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Prop Pitch

A quick chart is provided at the bottom of this page for reference estimating propeller pitch based on 100% efficiency.

Rule of thumb

  This rule of thumb formula assumes a 80% propeller efficiency.

p = v * 1056 / r

where
p = pitch in inches
v = cruise speed in mph
r = engine speed in rpm

For real world calculations propeller efficiency must be considered. Some typical metal or composite prop efficiencies are as follows.

 Constant speed: 92%
 Fixed climb prop: 75%
 Fixed normal prop: 82%
 Fixed cruise prop: 90%

Wood props are usually about 5-10% less efficient than the values shown.

MPH 120
RPM 2800
Efficiency  90 %
Pitch 49 in


MPH
RPM
Effeciancy %  


Propeller Pitch at 90% efficiency
Example: 100mph cruise @ 3000rpm = 32" pitch
Cruise MPH
RPM
Prop Pitch(inch) 90% efficiency


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