Leonardo da Vinci redesigned catapults to hurl stones using a spring-powered arm.
His military studies included machines that stored energy in bent wood, twisted material, or other spring-like systems. Releasing that stored energy could drive a throwing arm forward and launch a projectile.
Leonardo’s catapult drawings show his interest in improving older siege technology through geometry, leverage, and controlled release. The goal was to increase power while making the machine more predictable and practical to operate.
Catapult is the general name for a projectile-launching siege machine. A trebuchet uses a counterweight, while a ballista resembles a large mechanical bow. Leonardo’s spring-driven designs are therefore best classified as catapults rather than those alternatives.