Influence of the Orifice on Measured Pressures
This is a 1926 NACA Technical Note from the National Advisory Committee for Aeronautics, a government research report on how the opening of a pressure tap affects readings taken in wind tunnels, written for aeronautical engineers and researchers. Its pictures are plain graphs of pressure ratios against angular position of the orifice, with curves labelled by angle and orifice diameter, plus photographs of a six-inch wind tunnel and test apparatus. A designer could take from them the clean, gridded plotting style and the restrained black-and-white technical look of mid-century engineering documentation.
