Play Catapult

The middle ages were a turbulent period in Mesopotamia. The westward expansion of the Saljuq Turks in the 11th century was followed by periodic warfare with Western crusaders which lasted for several centuries. Finally, the Mongol invasion of 1258 destroyed many towns and villages. Throughout this period, siege weapons such as catapults played a major role. There were two main types of catapult: torsion-powered weapons, called onagers in the West, and counterweight-powered machines, known as trebuchets. Although powerful, these machines were relatively simple. Follow these steps and you can construct your own trebuchet.

Instructions

1 Decide the scale of your trebuchet. Medieval catapults varied in size, but some trebuchets were 50 feet tall, capable of shooting nearly a mile. A scaled-down version can be as small as you want. A foot-tall trebuchet will throw its ammunition as far as thirty feet.
2 Plan your trebuchet. The amount of detail you can build depends on scale, but the basic framework is the same. You'll need a swing arm, two long base pieces, two uprights, three crosspieces for the base and two triangle-shaped supports for the uprights. Cut these out of wood using your saw or craft knife. The swing arm should be a third as long as your base pieces and your uprights should be a sixth shorter than the base. The base crosspieces should be as long as you want your trebuchet to be wide. This should be about half the length of the upright.
3 Attach the uprights to the bases at right angles. Lay out a base piece, then place the upright against it, 1/4 of its length from the forward end. For smaller models, these can be attached with wood glue. For larger models, you may need to fit the upright into a slot in the base. Secure the two pieces by screwing the triangular support piece to both of them. Repeat the process so that you have two matching supports with attached uprights.
4 Attach the crosspieces so that they join the two halves of your base. One crosspiece should go at either end, with the third located behind the uprights. Your trebuchet will now resemble a rectangular frame with two uprights protruding from it. Glue or screw the crosspieces in place and, if necessary, leave them to dry. Cut a final thin piece of wood or paper and attach it across the top of the base to create a smooth surface.
5 Select the length of metal rod or pipe you want to use for your axle. Drill a hole 1/4 of the way down your throwing arm, making sure that the axle fits into it. Drill another hole on either side of this hole. The distance between the holes should be 1/16h of the length of the throwing arm. Insert a screw hook into the end of the arm closest to the holes.
6 Drill holes of the same size near the top of the uprights. Insert the axle through one upright, then through one of the holes in the throwing arm, then through the other upright. Make sure the throwing arm has room to swing freely.
7 Attach your counterweight to the hook in the end of the throwing arm. The counterweight should be a heavy, dense object. Medieval trbuchets used containers filled with stones. Use wire or cord to connect this to the hook, making sure the arm can still swing freely.
8 Insert a bent nail or pin into the head end of the throwing arm. Place a screw hook in the underside of the arm near the head. These will form the attachment points for the pouch which will hold your payload.
9 Cut a sling pouch out of cloth or leather. Attach a length of cord to each end of the pouch. Tie one firmly to the screw hook at the head of the throwing arm. Make a small loop from wire and attach it to the other. This will fit over the bent pin at the end of the throwing arm. You'll have to adjust the length of the cord and the angle of the pin to guarantee a smooth release.
10 Test your trebuchet. Place a projectile in the pouch and place the pouch on top of the base. Depress the throwing arm, raising the counterweight. When you release the arm, the counterweight will drop, whipping the sling around in an arc and releasing the projectile.