Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How to build a scale model of a trebuchet?

  1. May 16, 2004 #1
    Anyone have some ideas about how to build a scale model of a trebuchet?
  2. jcsd
  3. May 17, 2004 #2


    User Avatar
    Science Advisor
    Gold Member

    Um, what scale? I helped my nephew build one with the erector set type stuff that I believe is called k-nex. Have you ever watched one in action? I seen something on NOVA on PBS and just by watching it was able to build the model one in less than half an hour. The model one was fun, but I'd like to make a LARGE one that could fling oh, say a small car or something. Hmmmmm, maybe a large bladder full of water. LOL I already have the large surgical tubing slingshot that is used for water balloons, but imagine flinging about 200 gallons of water.
  4. May 18, 2004 #3
    You can buy kits and plans, or look at finished ones and figure it out for yourself. I have the tabletop model - it flings stuff about 30 ft.
  5. May 18, 2004 #4


    User Avatar
    Science Advisor
    Gold Member
    Dearly Missed

    incredible as it seems I've seen photos of one flinging an upright piano
    it was a fullsize upright and got flung way far (but I dont remember how many yards)
    must have made quite a noise when it landed
    the photos were in some wide circulation magazine like National Geographic but I dont remember which----quite a while ago
    maybe someone else remembers
  6. May 19, 2004 #5


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Something very similar to this was done on a episode of Northern Exposure a few years back. Great show. That Trebuchet was acquired by the local Summer festival ( Corvallis Oregon, Davinci (sp?) Days) they set it up one summer and used it to throw pallets full of old computer parts. It never matched the throw shown on the show. But still a pretty impressive machine. I belive that it was hard to store and set up so am not sure what its ultimate fate was.Davinic Days Trebuchet
    Last edited: May 19, 2004
  7. May 19, 2004 #6
    Oh, sure. I finish my degree in '95 and the next year they get a trebuchet. :grumpy:
  8. Jun 28, 2004 #7
    Trebuchet episodes

    Check the History channel in your TV program guide. I've seen a couple of programs on the subject. One is called 'Mail Call', and in that one there was an episode in which a medium sized trebuchet was used to fling watermelons. The other was on a program dedicated to the Trebuchet, and this one, if it is repeated might be announced in the guide. In it, a large Trebuchet is used, among other things, to throw an upright piano. (There may even have been another program on the subject - - I can't recall for sure.)

    In any account, check the History channel (and maybe also the Discovery channel) in your guide. You could also try the History and Discovery channel websites. There may be some info there; or someone there may give you some information.
  9. Jun 28, 2004 #8


    User Avatar
    Science Advisor

    Anyone here ever solve all of the equations for a trebuchet? It is a tough problem - or a bunch of moderate problems I should say.

  10. Jun 28, 2004 #9
    One of those history channel shows about the trebouchet had a bunch of guys in England building a full size replica of a medieval trebouchet from wood with lead for the counterweight. With it, they flung sandstone balls weighing 250 lbs. They had made a section of medieval castle wall to aim at and try to knock apart. Adjusting the aim on such a massive piece of seige machinery turned out to be tricky. They succeeded, though, and knocked the wall apart from something like 200 yards away.

    This team of people was working from scratch with only crude illustrations to guide them. One thing they discovered was that the wheels on the base weren't merely to wheel it into position. They were an important means of dealing with the recoil of a fling.
  11. Jun 28, 2004 #10


    User Avatar
    Science Advisor
    Homework Helper

    Trebuchets work from conservation of momentum, there's no recoil as such. In fact, the trebuchet is pulled forward while firing. Putting the trebuchet on wheels takes advantage of that forward movement, and makes the trebuchet more efficient.
  12. Jun 28, 2004 #11
    That makes sence. If you have no wheels the forward force puts a great stress on the frame. Then there is a restoring force in the opposite direction. It is a damped oscillation, really, that wastes energy and unnessesarily stresses the frame.
  13. Jun 30, 2004 #12
    Trebuchet project

    This may be a bit large, but here is a website for a college class project.

    http://www.nctc.tec.oh.us/webpub/kekegren/project2004/trebuchet/trebuchet.htm [Broken]
    Last edited by a moderator: May 1, 2017
  14. Jul 2, 2004 #13
    Treb Equations

    Speaking of........
    This is madness. I have much respect for this individual. This is going to assist me greatly in my construction :biggrin: http://www.algobeautytreb.com/trebmath35.pdf [Broken]
    Last edited by a moderator: May 1, 2017
  15. Aug 21, 2004 #14
    oi man i realy need sum help.....do u noe nething about the ebergies of a trebuchet like kinetic energy,etc. man i wood really preciate it...and email me at sexy_genius92@hotmail.com...and yeh i 14
  16. Aug 30, 2004 #15
    Flinging 200 gallon bladder of water? That's about 3/4 of a ton. I would think that you could seriously injur someone with that.
  17. Aug 30, 2004 #16


    User Avatar
    Science Advisor
    Gold Member

    Yes you could. I doubt I would ever try it, but not for that reason.

    Think about this: People shoot high power deer rifles all the time. They could seriously injure people too.
  18. Aug 30, 2004 #17
    I just wanted to make sure that if any college kids were reading this that they didn't get any stupid ideas. I remember being a college kid and there was no telling what me or my friends would do given an intriguing idea. :)
  19. Oct 11, 2004 #18
    My uncle actually worked on that project, having been hired as a master timber-framer. He's since built some smaller versions and used to do demos at schools. I'm thinking of building one myself as a project for my IB Physics class, and I'm curious if anyone has any resources relating to the maths...
  20. Oct 11, 2004 #19
    Junk Yard Wars did a couple of episodes on this. Threw a small car in one and a washing machine in the other. Really cool. Man that washing machine really flew! :tongue2:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook