Monday, 4 June 2012

Large scale Test trebuchet.

In an attempt to learn a bit more, overcome any design faults etc  before I try to build a small scale working version ( and have a bit of fun) I´ve built a large scale working trebuchet.
I´ve learnt a couple of things. The counter weight. It needs to be quite heavy...my first attempt I filled it with stones like they would have, but it threw very slowly, so I re-filled it with lead. I could also have moved the counterweight further away from the fulcrum point, but as there is only a couple of cm´s between underside and the running board, especially when the counterweight swings back and forwards after firing,  this was impossible. The only solution to increase the distance of the counterweight along the arm would be to increase the height of the middle section..which is now too late.
Also..the range can be altered by lengthening or shortening the strings to the sling as does slightly altering the angle of the pin that the loose line is attached to. Bend it a slight bit more away from the direction of throw and it increases the release time..which alters the flight..making it flatter, less of a high arc.
Set up as it is at the moment,  it throws a 4-5 cm´ds wide stone 20-25 meters.
Not far considering it´s size, but this is due to the positioning of the fulcrum and the weight of the counterweight,
No claims to historical accuracy....it´s missing a lot of supports and the actual body length is way to short at the front. I also left any winding gear off..it just seemed (at the moment) impracticle.
The axles for the arm and the counter weight proved difficult. I used metal tubes inserted into the arm, then other slightly longer thinner tubes held in place with washers were pushed through them. The bolts were then inserted. This made sure that no wood was touching moving metal and decreased the friction, which would have slowed the firing action down.
The trigger. I added this type of trigger, one using a pull cord after the one that was more historcally accurate, a pin that was knocked out, got me a whack on the ear from the arm releasing.

A couple of mini videos showing it in action




Hello to Marzio from Fog´s Soldiers. blog. In his own words " Fog' s Soldiers is a professional miniature painting service and a producer of high quality, handcrafted, scenery and model trains services."
Hello to Punkreaper from G+
Hello to Ralph Ashdown..I´ve seen your name mentioned on sean´s Blog..but no link from here?

Mike Whitaker has Just given a link to a site that works out the statistics of a trebuchet for you....
Virtual Trebuchet    Excellent..just what I was looking for. :-D

26 comments:

  1. You need http://www.virtualtrebuchet.com/Trebuchet.aspx

    Very useful site.

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    Replies
    1. !!!!!! Thanks Mike..that is B"§?ßy Brilliant!!!!! :-D
      Cheers
      paul

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    2. My son built a wooden kit of one over Xmas - we got about 9m range out of something with a 10" long arm powered by about 10 quid in pound coins :D

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    3. Great!!!! Any pics? I might build one double the size of this one..(just for fun) but using the Vital trebuchet statistics
      Cheers
      paul

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  2. Very nice, I love the videos!

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  3. Next...flaming projectiles! I used to shoot cotton swab tips in burning glue out the window with my Britains Ltd. Catapult. I love trubuchets. The look like they mean business as protrayed in the movies The Messenger, Kingdom of Heaven and I think in LOTR.

    ReplyDelete
    Replies
    1. I´m planning a flaming projectile ...a wooden ball wrapped in bailingstring and soaked in petrol....
      Cheers
      paul

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  4. Looks real good Paul! I thought you would come out with something like this :-D

    What did your neighbour say? ;-D

    Greetings
    Peter
    http://peterscave.blogspot.be/

    ReplyDelete
    Replies
    1. so far they just look and wonder what I am up too...mind you,,that´s a usual state of affairs with al the experiments that have been carried out over the last few years. They must have tons of "launched" objects that have landed in their garden.
      Cheers
      paul

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  5. Brilliant Paul, you can knock over figures from a distance with that, maybe a competition to see how many can be knocked down and people can guess....

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    Replies
    1. That could be fun.....I´ll have to dig out the 54mm knights and build a wall...
      Cheers
      paul

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  6. Looks like this could be fun!! Are you aiming to smash next doors windows????

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    Replies
    1. I keep getting told off by my better half for pointing it towards the nextdoors garden :-D
      Chhers
      paul

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  7. Nice! Classy way to deal with noisy neighbors ;)

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  8. Outstanding Paul, there would seem to be no end to your pursuit for the perfect projectile propeller!

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  9. You should read this. Our own trebuchet.

    http://philbancients.blogspot.co.uk/2011/06/our-own-personal-trebuchet.html

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    Replies
    1. Nice one Phil. It looks very nice,,,make a film!!!Your model is a mangonel....it has a fixed counterweight..;-D
      Cheers
      paul

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  10. Now that I have seen yours, here is now way I can post pics of my slap-shod made-of-scrap treb. Awesome work mate!

    I went on to make an onager which was a very different prospect and I found that the structure failed in the end unless some very heavy duty engineering mods were used. I drew the line at modifying the trailer for a 1:2 scale version...but I was tempted :-)

    I have my Scout Troop making these at about 1:5 scale at the moment to fling water bombs at eachother while they are canoeing.

    ReplyDelete
    Replies
    1. Post the pics :-D I tried an onager...a completely different beast to a treb..everytime it was fired it flipped over :-D
      Cheers
      paul

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    2. Mine too, until I anchored it down. Now you know where its name came from: Onager = Donkey

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  11. test it at your local police station ha ha!

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  12. Very cool.

    If you put wheels under your treb, it will throw approx 20-25% further. In my younger days, I used to be part of a team that competed in the "Pumpkin' Chucking" contest in Delaware. It's a hoot.

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  13. when I made one like that it threw errasers across the class but then everything else fell strait down. it was a little bigger than yours. we filled the bucket with BLACK SAND from the local beach. being iron sand it was really heavy. but the most damage it ever did was when the swining arm hit my friend in the face. wooops

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