Leonardo da Vinci designed a spring-powered catapult with a rotating throwing arm.
His military notebooks contain studies of siege machines, including catapult mechanisms that store energy before releasing it. In the design, large leaf springs or flexible elements are bent or twisted, then released to drive an arm forward. The arm launches a projectile toward a target.
Leonardo was not the first person to devise a catapult. Ancient Greek and Roman engineers had already developed several classes of projectile machines. His contribution was to analyze and redraw such mechanisms with the detailed mechanical studies characteristic of Renaissance engineering.
Catapult is a broad term. A trebuchet uses a counterweight, while many spring-powered designs are classified as torsion or tension engines. Leonardo’s machine is therefore best identified as a catapult rather than a trebuchet. Because the drawings are designs rather than records of a completed campaign, their battlefield use is not certain.