I'm a technology teacher on long Island and Im having my Metals two class design and fabricate a full size trebuchet that will be able to throw a 3-5 lb pumpkin. we have a full woods and metals lab, 8 welders, 2 mills, 8 lathes, plasma cutter, etc (all the tooling and raw material needed) there is a competition held on out here where schools compete every october. what design would be best? we will be designing it in Auto Cad. any help would be appreciated
Date: 02 Feb 2012 04:28
Number of posts: 3
RSS: New posts
There is no 'best' design unless you apply some really strict constraints. With no mention of a goal and, no restrictions on parameters other than projectile weight, it basically impossible to choose an optimal design. If you want to throw as far as possible, the ideal design is something that costs millions of dollars to build. If you want to optimize for cost, its free to throw 0 distance. Look at competitions with experienced entrants: there are many different designs they use. If there was a best one, the wold championship pumpkin chuck would not feature more than 6 very different designs.
If you are looking to build something efficient and compact, thats very different from a trebuchet that may take the same amount of work to build, but is simpler and larger with the same range. Until recently (and maybe even currently), the longest ranged trebuchets were just very large HCWs. If you haven't built trebuchets before, a HCW or FCW is a good starting place if you want a design thats not too hard to get right and gets good range for the effort. All the other designs are more complex and mainly efforts to get more range without simply increasing size. I also recommend building a small model first. If that goes well, you can try building models of a few more complex designs if you wish, and scale up which ever you like best.
Most common mistakes I for school project trebuchets: really heavy untapped throwing arms, crummy slings, and axels that are longer then needed (and then end up bending a ton).
Also, "Full Sized". Full sized generally means one of 2 things: medieval scale and can throw 200+ pounds a few hundred yards, or 8-10 pounds competition pumpkins. That said, I mainly work with stuff that fits on my desk.
Anyway, thats what I have to offer. Feel free to browse around the site and ask some more specific questions if you have any. If you want a higher volume of advice, the majority of the hurling community hangs out at TheHurl Message Board. You will get a ton of fantastic advice from those folks!
thanks for the advise so far. there are no real constraints, it has to go as far as possible(3-5lb pumpkin) and be able to be transported by the team to the field, thats really it. I was thinking something with in the size of 4'- 2'x8' maybe a little bigger if the design calls for it. I was planning to do something simple strong frame and towers made from 4"x4" steel hollow square stock. maybe aluminum throwing arm on the sling side and heavier steel on the counter weight side.