Metal spars
This is a 1926 aeronautical technical memorandum from the National Advisory Committee for Aeronautics, issued as a numbered report and held in the NASA Technical Reports Server. Its single page of line drawings shows cross-sections and test forms for metal aircraft spars, labelled Figs. 1 to 5. A designer could take from it the clean, schematic plate style of early engineering reports: labelled outline diagrams, dimension lines and small sequential figures arranged on a grid.
