Steel spars
This is a 1928 NACA technical memorandum on steel spars, issued by the National Advisory Committee for Aeronautics and held in the NASA Technical Reports Server collection, written for aircraft engineers. The page holds numbered line drawings of spar cross-sections and truss-like members in isometric and plan views, with dimensioned sketches and small fittings. A designer could take from it the clean, technical diagram style: thin uniform outlines, numbered callouts, and angular lattice structures that suggest engineering blueprints.
