Leonardo da Vinci designed a catapult to hurl stones using a curved spring.
His catapult studies show a large wooden frame and a powerful flexible arm or spring mechanism. Leonardo explored ways to store energy gradually and release it suddenly, allowing a projectile to be thrown toward a target. Some drawings include winding or tensioning systems intended to make the weapon easier to load than a simple hand-operated launcher.
The design belongs to Leonardo's broader work on military engineering in the late fifteenth century. Catapults were already ancient weapons by his time, so Leonardo was refining an established technology rather than inventing the basic idea. The design is also distinct from a trebuchet, which uses a counterweight, and from a ballista, which works more like a large crossbow. Leonardo's surviving sketches show his mechanical analysis, but not a confirmed full-scale field test.