Trebuchet  Siege  Machine  Challenge     1  

 The Trebuchet Challenge is designed for students in grades 9-12. Students will design, build and

operate a trebuchet within the prescribed specifications in order to compete against other teams by

flinging water balloons at a set of targets to demonstrate the team’s ability to control and predict

where the water balloon will land.

Trebuchet Competitions

The trebuchet competition will consist of three challenges. Points can be earned in each challenge and

the winning team will be the team with the most points earned throughout the three challenges. A

total of 110 points can be earned overall.

1. Horizontal Competition (30 points): This challenge will test the machines ability to, on

average, hit at a specified distance of 30ft. Points will be scored for the distance of three shots

averaged together. The maximum number of points is 30. One point is subtracted for each

foot the average is above or below 30ft.

2. Vertical Competition (60 points): This challenge will test the machine’s precision and

accuracy. Three concentric rings will be pasted on a piece of cardboard, stood upright at

about an angle of 85 degrees at a distance of 30ft. Points can be earned by hitting rings. The

inside ring is worth 20 points, the middle ring is worth 14 points and the outside ring is worth 8

points. A miss is worth zero points. Each team will have a total of three shots to score and the

final points for this section will be the summation of all three shots.

3. Moving Competition (20 points): This challenge will test not only the machine’s accuracy

and precision but also the trigger timing. Each team will get three attempts to hit a person

walking in a repeated line at a distance of 30ft. Every attempt will be made to keep the pacing

predictable. If any of the three shots hits the person the team will receive 20 points. Any

additional hits will not increase the score.

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Criteria

• Base Dimensions: 4ft by 4ft maximum

• Arm length (pivot point to sling mount point): 4ft maximum

• Weight mount point to pivot point length: 2ft

• Counter weights: A specific measured and reported weight

• Projectile: water balloon filled with 14- 16oz of water

Rules

1. Safety is of utmost concern. We recommend that all team members wear some form of helmet (e.g. biking helmet, baseball helmet, football helmet, hardhat) and safety glasses.

2. Trebuchets may be constructed from a combination of materials (e.g. wood, pvc, plastic, rope, etc.)

3. The trebuchet counter weight must be measured and when asked, reported to the parts police.

4. The trebuchet must be triggered remotely from off the machine platform. The student triggering the trebuchet must be at least 4ft away from the catapult. The machine may not be readjusted after attempting to trigger the remote, failure in the trigger releasing will result in the forfeit of that attempt.

5. The Parts Police in charge of technical inspection must inspect your trebuchet for safety and compliance before use. A checklist is provided to insure that your trebuchet meets all the competition criteria.

6. If any machine at any point in the competition is deemed unsafe it will be removed from the competition immediately.

7. No parts other than the balloon of water are allowed to disconnect from the trebuchet during the competition.

8. Each team will present a list of parts with a line itemized budget for the trebuchet to the Parts Police at the time of inspection.

9. The machine may not make use of any potential energy other than the free weights. Elastic potential energy may not be used.(i.e. no springs, rubber bands, or flexible arms). No pulleys can be used. The counterweight must be permanently attached.

10. Each team must submit their trebuchet for inspection at registration on the day of the challenge an hour before the competition is scheduled to begin.

11. Once the toss is completed and measured or recorded the result of the toss is final. 12. Each team captain will signal the field judges that they are ready to trigger their launch.

Each team must wait for the announcement from the field judges before triggering the trebuchet launch. Teams must launch in a timely fashion or the attempt will be forfeited.

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Process

Before the event:

1. Register for the trebuchet challenge 2. Research history and use of catapults 3. Brainstorm catapult design 4. Construct catapult 5. Document design process in a “Statement of Invention & Journal” 6. Test your catapult for distance, accuracy and precision During the event: 1. Check-in at registration desk and receive a copy of the checklist and your lane number. 2. Move trebuchet to correct lane number on siege field. 3. Fill out checklist. 4. Parts Police will come to complete inspection. Give them the completed checklist. 5. Once approved and announced, practice with water balloon.

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Statement of Invention Scientific Journal

Every project must have an accompanying journal. The scientific journal is a STATEMENT OF INVENTION that documents your work throughout the design process and proves the assumptions and statements.

An example of how to set up a scientific journal is provided. All documenting journals are organized with notes on the right hand side and calculations, test results and drawings on the left. Pages can be left blank depending on the type of information recorded. The top of each page should include the recorders name, project name and date.

The journal must include an itemized list of parts with costs.

The journals should be submitted upon inspection to the Parts Police.