Frits Koolhoven's designs bore his initials whoever he worked for, and here his name is also painted on the rudder of a NVI FK.31 reconnaissance fighter. Koolhoven himself is the large man talking to an officer to the left of the tailfin. First flown in 1923, the FK.31 set some world speed records with payload flown by Charles Descamps in January 1925, but was a failure in Finnish and Netherlands East Indies military service. A Netherlands army fly-off against the Fokker C.V was lost in February 1924. This is the prototype of an improved version, seen during another unsuccessful pitch against the C.V on 11 May 1925. Registration H-NACF has been worn by this airframe. Photo from: Nederlands Instituut voor Militaire Historie

This photo was added on 17 December 2020, and has since been viewed 599 times.