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Trebuchet Basics. Fritz R. Fiedler. Basic Sling Trebuchet. Example Frame. Example Beam. Example Tip Detail. Release. Trigger. Sling. Basic Trebuchet. Basic Trebuchet. The Throw. v 0 a. h. Definitions. Energy Equations. Range. Efficiency.
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Trebuchet Basics Fritz R. Fiedler
v0 a h Definitions
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
Projectile • 3 lb exercise ball (m2) • Compute range with different counterweights…
Example Simple Calculation assume: h = 4 feet m1 = 50 lbs given: m2 = 3 lbs R < 67 feet
Design Flexibility What aspects of the trebuchet can be varied (after primary construction) to change throw distance?
Design Flexibility • Counterweight mass (m1) • h: • 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/