Leonardo da Vinci designed a large catapult powered by a bent wooden frame.
His military drawings include catapult mechanisms that stored energy in a flexible component and released it to hurl a projectile. Some designs used a broad, leaf-shaped spring or bent beam rather than the torsion bundles found in many ancient catapults. A release mechanism transferred the stored energy to the throwing arm.
A catapult is a broad category of projectile-launching machine. It should not be treated as a synonym for a trebuchet, which uses a counterweight and gravity, or for a cannon, which uses expanding gases from an explosive charge. Leonardo's proposal belongs to the spring-powered family of siege machines.
Leonardo produced many military-engineering sketches while seeking commissions from rulers in Renaissance Italy. Surviving drawings do not prove that this exact large catapult was constructed or used. They do show his characteristic effort to improve old machines through stronger frames, controlled releases, and more efficient energy storage.