Ideally an aerofoil section should not have the parasitic drag but in reality it will surely have some parasitic drag.
Parasitic drag is the sum of profile drag and interfernce drag.
Profile drag is sum of Skin friction and pressure drag
1. Usually the aerofoil is designed to give the greatest decrease in Skin friction drag at low lift coefficients or in other words at high speeds
2. Pressure drag arises due to overall presure didtriburion of an aircraft, it the diffrence between forces caused by high pressure on the forward portion and low pressure on the aftportion of the aircraft
3. interference drag is caused by regions of turbulence at junctions
All the three factor above may be small for heli blades, will they be increasing more than reduction in induced drag ?
Hard to answer that i suppose.
