Catapults were siege engines used before the advent of gunpowder to hurl projectiles over castle walls. They stored energy through tension from bent wood, twisted rope, or heavy weights rather than explosives. Common projectiles included stones, arrows, flaming barrels, and even snakes or heads. The timeline shows catapults evolving from early tension designs to gravity powered versions used by various civilizations from 400 BC to their replacement by cannons in 1400 AD. Major catapult types included ballistae, onagers, and trebuchets, storing energy through tension, torsion, or gravity.

1. Engineering Week 2011
Story of the Catapult
History, Types, Physics and Model Building

2. Before the days of gunpowder, the military used large timber machines to
throw rocks, arrows and flaming barrels of tar at and into castles and forts. In
ancient days, countries, towns and neighbours would often be at war, trying to
take each others land, riches and treasure. To prevent attack from invaders,
towns and wealthy land owners built forts and castles for protection. The forts
had very thick stone walls and were sometimes high on top of a hill or
surrounded by a moat. The walls had protected openings to shoot arrows and
throw stones and pour burning fat from, so attacking a castle was not an easy
job.

3. Despite the difficulty of attacking a castle, there was often war and some
people within the military started to specialise in building machines and
structures to help in attacking castles. The builders of the machines called
siege engines were some of the earliest engineers. About 2,500 years cross
bows started to grow larger and more powerful and these developed into
powerful and heavy machines that could fling that could fling large projectiles
at and over castle walls.
The machines called catapults didn’t use explosives like today’s military
weapons, instead they used energy stored in bent timber and sinew, twisted
rope or heavy weights.
What were some of the things that were tossed by catapults? stones, arrows,
burning barrels, snakes, heads.

4. Catapult Timeline
400BC - Early tension catapults that operate like large crossbows appear
340BC - First torsion powered ballistae built in Greece
146BC - Romans use over 400 onagers and ballista in a siege at Carthage
380AD - Romans use slings on their torsion powered onagers
500 - Gravity powered catapults appear in China
600 to 900 - Gravity powered catapult technology move into Europe
885 - Vikings besiege Paris using catapults
1304 - Edward 1 of England builds Ludgar the War Wolf to defeat the Scots
1400 - Gun powder and canon replacing catapults
1480 - Last major use of catapults in a seige by Greeks against attacking Turks.

5. Types of Catapults or Siege Engine
Ballistae

6. Onager

7. Trebuchet

8. Trebuchet

10. Catapult Power
• pumpkin catapult record 620m (trebuchet)
• largest trebuchet currently in operation
18m high

11. Catapult Physics
Energy Source
• Tension spring
• Torsion spring
• Gravity
Mechanisms
• Lever - mechanical advantage
• Pulley
Wheel & axle