Wind-tunnel tests of several forms of fixed wing slot in combination with a slotted flap on an N.A.C.A. 23012 airfoil
A 1939 NACA technical report of wind-tunnel test results for an airfoil with a fixed wing slot and slotted flap, published by NASA's Technical Reports Server. The pictures are engineering graphs with plotted curves, grid lines and labelled axes showing lift, drag, pitching moment and hinge moment against lift coefficient, so a designer might take only their dense technical line-and-grid layouts for diagrams.
