High Performance MPX Foil/Self-righting Trimaran-The Test Model

Discussion in 'Multihulls' started by Doug Lord, Dec 28, 2010.

  1. David Cooper
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    David Cooper Senior Member

    You're just trying to play games with words to try to have your cake and eat it. Downforce is not a little bit less lift. Downforce is only a valid description of something generating a force downwards. I've just checked half a dozen dictionaries to make sure and not a single one of them agrees with the way you're trying to use the word. All of them very specifically talk about generating a force downwards.
     
  2. Doug Lord
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    Doug Lord Flight Ready

    If the windward foil is operating at its designed flight altitude with the flap in neutral(neither up or down) and the rig is hit with a small gust the flap on the windward foil will go up slightly as a response to that gust. When it goes up it generates a small amount of downforce to restore the windward hull to its designed flight altitude.
    Similarly, the leeward foil flap goes down slightly to generate a small increase in the amount of lift on the lee foil to restore the lee hull to its designed flight altitude.
    --
    That's what happens, those are the facts-accept it or not.........
     
  3. Doug Lord
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    Doug Lord Flight Ready

    Fire Arrow Foiling System Testing and Development

    Post 2251 How the Fire Arrow works:
    From 7/24/14-the first day the foil system worked perfectly:

    [​IMG]
     
  4. Munter
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    Munter Amateur

    I forgot the other regularly deployed tactics which are to:

    1. Attempt to redefine what is being disagreed about to something where there is no disagreement to take attention away from the actual problem. Note post 2282 does not attempt to address the core issue which is the definition of downforce but puts up a strawman argument about the working of wands and flaps on a topic that is not under dispute.
    2. Repost pictures and extensively requote himself to push posts which he finds challenging into the background – see post 2283 as an example. Often this is done concurrently with editing past posts without acknowledgement so that the endless repetition is not as obvious to those who aren’t aware of the full thread history. Most people have the humility to be able acknowledge when they make changes, particularly if they are anything more than the correction of typos.
     
  5. OzFred
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    OzFred Senior Member

    Some videos to compare Doug's foiler with one that has gone through a test and development program guided by real–world experience. PerthMini40man has worked through various foil configurations and sail plans, the result is a pretty stock looking foiler that works very well.

    Turn the sound off first.

    Doug video short version (1 min 51 sec): http://www.youtube.com/watch?v=7Mok3d4KiMI
    Doug video long version (7 min 47 sec): http://www.youtube.com/watch?v=4YBOEolFqiE

    PerthMini40man video (7 min 5 sec): http://www.youtube.com/watch?v=nzTf9pedWdE
     
  6. redreuben
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    redreuben redreuben

    Fred it's all been said before, the only thing that seems to matter to Doug is word count.
     
  7. Doug Lord
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    Doug Lord Flight Ready

    ============
    Ian Holts trimaran foilers are excellent! But there is a big difference between the types of foiler: his are race boats with an excellent foil system and multiple rigs.
    The Fire Arrow is an exact SCALE model using an experimental foil system that has been designed, built and developed over several years. In the last video, where the hydrofoil system worked the way it was supposed to for the first time, there was still a problem with the rudder directly related to the radio set up.
    The Fire Arrow uses an experimental foil system-never before used on another trimaran ever- that worked perfectly in its last test sail, July 24, 2014 in very light air and relatively big waves(for the wind speed).
    Oh, and my first production rc sailing foiler-the F3*- was done over 20 years ago......
    *worlds first production RC sailing foiler
     
  8. David Cooper
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    David Cooper Senior Member

    A reduced positive = a negative: that is now a fact because the Lord says so (a foil generating reduced positive lift = a foil generating downforce [which to everyone else on this planet means negative lift]). We must now rewrite all books on math and physics to take this into account.
     
  9. Doug Lord
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    Doug Lord Flight Ready

    "...or not...", I guess. That's unfortunate David....
     
  10. OzFred
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    OzFred Senior Member

    It seems you had a different opinion when discussing this recently on Sailing Anarchy with statements like:

    14' Stunt S9 Foiling Cat.

    I don't think anyone can interpret that as anything other than "down force" is pulling down. And apparently you always said that, until now.
     
  11. Doug Lord
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    Doug Lord Flight Ready

    What? I don't understand your comment at all. The windward foil on most dual, independent wand systems can do anything from pull down at max downforce or generate just a tiny amount of downforce-whatever it takes to restore the hull to its design flight altitude-totally controlled by the wand.
    On the Fire Arrow downforce can be almost as much as the weight of the boat in extra RM. It's a potentially great advantage on a boat like the Fire Arrow that allows instantaneous response to gusts and allows the full size version to be sailed with a very small amount of movable ballast. A single crew could sail this boat in the same general wind range as a crew of two because the mainfoil downforce will make up for the difference in crew weight.
    --
    On the oversquare Fire Arrow full size version the crew always sits to one side of the cockpit or the other-there is no running out to the ama because there is no need for the extra righting moment that would provide. That's because of the innate RM provided by the 22' wide platform backed up by mainfoil downforce whenever required.

    [​IMG]
     
  12. Doug Lord
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    Doug Lord Flight Ready

  13. PerthMini40man
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    PerthMini40man Senior Member

    Attached Files:

  14. Doug Lord
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    Doug Lord Flight Ready

    RC Foilers

    Good stuff-thanks Ian!
     

  15. Doug Lord
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    Doug Lord Flight Ready

    Outward pointing foils

    This picture is just to illustrate how Hugh Welbourn handles his outward pointing foils on the Q 23. His foils are designed to not develop lateral resistance when flying-he uses the keel for that. Greg Ketterman tested outward pointing foils on the Trifoiler and he also found them slow. But his outward pointing foils still had to develop all the lateral resistance for the boat. He explained to me that they were high drag due to having high and low pressure on the same side.
    So make sure the outward pointing foils are just generating vertical lift and no lateral resistance. Add a daggerboard. Might be a good trade off for substantially increased RM.


    [​IMG]

    This section is the exact opposite of a section designed for lateral resistance-it's worth careful study.On a "normal" boat with dual foils the flatter part of the asymmetric section would be on the outboard side of the trunk. The TOP of the picture is the lee side of the boat:
    [​IMG]

    [​IMG]
     
    Last edited: Apr 13, 2016
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