Innovations in 34th AC

Discussion in 'Multihulls' started by Cataphract, Sep 2, 2012.

  1. Cataphract
    Joined: Mar 2012
    Posts: 28
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    Location: New York/ Cambridge

    Cataphract Mechanical Engineer

    Hello to all,

    I'm starting this thread as a discussion of the new and interesting features we see on the AC72 yachts that are just starting to be unveiled.
    What are they there for and how do they work?

    For example, on Oracle's yacht there is a large longitudinal ridge protruding downwards from the midship line. What is it's purpose?
    It also appears that the rudders and daggerboards are equipped with vertical lift foils. Is it safe to assume that they plan on flying both hulls, as the AC45s demonstrated?

    Hope to hear some more questions and discussion!

    Best regards,

  2. Doug Lord
    Joined: May 2009
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    AC Innovation

    This Cup is providing very significant innovation:
    1) new multi-element wing sails are significant and are probably a lot more efficient than the one used on Dennis Connors catamaran years ago. Lots more to learn
    about new control systems.
    2) Perhaps the most significant thing about this Cup is the introduction, for the first time in the 161 year history of the Americas Cup, of lifting foils- not just as "foil assist" but also to fully fly the boat as Team New Zealand has already done. This is profound innovation in and of itself.
    a. A technically fascinating part of this is that Team New Zealand and the flying Oracle 45 are not using conventional(and draggy) altitude control systems like wands or "feelers". What they are using is a bit of a mystery and it seems to result in steady flight. I think they are manually and or hydraulically pivoting the leeward daggerboard to change the angle of incidence of the mainfoil resulting in stable flight. We'll see but one things for sure: whatever they are doing may have profound implications for foilers of the future.
    Hydroptere and some other foilers use surface piercing foils where the altitude is controlled automatically by the speed of the boat. Boats like the Rave, Hobie trifoiler, Osprey and Skat use fully submerged foils but they have to have "surface sensors" like wands or feelers to contol altitude. A couple of Raves were modified and raced with no surface sensors with altitude 100% controlled manually.
    It's exciting times and learning about this will be one of the high points of my life......

    PS- Welcome to the forum, John!

    Pictures, Lto R-1) Greg Kettermans Hobie Trifoiler, which uses surface sensing feelers sticking out in front of the boat to control the main foils. The system automatically controls altitude and Righting Moment(!), 2) & 3) Sam Bradfields Rave and the 40' Skat that use "wand" surface sensors that control flaps on the mainfoil to maintain altitude-and like the Trifoiler, control Righting Moment, 4) Team New Zealands 2012 AC 72 flying 100% on foils with no apparent altitude control system. There is an altitude control system because flight was stable but just what it is and how it works is not known for sure. This is the first AC boat in history to fly on foils and the first AC boat in history to do almost twice the 20 knot wind speed on one of its first sails. Kiwi innovation at its most profound!

    Attached Files:

  3. groper
    Joined: Jun 2011
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    Location: australia

    groper Senior Member

    why cant they control the altitude simply by trimming the twist in the wing sail?

    Set the board angle for the new tack when they tack and lower the board, then fine tune the machine manually on the fly... twist off, bow up... twist on, bow down...?
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  1. Doug Lord
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