These are pictures of the trebuchet I built for the Science Olympiad event "Storm the Castle." In this event, trebuchets are limited to a maximum height of 1 meter and a CW between 2-4kg. Projectiles range from 40-60g. The machine also isn�t aloud to contribute any energy to the firing motion. All these limitations! Why? Because the object is to maximize range, and you can't just have someone show up with a counterweight so large that it pushes a piece of uranium to critical mass and nukes the projectile to Australia. Scoring goes by distance vs predicted distance. For this event, you have to have a machine that you know well. When the trial rules for this event came out I was so pumped because I had always been a hurling enthusiast. Me and one of my friends set out to design a Trebuchet to beat all others. He had an old bicycle wheel laying around, so the wheel treb was born. The wheel treb originally was just a wheel with a throwing arm sticking out. The CW was attached with a piece of rope, giving it a semi straight drop. Eventually, a pulley was added to get a better and straighter drop. This entire design was based on the idea of an efficient long straight drop as opposed to the traditional short curved drop of a normal treb. The wheel treb was built out of rotting wood and looked like something Da Vinci would build(not like I am comparable with him in any way...) Anyways, as some of you might be thinking, the wheel treb flopped like the XFL. The wheel was really heavy and had just too much mass to accelerate. Its shots with a 4kg CW were just not up to the standards I was looking for(I couldn�t shoot at the neighbors dogs from my house and I couldn't "hunt" the ducks on the local golf course.) So, after a little more planning, I took out the wheel and left a couple spokes. It�s a really simple, but effective design. It is designed around the concept of simplicity and straight drop. And somehow it works. It got 5th at the national competition last, May, although it could have done better. A good word do describe the experience of Socorro at nationals was: "shafted." but owell, there is always next year. The traditional design also has a few cool variations. The spokes can have different lengths, changing the short arm to long arm ratio. This is like a transmission on a car. The variable ratio can (theoreticly) make the arm accelerate faster and maybe even make the machine shoot further. The trebuchet can be called a transmission trebuchet as opposed to a spoke trebuchet(which makes a whole lot of difference, because responses to the name have changed from "huh?" to "what?")

ADVANTAGES

• straight drop of 1m...
• arm+spokes can be light because the only experience any stress during the launch. Individual spokes are compression beams.
• Easy to build(can be built with nearly all wood at right angles.) The only expensive part is the pulley used to redirect the string, which was indefinitely borrowed from a boating fanatic.
• Looks different than most other trebuchets. In a good way. Designed to be ergonomic and aestheticly pleasing.
• Finally, it offers a new way to look a straight drop. Lots of people use the FAT. But so what?!! Be different! Want a refreshing slap in the face? check out the spoke treb!

Distadvantages

• Flimsy arm can sometimes bend, shooting things straight up... Not that this is a design flaw, just a specific model flaw.
• Arm goes Whak! Im not an Onager enthusiast because of that reason alone. Even if you get the release timing right it still hits with a good deal of force. This might be counteracted by putting a weight on an additional spoke, along the same line as a throwing arm. Of course that kind of makes it a hybrid, doesn�t it?
• This thing isn�t the most efficient machine out there, but it still does pretty well at competitions. Its performance is equal or greater to that of a conventional FAT. Of course the kit they sell on Trebuchet.com is not a conventional FAT. Anyways, another problem I can forsee with this machine is scalability. You could scale a FAT up till it used the sears tower as a throwing arm, and everything would be fine. But scaling this thing up would be much more difficult. Unless the counterweight is raised by method other than pulling the arm back, the spokes and axle will take a bunch of stress. You can just slap on the epoxy for these small machines, but I doubt that would work with bigger ones. For those of us who don't even have a decent place and decent tools to work with wood, producing a large wooden axles+spoke attatchments etc that can take the stress is very difficult. I could see metal being a possibility, but that would make the "whack" factor reffered to above a bit more violent. So its gonna take some work to scale this thing up to a decent neighbor terrorizing size, but if a tornado can pluck the feathers off of a chicken and leave it alive, its possible.

I think building a large on of these would be really cool... I just might.

Comments, questions... Email [email protected]. Or just chuck a rock through my window with a note wrapped around it. Its all the same to me.

Back to paradise(if you aren't already there)