[Sam N.]

Most shooters took inspiration from the team that released their design rather early in the build period. Our team planned to build a shooter all along, and endeavored to make several prototypes before the real thing. This is what we learned.

Pneumatic pistons by themselves (directly pushing a ball) are not enough to get the ball over the overpass when firing from the ground. This comes from the fact that the pistons extend too slowly (the inherent problem of filling large chambers with small air tubes). While the pistons did provide enough force to move the ball, but they did not deliver that force quickly enough.

The question we were faced with is: what can deliver the same amount of force on the ball over a shorter period of time? To us the answer was clear: springs.

Huge springs, two of them. 240lbs of force combined. We used two 2in bore pneumatic pistons to extend these monster springs, and a small .5in bore piston to operate a latch that would release all this potential energy when retracted.

That's the concept. The actual construction was more complicated. We were faced with more problems such as: how can we extend the springs with the pistons, and then disengage the pistons from the springs when we wanted to fire. Keeping the pistons connected to the springs would lead to an unwanted decrease in firing speed.

I will post some pictures of our spring-loaded catapult later if I have time. Any questions are welcome.

Sam