Experimental Investigation of Wind-Tunnel Interference on the Downwash Behind an Airfoil
This is a 1937 NASA technical report on wind-tunnel interference, written by NASA engineers for aeronautical researchers and wind-tunnel testers. Its pictures are engineering line charts of airflow contours around an airfoil, a plot of jet-boundary corrections, and a schematic of a self-synchronous motor balance with a calibrated dial, drawn in clean black linework with dense grid lines that a designer could borrow for technical diagram styling.
