Flow Observations with Tufts and Lampblack of the Stalling of Four Typical Airfoil Sections in the NACA Variable-density Tunnel
A 1938 NACA technical report by NASA's Technical Reports Server, issued for aeronautical engineers and researchers, recording tuft and lampblack flow observations of airfoils as they stall in the variable-density wind tunnel. The pictures are charts plotting section angle of attack against lift coefficient, with stacked horizontal bars marking flow states such as transparent, intermittently separated and separated flow, above small airfoil profile sketches. A designer might take from them a clean, restrained scientific chart style built on thin grid lines, bold bars and simple airfoil outlines.
