Vampire Cat with Canted T-foils

Discussion in 'Multihulls' started by Doug Lord, Sep 4, 2014.

  1. Jim Caldwell
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    Jim Caldwell Senior Member

    Mainly because the rules don't allow it (A Cat, AC Cup) but I expect that to change.
     
  2. Doug Lord
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    Doug Lord Flight Ready

    ======================
    That is just absurd. As is the notion that using carbon fiber on models is a waste of money-- just completely wrong. 99% of all the top rc raceboats are built with carbon. 20 years ago I did an experiment using e-glass for one hull and carbon for the other with the same tooling: carbon was slightly lighter and many times stiffer. Oh, and my test model uses two t-foils and two UptiP foils(one uptip at a time). I designed and built the worlds first production RC foiler, the F3, 14 years ago using the Bradfield system with dual wand controlled main t-foils and one rudder t-foil-built with carbon. You seem to know what you're talking about most of the time and I've followed your projects which are tremendous! But your comments here are just plain wrong and unfortunate.

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    The canted T-foil system certainly appears to have some advantages over a "normal" T-foil. But the UptiP foil has a tremendous advantage in being able to act as a single main foil controlling altitude for the whole boat with no wands or "feelers". Some people would say that having an"L" foil and/or UptiP foil can be structurally stronger than a "normal" t foil with asymmetric loading of the t foil under sail.
     
  3. groper
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    groper Senior Member

    I too have followed you stuff for quite some time...

    What kinds of fabrics have you used to build your boats? Of course carbon is stiffer than glass all else remaining constant, but if your comparing 1 type of fiber reinforcement to another then you can end up with a higher strength using glass compared to carbon. You may already know that, but I see a lot of woven carbon in your boats which is exactly what I'm talking about.... woven fabrics are about 2.5times lower in strength and half the stiffness compared to stitched or non crimp fabrics. So if you switched to a non crimp fabric, you could have eglass giving similar structral performance to woven carbon with 1/10th the price tag...

    This is somewhat of a detour, but it helps illustrate the point, if you look at the fastest multihulls of the last 50 years, upto say 30 feet loa, most of the old ones were built in plywood. A lot of the new boats are now done in carbon, but have you noticed how little the weight has changed? This is because plywood is strong Enough and stiff enough, for the small panel spans on the smaller hulls they employ. Your models are an extreme extension of this. The main reason for the slightly improved speed in the modern boats is the rig and sail improvements, and of course the foils.

    No offense was intended doug. I respect you and your work, I just don't agree with all of your choices... And for all the stuff you dig up on foils, of which I read a lot of it, I don't often see much which considers the structural design of them- just an observation...
    image.jpg
     
  4. Doug Lord
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    Doug Lord Flight Ready

    Thanks. For my production RC hulls 1993-2002 I used 5.7oz woven carbon sometimes with 1.5oz kevlar. I used unidirectional, woven and carbon tow for foils and reinforcement. Years ago I introduced myself to Eric Sponberg and he has been a big help for structural engineering questions over the years. For a long time the only place I could buy small quantities of carbon or glass was Aircraft Spruce and Specialty. I don't try to build carbon masts or tubes-I buy them from places like Forte(very light carbon wingmast from a small spreader section) or RockWest for tubes.
    For RC hydrofoils, after I settle on a laminate, I test the foil to 3 times the predicted load. Some foils on the Fire Arrow have been heavily modified(until they work right!) . The process on that test model now(once we resume testing) is to reduce drag w/o reducing low speed take off.
    If the full size version of the Fire Arrow or Crossbow is ever built it will structurally engineered by Eric and largely built by Falcon Marine. I'll do the fit out and rigging. The foils and rig will be my design.
    I just figured out a new mainfoil to test that eliminates the dual wands-IF it works.
    I'm always interested to learn new stuff and spend a lot of time researching. However, I don't react well to sweeping pronouncements about most anything though I have been accused of doing the same thing sometimes but I deny it emphatically.
    PS-good luck with your boat projects!
     
  5. Doug Lord
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    Doug Lord Flight Ready

    Attached Files:

  6. Doug Lord
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    Doug Lord Flight Ready

    Vampire

    From The Foiling Week:
    "The Vampire Project is a collaboration between catamaran sailor William Sunnucks and boat builder Graham Eeles to develop a new breed of foiling catamaran in Brightlingsea Essex. It is based on the the International Moth foil design which is quite different to the America’s Cup line of development."
    The major differences between the Vampire foil system and the foil system using UptiP foils in the AC is that the Vampire foils use flaps that are controlled by wands. The wands (like the ones on the S9 cat and Moth) are mounted forward of the foils. Another difference between this wand controlled foiler and the Rave ,Osprey and S9 is that the windward foil on the Vampire is retracted and the two mainfoils are canted outboard at the bottom.
    __________________

    https:www.//youtube.com/watch?v=To2yjKkozZM
     
  7. Doug Lord
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    Doug Lord Flight Ready

  8. Doug Lord
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    Doug Lord Flight Ready

    Vampire

    Story here: http://www.catsailingnews.com/ The Vampire trounced a fleet of other foilers and cats in the Forts Race 2016 and won line honors even after breaking a foil. Beating the NACRA 20 FCS by five minutes!

    [​IMG]
     
  9. redreuben
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    redreuben redreuben

    Fire starter

    Dougs boat at it's most impressive. Chopped strand matt would have been plenty.
     

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  10. gypsy28
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    gypsy28 Senior Member

    Foiling catamaran beats a fleet of mostly non foiling catamarans......Not really much of a surprise there. Surprising how close the Tornado and F18s were. Lower half of the fleet on corrected time isn't that impressive to me......
     
  11. Doug Lord
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    Doug Lord Flight Ready

    Vampire

    Now, now: he not only whuped 16 "normal" cats, he beat the foiling NACRA 20FCS by something like 5 or 6 minutes and that is a well done for a guy who has developed his own boat and unique foil system from scratch.
     
  12. Doug Lord
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    Doug Lord Flight Ready

    The Vampire foiling cat is continuing its winning ways: Eurocat 2018 Day 2: Raid Results | Catamaran Racing, News & Design https://www.catsailingnews.com/2018/04/eurocat-2018-day-2-raid-results.html#more
    The cool thing about the foil system on this boat is that it uses canted wand controlled foils but only one mainfoil at a time. All the other cats with wand controlled foils(S9, IFly, Whisper) use two mainfoils at the same time. Those boats are capable of having the foils generate RM for the boat but don't normally do that.
     

  13. bjn
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    bjn Senior Member

    I think the key is that the foils are canted.

    Every time the flap pushes the boat up, it also pushes it to windward, so to speak.

    I think there was one pic with both foils down. Maybe used when sailing downwind at deep angles? And in light winds?
     
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