Trebuchet construction

[intergalacticman]

OK SO its spring break and im building a trebuchet by Friday.:twisted:
i have the wood a 30$ lowes gift card and a 15$ target gift card BOOYAH
im going on my supply run tonight but if my mom is too tired to drive me it will delay the project by one day (i only have 5). its somewhat smallish, the arm is around 8-10 feet long(i cant decide) and it will throw grape shot(tennis balls).
ive been researching the optimum dimensions and ratios for like a year and and im reallly excited that i can start construction :)

[jdbnsn]

You gonna build up to the pumpkin chunkin size? Someone here did that last year but I forget who.

[Omega]

You should build an air-powered mortar or something of that sort. I plan on doing that sometime.

Small? 8 foot arm? Jesus christ! If an 8 foot arm is small for you, I don't want to know what big is.

[Aero]

You should build an air-powered mortar or something of that sort. I plan on doing that sometime.

Small? 8 foot arm? Jesus christ! If an 8 foot arm is small for you, I don't want to know what big is.


8 ft is small, mine was about 12 ft:smoker:

Here my thread about it, pictures are on page 2:
http://thebestcasescenario.com/forum/showthread.php?t=4927

Yeah man, my friends and I built a catapault last year and took 1st in the World Punkin Chunkin Competition in Delaware for youth (we beat all youth but the air cannon...stupid corporate sponsorship) last november. If I remember right we had about a 12 foot boom at a 3:1 ratio (3 feet above the spring abnchor point and then 9 feet to the sling anchor point). For tennis balls you will want to have a higher ratio because they are so light., you couild easily run a 6:1 with the propper weight.

Remember, you don't need a big machine to throw a tennis ball that far. No matter what the quality of the machine is much more important than size. At the competition a kid was playing with a machine about 1.5 feet tall, and throwing golf balls a good 75-100 feet, its all in the design. Any questions feel free to ask, I'll try to help with what I can.

[SgtM]

:pics:

[nil8]

I just had a horrible thought.
Golfball air cannon.
Repeating golfball air cannon.
Sweet.

[intergalacticman]

yeah sorry about the pics i might be able to mangage some with my mom's cellphone camera but im not starting construction untill thursday hopefully

but i made a k'nex model this morning and its sweet
it throwing a projectile made of 4 tennis balls duct taped together into a pyramid shape.
Air mortar??? sounds too expensive

i didnt use golf balls since those could do some real damage to things( isnt that the point of a siege engine? lol )

[intergalacticman]

ok i took some pictures ill have them by monday prolly. im 3/4 finished i just need to drill some holes and im set. the launch date is unknown

[GT40_GearHead]

:pics:

[Canadian Eh?]

^Agreed

[intergalacticman]

Ok Pictures!!!!!!:banana:
its like 1/2 finished so heres my progress
http://i119.photobucket.com/albums/o147/intergalacticman/155419710_511721266_0.jpg
the full arm
http://i119.photobucket.com/albums/o147/intergalacticman/155420549_511724251_0.jpg
close up arm and axle
http://i119.photobucket.com/albums/o147/intergalacticman/155420209_511723046_0.jpg
the folded up supports
http://i119.photobucket.com/albums/o147/intergalacticman/155421249_511726733_0.jpg
the projectile on my desk ( 4 tennis balls duct taped in a cone shape)

ENJOY!

the final assembly and launch will be this saturday:D

[intergalacticman]

http://www.vzwpix.com/mi/155421042_511725982_0.jpeg?limitsize=500,520&outquality=56&ext=.jpg&border=2,0,0,0

[Maz]

I just had a horrible thought.
Golfball air cannon.
Repeating golfball air cannon.
Sweet.

already done. by me, by pretty much every other potato cannoneer

[Aero]

looks good. What are you using for the axle? It looks like Aluminium? Or Threaded rod? Hope the doesn't bend too much. Also, fiddle around with it to get the best shot (obviously :p) Remember the higher you get the weight the more energy it has, so it may help if you shorten your throwing arm to get the weight higher, just an idea ;). Good luck, let us know how it goes.

[intergalacticman]

looks good. What are you using for the axle? It looks like Aluminium? Or Threaded rod?

its a 3 foot long threaded rod 1/2 inch diameter. it shouldnt bend




Remember the higher you get the weight the more energy it has, so it may help if you shorten your throwing arm to get the weight higher, just an idea ;).
what:? :? i dont understand what you mean

[xRyokenx]

He's talking about basic leverage. The longer the arm the more of an effect the force has on it. Look it up on Wikipedia if you need a bit more of an explanation.

It's looking good to me, my neighbor built a small one for a class he was taking, he launched it on his gravel driveway and it slid back about 10 ft (3 meters), and the golf ball went across the street to the neighbors yard, heh heh... and the one he made was only a couple feet tall (the frame, that is).

Oh, and when I first opened this thread, I just want to point out that the pics were screwed up, they overlapped the other posts.

[intergalacticman]

oh yeah i know what you mean, the short arm is 2 feet long and the long arm is 6 feet long

[intergalacticman]

OK!!! tomorrow (the last day of school) me and my friend aka firemonkey91 are going to FINALLY finish up this project (now i just have to complete my SR-71 project) Im ordering pizza, and some of my LAN buddies are coming for the inaugural launch of the WonderSquid II. (WonderSquid I was my knex model lol)

[intergalacticman]

its all completed, its a little wobbly, but a few crossbars should help. my friend took some pics and they will be here soon. the axle (.5 inch threaded rod) bent alot, but no permanent damage was caused. I forgot to plan the sling so it was quite rudimentary and we only threw 60 feet. after i work out the bugs on it, it should become the menace of everyone in Irvine. We also borrowed some sand from the playground, and commandeered my neighbors recycling bin to haul it back. I cant wait to get in some long range (300meters) sieging.

[luciusad2004]

I look forward to seeing images of this. I always wanted to be able to build something like this but figured it would be difficult. Now that i look at it i guess it doesn't seem as complex as i used to think it was.

[intergalacticman]

yeah well the building is the easy part. Getting it to fire 300 meters (max range in the simulator i have) instead of straight up is the harder part. Especially when a box full of 20 pound sand bags are close to whacking you in teh face.