Leonardo da Vinci designed a giant crossbow with an unusually large bow and winch mechanism.
The weapon appears in Leonardo’s military studies from the late 15th century. Its immense bow was intended to launch large bolts or other projectiles, while a mechanical winding system would help draw the bowstring. The winch addressed the enormous force required to bend such a large bow.
Leonardo’s interest was not limited to making a weapon larger. His drawings explore how structure, leverage, tension, and movement could improve a siege device. The broad frame also suggests that stability and transport were important engineering problems. A giant crossbow would have been difficult to operate and move in practice.
Popular illustrations sometimes present the design as a proven battlefield weapon, but the surviving evidence is a set of plans rather than a documented military deployment. It should not be confused with a trebuchet, which uses a pivoting throwing arm and counterweight, or with a hand cannon, which uses explosive propulsion.