The Aerodynamic Characteristics of Airfoils as Affected by Surface Roughness (1933)
NASA Technical Reports Server (NTRS) · leaf 15
Lift coefficient, Cl Angle of attack for infinite aspect ratio, ci0 (degrees) at} Figure 6.-Section characteristics as affected by location of surface roughness cn on lower surface near leading edge.
NASA Technical Reports Server (NTRS)
Internet Archive · NASA Technical Reports · Public domain (US government work). Free to use for anything.
