Study of the resistance offered by propellers rotating on an airstream
A 1921 technical report from NASA's Technical Reports Server, a scanned engineering study of how propellers resist airflow when spinning in a wind stream. Its pictures are performance graphs of propeller thrust and torque against revolutions per minute, drawn as solid and dashed curves across several airspeeds and pitch ratios. A designer might take from them the clean, labelled line-graph style of early aeronautical engineering and its dual-axis chart layout.
