The propeller advance ratio is a dimensionless parameter used in aerodynamics to characterize the performance of a propeller. It describes the ratio of the forward speed of an aircraft to the rotational speed and diameter of the propeller.
Where:
- = Propeller advance ratio
- = Airspeed (velocity) of the aircraft
- = Rotational speed of the propeller (in revolutions per minute, RPM)
- = Diameter of the propeller.