America's Cup - Wing profile

Discussion in 'Multihulls' started by Viktor from Cze, Jul 3, 2013.

  1. Viktor from Cze
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    Viktor from Cze Junior Member

    Hello,
    do you know any information about profiles of wing in 34th AC??? There are some pictures but no descriptions like "NACA .... or whatever... I'm traing to design my own wing for Open 18 (for catamaran F 18 - I'm from Czech Republic and at this moment we don't have any experience with wing sail technology, but we would like to start...). At this moment I use NACA 0018-83, and NACA 0010-73 drom X-Wing system... but I think, there are many chances....

    Thank you very much for your help!

    Viktor
     
  2. Doug Lord
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    Doug Lord Flight Ready

  3. PAR
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    PAR Yacht Designer/Builder

    Flow dynamics is still flow dynamics. You can bet the AC boats aren't using NACA 00 series sections, but the bottom line is you'll need to select your sectional shapes around the performance expectations the yacht will experience. Most selections will require some testing, which is costly, but you should be able to get close with some honest questions about the performance envelop, your boat as potential for.
     
  4. DCockey
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    DCockey Senior Member

    My guess is the AC 72's are using custom sections, not "off-the-shelf" sections. And I wouldn't be surprised if the section shape varies along the span rather than being a single section shape for the entire wing.
     
  5. PAR
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    PAR Yacht Designer/Builder

    You can bet the sections vary David. I'll offer 10:1 odds they do.
     
  6. tomas
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    tomas Senior Member

    I think so too.

    Main foil on Luna Rosa's AC 72
    (doug found this picture)

    [​IMG]
     
  7. PAR
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    PAR Yacht Designer/Builder

  8. tomas
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    tomas Senior Member

    Oops.

    :eek:





    (Doug has succeeded in drilling the AC foils into my brain. )
     
  9. Red Dwarf
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    Red Dwarf Senior Member

    Actually that's the new Bondo series foil.:p

    I have no idea what is going on in that picture. Those are not templates for checking the section and wood parts look pretty useless. I have faired in a high performance glider wing (every damn year) and it does not work like that picture.
     
  10. PAR
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    PAR Yacht Designer/Builder

    It appears the wood is just to support the paper templates vertically.
     
  11. Petros
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    Petros Senior Member

    almost certainly they have a three dimentional surface designed by CFD. They have been designing aircraft wings that way for almost 40 years, it is really incorrect to refer to it as a "section", it is a complete shape that they tweak to get the desired pressure distribution. the software generates pressure maps that look like topographical maps; these are checked for various speeds and angle of attacks. and with each iteration they change and alter the full shape, twist, thinkness, camber, etc of the surface along its entire length.

    Not likely they will publish the full geometry of the surface, they spend a LOT of money developing that shape. They will not give it away.

    So you are on your own if you want to copy it.
     
  12. PAR
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    PAR Yacht Designer/Builder

    Agreed Petros, but templates used in that fashion are sectional., besides this is what most understand and the two fairing that foil probably can't spell CFD, but can check for gaps under that section profile.
     
  13. CT 249
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    CT 249 Senior Member

    A few years ago when this question was asked here or on SA, Steve Clark said something to the effect of "sections don't matter, just work out how to build it so it works."

    Steve, Mark Drela and Tom Speer have posted a lot here and Steve and Tom have posted on SA, so you have a priceless opportunity to learn from some of the best sources around.
     
  14. philSweet
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    philSweet Senior Member

    I think they are trying to capture the profile with a putty backed by wood.
     

  15. Red Dwarf
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    Red Dwarf Senior Member

    Yes that seems to make most sense. But they are going at it in such a half a$$ way that it is hard to believe. Those templates are just thrown together with poor repeatability and no way to reference one template to another and to a datum.

    With the budget they have they should use a Faro arm or the Faro laser tracker either of which will take one tenth the time and 100 times more accurate.

    So I wonder why all the Bondo is on there. Is the mold so bad it took that much bondo to fair the surface? Hence the loss of control over the profile.
     
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