The drift of an aircraft guided towards it's destination by directional receiving of radio signals transmitted from the ground
A 1925 technical note from the N.A.C.A. series, issued by the National Advisory Committee for Aeronautics, on how an aircraft's drift can be corrected when it homes in on a ground radio transmitter. The page carries two plain line-and-grid graphs: a vertical flight-path plot labelled Start and Finish, and a small chart of drift against percentage increase of air distance flown. A designer could take from it the clean, schematic look of early engineering diagrams, with thin curves on squared grids, sparse labels and generous white margins.
