|By bavetta, torpex, rubix, rustaman, damonv|
We built a 15 foot tall (30 foot extended) trebuchet and fired water balloons and other similar projectiles.
The hall we live on at our dorm (Tetazoo) voted to spend the money garnered from having Laura Stewart as a faculty fellow to hold the 1st "Laura Stewart/Tetazoo build day". We went to Home Depot and bought supplies in order to build 2 to 3 smaller trebuchets. When the day came around, not many people were immediately interested in building them, so it was decided to build one large one instead.
There is not a lot to say about the construction, you can pretty much get it all from looking at the pictures. There are ratios that many trebuchet webpages say are good to have - length ratios, weight ratios, etc. We thought about them in the design phase, but ignored them during construction.
We made a frame out of 2x4s, decided that it was too weak, then kept adding 2x4 supports and cross-braces until the frame felt more sturdy.
The axle was made from a 1.5" black pipe sliding around a 5/8 steel rod. It worked really smoothly, at the end we noticed that it had bent slightly from the large weight, but it still seemed to work without much friction.
The weights were concrete that we cast a few days earlier: three 60lb weights and one supa-mother 300-400 pound monster. We put U-bolts in the concrete before they set so that we could attach them to the arm.
Here were the results of one day of testing [in ft]:
22, -5, 3, -33, -38, -30, -6, 0, [change to large weight] 0, 0, 28, 204, 126, 232
Just when we started getting the hang of it the big weight fell off of the arm (see the last photo) and we called it a day. We are apparently going to try a second run this next weekend. We'll update the results after it happens.