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Leonardo da Vinci: A War-Machine Investigation

For our final project in History 14, STS 121 The Worlds of Leonardo da Vinci, we decided to research Leonardo's catapult designs and build a small model. The model, when finished, was 24 inches tall in the fired position and 14 inches tall in the cocked position.

The model uses a large counterweight, which through gravity, falls and causes the main lever to whip around in a circle. Attached to the lever is a sling pouch in which a projectile, in our case a wooden ball, is placed. When the lever swings around, the sling launches the ball in a circular projectile motion at the target. The whole process is triggered by a simple pin placed between two screws, holding the counterweight up high. When the pin is removed, the counterweight drops. The model also has four wheels, making it a mobile piece of artillery, ideal for siege in that it could have hurled rocks at fortified walls or been modified and placed closer to hurl fire past the walls into the fortress itself.

We tested the range of the catapult and found that with a medium size ball, diameter about 1 inch, has a range well over 30 feet.

Centuries before the practical use of gunpowder, ancient armies employed these catapult artillery against castles and fortifications using enormous throwing machines powered by humans, twisted cord, bent wood and metal, or gravity. These great siege machines, or engines, hurled large stone balls and flaming tar to breach castle walls and set fire to interior buildings. This type of catapult, called a trebuchet, powered by gravity alone, was the most effective siege weapon of its time.

The interesting thing we discovered in our research is that this type of catapult, of which we were inspired to build by some of Leonardo's drawings, had actually been invented in the 12th century. Our project became less of a study of Leonardo's innovativeness and more of his artistic and also improvisational ability. He must have taken the models for his catapult drawings and then added on some of the features particular to his designs as a means of improving them. He did not, however, invent them originally.

One of his drawings shows almost an exact replica of the commonly-used trebuchet catapult. However, others of his drawings show modifications such as levers and wheels to crank the lever into place, and also bendable levers which look like branches of sapling trees which, with more torque, could hurl a projectile even further. However, this type of bendable lever might not be very durable or long-lasting.