Hydrofoil winglets?

Discussion in 'Multihulls' started by Stefan H, Jan 5, 2010.

  1. lesburn1
    Joined: Oct 2007
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    Location: 40:09:01.3 - 75:07:29.5

    lesburn1 Junior Member

    their winglets have winglets

    Damn, their wing have winglets and their winglets have winglets!
    [​IMG]
     
  2. Munter
    Joined: Jul 2007
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    Munter Amateur

    Keep going lesburn! Soon you'll have that quirky loop keel that somebody was trying to flog on here a few moons ago.
     
  3. daiquiri
    Joined: May 2004
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    daiquiri Engineering and Design

    Doug, regarding Brett Burvill's foiler... Do you remember any figures about speeds attained with this foil configuration?
     
  4. daiquiri
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    daiquiri Engineering and Design

    Private, temporary and off-topic

    You are right, dear anonymous reader - it was all unecessary and uncalled for. But that's what this forum is about, an exchange of opinions... Sometimes right and sometimes wrong ones. ;)
     
  5. Doug Lord
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    Doug Lord Flight Ready

    ----------------------
    Daiquiri, I think it was the very low twenties or high teens. It wasn't until the bi-foiler configuration was used that speed really took off-theres a sort of history of the bi-foiler version in "Moth on Foils" since every class speed record is documented....
     
  6. jehardiman
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    jehardiman Senior Member

    Returning to the original picture of l'Hydroptere inverted, there are a few other features of note.

    The amas are designed with a planing step and look much more like a flying boat float rather than a convential tri's ama.
    The main foils have a deep hollow in the pressure face indicating a leaning towards cavating foils or at least agressive camber forward of the 1/4 cord point. Hovever, photos at http://foils.wordpress.com/2008/12/01/lhydroptere-vise-les-100-kmh/ show little cavitation.
    The main foils have flow fences on thier backs (low pressure side) but not thier faces.
    The rudder/strut has flow fences down its depth.
    The rudder/strut lift foil has winglets on the ends for both the face and back.
     
  7. Chris Ostlind

    Chris Ostlind Previous Member

    Geez, Daiquiri... you got hit too? That's sad

    Opinions are personal expressions. Since you are a guy with your own personal expressions, both for and against, you should already know that they come and they go based on the moment of the expression.... you don't really feel that your expressions are timeless and more important than those belonging to others, do you?

    If you do, that would put you in the same category as Berlusconi and no self-respecting boat guy would want to identify with that particular sociological bent, would they? ;-)
     
  8. daiquiri
    Joined: May 2004
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    daiquiri Engineering and Design

    Noooo Chris... maybe you didn't understand the sense of my post (and you rightly couldn't). :)

    I got a negative rep with a one-word explanation - "necessary?" So, not knowing what was that suppose to mean, I made a guess that the message was "did you really have to write all that crap?" and, based on that, have replied to the anonymous guy, hopefully in an educated way.

    I don't care too much about positive and negative points anymore. Though I did care once... for pure vanity, I guess. Negative reps mean nothing in my (or yours or whoever's) ordinary life and don't give or take anything to my daytime job or to my knowledge. If one disagrees with what he reads, then rather than leaving uncomprehensible comments and negative reps, he can write his opinions down in an argumented post... That is how one can make a difference in other guy's life through this forum, and spread the correct knowledge. A correct knowledge gained in that way is valuable and very appreciated indeed.

    How can I be against other people's expressions anyway? I learn something new each time I come to this forum! :)
     
  9. Chris Ostlind

    Chris Ostlind Previous Member

    So, which one of us gets to be the designated decider of said correct opinion?

    Remember that not all of the information discussed on this Forum is quantifiable. A good deal of it has to be perceived and sorted by other means. Unfortunately, in the rush to explain everything about sailing with math and engineering principals, the obvious part about our humanity just gets pushed aside.

    It's a sad day, indeed, when we forget to honor the most essential component of our make-up... the part that was there long before anyone thought to devise the math aspect with numbers.

    So, I guess that maybe you couldn't rightly understand, either... How could you?
     
  10. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    Look, I truly and sincerely don't understand what you mean... Call me dumb or whatever you want, but I don't. :(
    Where in particular did I loose my humanity in this discussion, according to you?
     
  11. matt H.
    Joined: Jan 2010
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    matt H. Junior Member

    a system of valance , winglets and hull frequencies
    in hopes of achieving a sectional true up ward stability
    using frequencies .to ease the push friction possibility
    of water molecules around surfaces to reduce drag
     
  12. Doug Lord
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    Doug Lord Flight Ready

  13. Max Forkman
    Joined: Aug 2017
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    Max Forkman New Member

    Hi im working with a hydrofoil project now, currently analyzing the effect os using winglets. I wonder if you know where i can read more about the cavitation reduction by using winglets bended towards pressure side you are mentioning in the end of this post. Thanks in advance !
     
  14. OzFred
    Joined: Nov 2015
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    OzFred Senior Member

    Winglet design depends on what you're trying to achieve. In the case of tip vortices, there are other, more efficient approaches such as longer, thinner tips (e.g. Boeing Dreamliner and Team New Zealand AC50 foils). Winglets achieve a similar effect in a shorter span but less efficiently. When designed solely for vortex reduction, they tend to be very small (in comparison to overall span) and toward the trailing edge.

    Winglets are also used as vertical stabilisers, similar to traditional aircraft tails (or centreboards in boats). In that case, they are generally very much larger than those for vortex reduction.

    I'm interested to know how they're applied to reduce cavitation.
     

  15. Barry
    Joined: Mar 2002
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    Barry Senior Member

    Vortices in action
     

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