Fin Keel Technology

Discussion in 'Boat Design' started by delmarrey, Jul 12, 2007.

  1. delmarrey
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    delmarrey Junior Member

    Some where recently I read and article, I believe a magazine article in a .pfd format, that showed by adding a 15 degree wedge to the front of a fin keel right at the hull joint, that it improves the drag ratio.

    I haven't been able to find that article again and was going to use their formula for my IOR designed vessel.

    Can anyone point me to that article or another that would has the same info??

    Thanks…………………………_/)
     
  2. tspeer
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    tspeer Senior Member

  3. Raggi_Thor
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    Raggi_Thor Nav.arch/Designer/Builder

    Attached Files:

  4. delmarrey
    Joined: Jul 2007
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    delmarrey Junior Member

    Yes Sir, That's it! Just what I was looking for. Thank you very much. I'll bet I can find it in my favorites now by the above address. I must have over a thousand links saved and catagorized but didn't rename this one to ID it well enough.
    Thanks again!
    ..................................................................._/)
     
  5. Pericles
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    Pericles Senior Member

  6. Raggi_Thor
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    Raggi_Thor Nav.arch/Designer/Builder

    Yes, but sailboats operate on more variable angles of attack :)
     
  7. Raggi_Thor
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    Raggi_Thor Nav.arch/Designer/Builder

    Most info i search able, but maybe not ProBoat, because the pages we see are pictures, not text?

    Just remember the very important point: There is no good changing the planform of a keel (or other foil) if you can't keep the correct profile in all sections.
     
  8. tspeer
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    tspeer Senior Member

    The fighter leading edge extensions are for a completely different reason and work in a completely different manner. They exploit separated flow - shedding a vortex that improves lift at high angles of attack as it flows back across the wing. They have sharp leading edges to promote separation as the angle of attack increases. This is not the way to minimize junction drag due separation of the body boundary layer approaching the leading edge.

    The dillet is also a leading edge extension, but its purpose is to eliminate separation at low angles of attack. It is small and rounded. This picture of a Boeing 767 horizontal stabilizer with a dillet shows it from a different angle than the planform sketched in the article above. You can see that it is very different from a fighter's leading edge extension.

    [​IMG]
     

  9. jehardiman
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    jehardiman Senior Member

    Hydro dillets tend to be shaped different then aero dillets. Here is an oblique shot of one, there are very few true beam shots available.

    [​IMG]
     
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