Abraham Robinson worked in applied mathematics for several decades. MathSciNet lists 12 articles by Robinson in wing theory. His production included the book
Robinson, A.; Laurmann, J. A. Wing theory. Cambridge, at the University Press, 1956.
The book is full of references to infinitesimals. Thus on page 36 one finds a reference to "infinitesimal horseshoe vortices of constant strength". Five years later Robinson published his first publication on infinitesimals in
Robinson, Abraham. Non-standard analysis. Nederl. Akad. Wetensch. Proc. Ser. A 64 = Indag. Math. 23 1961 432–440.
Are there any sources or references in the literature to a possible connection between Robinson's work exploiting infinitesimals in applied mathematics, on the one hand, and his eventual development of a rigorous mathematical theory thereof, on the other?
Note 1. See http://mathoverflow.net/questions/156928/is-there-a-source-linking-robinsons-work-in-wing-theory-with-his-theory-of-infi for a more vigorous discussion.