Does propeller size affect total drag force of plane? Integration of pressure distribution of  each blade  get net force(thrust) which is allways pointing forward.So there is no drag force at  any propeller ,that tells that size of propeller doesnt change total drag force.
So plane with propeller of 1m diameter will has same total drag force as plane with propeller of 2.5m diameter?
(if both planes are same and both propellers have same thrust force,and both propellers are fixed at tail so wash not blow at plane body,causing aditional skin friction and pressure drag)
boat analogy:
Why all speeds boats use small propellers,instead big ones?I allways think reason was big propellers increase boat overall hydrodynamic drag,but when I better think propeller cant cause drag when producing thrust!
the drag force that a propeller generates while under power is expressed as a torque applied to the engine's crankshaft and arises because of skin friction on the propeller blade surfaces. as long as the prop is generating net thrust it is not generating drag in a direction opposite to its direction of travel.
Prudent design of the prop blades guarantees that no portion of the blade is ever generating backwards thrust for all possible combinations of airspeed, RPM, and blade pitch.
A propeller that is not generating thrust is generating drag which does act against the airplane's direction of travel.