1. Trebuchet Basics Fritz R. Fiedler

2. Basic Sling Trebuchet

3. Example Frame

4. Example Beam

5. Example Tip Detail

6. Release

7. Trigger

8. Sling

9. Basic Trebuchet

11. The Throw

12. Definitions v 0  h

13. Energy Equations

14. Range

15. Efficiency What affects efficiency and what would you expect the actual efficiency to be?

16. Efficiency Does not include effects of: mass of beam friction air resistance …? Efficiency ~ 50% or less (compute for report!) so R m < hm 1 / m 2 )

17. Required Information h : by design m 1 : by design m 2 : given

18. Projectile 3 lb exercise ball (m 2 ) Compute range with different counterweights…

19. Example Simple Calculation assume:h = 4 feet m 1 = 50 lbs given:m 2 = 3 lbs R < 67 feet

20. Design Flexibility What aspects of the trebuchet can be varied (after primary construction) to change throw distance?

21. Design Flexibility Counterweight mass (m 1 ) h: –fulcrum height –starting position –beam length – how? sling length release angle

22. Counterweight Design Constraint: must fit in 5-gallon bucket. What materials might be appropriate?

23. Counterweight 5 gallons = 0.67 ft 3 water: 62.4 lb/ft 3 sand (dry): ~110 lb/ft 3 sand (saturated): ~135 lb/ft 3 concrete (ordinary): ~120-150 lb/ft 3 steel: ~490 lb/ft 3 lead: ~710 lb/ft 3

24. Other Considerations Will it tip over? Will the beam break? Will the sling snap? Will the throw be straight?

25. References http://www.ripcord.ws/ http://www.algobeautytreb.com/