BRAVES

1
BRAVES

• Cleve Fann
• Josh League
• Craig Pope
• Bill Pryse
• Allan Quaife

2
Overview

• Engineering Analysis
• Dynamic Loading
• Material Selection
• Added Weight
• Torsion Spring Selection
• Human Interface/Safety
• Conclusion

3
Dynamic Load Analysis

• Maximum moment on wings
• Maximum moment on arm
• These moments use the weight of a 300 lb man as
  the maximum load
• 300 lb is the weight limit for most stands on the
  market today

4
Material Selection
Mass Equation
Shape Factor
Material Index
Cost Equation
5
Material Selection Constraints
6
Material Selection Results
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Weight

• 18 lbs before the addition of wing and arm
• Aluminum Arm

• Carbon Steel Wings
• New weight is 21 lbs
• Less than 20 increase in total weight

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Torsion Spring Selection (for Stopper)

• Desired Traits
• less than 5 lbf required to engage
• maximum of 3 in. vertical travel to fully engage
• Assuming stopper length of 7 in.
• maximum torque 35 in.-lbs
• maximum rotation angle of spring

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Torsion Spring Selection (for Stopper)

• Steel music wire inexpensive alternative to
  stainless steel
• Clockwise or counter-clockwise 90 spring to fit
  inside angle of the stopper
• McMaster-Carr lists numerous options

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Torsion Spring Kinematics
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Human Interface/Safety

• Safety remains at forefront of concerns
• As with ALL tree stands, safety harnesses must
  be worn correctly at all times

• The wings and gun arm are NOT meant support the
  entire body weight of grown person
• Wings and arm will be designed to withstand a
  reasonable amount of load, which might occur in
  an emergency situation

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Deliverables

• Next Week
• Part Drawings
• Ongoing
• Website Development