wiggle drive propulsion application

Discussion in 'Propulsion' started by SudorracMechEng, May 7, 2012.

  1. SudorracMechEng
    Joined: Mar 2012
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    SudorracMechEng Junior Member

    Craig, could you please tell me which angles are you running in that video.
    Have you done many experiments varying the angles?
    I could refer you some literature, that i obtained through my university - that will show you experiments performed - whereas the heaving and pitching angles were varied and measurements on thrust and efficiency were obtained.
    This would allow you to optimise your boat more for efficiency (higher top speed) or a higher thrust system.
    Ofcourse this depends a lot on fin geometry. What amount of sweep are you using? What material is the fin made out of?
     
  2. swashdrive
    Joined: May 2012
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    swashdrive Junior Member

    The fin is attached directly to the swashplate rim perpendicular to shaft rotation, there are no linkages. Like i previously said, pretty much what Jkell has setup in his orni devise.
    I have done extensive testing on what i call "deflection angles" because the two (pitch & stroke) are the same or predetermined from the one mechanism.
    I found with the foil shape i'm using, ## degree to be just enough to get on the plane but not to excessive that it holds back top end, (which i have GPS'd to 75kph) I found that at higher speeds than 75k cavitation occurred within the fin, foil shape ?
    But not a bad result !
     
    Last edited: May 30, 2012
  3. kjell
    Joined: Aug 2005
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    kjell Senior Member

    The main differences are that the mechanical load in the Kjell-Wiggle-Drive is supported by Sealed Radial ball bearings and the Wiggle Head is not touching the rotating plate. The load in the Swashdrive is supported by Axial ball bearing touching the rotating plate. Both are moving the fin in the same way.
     
  4. Boston

    Boston Previous Member

    as I'm trying to envision these mechanics I'm curious how you transfer the forward thrust if the fins floating in the swashplate, I'm sure there's a bearing in there somewhere but would you discuss that aspect of the device. It would be fun to build one of these things and put it on my model.

    Cheers
    and thanks
    B
     
  5. kjell
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    kjell Senior Member

    The thrust is produced by the “Kjell-Effect” produced by the angular movement.
     

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  6. swashdrive
    Joined: May 2012
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    swashdrive Junior Member

    Gday
    I would really like to share & disclose the way my mechanics move the fin to make it swim, but i really fear it will get hi-jacked by Mr Kjell, he already thinks i'm using an "axial ball bearing"... what is that ?
    Fish have been swimming like it and birds fly like it for millions of yrs, i will not contribute my device for some "******** Kjell effect".....what is that about ?
    Sorry but i have to contain the mechanics as confidential an just use the term swashplate !
    regards
    craig
     
  7. Boston

    Boston Previous Member

    well I for one have a little something called ethics and I can assure you I understand where your coming from. I'm not accusing either of you, as I've not looked into any of the issues you guys seem to be having, but I'd be real curious to see how that bearing ( gotta be some kinda gimbol set up ) transfers that load.

    I got the part about how the swashplate can dictate both pitch and arch but I'm just not clear on how the pivot deals with transferring the load.

    One thing I was thinking of though was that if the fin was made out of some kind spring steal then its stiffness might modify the pitch ( angle of attack ) as its accepts the load.
    just an idea
     
  8. Frosty

    Frosty Previous Member

    It would have been difficult to have evoluted into anything else. I know not of any rotating muscle organism. If there was, it is likely the fish would not swim this way.

    Squid are jet propulsion.

    If you have ever stood at the bow and seen Dolphins, there ability to swim so fast seeming effortlessly is amazing, yet the power used is not visable.

    It would be extremely interesting if nature had evoluted a propeller and given us a bit of help as it has in other fields such as fins and flying.
     
  9. Boston

    Boston Previous Member

    actually frosty there is a spinning type drive in nature, its on some amoeba somewhere and its really pretty interesting, although its also pretty damn inefficient, which is why all larger forms used a fin, flipper, feather, foil or foot type arrangement.

    I'll see if I can go dig up a diagram of the critter I have in mind

    Cheers
    B
     
  10. spork

    spork Previous Member

    The flagellum motor is the only thing I know of to have evolved rotary motion.

    http://en.wikipedia.org/wiki/Flagellum

    Amazingly - "The rotor alone can operate at 6,000 to 17,000 rpm, but with the flagellar filament attached usually only reaches 200 to 1000 rpm. The direction of rotation can be switched almost instantaneously..."

    [​IMG]
     
  11. SudorracMechEng
    Joined: Mar 2012
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    SudorracMechEng Junior Member

    Frosty - You clearly need to do some research into this area.
    Conventional propellers are quite inefficient - 70% if you are lucky.
    Efficiency of propulsion mimicking the whale fluke have achieved efficiency's of greater than 87%. Ofcourse there are limitations, and many areas where it is better to use a propeller. But to merely say, a propeller is MORE useful in all areas is ludacris and is only detrimental to understanding and learning.
    Engineering would of never progressed if such thinking had of been prevalent.
    Enormous amounts of research has shown propellers are not the most efficient propulsion.
     
  12. Frosty

    Frosty Previous Member

    Learn to read --where did I say that? I did not say that.

    Quote it if you can find it.

    And it is 'ludicrous'.
     
  13. SudorracMechEng
    Joined: Mar 2012
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    SudorracMechEng Junior Member

    Boston:
    - Did you mean "reverse"?
    I have two degrees, mechanical engineering and business.
    I research biomimetics.
    Firstly, lets not argue the semantics of spelling and reading.
    Lets look at the facts.
    Your argument - that basically we should use a propeller because its more efficient, as you said above "anything that reverses backwards and forwards wastes energy"
    It is quite easy to achieve Reverse Karman' street effect using an oscillating foil, once this effect has been achieved - efficiency is optimised.
    In turn, results are achieved that are MUCH higher than propellers.
    So you can sit here and argue about my spelling, or "reading" ability - or you could simply talk about fundamental hydrodynamics. If you have any factual contributions, please let us know :)
     
  14. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    May not be the most efficient form of propulsion, but it gets down to what is practicable, and so far that is how things stand, even with enormous $$$$ incentive to improve efficiency even incrementally.
     

  15. Frosty

    Frosty Previous Member


    Sigh----- where did I say that?

    You do have a problem don't you.

    Wow on the mechanical qualifications, your the only one here to have any.

    How you manged to do that with your inability to read makes it even more astounding.

    Now-- I suggest you get your facts straight or your request to have a sensible conversation is unlikely.

    I appreciate your just bursting to educate us all on fins but slow down and get it right.
     
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