Kobe+and+Justin's+Trebuchet

__Introduction__ The objective of this design project was to design, construct and fire a working trebuchet. Throughout the phases of the design, there were many various obstacles that had to be overcome. Some of these challenges were for example: what type of materials to make, how much weight should be used for the counter-weight, how long the arm should be etc. There were many variables that were tweaked with in order gain the maximum distance. Through all the phases many things were learned and it was a great experience.
 * Physics 30 - Trebuchet Design Project **

2. Materials 3. Building phases 4. Testing Phases 5. Test Results 6. Variations 7. Conclusion 8. Photos of own Trebuchet ||
 * Categories ||
 * 1. Background information

__Background information__

__Materials__ Balsa and spruce wood (we made two trebuchets, one made out of balsa and the other out of spruce), a rubber toughened glue, a drill with various drill bit sizes, a jig saw, sand paper,

__Building Phases__ 1. We measured out all of the pieces necessary to build a trebuchet. We decided to go with a double re-inforced base (so basically the walls are two layers thick), so we needed: four 20' pieces for the exterior sides and vertical sides, two 9' pieces for the top and bottom of the frame, and four 7 15/16' pieces for the inside lengths, and two 7 3/4' pieces for the interior for the top and bottom portion of the base. 2. After all the pieces were cut, they were sanded down so they weren't so rough. We then glued the pieces together forming a rectangle with an extra interior wall with a piece missing on the lengths. This is where the two extra two 20' pieces would fit in. We decided to intergrate the vertical sides into the frame so it would reduce the overall stresses on them. 3. We drilled a hole through the sides. We hollowed out a hole into the wood about a 1/4 inch thick that was about 5/16 big for a. After that was complete, using the _ as a pilot hole we drilled a hole through that was 6/32 of an inch big. 4. By placing the dowel through this hole we now have a pivot point for the arm. Now the next section was probably the most difficult because we had to form a perpindicular section with the pivot point and the arm otherwise we would have the trebuchet firing at a weird angle. After that was completed we wrapped some string around the joint and add some of the rubberized glue to help strenghthen the joint. 5. We decided to use a small satchel for the holder of the christmas ornament. The satchel had to made correctly with the right bend in the nail at the top of the arm otherwise it would be released too late or early causing a bad launch. If this happened we would not be able to get the maximum distance we could have. (These building steps were for our original trebuchet, but unfortunately broke) __Testing Phases__ Our testing is mainly going to be focused on the length of the arm and finding the "perfect" place to place the pivot point. We will also be adding various weights and see how that effect our results.

__Test Results-__ ( These results were for our competition trebuchet)


 * Trial || Mass (kg) || Arm Length (m) || Dist. (m) || P = d/ml ||
 * 1 || 1.5 || 0.75 || 4.0 || 3.6 ||
 * 2 || 1.5 || 0.75 || 4.0 || 3.6 ||
 * 3 || 1.5 || 0.75 || 3.9 || 3.5 ||
 * 4 || 1.5 || 0.75 || 4.0 || 3.6 ||
 * 5 || 1.5 || 0.75 || 4.2 || 3.7 ||
 * 6 || 1.5 || 0.75 || 4.0 || 3.6 ||
 * 7 || 1.5 || 0.75 || 4.2 || 3.7 ||
 * 8 || 1.5 || 0.75 || 4.1 || 3.6 ||

__Variations__ As stated before our first trebuchet broke so we had to quickly construct another one that was not as light. So one of the bigger variations would have been the type of material used. Our first trebuchet was made of balsa which made it super light weight but very weak at stress points. The second trebuchet (which was the one used on competition day) was made out of cedar. Cedar is a very strong but heavy material. Another variation could have been the material that the arm was made out of. We had decided to use a small carbon fiber shaft that was light and that could bend. We had intended on using the flex of the arm to our advantage but due to lack of time, were not able to. If we had used a wooden arm, we may have been able to launch the christmas ornament with a heavier counter weight.

__Conclusion__ The project taught us a lot of the various different laws of physics behind a trebuchet. There are a "lot" of forces working against one when trying to build one. One would have to look at many different factors in order to achieve maximum effiency in one, like: type of materials, lenght of arm, overall weight, mass of object that is being thrown, inertia etc. __Photos of Project__