How to Build a 1-Meter Catapult

Make rectangle of wood 2 meters long and 1 meter wide. Bolt all the pieces securely together with carriage bolts. This is your base. Lay another plank lengthways down the center of the rectangle and bolt it down.

Cut two lengths of lumber 110cm long. Stand them up vertically inside the base with the end of one pressed flat against the one of the base's long edges and the end of the other pressed against the other long edge. Position the ends right in the middle of the long edges. Each side will now look like an inverted T with the horizontal piece twice the length of the vertical. Bolt the end of each upright piece to the base.

Cut four lengths of lumber 141cm long. Use them to make two isosceles triangles standing upright, one over each of the long sides of the base. The base forms the long, bottom side of the triangle and the 141cm lengths join at the ends of the base. Cut one end of each 141cm length at an angle so that it sits flush on the end of the base. Cut the other end so that the two pieces forming the sloping sides of the triangle fit flush together at the apex of the triangle. Bolt them into place and also bolt the tip of the triangle to the upright length of lumber. You should now have an isosceles on each side. Each triangle should be divided into a pair of right angle triangles by the upright.

Drill a hole through the center of the planks at the apex of the triangles. Cut a length of lumber 1 meter long.This is the catapult arm. Drill another hole 20 cm from its end. Position it between the holes in the two triangles. Slide the metal pipe through all the holes to form the axle of the catapult. Drill holes through the pipe two cm from each side of the planks and fix carriage bolts through them to make sure the bar and the catapult arm do not slide around too much.

Drill a hole in the short end of the catapult arm. Slide some rope through it and tie on some weights. About 10 or 20 pounds would be adequate. Drill another hole at the other end.

Tie rope through the hole and cut off the rope at about the 40 cm mark. Tie one corner of 20 cm square cloth to one end and tie another length of rope to the opposite corner. At the other end of this rope tie the metal ring. Bang a nail half way in beside the hole. Cut the flat head off the nail and bend it almost flat against the catapult arm. Twist it so that it it points toward the top corner of the plank.

Lay sand bags over the base, particularly at the front and back. Put a tennis ball in the square of cloth, and slip the metal ring over the bent nail. Pull the business end of the catapult arm down to the ground. Lay the rope and sling out along the central plank. Get into a safe position and release.

Twist the nail upwards if the catapult is releasing too early and downwards if it is releasing too late. You might need several tries to get this exactly right.