Trebuchet Design Project

Trebu what?

Purpose

For physics I students to research the history and development of the trebuchet as a siege machine. In particular, we are interested in the physics of the trebuchet (leverage, mechanical advantage, center of mass, etc.). Students will also design, build, and refine a model trebuchet that will throw a golf ball.

Research Process ≠ things you're looking for

• When was the trebuchet invented?
• What was it used for?
• What is the typical projectile?
• How tall was the typical trebuchet?
• What are major types of trebuchet?
• What is the optimal position for the armπs axle?
• What is the optimal length for the sling?
• How many people did it take to build a trebuchet?
• What materials were used to build trebuchet?

Design limitations

• The trebuchet arm must not exceed 36 inches (91.4 cm) in length. Release mechanisms and sling hook may extend beyond the end of the trebuchet.
• Counterweight must not extend beyond the end of the trebuchet arm for fixed weight designs.
• Hanging weight trebuchet must have means to stake the frame to the ground. Stakes measuring 3/8" in diameter will be provided
• Fixed weight trebuchet must be equipped with at least four wheels (one on each corner of the trebuchet base) that will allow the trebuchet to roll along uneven ground during operation. All wheels must remain on the ground during operation.
• The total weight of your trebuchet arm and counterweight must not exceed 30 lbs. regardless of design type. The arm and counterweight must be able to be removed from the frame to weigh it before launching at school.
• Your trebuchet must be powered solely by gravity (your counterweight). It may not have any springs, rubber bands, torsion bundles, torsion bands, torsion beams/rods or any other active means to rotate the trebuchet arm.

Safety

• Never, ever stand in front of or behind your trebuchet while loading the sling or during operation. This is of prime importance. The golf ball projectile may be launched with enough speed to cause very serious personal injury.
• Be aware that the projectile may release at any point during rotation of the arm. This can make the projectile travel anywhere in front of, behind, or above the trebuchet. When conducting trials of the trebuchetπs operation be sure that you are operating it in a location where the projectile wonπt damage anything.
• Your design must incorporate a release mechanism that is remotely operated by means of pulling a rope or string from a distance of 2 m from the side of the trebuchet.
• It should be built very solidly so that it doesnπt come apart during operation. Remember that thereπs a lot of force and speed involved here!

How to do this project:

• Work individually or with one other person on a project. Groups of three or more are not acceptable. You may work with someone in another section. Be aware that you will have to build a model trebuchet so at least one person should have access to the tools and materials needed to build such a model.
• Your trebuchet model DOES NOT have to be large or complicated. It can be built using common household materials. Do not think that it has to be exceedingly large or complicated! The performance of your trebuchet will be calculated using a formula that accounts for the length and weight of its arm.
• You may not build you trebuchet from a trebuchet kit. It must be built from scratch.
• Making a trebuchet requires a lot of trial and error. You will probably run in to
• Conduct thorough research using high quality sources.
• Write a substantive paper that

What kind of class time do we have to work on this?

At least two class days will be devoted to designing and building your trebuchet. You can work on your trebuchet during activity period and after school any day. I canπt always stay after school so check with me in advance.

When does it have to be done?

We will launch trebuchet on May 19 & 20 with the 21st and 22nd reserved as rain days.

Where do I get my information from?

Hit the Internet. The Internet is a haven for people who like to hurl things through the air. Youπll find hundreds of sites devoted to trebuchet. I do not have any books dealing directly with trebuchet but you will find plenty of information about the physics fundamentals that makes a trebuchet work in any physics book.

This project is worth 100 points

Trebuchet model - 60 points

Meets the design limitations and safety requirements as stated above. A maximum of 30 points will be awarded based on the actual performance of the trebuchet (outcome of formula that accounts for range as well as length & weight of arm).

Paper - 40 points

Your paper must address all of the issues presented in the Research Process section above. It must be well written, complete, and concise. Be sure to tell about all the design changes and modifications you had to make during construction. Describe the process you used to adjust the trebuchet to shoot with the maximum range. Reflect on the challenges you faced during the design and refinement process.