This is a trebuchet we made for our Concept Physics class. Our trebuchet threw a golf ball a distance of over 29 yards! We were the only all girls group in our class and we built the best trebuchet. We did a little bit of research and set out to construct our own and here is what we created!

Step 1: Materials

7 - 4 ft long 2x4"s
2 - 2 ft long 2x4"s
4 - 3 ft long 2x4"s with the ends cut at 45 degree angles
4 - swivel chair wheels
1 - 2 1/2' re-bar
an eye hook
4 ft of string
a sack
1 laundry detergent basket
In step 2 you state that ..<br><br>&quot;The wheels not only help with transportation but also allow more force behind the throw of the trebuchet.&quot;<br><br>what is the basis for the assumption that the wheels add to the force? <br><br>the only way I see that being possible is if you are rolling the trebuchet downhill at the time of launch, and even then the added momentum would be negligible unless it is an insanely steep hill.<br><br>
Wheels on the trebuchet let the weight at the end of the arm fall along a straighter path than the arc it would fall along without wheels, which pulls the trebuchet forward at the end of the swing, making it more efficient.
<p>Upon reading Lorddrake's description of the Trebuchet rolling down hill I couldn't help but chuckle at the imagery it created in my mind. However the visual rocks and makes sense as to why the wheels would work! However I think I might see a flaw in this via their design. They stated they used swivel chair wheels which do not have a strong reputation for gliding in a straight line or doing so without resistance (aka &quot;swiveling&quot;). I think this type of wheel would throw the machine off if it were to have a strong enough counterweight. Perhaps the machine could rest on rails to travel from the front to the back in the swing and a spring attached to return it's momentum forward and again, increase the efficiency without losing any energy through the swiveling wheels. It would also negate sway to the left or right during firing which would increase accuracy substantially. But this was a cool siege machine! I build a small tabletop size one that I'll be making another version of and posting a build soon!</p>
thanks for the explanation and the visual.
It let's it have a little more momentum
<p>what type of wood did you use for it??? I am trying to build it for a school project so I need to know what type of wood it was made of. </p><p>cheers</p>
<p>The instructions for making this trebuchet were vague and often incorrect. The three-foot long 2x4s are too long and don't fit within the frame on the bottom. The supporting beams in the photo also dont look three foot long. Two and a half-feet or two feet would be more appropriate for the supports. The order for doing things is also really inconvenient. It makes a lot more sense to drill the holes and to add the nail/eye-hook to each end of the arm before attaching the arm to the other two four-foot long 2x4s with the rebar. Also, attach the supporting pieces of wood to the four-foot long 2x4s before attaching them to the base. The string lengths specified are also too short (and also much shorter than the picture shows). Finally, there are no instructions for how to create the sling. We basically made something up and our trebuchet didn't shoot. </p>
<p>You use the sack as the sling</p>
<p>Do you have any pictures showing the sack/sling set-up?</p>
Seriously nice job I'm a freshman in high school I have seen many but yours was the most professional and clean cut
I recently made a trebuchet for a robotics course to chuck a 30lb pumpkin. Using a 150lb trashcan my team only got the pumpkin 12 meters. Of course we made ours out of PVC&nbsp;held together with pneumatic-tubing! <br />
(Oops, it didn't upload)<br />
Your design is the reason for lack of range.<br>Instead of the smack against the stop bar, you should use a sling on a rail. The sling will give you the extra force and speed. Your system will shortly destroy itself because of the violent stop at the end of the shot. Properly built a trebuchet is a powerful and quiet weapon.<br><br>As for Kitman's responses... I don't think he was being overly rude, just frank. He's right, we should not be giving our children a rosy ride. Bullying isn't necessary, but the real world is rough. Your employer or the scientific community will not give you a pass because of your age or handicap. Accuracy counts. There is a lot of jealousy and frankness out there. Also people want their mention if you use their data. Don't ever forget to include your sources.
I think you guys did a great job! Question though... What did you use for a sack, and how large was it? Another thing: How far along the arm did you drill the hole for the rebar?
This is really cool, I&nbsp;may try it myself
heh now to buy&nbsp; some grenades/road flares/beehives/watrer ballons with time release sodium capsules

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