A Cat on foils wins NZ Nationals/ Worlds Start Tuesday

Discussion in 'Multihulls' started by Doug Lord, Feb 8, 2014.

  1. Baltic Bandit

    Baltic Bandit Previous Member

    Others who sail

    Note Also that in other forums where A Class sailors are actually engaged in the conversation, the notion of a twist grip being adequate for dealing with waves and gusts has been put to rest. the consensus is two fold
    1. Once you are up on foils, whether you change the AoA of the rudder foil or the mainfoil doesn't really matter -- because what you are doing is changing the net AoA of the system. IOW its the same thing as an airplane: you can have articulating wings (as some of the early attempts had), you can have a canard (as the Wright Bros did), or you can have a tail empanage (which all modern aircraft have) and it is the RELATIVE lift vectors of both surfaces that determine the AoA of the main lifting surface
    2. the twist grip is sufficient for setting the TRIM of the two, but it is insufficient to control the AoA in reaction to gusts or waves. The best example of this is the need for Boeing to install a Yaw Damper on the 747 because pilots with manual input controls on the rudder and elevator could not adjust fast enough to prevent catastrophic oscillations in certain circumstances.
     
  2. Doug Lord
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    Doug Lord Flight Ready

    A Class Cats on Foils!

    From Scuttlebutt Europe and Vsail--excerpt of the story of the last race of the Worlds: http://www.vsail.info/2014/02/16/glenn-ashby-is-the-2014-a-class-word-champion/

    Ashby was among the leaders off the line followed by Tuke and Burling looking for wind in toward the shore before heading out to the middle of the course. By the top mark Ashby had secured the lead. At the first bottom mark it was still Ashby followed by Peter Melvin and Blair Tuke. Most of the fleet appeared to favour the shore and left side of the course following Glenn Ashby. Peter Burling, Blair Tuke and Nathan Outteridge took the right hand side of the course on the final beat hoping for a wind shift to allow them to make a significant gain on Glenn Ashby. The wind shifted some 120 degrees and in the end the right paid dividends, compressing the frontrunners, and giving many a chance by the final top mark. Glenn Ashby had a bad gybe at the top mark and left the door open for Nathan Outteridge to pass on the run home.

    Nathan Outerridge crossed ahead of Glenn Ashby from Ray Davies and Blair Tuke. Nathan Outerridge had built his reputation for being a master in light conditions and displayed his immense talent by foiling across the line to a round of Australian Cheering. emphasis by dl

    The final race results do little to upset the leader board, and if anything go on to cement the three top racers in their podium places. The 2014 A-Class World Champion is Glenn Ashby (AUS), second is Blair Tuke (NZL) with Peter Burling (NZL) in third.

    Most notable perhaps is the fact that the top four places are all members of the America’s cup syndicate Emirates Team New Zealand. emphasis by dl

    Glen Ashby said at the finish:
    “It’s one from the best world championships I’ve been to from the point of view of all the new technology introduced to the class and the ideas from people from all over the world here at the regatta.”
     
  3. Baltic Bandit

    Baltic Bandit Previous Member

    Not sure why that is notable? all are pro sailors who get more time to train as well as had top notch prepped boats.
     
  4. Doug Lord
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    Doug Lord Flight Ready

    A Cat on Foils!

    Well, the concensus seems to be that the A Cat foilers are here to stay. I hope the guys that want to change the rules don't succeed because it will just open up more unforseen consequences. The fact is the guys that have made these boats foil-well in lighter winds and leaving a lot to be desired in stronger winds-did so in the face of a rule designed to prevent foiling. If they can advance so far that they win a World Championship in light and heavy air they will surely be able to improve control and make it a bit easier to foil
    without changing the rules!
    I wish the class good luck-it is one of the greatest classes around.....
     
  5. P Flados
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    P Flados Senior Member

    Doug,

    The fact that a few well funded and very skilled guys did good does not mean that the their solution will be a good choice for others.

    With no rule change, foiling is likely to be both expensive and less stable than it could be.

    If the class wants to avoid the cost escalation of foiling, they need to go back to straight (or almost straight) boards.

    If the want to let foiling progress, they can expect better results if they loosen up the rules.

    If they want to allow foiling, but want to keep cost down, they probably need to increase the minimum weight.

    I would actually use this to "phase in" foiling. Straight boards get to stay where they are and foilers have to weigh in at say 10 kg (22 lbs) more. This way, board makers do not have to go with the absolute top dollar builds to keep weight down.

    I know that foiling will get better even with no rule change. For the near term, I am not sure how much better and I am not sure the available foiling options to the bulk of the class will be all that satisfactory.

    On the other hand, why not open things up if they are going to let foiling continue. This would let the pioneers go for the best solution they can find.

    You are proponent of the "Foils are the Future". For many forms of sailing I tend tend to agree. I am also a proponent of "may the best foil win", i.e. use the right tool for the job (instead of a rule workaround foil).
     
  6. Blackburn
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    Blackburn Senior Member

    If the rules were changed to allow board insertion from below, then many existing boats could upgrade to foils - something I was told the other day by an A-class sailor.

    He didn't think it was any complication in regard to launching or coming ashore, that one had to wade alongside the boat in either case, and that such a rule change would offer both a much less expensive and more inclusive way to adapt to foiling.
     
  7. Baltic Bandit

    Baltic Bandit Previous Member

    Well there still would be a challenge with the kinds of foils. the limit of how far from centerline the tip of the foil must be in static configuration has a limit on how you can build the kinds of "J foils" that the AC boats used. and the "j-foils" have the advantage that with dihedral and the effect of spanwise flow on lift, a flow rate that is coupled to increases in leeway as the foil rises out of the water - leads to a type of heave control that makes stable foiling more feasible for "mortal" sailors
     
  8. Doug Lord
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    Doug Lord Flight Ready

    A Cat on Foils!

    ==================
    Paul, it just seems to me that the history of foiling development in the A Class tends to indicate that now that they're foiling ,improving control is just a matter of time without changing the rules. We'll see how it goes....
     
  9. Baltic Bandit

    Baltic Bandit Previous Member

    control improvement is dramatically mediated by the rules
     
  10. P Flados
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    P Flados Senior Member

    Doug,

    I see three major choices to ride height regulation:

    • Passive Control. Until recently, inherent ride hide regulation was known to be available via ladder foils, Vee foils and the simpler single foil per side surface piercing foils similar to Hydroptere. Recently the solution found by ETNZ (aka "uptip") was a signification addition to this category.
    • Active automatic control. Feelers (trifoiler), wands (Braffield & moth) and electronic all provide feedback to move either the foil or a flap.
    • Active manual control. This come in two flavors. The first is obvious, a flap or foil AOA is adjusted via a joystick, twist handle, or even buttons & grinders (AC cup winning OR 17 on upwind was probably a hybrid of manual and passive). The second flavor is the recent A Class cats with body movement, tiller and sail adjustments being used.

    For the A class they do not have the luxury of a sailor that can focus on continuously operating a manual control for flaps or foil AOA. This kind of control is just probably beyond reason for a single hander.

    The uses of more indirect controls (body placement, etc.) allow a really good crew to get some amount of control by feel. The top guys are used to quite a bit of this with their traditional balancing of the boat on one hull and moving fore and aft as needed. However without some amount of natural heave dampening, the A Class foiling boat ride height stability was just barely good enough for the top guys.

    So, I just do not think it is likely that there will be a drastic improvement in a "sailor friendly" A class foiling unless either someone comes up with an entire new mode of passive control or until they change the rules to allow something like: surface piercing (remember what could be the granddaddy of A Class foilers - Dave Carlson's wooden Cheetalope), wands or uptip boards.

    Any class that has fast but "mean" boats does not sound like what foiler proponents should be pushing.
     
  11. Doug Lord
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    Doug Lord Flight Ready

    A Cats on Foils!

    Paul ,did you watch Nathans video? Seems like he had pretty good manual control of the AOI of his lee foil. But basically I agree with you.
    My latest thinking is for a Bradfield wand system where the wand is attached to the board, but instead of dual independent wands and two foils operating like on the Osprey, only the lee foil+wand would be used with the windward foil + wand retracted. Nathan had a good solution for raising the windward foil as well. Using the Bradfield system on a single main foil would eliminate the incredible loads a dual system generates which would keep the weight down but still allow the virtually automatic control of a wand. It would be light, easy to sail and easy to retrofit to almost any A since nothing is attached to the boat. Just rig the appropriate lines reinforce trunks if necessary and foil.
    Nothing that I've seen is simpler, easier to use, easier to rig or easier to launch. A T-foil could be used or an "L" foil with a flap would be less drag(as long as it was pointed inboard). Few ,if any, manual AOI adjustments would be required during a regatta with this system.
    "Up-tip" foils with manual AOI adjustment like the Flying Phantom would possibly be faster in a straight line , but the Bradfield single main foil system would probably win around a course because of it's ease of use.
    What do you think?
    -------------------
    While I think the above system would be best, I seriously doubt that it could get thru the rules process. I am still convinced that the brilliant A Class sailors that have made it possible to win a World Championship on foils while faced with a hostile rule are highly likely to be able to refine their systems for better control and ease of use without changing the rules.
     
  12. Baltic Bandit

    Baltic Bandit Previous Member

    Yes Doug Outteridge said he had a AoA control. He also said, in that laconic antipodean understatement that "but there's a bit on when you are foiling" - which basically says that when he is foiling, he rarely if ever has time to spare to adjust the AoA.

    Note also that under the way the rules are being interpreted, specifically RRS 52 - wands are not allowed as they are an energy input from external sources.

    Nor is Nathans solution for raising the windward foil all that particularly great for 2 reasons
    1. it adds drag in the lift process - of course if everyone faces this its a bit less significant, but if a system can address this, its an advantage
    2. It adds randomness - which in bigger waves is a significant factor. Particularly in a boat where you have "a bit on" while foiling

    Nor is there any evidence that a T-foil would be faster - in fact there's a fair line of reasoning that it would be slower. In the A class, your foils cannot extend past the external sheerline of your hull. This means that you cannot have externally canted T foils. And yet without external canting, the ability to fly the weather hull for drag reduction goes away.

    Now in theory you can fly the weather hull in a flat configuration, but that requires more grunt for takeoff (as you are needing to achieve the same takeoff speed with almost double the immersed drag)

    And a single main foil is also banned by the rules for the same reason that dual surface piercing foils are banned in Moths: the latter makes a moth a catamaran and the former makes a catamaran a multihull.

    PF - arguably heave adjustment via spanwise flow (which occurs with L foils as well as "C" foils -albeit less stably) is arguably a form of "active" control. I would differentiate the two as "mechanical" vs. hydrodynamic control
     
  13. P Flados
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    P Flados Senior Member

    From a what is the fastest possible solution angle, I would currently give the edge to an L foil with some amount of "uptip" built in along with a small deflection mid span crescent shaped flap (wand controlled) along with a fully retracted foil on the windward side.

    From a what is best for a "quick fix" to get fast reliable stable foiling, I would lean toward a wand controlled T foil. Asymmetric if required (if they are held to B Max).

    From a what will give the most people a chance for a foiling rush with the least potential for negative impact I would push rules for:
    • No flaps anywhere
    • No automatic active control (by this I mean no parts designed to move based on feedback generated at some other location)
    • Any boat that fits the 2013 rules get to stay at the 2013 min weight
    • Any boat with straight foils can come in 10 kg lighter.
    • Any boat with "new foils" has to be 10 kg heavier (keep the new foils as low cost as possible and leave room for beefing up the boats).

    I see a lot of untapped potential for the uptip L foil concept.

    With just some simple shore based cant adjustments, an uptip L foil can probably go from friendly enough for the low end, to just stable enough and very fast for the top guns. This has an emotional advantage in that it lets people get in on the foiling game without feeling that they have to pick second class equipment to start with. It also rewards guys that let it all hang out yet manage to not crash (too much).

    I feel that given a chance, this class could focus some of the best innovators in cat sailing on unlocking the potential of the uptip foil. Doing it at the single hander level does the most good because this is where "simple to sail" is so important, yet the benefits of advancements are easily scaled up to bigger boats.
     
  14. Doug Lord
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    Doug Lord Flight Ready

    ================
    The "uptip" foil, as has been used so far, relies on leeway for altitude control with frequent(Hydros) to relatively infrequent(Groupama/Flying Phantom) manual angle of incidence adjustment AND a three foil arrangement(single main foil). With uptip foils the windward foil must be raised. Now , Nathan had a system on his boat to accomplish that and a way to lift the windward foil-he just didn't have an uptip foil. But even though he had such a system how many others could handle AOI adjustment while out on the trap handling the mainsheet and steering?
    The single main wand controlled foil is so simple requiring only that the windward foil+wand be retracted-but apparently requires a rule change .
    click-
     

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  15. Baltic Bandit

    Baltic Bandit Previous Member

    No doug, you don't have to raise the windward foil with J boards (calling them "uptip" implies its only the tip that is up, and what you really have is a dihedral configuration that relies on spanwise flow to attenuate lift). but you get a lot of drag if you do not.

    A single main wand controlled foil is a monohull, not a catamaran. And a moth - because it is lighter - will be faster.
     
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