Observations in Flight of the Region of Stalled Flow over the Blades of an Autogiro Rotor (1939)
NASA Technical Reports Server (NTRS) · leaf 18
N.A.C.A. Tecimical Note No. 741 Fig. 6 … Figure 6.- Experimental and theoretical outer boundaries of the region of stalled flow for ^ ■ 0.35. The YG-1B autogiro rotor.
NASA Technical Reports Server (NTRS)
Internet Archive · NASA Technical Reports · Public domain (US government work). Free to use for anything.