Trebuchet

Jake had a "catapult project" for science class. They were challenged to build catapults for launching tennis balls as far as possible. The rules stipulated that they couldn't use any kits or prefabricated pieces, and that the catapult must fit within a 2x2x2 ft area, with the vertically extended catapult arm no higher than 2 ft. Because the project allowed incorporating something like a non-rigid sling, which could operate outside the 2x2x2 area, we decided to pursue such a design; technically making our catapult a "trebuchet".

This video shows the trebuchet being fired in our backyard after we finally got it working. The technically keen will likely notice that launching angle is not optimal -- its actually launching the ball downward. Jake chose not to pursue any further "tuning", so this is the best it got- which was still quite satisfying for us. Jake's favorite part of the project was creating graffiti to adorn his machine, which he spray-painted onto the side of the trebuchet. Jake's graffiti reads:

Cum catapultae proscriptae erunt
tum soli proscripti catapultas habebunt

This roughly translates as: When catapults are outlawed, only outlaws will have catapults