Catapult Design Help

I need some help with the design of a catapult for a school project if any one has any experience or advice on one. There are only a couple of rules: can be 50cm x 50cm x 100cm max, must be gravity powered, and must have a remote trigger. I think it needs to throw about 30yds accuratly. I also need it to be pretty simple to build because I don't have a lot of time.
Thanks

 

The "gravity powered" aspect of this is the "gotcha". I have built a bunch, usually a LOT bigger than that. Because of that gotcha, you are going to need to go with one of the counter-weighted designs. Fortunately for you, there's plenty of plans online. The remote trigger is usually just a length of rope to release it. Think of a teeter-totter type design...

Have fun. This is a great project.

 

BTW, start here for TONS of info on gravity powered siege weapons, including the classic trebuchet. http://www.google.com/#hl=en&safe=off&q=trebuchet+&aq=f&aqi=&aq=f&aqi=&oq=&fp=7d15299a959dbb33

 

I think I know what I am going to build, But I am kinda looking for some tips. One thing I would really like to know is where to place the hole in the arm for the pivot. what ratio five you the best distance.

 

Where is Chris 4x4 when you need him...

 

http://andypsionfan.users.btopenworld.com/trebdrop.html

http://thehurl.wikidot.com/tuning
http://www.io.com/~beckerdo/other/trebuchet.html
http://www.penguinslab.com/trebuchet.htm

 

I thought that too, than I thought he might use it to take out California.

 

I figured you couldn't really be on here 24x7 like they say... so I could pinch-hit until you arrived

It's all yours from here...

 

Wow thanks alot for the help this shoulld get me through.

 

Definitely build a trebuchet. Takes some calibration and adjusting to get it to release at the right time, but when you do, its dead on accurate and gets good distance.