Fall Design Catapult

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This catapult was built using 1/4 inch MDF for the Lakehead Fall Design Competition. The project was cut out with an Epilog Mini 24, 40 watt laser. The bucket of the catapult was created using a Dremel 3D20, printing it out of PLA. How I Designed This Design Overview The catapult was designed to come together like a puzzle and have connections that require no form of fastening. It can be easily assembled and reassembled. However, to improve rigidity and durability, the use of wood glue is recommended between all "slide in" connections. Note: The AutoCad file dimensions are given in inches while the .3ps file dimensions are in cm. Torsion System The catapult was designed to be powered by a torsion system. The creators used fishing line as the material, which turned out to be fairly elastic. Approximately 60 passes of the fishing line were made between the handles. Although the fishing line worked well, other materials may be available that could yield a greater power output. In addition, two screws were used for the handles of the torsion system. These screws make it easy to increase or decrease the power of the catapult. It is essential to note that the screws should settle in a position parallel to the base (horizontal) of the catapult to evenly distribute the force between both supports. If the screws are left perpendicular to the base (vertical), they tend to damage the section of MDF located between the two supports when the torsion material is subjected to high amounts of tension. To view how to wrap the material for a torsion catapult, see below: Video link: https://youtu.be/PRSBKm1encM Image of how the torsion system should be set up. Video of how the torsion system should be set up: https://youtu.be/PRSBKm1encM Future Improvements To improve the catapult design, the bucket attachment could have been made slightly larger than the dimensions of the catapult arm. This is due to the fact that the bucket was a very tight fit onto the arm. Additionally, other materials could have been experimented with in order to improve the ability of the torsion system. The fishing line used was very timely to install and was fairly easy to snap if the handles were tightened too much. Moreover, the bumper created to stop the arm could have been altered to better facilitate the angle at which the arm would hit it at. Upon prototyping, the bumper often would fall off since the arm had a tendency to hit it upwards (when the bumper was set up to stop the arm at a shallow angle). References "Catapult Physics." Real World Physics Problems. N.p., n.d. Web. 03 Dec. 2016. http://www.real-world-physics-problems.com/catapult-physics.html. Credits go to Matt Olinski.