Fokker S.IV

The Fokker S.IV was a military trainer aircraft produced in the Netherlands in the mid-1920s, essentially a radial-engined development of the S.III. It was a conventional single-bay biplane with staggered wings of unequal span braced with N-struts, with the pilot and instructor in tandem open cockpits and a fixed tailskid undercarriage with a cross-axle between the main units. It could be powered by a variety of engines in the 75 to 97 kW range, including the Siemens-Halske Sh 11, Le Rhone 9J, Bristol Lucifer, Armstrong-Siddeley Mongoose, Oberursel UR.II and Clerget 9B, and the Le Rhone 9J nine-cylinder rotary of 82 kW is the engine given for the standard specification. The Royal Netherlands Army Aviation Group purchased 30 and used them right up to the German invasion of the Netherlands in 1940. On 14 May that year a few surviving S.IVs escaped to France alongside some S.IX trainers but never flew again.