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Propellers

Propeller are rotating airfoils which produce thrust.

Propeller chord

  • When an aircraft is stationary the propeller is largely stalled
  • As the aircraft speed increases the propeller becomes more efficient

Propeller Slip​

Propeller slip

  • Geometric pitch: the distance the propeller should travel based on its design
  • Slippage: Distance between the geometric and effective pitch

Propeller Twist​

Propeller speeds

  • For a given RPM the tip of the propeller is traveling much faster than the hub
  • This means the outer portion needs a lower angle of attack to produce even thrust across the whole diameter
  • For fast-spinning propeller, the tips can also approach the speed of sound

Fixed-Pitch Propellers​

  • A fixed-pitch propeller is only optimal at one specific airspeed
  • Different trade-offs
    • Slow speed / high angle of attack (climb propeller)
    • High speed / low angle of attack (cruise propeller)