Aero II

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Aero II Lecture 32 Propellers
J. E. Brandenburg EAS 3101 Spring 2007
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Agenda

• Stall Speed
• Propeller theory
• Propeller designs

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Stall Speed
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Stall Speed
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Stall Speed
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Propellers
Cessna Skyhawk-a highly optimized low speed
aircraft
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Propeller sections
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Propeller Theory
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Propeller at takeoff(two extremes)
Reaction force
Propeller hub
Propeller tip
Lift
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Propeller Theory
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Propeller Theory
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Propeller Theory
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Propeller Theory
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Propeller Theory
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Propeller Theory
?1
?2
?
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Fixed Pitch Propeller
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Adjustable Pitch Propeller
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Propeller Development

• Wright brothers developed first successful
  propellers-fixed pitch
• Two-pitch propellers were introduced to give good
  low speed and high speed operation
• Fully variable pitch was introduced to allow full
  control of pitch
• Constant Speed propellers are automatically
  adjusted continuously to keep engine at optimum
  RPMs

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Propeller Choices
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Propeller Evolution With Increasing Engine Power
Early War Spitfire-1938
Mid War Spitfire-1943
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Propeller
Late War -1944-Buzz Bomb Chaser
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Russian Bear Bomber
Contra-rotating propellers on Turboprop engines
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Russian Bear Bomber
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C-130 Hercules
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C-130 Hercules