Testing airplanes in flight: determining position of resultant of action of air and longitudinal stability of an airplane at different angles of attack
This is a 1922 aeronautical technical report, issued through the NASA Technical Reports Server, on flight testing airplanes to find where the resultant air force acts and how longitudinally stable the aircraft is at different angles of attack. The two pictures are line diagrams in a plain engineering style: one shows a force and centre-of-gravity layout on a wing-and-line schematic, the other plots elevator angle against angle of attack with two sloping lines marked g and g' and dashed guide lines to points F and F'. A designer could take from them a clean, labelled technical diagram style with dashed construction lines and minimal lettering.
