I consider the "fairground" concept of the catapult a little lame in theme. I mean, a medieval catapult should be a tool of besieging, not in an amusement park. I like JBs idea of using the catapult for a kind of "anti-flier" mechanism, but would rather endorse a redesigning of the tiles, albeit reusing the same basic tile configurations. Maybe an inclusion of the Besiegers/Kathars conzept would make a thematically fitting expansion.