Having read about a number of catapults recently, I realized I should ask for clarification on the term. It tends to have two distinct definitions in English, one quite broad and one quite narrow. The broad one classifies all sorts of stuff as catapults, including trebuchets, ballistas, etc. This is probably familiar to many as it applies on aircraft carriers with the aircraft catapult. The narrower definition would be the more classical one, based on elastic/tensile forces being used, elastic potential energy is stored to be released by swinging an arm with the projectile in it. So I'm wondering what common design approaches are. Maybe some are elastic bands with a slip gear to rotate the arm down until released. Has anyone tried using nylon rope wound around an axle similarly to classical catapults? Are people just swinging arms directly from motors using gears? Etc.? Thanks.