Model Catapult

Project IX:

Model Catapult

SDS22 Intro Engineering: Period 2

Group 1: Rinor Ahmetaj, Sophia Cai, Andrew Gazal, Mahzabin Hasnath, Susan, Grace Li, Joshua Mangroo, Satesh Seonarain, Daniel Xu

Document by: Satesh Seonarain

Project Objective: Document an existing catapult design, including sketches, dimensions, materials, Bill of Materials, and estimated build procedure. Using this documentation, replicate the existing design using all the same parts and materials.

Materials:

-Power drill

-Hacksaw

-Catapult arm

-Nuts, bolts, and screws of various sizes

-Hacksaw

-Wood

-Bubble wrap, rubber bands, straws, and cups (egg o'naut)

-Purple paint

-Container lid

Goals and Constraints:

-Only materials in the bill of materials is allowed to be used.

-Time constraint

-Eggonaut must be built to fit the launch pad of the catapult and be light enough for launching, parachutes are not allowed.

Research:

Ancient Greeks are said to have been the first to use catapults, using it to launch large projectiles at a high velocity over a large distance. As weapons of war, the catapult provided a way to use little effort as it hurled objects such boulders to the enemy. Up until WWI, the catapult was used as a weapon before the introduction of mortars made the use of catapults obsolete. The catapult is able to store massive amounts of potential energy as it builds tension. Once it is released, kinetic energy is formed from the potential energy and the object is projected forward. To increase the kinetic energy, extra tension would have to be built which would in turn increase the potential energy. Increasing the kinetic energy would in turn cause the projectile to travel at a higher velocity and acceleration as well as travel further. The first law of motion says that objects at rest remain at rest unless a force is exerted on it. The tightened rope releases the kinetic energy, which will in turn cause the catapult arm to launch forward which will project the object in the air.

Catapults are essentially third class levers. A third class lever, is a lever in which the fulcrum is on the end of the lever while the load lies on the opposite end. The load can be launched when a force is exerted on the lever's middle. This is the exact way a catapult operates. The load is positioned on an end and the tightened rope is tied to the opposite end. The fulcrum is the rope itself and the force that moves the lever is the energy released as the catapult arm is let go.

A catapult is not that different from a third class lever. A catapult acts like a simple machine that allows the launching of heavy objects to be easy. Simple machines all provide a type of advantage mechanically. Advantages like this allows heavy objects to be launched using a lesser amount of force than what is required usually. The better the advantage mechanically, the lesser amount of force will be required to project the object a further distance.

Procedure:

First the eggonaut was designed and completed. The eggonaut was built using styrofoam cups, bubble wrap, straws, and rubber bands. First, the bottom halves of two styrofoam cups were cut off. Straws were then cut into small segments and placed on the bottom of each half. Bubble wrap was then placed on top of the straws to cushion the egg. The egg was then placed inside the bubble wrap and the two halves were put together and taped. Rubber bands were then stretched around the entire structure to ensure it would fall apart.

Sketch of Eggonaut

In order to begin the construction of the catapult, certain tasks had to be completed beforehand. One