the spoon bow of Britannia, the metre boats, Dragons and J classers, we get into rhapsodies about the clipper bow, and we don't like boats with vertical stems (which were thought beautiful in Watson's early days).

    I'm not sure about the real life efficiciency of wing sails * but they can look attractive and given time, we'd think a nice wingsail was as beautiful as the wing of a Spitfire,t eh gaff of a Friendship, or the bonnet of a Bugatti.

    * they have been tried many times, from the 1940s on, in racing classes; International Canoes, Moths, 18 square and C Class cats. Only in the latter, which are stable boats where low drag is incredibly important (if I'm correct) are they dominant - and even there, they took a long while to beat the soft sails and didn't always achieve that.

    They may be like wing masts (which I use and enjoy) in that the theoretical advantages are often hidden in practise. They've been tried in various classes for about 70 years and apart from a few quite distinctive monos (fairly stable but efficient boats with fairly small sails ie NS14s, Tasars) and some multis, they remain unproven.

    Like 'em as I do, it seems that when many of the best designers (Bethwaite, Curry etc) and classes have tried and abandoned them (including Suicides, Moths IIRC, windsurfers, Flying Ants, Cherubs, 18' Skiffs, Canoes, 12' Skiffs, R Class, Renjolle etc) the only possible conclusion I can draw is that the theory doesn't match up with reality and therefore the theory must be wrong (or rather, it doesn't allow for all the factors).
     
  5. wingsails
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    wingsails Kim Prentis

    The sailing club does not exist at Copeton any more I just try against others that sail there. If you are interested there is a very active club at Keepit Dam between Tamworth and Gunnedah. I ad a run there but embarrassed myself and got beaten severely, Found later some gravel got stuck in the wing pivot so it couldn't track, not a problem at sea but country roads are a different thing. Let me know if you would like a trip out and will try to meet you. They are a pretty good crew out there but the breezes can be tricky, Kim
     
  6. wingsails
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    wingsails Kim Prentis

    Has anyone seen a conventional rig track the wind automatically yet?
     
  7. RHough
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    RHough Retro Dude

    No, that is one of the strong points in favour of the wing systems. :)

    The ability to use trim as a throttle and just point the boat is very clever and reduces the workload for the crew.

    If the system is properly designed it should sail quite nicely. If the CE of the wing system is not placed correctly however, it cannot be trimmed to bring an out of balance helm back into balance. This would limit its use on boats that change helm balance with heel (most Mono's) and makes it well suited to catamarans.
     
  8. Ari
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    Ari Patience s/o Genius

    If the system is properly designed it should sail quite nicely. If the CE of the wing system is not placed correctly however, it cannot be trimmed to bring an out of balance helm back into balance. This would limit its use on boats that change helm balance with heel (most Mono's) and makes it well suited to catamarans.[/QUOTE]I had been following this discussion with real interest, hope you don't mind elaborating on on the highlighted part. My intention is to use free standing mast coupled with Dragon Wing - old Chinese junk wing sail on my motor sailor.
     
  9. RHough
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    RHough Retro Dude

    I had been following this discussion with real interest, hope you don't mind elaborating on on the highlighted part. My intention is to use free standing mast coupled with Dragon Wing - old Chinese junk wing sail on my motor sailor.[/QUOTE]

    Sure, as a boat heels the drive force of the sails becomes further off the centerline. The distance between the hull's resistance and the sails drive tries to turn the boat. Most sailing boats have increasing weather helm as the boat heels for this reason.

    A catamaran does not heel as much as a mono, so the sail effort is not as far from the centerline of the boat, plus the leeward hull has increased resistance that will balance out the sail force.

    On a split rig, the fore and aft sails can be trimmed at different angles to better balance the boat. Too much weather helm is helped by easing the aft sail and trimming the forward sail. Lee helm is corrected in the reverse (Trim aft and ease forward). A really well designed boat can be steered and balanced to be self steering with sail trim and the rudder locked.

    With a freely rotating sail (not sheeted to the boat) like the wing drives in this thread, placing the mast in the right position will have a great effect on how the boat sails. Too far forward and it will take too much rudder to turn the boat into the wind, too far aft and it will be hard to turn the boat downwind. The ideal for good performance when sailing up wind is to created a bit of weather helm with the rig and have to set the rudder to turn the boat away from the wind, this makes the lift from the rudder work with the lift from the keel or daggerboard(s) to reduce leeway and sail closer to the wind. If the rig is too far forward it will want to turn downwind (lee helm) and the rudder force to keep it turned into the wind fights the keel and increases leeway.

    A boat with two self tending wing rigs would be very easy to balance on a monohull. A 80/20 or 90/10 split of area would allow the large wing to work hard and create a bit of lee helm and the small wing could be use to create the bit of weather helm needed to sail upwind. Because the main wing is forward enough to create lee helm, the boat would be stable off the wind as well.
     
  10. Ari
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    Ari Patience s/o Genius

    Thank you RHough. Earlier I thought that this rig is not suitable to mono. After your explanation I'am quite clear about it's application and expected behaviour on a mono.
     
  11. kjell
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    kjell Senior Member

    To be able to keep the Wing-Drive inside the beam of the mono hull it has to be spitted in to two smaller Wing-Drives. As smaller the wings are. Easier to build and install.
     

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  12. Andy P
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    Andy P Junior Member

    [​IMG]

    So is this still the only actual wing sail boat?
     
  13. kjell
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    kjell Senior Member


    Yes. This is my test bench with the possibility to show how it works. After three years of excellent test results I offer my idea to the modern sailing world.
     
  14. wingsails
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    wingsails Kim Prentis


    Have a look at www.wingsails.net .my tri is there and also the cat with 1 wing ,have added an extra wing to the cat and sold it pictures not up yet.
    There are lots of others too .f you do a search on wingsails thru google etc
     

  15. wingsails
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    wingsails Kim Prentis

    Here is an older picture of the tri. A spitfire wing it is not , YET but working on it.
     

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