Trebuchet Basics Fritz R. Fiedler

Basic Sling Trebuchet

Example Frame

Example Beam

Example Tip Detail

Release

Trigger

Sling

Basic Trebuchet

Basic Trebuchet

The Throw

Definitions v0 a h

Energy Equations

Range

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

Efficiency Does not include effects of: mass of beam friction air resistance …? Efficiency ~ 50% or less (compute for report!) so Rm < hm1 / m2)

Required Information h : by design m1 : by design m2 : given – how computed?

Projectile

Example Simple Calculation assume: h = 4 feet m1 = 100 lbs given: m2 = 4.1 lbs R ~ 98 feet

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

Design Flexibility Counterweight mass (m1) h: sling length fulcrum height starting position beam length – how? sling length release angle

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

Counterweight 5 gallons = 0.67 ft3 water: 62.4 lb/ft3 sand (dry): ~110 lb/ft3 sand (saturated): ~135 lb/ft3 concrete (ordinary): ~120-150 lb/ft3 steel: ~490 lb/ft3 lead: ~710 lb/ft3

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

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