Here is a remarkable little catapult that has taken a lot of time to build and has gone through several transformations and improvements.
The wheels are a great addition. If you are going to build a mid sized to large catapult you might want to put wheels on yours just like on this one.

The different types of woods, the log-style wheels,
the chicken wire and the triangles at the front of this catapult make it
look really medieval!

Caleb's Upgraded catapult

Caleb has modified this catapult and completely reworked and redesigned it to be lighter and to throw projectiles even further. This new catapult design even has a sled on it. You can learn more about this new catapult here: Caleb's Sled A Pult!

Caleb Has also built a Trebubuchet that launches a projectile 120 feet. You can see it here: Caleb's Trebuchet