# Trebuchet Basics - PowerPoint PPT Presentation

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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

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## Trebuchet Basics

Fritz R. Fiedler

v0

a

h

### 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/