General Discussion of Test Methods for Radiators
A 1919 technical report from the NASA Technical Reports Server, a government aeronautics document, setting out test methods for aircraft radiators. Its pictures are plain line diagrams of test rigs: pipework, valves, gauges, thermometers and a wind tunnel section with a specimen radiator. A designer could take from them a clear schematic vocabulary of labelled apparatus drawn in simple black ink linework.
