New Catamaran Foilers

Discussion in 'Multihulls' started by Doug Lord, Nov 18, 2014.

  1. Doug Lord
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    Doug Lord Flight Ready

  2. Doug Lord
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    Doug Lord Flight Ready

    DNA F4 foiler-Bermuda to Antigua:
     
  3. Doug Lord
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    Doug Lord Flight Ready

  4. Doug Lord
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    Location: Cocoa Beach, Florida

    Doug Lord Flight Ready

  5. Doug Lord
    Joined: May 2009
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    Location: Cocoa Beach, Florida

    Doug Lord Flight Ready

  6. Doug Lord
    Joined: May 2009
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    Location: Cocoa Beach, Florida

    Doug Lord Flight Ready

  7. Doug Lord
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    Doug Lord Flight Ready

    Last edited: Nov 10, 2017
  8. Doug Lord
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    Doug Lord Flight Ready

    Attached Files:

    Last edited: Nov 17, 2017
  9. Doug Lord
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    Doug Lord Flight Ready

  10. Doug Lord
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    Doug Lord Flight Ready

    UPDATE-pdf for the VMG design below. Remarkable Innovation: they plan on using a center lifting foil!

    " ✔ Foil arrangement and systems: T foil Rudders (can either be coupled or uncoupled to adjust the righting moment) > Main T foils (can either be coupled or uncoupled to adjust the righting moment) > Optional Central T foil: Operates as a light wind booster. The central foil raises out of the water when boat speed is high enough > Elevators of different sizes available for the different circuits > The control system is a mechanical solution to reduce the maintenance issues (wand) > The daggerfoil cases allow the foils to be pre raked to operate efficiently in a wide speed range >The daggerfoil case can also fit a standard centre board for lightwind conditions in case of a non one design regatta."
     

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  11. TANSL
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    TANSL Senior Member

    Frankly I feel somewhat dizzy with so much "innovation", every day we have a different one. A lot of "innovation" but few new things. And, about technology, nothing.
    Why the "L" foilers no longer serve and now the "innovation" are the "T" foilers ?. Can anyone answer?. Someone has some technical data, some calculation or anything, that allows us to know so many "why" on these boats (well, let's call them renders because none of them is a boat)?
     
  12. sigurd
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    sigurd Pompuous Pangolin

    The L foils are mostly just a way to get around the ban against flaps and active incidence control.
     
  13. TANSL
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    TANSL Senior Member

    Thanks for trying, @sigurd. And that, that I do not understand (excuse my ignorance), why can not be done with the "T" foils?
     
  14. Doug Lord
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    Doug Lord Flight Ready

    I'm constantly amazed that people continue to call uptip foils "L" foils!!! The foil invented by TNZ in 34 that provides automatic altitude control with no moving parts is called an "uptip" foil, not an "L". An "L" foil* has no ability to control its flying altitude w/o constant intervention by the crew as we saw in the AC 50's. UptiP foils are used in at least two of the Ultim trimaran amas because of their ability to control flight altitude with little to no crew intervention.
    *Unless it is installed at such an angle that the immersed portion works like an uptip foil as on Maserati.......

    ==================================

    Link to Part 1 and Part 2: America's Cup 2007 2010 2013 - Feature Articles Index - From Cupinfo.com http://www.cupinfo.com/en/featuresindex.php

    Quote from the article,Part 1:

    When we were working on the rule, we knew you wanted to get as much lift as possible when you were going fast downwind,” Melvin says. "For instance, in the 2010 America’s Cup, sailed on giant multihulls, the maximum amount of lift we thought we could get was about 50% of the weight of the boat. At that time, we were still relying on the hull to provide pitch control, so what’s come out of this is the boats all now have elevators (the horizontal foils on the rudders).

    At Team New Zealand, we developed a new type of foil that allows you to keep your height above the water more or less steady. No one had been able to do that before, at least not on a course-racing boat that was not going downwind. We developed that mostly on our SL33 test boats -- they came with the stock constant curvature “C” foils and with those kinds of foils, you can generate 50% boat weight lift before they get unstable. But we noticed that when we could get one boat up fully foiling for a few seconds it would really accelerate away from the other boat – and that got the wheels turning. How, with such a huge potential benefit, can we achieve stable flight downwind? So our design team came up with the “up-tip” type of boards. We refined those on the 33s and our 72 is designed to do that and fortunately it worked right of the box."

    Uptip vs L foil.png
     
    Last edited: Nov 22, 2017

  15. TANSL
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    TANSL Senior Member

    You're right, things have to be called by their name, although the important thing, in my opinion, are the concepts. That is why "I'm constantly amazed that people continue to call moment arm" to what is indicated in the figure because, although the text could be correct, the concept, the indicated distance, is wrong.
    So we both agree as to you have to know how to speak but, I'm sure we also agree, you need clear concepts.
    Downforce.png
     
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