Building a waterballoon launching Trebuchet

[imonly12but im smart]

OK as you can tell I am 12 but fairly smart (wink,wink) This summer me and my friends plan to have a huge neighborhood water gun fight and I plan on building a waterballoon launching Trebuchet about 3 or 4 feet heigh. I need some help with the materials I should use and the weight of the well counterweight in fact I need most the dimensions but the height. For quick transportation I need to use wheels which will increase the velocity at which the waterballoon will travel but i am afraid that the waterballoon will burst before it has time to be released out of the sling. What type of sling should I use?

Oh yeah forgot to mention this... I am lazy and fairly broke(after all I am only 12)

 

[person11]

oi man i really 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

 

[Nenad]

you would have to do some calculations on projectile motion. You would also have to know Work/Energy concept. This think this project will be a little hard for you.

 

[pervect]

OK as you can tell I am 12 but fairly smart (wink,wink) This summer me and my friends plan to have a huge neighborhood water gun fight and I plan on building a waterballoon launching Trebuchet about 3 or 4 feet heigh. I need some help with the materials I should use and the weight of the well counterweight in fact I need most the dimensions but the height. For quick transportation I need to use wheels which will increase the velocity at which the waterballoon will travel but i am afraid that the waterballoon will burst before it has time to be released out of the sling. What type of sling should I use?

Oh yeah forgot to mention this... I am lazy and fairly broke(after all I am only 12)

There are some trebuchet simulator programs on the net, such as ATREB

http://www.trebuchet.com/sim/

The same website sells commercial kits. I have no idea of how good the kits or simulators are. I'd suggest sticking to the demo versions of the software and looking at the pictures for ideas - actually, I'd also suggest sticking to computer simulations unless you get your parents involved to be sure you're not doing anything unsafe.

 

[Belsamber]

A friend and I built one a few years back about the size you are talking about (as a prototype... Its big brother should be coming into existence this summer ) We didn't do that many calculations, just read a bit and played with the simulator to get a good idea of what was going on. There's an online book around somewhere on the physics of Trebuchets...

Anyway, I don't think the force will break the water balloons, its a fairly smooth delivery. We easily get a golf ball about 100ft, but you need about 70lb counterweight - the more the better. I know our dimensions aren't anywhere near optimal - 2.5' high, 4' arm and our mechanism is pretty crude, so you might do a lot better. I think the hardest part to design is the bearing, so do some thinking!

Oh, and I agree with pervect, get your folks involved and be carefull. We made a "safety" for it as a backup to the trigger, I suggest you do the same. Just something to make sure it stays cocked while you're loading etc. That arm gets up a hell of a speed without a projectile...

Good luck.