Wind-tunnel Investigation of Ground Effect on Wings with Flaps (1939)
NASA Technical Reports Server (NTRS) · leaf 23
10, 11 Figs N.A.C.A. Technical Note No. 705 … 24 £ 20 E a 16 * £ | 8 12 Q) 8 W CO CD L u 4 (D Q 2.4 0 .4 .8 1.2 1.6 2.0 Free-air maximum lift coefficient, CLmax Figure 11.- Effect of free-air maximum lift coefficient on decrease in maximum lift due to ground effect at 0.7 cw below wing.
NASA Technical Reports Server (NTRS)
Internet Archive · NASA Technical Reports · Public domain (US government work). Free to use for anything.