Roll Control using foils

Discussion in 'Sailboats' started by Wingz, Oct 19, 2010.

  1. Wingz
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    Wingz Junior Member

    My post attachments button still does not work, so I can't post pictures- However check Patent #4843987 July 1989. It looks like what you are talking about. http://patft.uspto.gov/
     
  2. Munter
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    Munter Amateur

    It does sound like what I was talking about with respect to wing sails but it doesn't appear to mention underwater foils working in the same manner. Does it matter - no way!! :) Just having some fun.
     
  3. Wingz
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    Wingz Junior Member

    Number one rule in my life - If you are not having fun, go do something else.
     
  4. FAST FRED
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    FAST FRED Senior Member

    The problem with all of these things is what happens when it breaks? Does the boat become uncontrollable?

    The stability centerboard would simply be raised , like any center board if the ability to direct it for roll control were lost..

    FF
     
  5. Wingz
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    Wingz Junior Member

    On this boat, if I were at speed and the wing controlling the heel broke, or if something happened to the mechanism so that I could not keep the wing properly extended, most likely the boat would simply roll over and crash. However, considering that getting to know this boat, it is possible (although extremely unlikely :p) that I might capsize it numerous times, I built it with three air filled, sealed compartments. Each compartment contains enough air so that in a worst case scenario, that I crashed horribly and broke two of the compartments, the third would still float the boat. The first compartment is everything in front of the mast, between the deck/inside walls, and the hull. Then as the wings separate the hull aft of the mast into two sections, each of these sections is also a separate flotation compartment. The approximate thickness of these compartments is 4 inches +/- 2 inches depending in the curves of the boat.

    Also, considering that at times, I am may hit waves that could come over the bow of the boat, I made the deck to be about 4 inches higher at the bow than at the stern. This should allow for any water entering the boat to simply run out the stern. As the stern is open, the standing waterline is about 1.5 to 2 inches below the deck there, and on plane it lifts from that. I also flared the top rail of the hull out a couple of inches to try to keep the boat a little dryer topside.

    This arrangement also allows for easy righting when ever I do capsize. By standing on an extended wing, the mast comes up and the boat rights itself. All the water in the boat then runs out the back and I am ready to go again.
     
  6. BATAAN
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    BATAAN Senior Member

    Bravo. Keep experimenting and make it work.
     
  7. Cheesy
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    Cheesy Senior Member

    Have you used Xfoil or anything similar to see how much lift your wings are actually generating?
     
  8. Wingz
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    Wingz Junior Member

    Before I built these wings, I tried out every program I could get my hands on to get some insights as to 'best shape'. Each seemed to give me a different answer and none being definitive. Also everything being written for air rather than water was a problem. The version of Xfoil I had was more 'write your own program' than I wanted to deal with. So, while I am sure that someone out there can come up with at least 100 more efficient shapes, I had to narrow it down to a basic shape, something that I could build with limited tools and materials. Something that I could use as a base shape for comparison later.

    What I came up with was a foil with a 12" chord. The front edge being a 1/8th inch radius and a high point 4 inches from the front (33% of the chord) and almost 1" deep (12%) The curve is an ever decreasing curve from front to back, with the idea that as the water hits the front edge, it is deflected up around the curve, increasing its' speed. On the front part of the foil, the oncoming water above the front edge ensures that the deflected water stays attached to the foil in spite of the severe curve. As the laminar flow passes the high point, there is no more on coming water flow to hold the water to the curve, however the curve continues to fall away from the flow, but more gently, continuing to speed the flow. As the laminar flow reaches maximum velocity at about 2/3 the chord length, it becomes harder and harder to keep it attached to the foil, so the last third of the distance the curve is very gentle, going flat over the last 2 inches to minimize the separation turbulence.

    How much lift will all that give me? I really don't know. Considering the varying speeds and all the other variables we could run into, the calculations go far beyond anything I am going to do. But the question remained "How big should I build the wings?" The only answer that made sense was to build them as big as I could. I can always retract a wing for less roll control, but sometimes, I'm going to need all that I can get.
     
  9. dylantorquerol
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    dylantorquerol Junior Member

    sorry for not reading this whole thread:
    Why can't you just put a hydrofoil on the keel. Now most of you know that moths have a flap of their hydrofoil, to adjust height in the water, like an airplane elevator. Now, instead of having just one flap of your hydrofoil, separate it in the middle of the wing. Now you have roll control. if the boat is on a starbord tack, it wants to heel to port/leeward. Just lift the left hydrofoil flap, and now you heel to starbord some. I do know that there is the drawback of drag though, so…
     
  10. Wingz
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    Wingz Junior Member

    I think you are on the right track. Airplanes use aerolons on the outboard area of their wings to control roll, primarily for banking into a turn. My feeling is that the extra drag induced by such a system would be well within the acceptable range, considering the other advantages. The more we use foils in the water, the more important this will be. I haven't been able to get there yet simply because of the time/expense/labor involved in actually doing that, but I think it is necessary work. I wonder if you could elaborate on the idea a bit.

    It is strange, we have been using foils in the air for a hundred years. But using them in the water, with a few exceptions, seems to elude us. It seems to me that we are at the stage of the Wright Brothers when they first flew at Kitty Hawk. Thinking of it that way puts this whole concept into a very exciting prospective. Knowing where the Wright Flyer led to, gives the whole idea of hydrofoils a vision and direction for more work in the field.

    If you can check patent # 20080216728 at http://patft.uspto.gov/ , this looks like something similar to what you are talking about. If you haven't been to the patent office site before you will need to install a tiff viewer to see the images. It is free and easy to install , check 'How to view images' on that page. Doing quick searches on the site can give you hours of entertainment and lots of new ideas.
     
  11. Doug Lord
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    Doug Lord Flight Ready

    ==================
    Don't you think that underestimates the situation a whole lot?
    Foils are used on cruise ships, freighters and yachts ect for roll control and have been for years .Hydrofoil ferries are common place in some areas of the world.
    Large trimarans use foils for lift and are going faster than ever because of it. Foils are being applied across a wide range of keelboats to lift, reduce wetted surface and add RM. The fastest sailboat in the world is a ballasted hydrofoil....
    The Moth monofoiler is the fast small sailboat-mono or multi-under 20'. The R Class is is the first two person monofoiler to begin to convert to full flying hydrofoils. The I-14 and National 12 classes ,among others, have adopted rudder t-foils for vertical lift and added pitch control.
    Mirabaud ,the largest monofoiler currently afloat, just beat the Moth at Weymouth Speed Week. In France, at the "Trophee St. Clair" hydrofoil equipped kite boards just showed that they are capable of beating "normal" kiteboards. Bradfield is about to start testing his 18' carbon "Osprey" and Ketterman is developing a new foiler as well. Lots of development all over the place.
    -----
    There are sources of information that can help you learn not the least of which is www.foils.org THE organization for those interested in foils.
    Study, experiment with models and full size-foils at model size can teach you a lot and the information is almost directly transferable-according to Dr. Sam Bradfield-one of USA's foiling pioneers. The best book on the subject of small experimental hydrofoils is Ray Velinga's "Hydrofoils Design Build Fly" ISBN #9780982236116, published in 2009 by Peacock Hill Publishing ,Gig Harbor, Washington. This IS the bible for anyone interested in hydrofoil experimentation!
     
  12. ChuckieBlood
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    ChuckieBlood Junior Member

    Had something to say, or did until Cavalord started with the ugly comments on other thread.
     
  13. CutOnce

    CutOnce Previous Member

    Just have to point out that viewing patents gives you lots of OLD ideas - the new ones aren't there yet. Much of what is patented won't stand up to serious evaluation - in many cases there is established prior art that was never found by the patent agent verifying the claim.

    The next thing to point out about patents is that they in no way establish the practicality, usefulness or value of the "idea" in question - many patents are on useless, impractical and valueless concepts.

    --
    CutOnce
     
  14. mark775

    mark775 Guest

    Daiquiri , Doug, perhaps others, When I was doing my foil rudder last year (Thanks again Daiquiri - the rudder is wonderful!) I did some studies in shape changing foils. Might that be of use here or on your foilers? I can do this and it is expensive:
    shape change 09.jpg
    Combine a rotating shaft (overbalance) and large forces could be applied. (I chose to not go this route because my reason for wanting do it was to have a fixed shaft, thus no possible leak and no steering gear and I could not get it to bend enough to accomplish this for my rudder.) Thanks, Mark

    Pardon me but I don't know much about sailboats and this may not belong here.
     
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  15. Doug Lord
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    Doug Lord Flight Ready

    -------------------------------
    I would think it would be usefull if it would eliminate a flap and yet allow a strong attachment between a vertical fin and the foil. Ask Tom Speer what he thinks. Is the foil section pretty much variable using your system-in other words can you use foil design software to design a section for a specific application and then incorporate your system?
    Whatdo you think,Slavi?
     
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