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Propeller Pitch Calculator

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Select Units:
SI Units US Customary Units

Select station increments:
Initial station
mm
Increment
mm
Maximum station
mm
Input Values and Units
Airspeed
kph
RPM
rpm
Blade Angle of Attack
deg
    
Results
 
 
Comments

(Based on work by Pete Soule.)

These calculations use either:
  • units (they used to be called metric) of millimeters (mm) and kilometers per hour (kph).
  • US units of inches (in) and miles per hour (mph)

The calculations do not include the effect of inflow. This is the increase in the velocity of the air in front of the propeller disc that can be felt by holding a hand in front of the propeller while the propeller is turning. This has the effect of increasing the effective airspeed. To account for this the input airspeed must be higher than the timed airspeed. A rough approximation for F2A is 5 kph addition to the airspeed.

The angle of attack has been adjusted near the tip for the effect of Mach number. An approximate Mach number for the blade station in question based on a 25°C day (77°F) day is output.

The "angle of attack" is measured from the pitch gauge reference. In most cases this is different from the conventional airfoil datum.

The default initial station position and station increment are taken from a Prather pitch gauge. If you have a different way of measuring a prop, adjust those parameters accordingly.

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