The catapult is based
on an ancient design. This catapult was
built entirely out of 2X4, cotton rope and a wooden dowel in and aluminum
sleeve. First the frame was built. It is rectangular in the dimensions of 1X2
feet. Then 2 towers were added, and
across an arrestor bar was placed, also made of 2X4. The purpose of this arrestor bar is to stop the swing arm in its
travel and release the payload. 2
supports were put in place to support the tower, but weren’t really necessary. Then, around the towers, through the frame,
holes were drilled to pass 2 ropes through.
These ropes attached to the swing arm, which was made of hardwood
dowel. They were wound up, such that
they were creating tension, and then held in place by the arrestor bar. Here was where the aluminum sleeve came in
handy, because the swing arm length was bigger than the frame. So to wind up the catapult, we wound the
sleeve, which was 9 inches long, and then inserted the swing arm. Finally, to mount the photogates, I added
two brackets on the towers, but since the catapult was pretty deadly, it always
jarred them loose, and our timer was messing up. To fix this, we mounted the photogates and lasers on lab
stands. Don’t believe me? Check out the picture
Mounting the photogates on the project. We later figured out this wouldn't work, so they were moved to lab stands.