The V4 prototype Fokker Triplane belonging to Voß was equipped with a captured Le Rhône rotary engine. The 110 HP engine was used in many allied aircraft to include the popular Nieuport 17 fighter/scout. By 1917 German manufacturing was having difficulties keeping up with her war needs and it was not uncommon to press servicable captured engines back in to service, especially an engine as reliable as the Le Rhône.
In the case of Voß's triplane Fok. F.I 103/17 it was a Le Rhône, Type J, 110 Hp, s/n 3247. It was taken from a captured British Nieuport 17.
The 110 HP Le Rhône