The Fokker V.9 was part of a series of experimental aircraft which led up to the low-production D.VI fighter. The aircraft were very similar, varying in detail and power plants. The V.9 was powered by a 60 kW (80 hp) Oberursel and first flew in December 1917; all others flew in 1918. The V.12 was powered by an experimental 119 kW (160 hp), Steyr-Le Rhône engine. The V.14. Like the V.12, the V.14 was powered by the 119 kW (160 hp) Steyr-Le Rhone. The V.16 was powered by the 81 kW (110 hp) Oberursel Ur. II. The V.33 was a development of the V.9. It was tested with both 82 kW (110 hp) and 108 kW (145 hp) Oberursel engines. Bibliography References http://www.dutch-aviation.nl/index5/Military/index5-1%20Fokker%20Military%20Aircrafts.html 1910s German fighter aircraft V.09 Rotary-engined aircraft Single-engined tractor aircraft Biplanes Aircraft first flown in 1917