The propeller efficiency (ηp) represents the efficiency with which a propeller converts the power input into thrust. It is a dimensionless parameter often expressed as a percentage. There are two common ways to calculate the propeller efficiency, and both are related to the advance ratio (J) and the thrust coefficient (CT) and power coefficient (CP).
ηp = Propeller efficiency (dimensionless or as a percentage) T = Thrust produced by the propeller (in Newtons) V = Forward speed of the aircraft or vehicle relative to the air (in m/s) P = Power input to the propeller (in Watts)
ηp = Propeller efficiency (dimensionless or as a percentage) J = Advance ratio CT = Thrust coefficient (dimensionless) CP = Power coefficient (dimensionless)