another idea

Discussion in 'Projects & Proposals' started by yipster, Jan 28, 2003.

  1. yipster
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    yipster designer

    "sailboat" going straight upwind fast
     

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  2. plymouth
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    plymouth Junior Member

    I've been curious about whether this really works for a while - this was the first one I remember seeing:
     

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  3. plymouth
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    plymouth Junior Member

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  4. plymouth
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    plymouth Junior Member

    I don't know the designer and author of that site, but it's interesting...
     

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  5. yipster
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    yipster designer

    more idea's

    Don’t laugh when I remember I placed sunshade blades in my bicycle wheels trying to get forward lift as a kid… this upwind sailing always intrigued me. Got that anigif from a multihull (magazine) site I cant find back easy now but saw your photo there among other experimental boats. Reading that site was interesting. How about a wave powered catamaran? Here another serious experimental boat site http://www.stevproj.com/Carz/XBoats2.html

    :) yipster
     
  6. gonzo
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    gonzo Senior Member

    Let's see. The Law of Conservation of Energy should hold for boats too. That means that there will be losses in heat and fricton between the wind vanes and the propeller. Add to that surface friction of the hull and wave resistance. I don't see how the residual energy could possibly move the boat forward.
     
  7. Polarity
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    Polarity Senior Member

    For sailing dead upwind ....Isn't there something about every action having an equal and opposite reaction? ....:confused:
     
  8. BrettM
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    BrettM Senior Member

    Gonzo,

    Remember that the surface friction and wave resistance will only occur if the boat moves forward which is the point of the exercise. The concept really only needs to overcome the resistance of the wind itself to gain any forward movement.

    I don't know much about these things but maybe they do work. There once was a time when it was believed that you couldn't sail faster than the wind itself which we all know to be possible.

    brett
     
  9. gonzo
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    gonzo Senior Member

    How do you move through the water without friction or wave resistance?
     
  10. BrettM
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    BrettM Senior Member

    You can't.. My point was that to achieve forward motion you only need to develop effective propulsive force greater than that required to overcome the resistance of the wind (if going to windward). The suplus force then would equal the hull resistance (Total inc added wind resistance etc) at the final hull speed. (which may not be that great). As I said before, I haven't seen these things but maybe it is possible to get sufficient efficiency out the system for it to work). Don't see myself trying it either.

    On the other hand at the very least I can see it will go downwind if that is where you wanted to go.
     
  11. gonzo
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    gonzo Senior Member

    The Law of Conservation of Energy says that in a case like this the force of the wind on the vanes plus the hull will produce "an opposite and equal reaction". That is, in the opposite direction of the wind or downwind. There is not enough energy left to propel the boat forward.
     
  12. yipster
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    yipster designer

    its an intriging idea i agree.
    its one of those things i always wondered of before. i belive it to be possible and think brett is giving the explanation in his first reply.

    from plymouth's site http://www.oceanblueone.com/art.htm i read this:
    [​IMG]
    Peter Worsley (who has this design patandted) and pictured here i asked to reply and i hope he will. i would be very curious to hear some more as i dont belive the movie model at the top is sailing downwind. wish i could find that site back where i got that video from, it also had many variations on the theme.

    when not having my fingers still in bandage and engaged in building a crazy enough model allready i would run out to a model shop for parts needed, build and test it. i dont know why i allways want to check upwind, downwind indeed is easyer :D yipster (guess i better wait trowing more "crazy's" in?)
     
  13. BrettM
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    BrettM Senior Member

    As I remember it, the law of conservation of energy has nothing to do with equal and opposite reactions. It merely states that energy can neither be created of destroyed but merely changes form. ie kinetic, plus potential etc is always constant. On the other hand equilibrium occurs when all forces are balanced.

    Unsing Gonzo's approach, no yacht or dinghy sailing in the world can go to windward at all. Nor would it be possible to sail downwind with an apparant breeze from forward of the mast. As I said, I'm no expert with these things but I keep an open mind. They may very well spend all day tacking back and forth and getting nowhere.

    no offence Gonzo:)
    Brett
     
  14. gonzo
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    gonzo Senior Member

    My approach shows that no boat can sail straight to windward. As we all know, we tack upwind. The forward motion is the result of the force of the wind in the sails and the lateral resistance of the boat in the water. There are parasitical losses in friction wind and wave resistance and heat. I think the "Law of Conservation of Energy" applies because for that model to go upwind, energy would have to be created out of nothing. I am convinced that is not what happens there. I may be missing something when calculating the force vectors, but can't see what. If this works, it will revolutionize sailing. However, seeing is believing. All the designs I've seen that claim to go straight to windward don't work.
     

  15. BrettM
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    BrettM Senior Member

    Unlike a yachts sails , a rotating wind vane as fitted here will provide the same power to the propeller independently of the direction of the hull (neglecting any increase/decrease in apparent wind) due to is ability to maintain a constant angle of attack (unlike a yacht).

    It is easy to see that this may work when travelling downwind or across the wind. The problem with upwind is the drag of the hull and windage is aligned in the same direction. Hence you only need produce sufficient power to beat the uphill drag. It is this balance which will tell if it works. The movie above and the attached diagrams indicate that it probably does for some cases.
    Any excess energy is absorbed by the drag of the hull through the water ie the boat moves forward.

    PS I agree that the conservation of energy law does apply. Afterall it wouldn't be a law.
     
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