Speed measurements made by Division "A" of the airplane director
A 1923 NASA Technical Reports Server record of speed measurements taken by Division A of the airplane director, a technical report on aircraft performance testing. The four charts plot altitude, air density, climbing speed and airspeed against one another, with graph axes in metric and imperial units and labelled curves for individual aircraft. A designer could take from them the clean line-graph conventions of early aeronautical engineering, with dual metric and imperial scales, dashed reference grids and lettered data points.
