Building the Catapult
At the point these photos were taken, we were nearly finished building our catapult. During these three pictures, we were drilling holes in the frame to mount the axle for the throwing arm.
Prototypes
The photographs above are of our two prototypes that we build in a couple of days out of wood we found in Mr. Sevilla's classroom, and PVC I brought from home. The first two pictures are of a prototype that we constructed to test an idea for a mangonel-type catapult, in which an arm holding the projectile at the end is pulled back, and accelerated forwards by an elastic band. The second two pictures are of our ballista prototype, in which the projectile is accelerated along a track by a piece of PVC connected at both ends to an elastic band; the idea was that the projectile, a baseball, would roll along the track and gain front spin, which would propel it farther. However, the friction proved to be too hindering in the ballista design, and we unanimously decided to build a mangonel.