P. Ponk Aviation
Propeller Efficiency Calculator

Would you like to know how fast your propeller tips are traveling, how efficient your prop is at a particular RPM, and how much noise you are making? Enter some different combinations of prop diameter and RPM setting below to find out. Note: Ambient temperature is needed to determine the speed of sound for a particular day.

To produce maximum thrust at full power your tip speed should fall between .88 and .92 mach. To move between .88 and .92 mach usually takes a change of about 110 to 120 RPM. This of course varies depending on your particular propeller and the temperature.

If your tip speed is less than .88 mach you should increase RPM to achieve maximum thrust. If your tip speed is greater than .92 mach you should reduce RPM to achieve maximum thrust. Do not exceed the published operating limitations of your engine or propeller.

Over .92 mach the airflow begins to detach from the propeller which decreases efficiency and dramatically increases noise. To improve performance and public relations you should consider reducing RPM so as to fall within the .88 to .92 mach range. Your propeller will be producing maximum thrust which is good for you, and less noise which is good for all of us.