Leonardo da Vinci’s tank design was intended to be operated by eight men.
Leonardo drew the armored vehicle around 1487–1489. Its broad, conical shell was designed to protect the crew while the vehicle moved across a battlefield. Inside, men would turn cranks connected to the wheels.
The eight-person crew was necessary because the design depended on human power rather than an engine. The vehicle was not built in Leonardo’s lifetime, and its gearing has sometimes been criticized because the apparent arrangement would make the wheels turn in opposite directions. Modern reconstructions usually modify the mechanism.
The design is often called Leonardo’s tank, but it was not a modern tank with an engine, tracks, or a rotating turret. It was a proposed armored fighting vehicle powered by people inside it.