Dario Valenza: Stable Foiling in A Class Cat

Discussion in 'Multihulls' started by Doug Lord, Mar 6, 2013.

  1. Doug Lord
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    Doug Lord Flight Ready

    Boy, news and developments are coming fast and furious in the pursuit of stable foiling in the A Class catamaran(and in many other cats!)
    Dario Valenza is a very talented designer and builder and has designed an A Class cat called Paradox. He incorporated the foil design expertise of Martin Fischer and the result is a boat that foils stably with no altitude control system(except speed) and uses Class legal foils :
    UPDATE/CORECTION-- turns out my info was wrong: Dario has built this boat and invested a lot in it but the boat was designed by Martin Fischer.

    From Dario Valenza, an extraordinary innovator and talented designer-

    http://carbonicboats.blogspot.com/ excerpt:

    March 4, 2013

    "Martin's insights and numbers have been vindicated by the behaviour of the new boat. It handles very 'un-spectacularly' which shows the foils are doing their job.
    Rather than jumping and crashing, the motion is straight and level, unperturbed by external disturbances. As soon as the skipper starts to see white caps on the water, the technique is to flatten the boat out. The hulls nudge up until they are just clear of the surface and the magic carpet ride begins. Taking a small step forward keeps the foils loaded and the boat tracks straight and true with little regard for chop and wakes. All who have tried it so far have come away very excited saying stable foiling on an A Cat is a sensation unlike any other sailing they have done.
    The really remarkable fact is that it all happens automatically. There is none of the 'skirting the death zone' dance familiar to those who have tried to balance on C or J boards."
     

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    Last edited: Mar 13, 2013
  2. warwick
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    warwick Senior Member

    Doug in the Australian sailing magazine (Feb 2013) there is a boat test on Parodox.
     
  3. Doug Lord
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    Doug Lord Flight Ready

    -------------
    Thanks-could you paraphrase it if you've read it?
     
  4. Doug Lord
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    Doug Lord Flight Ready

    The Victorian A Class States were held in Australia in the last week. The Paradox was, apparently, sailed by a "competent" sailor and placed mid fleet. The DNA won most of the top spots. Generally under 10k wind.
     
  5. Doug Lord
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    Doug Lord Flight Ready

    Martin Fischer has designed the Paradox, Mayfly, and the foil system/hulls/platform for the Phantom F18, GC 32 and more.
    Here is an excellent interview with him: http://www.catsailingnews.com/
    Excerpt from the article:

    Paradox A

    - This year Dario Valenza is launching the Paradox, and you are responsible for its design. Which are the diff on this design/system from your previous versions?
    MF: The principal setup is the same as on the MayFly, but this time we added a system to adjust the dihedral angle while sailing. This is important to get a good all-round boat. At low speed a small dihedral angle is advantageous, whereas at high speed a larger dihedral angle is the better solution. On the Paradox we think we got both.

    - Main Diff for L rudders against almost defacto Winglets in production As?
    MF: To obtain positive pitch stability a lifting horizontal surface is absolutely necessary. The required size for pitch stability of the horizontal surface at the rudder can be computed from perturbation theory.
    The main parameters that go into the equations are the surface of the main foil and its position with respect to the centre of gravity. This type of computation gives you the minimum size for a neutral configuration (pitch stability = zero) and then it is the designers work to add some safety margins to this minimum surface. It seems that I am more conservative in terms of safety margins than the other A-Class designers, since my L-rudders are significantly bigger than the typical winglets - to be seen.

    A second point is the intersectional drag. The winglets form a sort of cross (+) with the vertical part of the rudder. This makes for 4 rectangular angles between surfaces and the corresponding intersectional drag. According to our simulations an L-rudder has less drag than a +-rudder for the same horizontal surface.

    - The Paradox will be able to fly in high winds?
    MF: Yes, I hope so
     
  6. k2mav
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    k2mav Junior Member

    ---Martin Fischer has designed the Paradox, Mayfly, and the foil system for the Phantom F18, GC 32 and more.
    Here is an excellent interview with him--


    Doug: Phantom and GC32 hulls/platform are from Fischer too.
     
  7. Doug Lord
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    Doug Lord Flight Ready

    In case anyone has doubts about the viability of the Martin Fischer foil system here is the Flying Phantom F18(designed by Martin Fischer) with the Fischer foil system and Frank Cammas sailing. It was pointed out to me by K2 that the foil closeups are "digitalized"(pixelated?) so their exact shape can't easily be copied. Also interesting in this video that the boat is flying with the windward foil retracted and in the article,Fischer says he needs both foils down in the A Class system.
    Note: the foils in this particular video are not Martins-there are several people working on the Phantom project and those foils belong to the other designer.

    http://www.youtube.com/watch?v=taJYT4eAiWE&feature=player_embedded#!
     
    Last edited: Mar 13, 2013
  8. Doug Lord
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    Doug Lord Flight Ready

    --------------
    Thanks, K2- you have mentioned a couple of times that you publish something- can you post a link here for me and others that may be interested? Are you catsailingnews.com?
     
  9. k2mav
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    k2mav Junior Member

    yes, and all the info is published there.
     
  10. Doug Lord
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    Doug Lord Flight Ready

    Great site-thanks for all the effort!
     

  11. Doug Lord
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    Doug Lord Flight Ready

    Reversible foils

    Brilliant new foil solution for the Paradox: reversible foils. In conditions that you don't want vertical lift just reverse the foils:
    http://carbonicboats.blogspot.com/

    UPDATE: turns out only the rudder foils are reversible on the Paradox.
     
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