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This year Iam going to enter the pumkin chukin contest in Delaware. It is 2 hours away from me so I decied to enter. http://www.punkinchunkin.com/main.htm

Iam going to enter the youth trebuchet class. The thing is going to be about 6 feet tall. 2 big A frames. My question what should the lenght of the boom be?? It is going to be triggered by air pressure from one of my potato guns. Iam hopeing for a least 100 yards. Iam going to use bench weights and some conret mold I got from my Dad's work. I have intill november so I have a while. Iam going to take my time on this. Any input would be great. Thanks for the help.

are you making it of steel?

The length of the arm depends on how tall it is and where the pivit point will be . I think the arm should be the last thing to build. After all is done measure from the pivit point to the bottom where the release will be. I beleive the ideal way to put the arm is 4:1 at the pivit point ________________|____

I dont really know anything about trebs but i saw that contest on TV this one time, it was pretty cool to watch those monster pnuematic guns and spinning things. Good luck to you bring us back a medal.

Here are some pics of my miny toothpic terrors.Made with toothpics,thread,putty,wood and wood glue.If you ever get bored than make these,they hurl peanuts 30feet.I haven't built a big one but I might when I get my arc welder.The concept is simple.

Mihlrad wrote:I dont really know anything about trebs but i saw that contest on TV this one time, it was pretty cool to watch those monster pnuematic guns and spinning things. Good luck to you bring us back a medal.

Lol that is the one I am going to. It was on the Discovery channel. I might get on TV this year.

About the arm, for a 4:1 it would be just for saying, 1' off the back and 4' off the front?? Thx

ya if you had a 5 foot arm it would be 4foot on one side of hte pivit and 1 foot in the other.. try googling trebs there are some cool programs that help with dementions and counter weights.

How did you figure the stuff out for yours?

Me and my friends built a wood treb that was about six feet tall. It wasn't very sturdy, put quite powerful and accurate. We launced tennis and bocce balls. For the counter-weights we used two 5 gal. buckets of sand. I also read that a 4:1 ratio is ideal. If you are trying to lauch pumpkins, I would suggest that you make your treb bigger and of metal. Also, make sure the bar that your arm pivots on is really, really, strong. Ours was a 1" steel (I assume) pipe and it bent under the weight of the sand. I would suggest a solid steel bar if you are going to put tons of weight on it. Also make sure that your weights are very secure or they could fly off and send you to the hospital.

hehe good idea with that, i made a treb back in the day for a school project it sucked arse really bad shot marbles about 50 foot

You should build a Floating Arm Trebuchet. I built one in a videogame once. It was Half-Life 2 :Garry's Mod. If you don't know what that is, it is a game that allows you to toy around with the most advanced physics engines in any game yet.

me too i play that , you could even make a potato cannon if you treid hard anuf!

Oh and, theres a book the theaches you all these things its sumthing like..

roman thebuchs englhis onagers blah blah blah and more ainheint artillery,

well anyway i ordered it of amazon.com should be here tomorro or the next day

Here is a page on trebuchets it has a "Virtual Trebuchet" Java App kinda like GGDT for trebuchets.

Virtual Trebuchet

use garage door springs instead of counterweights. more powerful,and much lighter (for transport)

Have you heard of yankee seige? check this out

read the whole page

http://www.yankeesiege.com/faq.html

Just make sure if you choose to use springs that they are 100% secure. If a spring came off under tension it might rip you in half.