Steam Canon

Cannons weren't all that practical on the battlefield in Leonardo's day, mostly because of their weight and lengthy loading time. So Leonardo experimented with already existing models to find ways to improve them. Thus he designed a breech-loading cannon, a three-barreled cannon, and even reportedly launched a rocket-powered cannonball 10,000 feet into the air! He may even have tested this steam-powered cannon, one of his most innovative designs.