Effect of altitude on radiator performance
A 1920 technical report from the National Advisory Committee for Aeronautics, held by the NASA Technical Reports Server, presenting test data for aircraft radiators. The two pages are engineering graphs for airplane engineers and designers, plotting energy dissipated and figure of merit against altitude and airspeed. A designer could take from them the clean, sparse line-graph style of early aeronautical data sheets, with thin curves, labelled plot numbers and a plain grid.
