Sterba Prop General Propeller Making Rules

Tip speed
RPM X Diameter Inches X .00436 = tip speed (Ft/Sec)
The normal maximum for a wood prop is 900 Ft/Sec
2700 X 68 X .00436 = 800 Ft/Sec


Geometric Pitch
RPM X Pitch Inches X .000947 = Speed (MPH)
This approximates the aircraft forward speed.
2700 X 60 X .000947 = 153 mph


Blade Angle
Pitch/Circ. = the arc. tang. = angle (Degrees)
To find the angle needed at any blade station for a desired pitch.
Example: 60 pitch, 68 diameter (214" Circ.)
60/214 = .2804, then arc. tang of .2804 = 15.70 Degrees