Catapults

Problem

Catapults as siege weapons became ineffective in 885-886 AD rendered useless by new defense technology, but they still continues to be used in military operations. The last large scale use of catapults as a weapon delivery device was in World War 1. Catapults were used to throw hand grenades across No Man's Land and into enemy trenches. Unfortunately for catapults they were soon replace with small mortars. Now catapults are used in target practice to shoot clay pigeons in the air, to launch food at siblings, and the most common use to launch planes into the air. An aircraft carrier doesn't have the runway space to allow for a plane to accelerate taking off as it would on the ground so a catapult is used to propel the aircraft into the air in a very short distance.

Design Challenge

As a member of a product development team, you are to design and build a mechanical launching

system that can deliver a small projectile predictably and repeatedly over a specified range of distances. You will use both technological design and scientific inquiry as processes to investigate and improve how your catapult performs.

Final Catapult Design

Criteria

• You may do research or collaborate with others to develop possible catapult design solutions, but you must have an original design that is your own creation.

• You will be provided a kit of materials to use in building your catapult. You are NOT allowed to use any other materials that are not provided in your construction kit.

• Any type of mechanical fasteners and adhesives are permitted.

• Catapults must be touching the ground when they are launching the projectile. You are NOT allowed to lift the catapult to gain any mechanical advantage.

• Each student must submit a design portfolio; along with their catapult prototype, that demonstrates the use of the Engineering Design Process in order to solve this design challenge.

Scope of Work

1. Research: Investigate Elasticity, and identify variables you can control to create a more accurate catapult.
2. Research: Material & Adhesive Strength to identify the strongest type of glue for the materials provided in your kit and how to gain the most efficient use of these materials in gaining the greatest mechanical advantage (simple machines).
3. Solutions: Generate three ideas or alternative solutions in the form of rough sketches; then chose the best solution based upon your research.
4. Development: Design, build, and test; collect data and analyze patterns of results; then calibrate your catapult prototype with a launching graph and frequency distribution chart to meet the challenge.
5. Communication: Produce a Design Portfolio that documents your design and its operation, including research, sketches, data, launching graphs & charts, notes, and evaluations.

Class Catapults

Competition Rules

Each catapult will get five scoring launches for distance and accuracy. The five launch scores will be used as the official overall score. In the event of a launch failure (rubber band breaking) the contestant will be allowed to replace the rubber band and launch again until a successful launch occurs.