Trebuchet Basics

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Trebuchet Basics

• Fritz R. Fiedler

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Basic Sling Trebuchet
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Example Frame
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Example Beam
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Example Tip Detail
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Release
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Trigger
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Sling
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Basic Trebuchet
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Basic Trebuchet
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The Throw

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Definitions
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Energy Equations
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Range
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Efficiency
What affects efficiency and what would you expect
the actual efficiency to be?
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Efficiency
Does not include effects of mass of
beam friction air resistance ? Efficiency
50 or less (compute for report!) so Rm lt hm1 /
m2)
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Required Information

• h by design
• m1 by design
• m2 given

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Projectile

• 3 lb exercise ball (m2)
• Compute range with different counterweights

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Example Simple Calculation
assume h 4 feet m1 50 lbs given m2 3
lbs R lt 67 feet
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Design Flexibility
What aspects of the trebuchet can be varied
(after primary construction) to change throw
distance?
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Design Flexibility

• Counterweight mass (m1)
• h
• fulcrum height
• starting position
• beam length how?
• sling length
• release angle

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

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Other Considerations

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

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References

• http//www.ripcord.ws/
• http//www.algobeautytreb.com/