01/31/2012. Remarks by Kees Kort: "By the typical form of the rudder, this is a post-WW I converted Thomas-Morse S-4. After the war lots of Thomas-Morse S-4 biplanes were sold on the second-hand market. About sixty were used till the end of the twenties when the machine did not meet the ever more stringent US air regulations.

Alike the pictured aircraft, many were converted with a 90 hp Curtiss OX-5 liquid-cooled engine, and some got a second passenger seat. Other 'civil' Thomas-Morse S-4 machines were converted to a side-by-side version with OX-5 by Yackey Aircraft Company. I do not have an explanation for the marking 17 R6 on the side of the fuselage."