Common air foil friction drag data
 

Folks, newbie here. Quick question, I am trying to find the Cdf data of common airfoils like NACA0015, 0020, 0025, etc., especially under low reynolds number conditions. I was reading a report lately that gave approximately 0.2 Cd, but 0.07 Cdp for NACA0020. This means friction drag accounts for 70% of the drag for an airfoil. RE # 150,000-200,000
Basically we are talking about a 10" long NACA0020 foil moving at 25mph.

This sounds really odd. I always thought air friction should be quite little in normal air conditions (low viscosity, etc.). But this clearly says 70%!!! What did I miss?

I believe your question is in regard to the contributions of pressure drag and skin friction drag to the overall drag on an airfoil. Given a low angle of attack, the main drag component will be due to skin friction. It is not until higher higher angles of attack (leading to flow separation) that the pressure drag becomes appreciable.