Foiler Design

Discussion in 'Sailboats' started by tspeer, Nov 12, 2003.

  1. Doug Lord

    Doug Lord Guest

    Thanks,Simon! Sure appreciate these pix..... I figured it out Simon,thanks!
     

    Attached Files:

  2. Tcubed
    Joined: Sep 2008
    Posts: 435
    Likes: 18, Points: 0, Legacy Rep: 318
    Location: French Guyana

    Tcubed Boat Designer

    It is quite an interesting development in near surface foil sections, at least to me, i' ve never seen anything quite like it and it would be very interesting to see some polars for it with some numbers, L/D and so on.
     
  3. fishwics
    Joined: Mar 2004
    Posts: 33
    Likes: 1, Points: 8, Legacy Rep: 10
    Location: UK

    fishwics Quiet member

    Note the leading edge is on the right in each picture.

    Somewhere on this forum are some sketches from Jon Howes and discussion posted about 18 months ago. (Sorry cannot be more precise than that)

    Simon
     
  4. Doug Lord

    Doug Lord Guest

  5. Doug Lord

    Doug Lord Guest

    -------------------------------
    Simon, what does the rudder foil look like? Looks very small-is it a similar section?
    The main foil looks like the aft edge is not sharp-but squared off-is that right?
     
  6. Tcubed
    Joined: Sep 2008
    Posts: 435
    Likes: 18, Points: 0, Legacy Rep: 318
    Location: French Guyana

    Tcubed Boat Designer


    It seems to me that this foil is quite different actually. Follows the second image as referred to in the above quote from Jon. The Tomahawk foil looks like it is designed to have a reattaching flow at certain regimes. Hopefully Jon can shine some light on these speculations. [​IMG]
     
  7. tspeer
    Joined: Feb 2002
    Posts: 2,319
    Likes: 303, Points: 83, Legacy Rep: 1673
    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    This isn't Matveev's material, but I just ran across NACA-RM-L52L11, which has test data for the waves behind a hydrofoil. This should help you locate the aft foil in the upwash from the forward foil.
     
  8. fishwics
    Joined: Mar 2004
    Posts: 33
    Likes: 1, Points: 8, Legacy Rep: 10
    Location: UK

    fishwics Quiet member

    Short chord, but fairly wide span. I suspect it had been borrowed off a Bladerider. (Sorry - didn't pay too much attention to it!)

    Remember this boat is a pre-production model. Production boats are not expected until the middle of the year.

    It's probably as sharp as you can sensibly get it in what looked like a moulded foil. About 1mm thick or somewhat less. About the same size as the steps on the upper surface.


    Simon
     
  9. sigurd
    Joined: Jun 2004
    Posts: 827
    Likes: 8, Points: 18, Legacy Rep: 65
    Location: norway

    sigurd Pompuous Pangolin

    I thought out this leeboard/foil arrangement, for putting under the vaka/ single aka joint of a proa. For my purposes, I wanted pitch moments to be resolved in the air mostly anyway, so it makes more sense to me than two foils, one at each end of vaka. If you were using a rig with a large yaw and pitch moment, then it would not make sense.
    With a kite, those moments can be small, and even automatically changed by towpoint movements.
    With a masted rig, they could be minimized by ama shifting back and forth, and balanced by extra aero surfaces.
     

    Attached Files:

  10. Doug Lord

    Doug Lord Guest

  11. sigurd
    Joined: Jun 2004
    Posts: 827
    Likes: 8, Points: 18, Legacy Rep: 65
    Location: norway

    sigurd Pompuous Pangolin

    Super interesting paper. The drag figures from the hull and tramps makes me wonder why the moths are not doing these things:
    1)Lower freeboard
    2)netting and not fabric tramp
    3)jibing the daggerboard so the hull can point straight into the wind (makes for funny landings at 20kt I guess)
    4)International Canoe style seat instead of tramp (with windward heel the lee tramp is the draggiest one I assume)
    5) if the tramp sail is removed as in 2 and 4 then it may start to make sense to make gunwales more rounded.
    ???
     
    Tcubed likes this.
  12. Doug Lord

    Doug Lord Guest

    Sigurd, I think an IC type sliding seat is against the Moth rules. But new foilers may well take advantage of sliding seats in various forms.
     
  13. ancient kayaker
    Joined: Aug 2006
    Posts: 3,497
    Likes: 147, Points: 0, Legacy Rep: 2291
    Location: Alliston, Ontario, Canada

    ancient kayaker aka Terry Haines

     
  14. sigurd
    Joined: Jun 2004
    Posts: 827
    Likes: 8, Points: 18, Legacy Rep: 65
    Location: norway

    sigurd Pompuous Pangolin

    I think I disagree. The hull/tramp (aero) drag is, according to the paper, a good bit of the overall drag at 20kt, and if you look at the drag reduction when heeled to windward, I come to a different conclusion than the author - the tramps look like they may not give less drag, but the hull allows air to go under it easier. Either way, the drag must be less if it is all pointed into the wind. I don't see how this would benefit a lowrider (not flying boat) since the hull would be out of alignment with the water. In fact in a lowrider, the opposite might be beneficial - jibing the board into the wind, to align the hull to the water. This might be what you are planning?
     

  15. Doug Lord

    Doug Lord Guest

Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.