The Measurement of Air Speed in Airplanes
This is a 1937 NACA technical note, issued by the National Advisory Committee for Aeronautics, on measuring airspeed in aircraft; it is a technical report for aeronautical engineers and researchers. The first picture is a dimensioned line drawing of a probe with a long tapered nose and a stem, and the second is a photograph of a pointed air-speed head with fins on a stand, captioned as figure 4. A designer could take from them the clean, schematic look of 1930s engineering diagrams and the sleek streamlined forms of early aircraft instruments.
