Better ergonomics and efficiency with symmetrical force distribution

Discussion in 'New project ideas' started by slingerprof, Dec 3, 2013.

  1. slingerprof

    slingerprof Junior Member

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    Hi slingshot artists,
    I think about a general problem of slingshots: The force on the forehand is not in the axis of the arm, but parallel to the arm. This forms a crank that twists the hand. In the launch moment the hand snaps forward and makes the shot inaccurate. This is why you need wrist support with arm rests on stronger slingshots.

    First I thought that this is the solution: https://plus.google.com/photos/1005...5667140618753009986&oid=100586243236722797878
    The problem with it is, that you get additional force on the forehand through the pulling rope, and it's not easy to handle.

    My concept to bring the force nearer to the arm axis is drawn in the attachment. You hold the ss in the middle of the pulleys. Both slings (upper and lower) go over your arm and you pull both slings together. So you divide the force, half over and half under your forehand. When shooting, you have to release only the upper sling.
    What do you think?
     

    Attached Files:

  2. VWscooby

    VWscooby Senior Member

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    It looks a lot like an unbraced gloveshot. When you release the top one, wouldn't all the draw force be transferred to the bottom one (Which you are still holding tight) bringing your hand back and punching yourself in the face?
     
    Last edited: Dec 3, 2013

  3. Tremoside

    Tremoside SINdustrial designer

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    A new idea is always interesting, but it's still a bit unclear how it improves ergonomics and how (usually problematic) pulleys help in this case.

    I think if your idea is working there are still lots of questions remain unanswered. Like aiming properly, band/tube life, band's hitting the frame, complicated reload and twisted bands/tubes etc.

    You can work it out I'm sure. Build a proto and test it. Experience is a treasure.

    Thumbs up for new ideas!

    Tremo
     
  4. kohlqez

    kohlqez Accident-Prone

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    I don't fully understand the diagram(i just looked at it), however; the title of this thread sounds very scientific and I'm interested to see how it turns out. Good luck!
     
  5. slingerprof

    slingerprof Junior Member

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    @VWscooby: When you release the top sling, only a part of the force is transferred to the bottom sling. Pulling the backhand even increases the force, if you don't hold it in front of your nose. The problem you describe exists even more in normal slingshots, if you release it, the backhand snaps back with full power that was previously in the rubber.

    @Tremoside: You need not necessarily rotating pulleys, they can also be static, or better round bended tubes. It is just a redirection of the rubber band. It improves ergonomics, because the forehand is loaded symmetrically and doesn't twist any more. One sling pulls at your thumbs' side, the other one at the little finger, so the hand doesn't twist any more.

    If I have time enough, I will make a prototype.
     
    Last edited: Dec 4, 2013