Wing spar stress charts and wing truss proportions
A 1926 technical report from the NASA Technical Reports Server, a set of engineering charts for stresses in wing spars and the proportions of wing trusses, presented for aircraft structural designers. Its pictures are dense grids of labelled curves plotted against percentage axes, with families of diagonal lines fanning across rectangular coordinate fields, showing how bending moment and load relate to bay length and overhang; a designer might take from them the look of precise graph paper, nested line families and tidy numeric tick labels.
