Despite a high resolution 3D printer was applied,
the procedure of grinding the airfoil outside
surface, especially in the case of small geometric
elements preceded the airfoil printing. This is particularly
important in the study of aerodynamics
because surface roughness is one of the factors
that can significantly impact on the behaviour of
air stream [5, 6]. Hand sanding with sandpaper of
small roughness was applied to grind the airfoils