One of the requirements of my HCC scholarship is that I complete an honors project of my choice this semster - I thought this would be a great oppurtunity for a fun project that I'd been wanting to do anyway: building a trebuchet! (And it counts as college credit! Killing two birds with one stone!) For those who don't know what a trebuchet is here is a picture:
It works on a relatively simple principle - a large weight on the end of the throwing arm (the large bucket you can see in the pictures) acts as a counter weight, pulling the arm up (it's pulled down near to the ground) with a high velocity, which allows the sling that holds the projectile to release the projectile at the upper point of its arc.
We're building a 1/3 scale model first and I'm proud to say it's almost done! It has a four foot arm and, when the arm is resting straight up, the total height is around five and a half feet. So the full scale will be sixteen or seventeen feet total (fun huh?). Need a visual? Here you go:
For illustrative purposes I found a picture of a model trebuchet that probably isn't scaled well, but it is a good representation of ancient trebuchets.
So we started the model by assembling the arm, after which we built the bucket to hold the counterweight.
We soon realized that the box had a problem - it shifted horizontally on its pivot bar causing a loss of our precious energy.
So, being the problem solvers that we are, we grabbed some tape and improvised.
A little later Aaron thought of a better solution - we braced it with some extra wood that added support to the main pivot on the arm as well - a good plan for the model and especially for the full scale.
After that was fixed we built the frame and found out that it's very unstable without supports.
So we took some time and fixed those many problem areas.
So here is another picture of our improved supports: I heard that a lot of illustrations improve your writing by giving visual reference to objects and concepts mentioned in your writing - I think it's because it distracts the reader from the author's odd sense of humor.
In conclusion . . . I'll show you another picture, yah!
Ours will not be this large (although I wish it could be)
See? Simple. (At least in theory)
Our full scale should be about twice this size.
Personally I like the little scaled man.
What you can't see here is that the arm is 4 feet long - pretty impressive for a model.
It's kinda hard to see in this picture but the circled part is where the problem was - the arm was sliding back and forth when we tested it - thats a no-no.
See the pretty green tape? It was very sticky and a pain to get off.
Solution number 2. I guess third time isn't always the best.
See all those little red circles? Those are problem areas. See the green circle? Thats the parts that need more supports.
Our new supports are circled - we put bracing on the back, sides and connected the frame in the middle. (If you're thinking: "Why did he mention the side supports (pural) when there is obviously only one?" Here's the answer - it's because the picture was taken before we added the other side support. Now that seems like a silly question doesn't it?)
Now the only problem is the wooden dowel - it can't take all the weight so we changed it to a metal bar instead.
Please take note that the helicopter is not to scale. (Although we wish it was)
Keep checking back for more updates as the project moves along!
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