Inside Out Library · ExploreNote on vortices on their relation to the lift of airfoils (1924)NASA Technical Reports Server (NTRS) · leaf 15Figs.1,2. … Fig. 2NASA Technical Reports Server (NTRS)Internet Archive · NASA Technical Reports · Public domain (US government work). Free to use for anything.More pictures from Note on vortices on their relation to the lift of airfoilsMore like this