Broomstick or crank Padding Plywood (1/4" to 1/2" thick, 15" by 18 and 1/2") Rope (strong, stretchy preferred,like kernmantle rope) Screws or bolts Weights (optional) Wood (preferably non-flexible, like oak wood) If using 2x4 planks collect: two pieces at 36", one piece at 30", four pieces at 15", and one piece at 18"[1] X Research source
Torsion catapults, which is the technical name for a normal catapult, have historically been built with heavy, reinforced sides, as these would allow for heavier payload, greater tensile force, and greater stability. [2] X Research source
Thick PVC pipe Metal pipe (lightweight, durable)
Do not use nails for this part of your frame. Nails are sensitive to the stress your catapult will exert, and could come loose over time.
When choosing rope, look for strong material that has some stretch to it. Kernmantle rope, like parachute cord, is an excellent option. [7] X Research source Take your cord back and forth through the frame and arm several times to ensure your rope is securely fastened to the frame. While lacing, don’t worry about keeping the rope tight. When you turn your handles, you will tighten the rope and apply launching force.
This should form a figure eight shape with your rope where you can clearly see the rope twisting together. The more twists you add through your over and under motion, the more tension and greater force your catapult will have. After securing your rope to arm and frame, you should not continue threading your line through the throwing arm. To achieve the tension necessary to throw a projectile, you must finish lacing by going through the frame holes, around the broom handles in loops, and over and under the throwing arm. Make sure your loops stay anchored around your broom handles.
This should form a figure eight shape with your rope where you can clearly see the rope twisting together. The more twists you add through your over and under motion, the more tension and greater force your catapult will have. After securing your rope to arm and frame, you should not continue threading your line through the throwing arm. To achieve the tension necessary to throw a projectile, you must finish lacing by going through the frame holes, around the broom handles in loops, and over and under the throwing arm. Make sure your loops stay anchored around your broom handles.
By installing a catch to the rear of your frame, you won’t have to pull the arm back to launch your payload. Simply release the catch after applying tension, and your arm will spring forward, stopping at the cross brace and launching your payload.
