Leonardo da Vinci designed catapults, including a large torsion-powered machine that used twisted ropes to store launching energy.
His military notebooks contain studies of siege engines and mechanisms for converting stored mechanical energy into projectile motion. In the catapult design, a throwing arm was pulled back and released, while twisted cords supplied the restoring force. Gears and a winch could help tension the machine before firing.
Leonardo’s catapults belonged to a long tradition of ancient and medieval artillery. They were not the same as his giant crossbow: the crossbow bends a bow and releases a string, while a catapult swings an arm. The surviving drawings show engineering proposals rather than evidence that Leonardo’s particular version became a standard weapon.