The Longest Slingshot Ever

Discussion in 'New project ideas' started by Technipion, Sep 10, 2017.

  1. Technipion

    Technipion New Member

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    Hello World,
    when I recently saw your "Wilma" video Jörg, I was instantly remembered of good old times. While laying in bed and just beginning to sleep at night, I then had some kind of "flashback" of an old video I saw.
    In 2012 I was watching one of your videos (idk what exact video) and following the YouTube recommended videos I somehow landed on an american video of a guy explaining how to chain up rubber rings to a band suitable for slingshots. While the technique itself is propably worth a seperate video, I then figured out you could bring this to a new level... :D
    I'm a terrible drawer, but the chaining is done something like shown in the appended image. You can buy kgs of rubber rings on Amazon Germany for under 20€, so this would be a cheap and quick'n'dirty project. Just buy a few thousand and make a rubber chain like 10m long or so. That could be drawn out to 20-30m ^^
    This would make it the longest slingshot ever, right? (Maybe even a world record?)

    It was just a quick idea, so if anyone else want's to give it a try, go ahead!

    Greetings Technipion

    chaining.png
    longest_slingshot.jpg
     
  2. NamenloserHeld91

    NamenloserHeld91 Senior Member

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    It own wight woud probably crush it. Also one man couldn't pull it. An what purpose shoud have such a long Slingshot anyway?
     

  3. Technipion

    Technipion New Member

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    I don't really see which weight you are talking about. The weight of the rubber chain? Well according to the manufacturer, 1000g of these rubber rings equals about 5800 pieces. They have a diameter of 10cm, so in the chain they will be 15,7cm long. A 10m chain will thus have a weight of about 11g. I would even recommend linking multiple rubber rings at once, so the final rubber band will have a higher drawing force.
    The weight of the fork is negligible, as it has to be mounted anyways.

    Why should one man not be able to pull it? Energy equals Force times Distance, and Power equals the Force itself. Instead of pumping 100J with just your arms in about 1m distance, you can now use your whole body (respectively your legs) to load 200J of energy over a distance of more than 10m. This seems pretty comfortable for me.

    What purpose does an ordinary slingshot have? It's just a toy for having fun and plinking around with. I never claimed there was a serious application behind this thing.

    Have a nice day, Technipion
     
  4. JoergS

    JoergS Administrator

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    I don't like chained bands much because of the fact that these rings break easily and it is almost impossible to fix that. The rubber used in such rings is much inferior to Thera Band, which can be bought in rolls 22,5 meters long.

    My longest slingshot (will premiere Oct. 1st on German TV) had a draw length of 13,5 meters...the relaxed bands were 2,7 meters long. Thera Band of course.

    If you use the full 22,5 meter roll, your draw would be 112,5 meters. That is certainly more than needed for serious slingshot artillery!
     
  5. Belargo

    Belargo Mad Scientist

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    Oh cool, another TV-gig. Which channel will it be on?

    Just out of curiosity, what ammo weight would be appropriate for that 112,5 meter-monster?
     
  6. Technipion

    Technipion New Member

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    Yeah those rubber rings are definetely not as high quality as thera band.

    Cool, I didn't know you could buy thera band that long. Sounds like a potential project in the future... :D

    Just take two trees and let the fun begin :cool:
     
  7. Pluto41

    Pluto41 New Member

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    I'm also interested in such a test because lately i have thought a bit about this. Butterfly shooters say they enjoy the extra power. But if you see a PFS (active) shooting its very fast too while the elastic is relative short; which raises the question for me. If you could have a draw length of a kilometer for example how fast would it projectile. Is there after a certain draw length that physics that prevents the projectile to go any faster. For example the elastic could get weird entangled with itself and the projectile and then it wouldn't be a very good weapon anymore. In my opinion there has to be an optimal band length to let the projectile out as fast as possible. It seems to me that longer is not perse better.
     
  8. JoergS

    JoergS Administrator

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    My experience is that you can simply exchange draw weight and draw length. In other words, it is the MASS of rubber and the factor of the stretching that counts.

    So my huge cannon (that will air Oct. 1st, on Kabel1, at 22:25 https://www.fernsehserien.de/abenteuer-leben/sendetermine/kabel-eins/01.10.2017-22:25-Uhr ) uses 44 full width TBG bands, 2,7 meters long, stretched to 13,5 meters (maybe a bit different, can't recall the exact figures). It throws a full size bowling ball at around 80 m/s.

    That is 118,8 meters of TBG.

    If you use the longest bands possible (22,5 meters), you need to use 5,28 bands total to replicate that effect. So you use three bands per side (for good measure) and start walking back 112,5 meters. Or, better, you attach the bands to your truck as the draw weight at full draw will be around 150 kg.

    You WILL achieve the same shot speed with the bowling ball, believe me.

    Of course it would be wise to use two extremely large trees standing quite far apart. The bowling ball will begin to fall when you release, and over 112,5 meters with an average speed of 40 m/s it will fall for almost three seconds until the ball leaves the pouch. You have to attach the bands to the very top of these very large trees to compensate. This will give the ball an upwards vector, fighting gravity.
     
  9. Technipion

    Technipion New Member

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    Holy sheet!
    That is like 13 kJ of energy, and bowling balls are made out of really tough material. Have you shot it against some stuff? Like a bag of plaster or a brick wall?
    I will definetely watch it!

    Do you think it would make sense to use some 10mm steel ball "shot" instead? Would be interesting to see :D
     
  10. Roi_Pigeon

    Roi_Pigeon New Member

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    Theraband seem to max out at a certain velocity (80 or 90m/s I think).

    The material just can't retract to its initial lenght faster than that. So from my understanding, shooting a tiny steel ball from that monster sized rig would mean that you'd get a steel shot flying at the maxed out speed of +/- 100m/s and get all of the unspent energy back to you in the form of the biggest bandslap in the known universe.
     
  11. Pluto41

    Pluto41 New Member

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    This is what i meant more of less with longer is not always better. Although this is only for me a mind experiment and i don't have time / physics knowledge or tools to back this up. By the way i'm talking about "regular" catapults forks. We all know that if the forks gets really wide this would be another game. I'm interested in a regular fork width. 10 millimetre steel and what would happen if you use really long bands.. Anyway looking forward to Joerg's experiment. Sounds like fun :) Best regards from Netherlands.
     
  12. Technipion

    Technipion New Member

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    Guys I know, I studied physics and had to graduate in material science :)

    A rubber band can't reach velocity higher than a material-specific constant (which is definetely!!! lower than the internal speed of sound). So like 110 m/s is max.

    But I meant to use a lot of 10mm steel balls, like 4kg of them. This would basically be a giant Slingshotgun :'D

    Anyway, every construction with that much rubber just must be a lot of fun, especially if Jörg designed it :D