The second of four S-3s for the US Army. This was the first scout type aircraft adopted by the army and SC on the fin may stand for Scout Curtiss. Photo from: Library of Congress

The S-6 was development of the S-3 with two forward facing guns above the propeller arc. Guns may not have been operational but mounted to test weight and balance. One S-6 was delivered to the US Army as serial 492. The S-6 was built at the experimental factory at Garden City, Long Island. The photo appears to be at Curtiss' Buffalo airfield as the buildings in the background appear in photos taken the year before Garden City opened. Photo from: National Archives at College Park, Maryland

The first production S-3 of four aircraft for the US Army. Photo from: National Archives at College Park, Maryland

Four S-3 were built for the US Army but it is not known if this was one of them or remained the prototype. Serials 322-325 applied to the army aircraft. They had the distinction of being the first scout aircraft used by the US army. It was two years after European air arms had introduced scouts. Photo from: National Archives at College Park, Maryland