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Tennis Ball Trebuchet

Team Urban Siege is proud to host a copy of the infamous Ripcord's Tennis Ball Trebuchet Plans. This set of plans is a good beginner's project, and scales pretty well too. The plans were designed and written by Ripcord (on TheHurl), and resided on his great trebuchet page for beginners. Other people around the world have preserved his plans (especially after a server snafu caused his site to go down for a year or so), and we have those here now. They have been slightly edited for grammatical issues, but are good to go. The plans use a lot of funky angles, but read through the plans first before cutting anything, and these should not be too much of an issue.

This set of plans is the one that Matt designed the Tennis Ball Trebuchet from, and modifies and scales very well. In fact, the basic proportions of Ripcord's plans were used for designing the Melon Felon. Our Tennis Ball Trebuchet used the same rough dimensions as Ripcord's, but we used stock 1x2 lumber (actually 3/4" x 1-1/2") instead of the smaller cross sections called for. To make it break down a little, we did not glue the outrigger base and outriggers to the machine, but used bolts where the outrigger base meets the frame, and also where the outriggers meet the frame.

This set of plans is very popular among first time builders, and is a great platform for experimenting with. It is fairly weak on the power, but can still power tennis balls, golf balls, and even baseballs an appreciable distance while giving the user a stable machine with which to learn the finer aspects of tuning.

Without any further ado, here's the link: Ripcord's Tennis Ball Trebuchet Plans (.zip file, 418 KB).

You will need to extract the .zip file to access the .pdf file, which can be read using Adobe Reader or any other program that can read a .pdf. Windows should be able to automatically extract the file (right click on it after downloading, click "extract all"). Mac users ought to be able to extract it too, using StuffIt or the like. Feel free to contact us if you have problems reading the file.

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Use "common sense" when operating trebuchets and catapults. Even little ones can be dangerous. Do not place anything you are not willing to lose in the plane of the arm rotation (this includes yourself, body parts, car windshields, cameras, etc). These catapults and trebuchets are capable of throwing just as far backwards as forwards, and the use of a backstop of some sort is recommended, though the use of one does not make the region behind it safe.

Also, just because the throw got away safely downrange does not mean the end of the danger. The arm is likely still swinging wildly along with the counterweight, and there is a sling whipping around. One thing many people fail to take into account is this sling; some people put a metal ring on the slip end of the sling and this ring can HURT when whipping around!

Have fun hurling, but please KEEP IT SAFE!!!