Propellers
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Propellers PowerPoint PPT Presentation


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Propellers. Parts of the Propeller. Props. The propeller is the unit that must absorb the power output of the engine and thus create the thrust. Thrust Horsepower is determined by the efficiency of the propeller compared to the Brake Horsepower of the engine.

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Propellers

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Propellers

Propellers


Parts of the propeller

Parts of the Propeller


Props

Props

  • The propeller is the unit that must absorb the power output of the engine and thus create the thrust.

  • Thrust Horsepower is determined by the efficiency of the propeller compared to the Brake Horsepower of the engine.

  • This lack of efficiency is defined as slip


Propellers

Slip


Stations

Stations


Blade pitch

Blade Pitch


Forces acting on the propeller

Forces Acting On the Propeller

  • Centrifugal Force

  • Thrust Loading

  • Torque Bending Force

  • Aerodynamic Twisting Force


Constant speed

Constant Speed

  • To help in efficiency constant speed props where conceived

  • Fixed Pitch props come in three models

    • Climb

    • Cruise

    • Mix

  • These propellers are excellent for their purpose but lacking in their opposition

  • The constant speed prop allows for maximum efficiency


Constant speed1

Constant Speed

  • Most constant speed props are also manually controllable pitch.

  • By being able to manually control the pitch we can

    • Assure no engine overspeed

    • Improve ride comfort

    • Maximize efficiency


Governor

Governor

  • Almost exclusively the controllable constant speed propeller is controlled my a hydro mechanical governor.


Governor1

Governor


Propellers

  • http://ehflyers.com/AeroLaulima/animations/links/propAndGovernor.html


Feathering

Feathering

  • Some propellers are given the capability of feathering. Increasing the blades pitch angle to 90°.

  • This allows the propeller when stopped to align with the slipstream, and thus decrease drag of a rotating disc.


Hot wet props

Hot/Wet Props

  • Some propellers have the need to shed ice or ensure ice does not form.

    • This is done in two ways

      • Alcohol Anti Ice

      • Electrical Deicing


Geared engines

Geared Engines


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