sergio stefanutti had already experimented with canard aircraft with the s.c.a. ss.2 and s.c.a. ss.3 "anitra" ("duck"), light aircraft built by "stabilimento costruzioni aeronautiche" (sca) at guidonia (a new city focused on aviation). the single-seat ss.2 had a canard wing configuration, fixed undercarriage and was powered with a 2-cylinder keller engine rated at . the ss.2 first flew in 1935, and one of the two prototypes was converted into a two-seater with a larger cna ii engine built by "compagnia nazionale aeronautica". this new aircraft first took to the air on 2 october 1937 and was officially revealed in milan at an international air exposition and the small fixed-undercarriage ss.2 was sent to passignano for evaluation. experience with this machine and the study of its aerodynamics led stefanutti to design a canard style interceptor and air superiority fighter, designated ss.4, very similar in layout to the ss.2 and ss.3.