Report KD 698 can be copied for free from my website:
www.kdwindturbines.nl at the menu KD-reports. The tittle of this report is: "The Gö 227 airfoil for use in windmill rotor blades". This airfoil has partly a convex and partly a concave lower side and therefore manufacture of rotor blades with this airfoil requires special skills. However, this airfoil has certain special qualities like a high optimum lift coefficient and a low Cd/Cl ratio, even for low Reynolds values.
