Procedures to Make a Catapult

About

• Catapults are made of a heavy A-shaped frame with a beam attached to the frame at a joint that allows the beam to pivot as an arm. The upper portion of the arm contains a counterweight, while the bottom of the beam contains a sling where the projectile object is placed. The bottom is then secured by a tie. To launch the projectile, the tie is removed from the base of the beam, and the projectile is launched into the air as the force of gravity pulls the counterweight downward and the bottom, sling portion of the arm skyward.

Designing

• The first step in building a catapult is using certain principles of physics in its design for maximum efficiency -- for instance, the force of gravity acting on the counterweight to achieve the necessary speed of release to launch the projectile. Regardless of the size of the catapult, effective designs take into account the length of the beam on each side of the pivot joint. The end attached to counterweight must be shorter than the end attached to the sling so that, when released, the arm moves with appropriate speed. Additionally, both ends must be proportional to the size of the frame and the weight of the projectile object.

Preparing the Materials

• The next step is gathering and preparing your materials for the catapult. Since catapults can be made of various sizes and for different purposes, the type and preparation of your materials will vary. For small, model-size or countertop catapults, consider using materials such as small pieces of wood, eye hooks and cardboard or poster board. Larger catapults are frequently made of steel rods, heavy-duty twine and larger pieces of wood. Once the materials have been gathered, they must be cut to the size indicated by your design.

Construction

• Again, the assembly procedure for your catapult will vary based on the size of the machine itself and the weight of the object you want to launch. Smaller-model and countertop catapults are generally assembled using wood glue, small nails and screws and rubber bands. Larger catapults require the use of larger screws and power drills equipped for drilling through metal. Assemble catapults of all sizes by joining together the boards or rods used for the A-shaped frame and then attaching the frame to a solid base. Then, take measurements and attach the arm and joint to the base. Once the arm is secured, lower the upper portion of the arm and attach the counterweight. Attach the sling to the bottom of the arm and secure it with twine or a clasp.