From https://www.defensemedianetwork.com/stories/naca-the-jet-age...
In 1951, Kraft issued NACA Technical Note 2416 that proposed a theoretical solution to the problem. Tests first on a modified DC-3 and later on a C-45 validated the theory, and by 1955 the system was perfected.
Can be downloaded from here.
https://digital.library.unt.edu/ark:/67531/metadc64927/m2/1/...