1. The Creation of Hera “The Treb Tigers” Stacy Costello & Jennifer Shore oh, and the dudes too: Travis Ford & Kevin Petros University of the Pacific Engineering 5 Lab: Tues, 6-8

2. Hera

3. Overview n This presentation will cover the design, testing, and analysis process that our group performed. Our goal was to successfully build a working trebuchet and to launch it in a competition against our fellow E-5 classmates.

4. Outline n Problem Definition n Design Approach n Results and Discussion n Suggested Improvements n Conclusions n Credits

5. Problem Definition n Our task was to design and build a fully operational trebuchet following guidelines provided by the instructors of E-5, Fall 2003. A trebuchet is a siege machine that uses a counterweight, arm and sling to launch various objects in battle at the opposing forces.

6. Working hard to define the problem

7. Problem Definition (cont.) n Constraints: –Must fit in a 3x4x2.5’ box –No weight restriction, but penalty –No prefabricated components n Criteria: –Must launch a 1 oz WAMO hacky sack –counterweight must be 12 pounds –must be released from 10 feet away

8. Design Approach n Preliminary Ideas: –we wanted a simple, yet efficient design that used a minimal amount of materials, thus reducing the weight. –we contemplated using wood or PVC pipe for the frame.

9. Refinement n Pros –Simple –Sturdy –Fairly light n Cons –Over engineered –arm was too heavy –Large release mechanism

10. A little friendly fighting… After all, boys will be boys.

11. Construction n Materials –Wood –Screws –U-bolts –Nylon rope –Stacy’s jeans –Metal rings –Steel rod –Dowel rod n Tools –Table Saw –Power drill –Screw drivers –Wire cutters –Needle and thread

12. Construction (cont.)

13. Analysis n Use of Algobeautytreb.com –Optimal lengths: arm length ratio 4-1, 30° pin angle, ¾ of arm sling length. n Field testing confirmed computer analysis. –Sunken field

14. Testing in the Sunken Field

15. Decision/Implementation Final Sketch

16. Final Trebuchet Setting up at the competition

17. Results/Discussion n Projectile Distance 50ft n Off by 6ft n Overall score -0.6 n Major Problems –Weight –Accuracy

18. Suggested improvements n Smaller wood n Use drill press n Smaller release mechanism n Lighter arm n Paint it pink

19. Conclusions n Learned how various factors affect the performance and overall score. –Weight –Accuracy –Design –wind n Teamwork was key! n We love our group!

21. Acknowledgements n Ripcord.com n Trebuchet.com n Algobeautytreb.com n Backyardartillary.com n Dr. Litton n Dr. Golanbari

22. Pictures!

30. The End