The helicopter was developed in 1938 with support of the German Navy. The Fl 265 made it possible for the first time to transition from powered rotary flight to autorotation and back again, making it the safest helicopter of its time. In contrast to the Fl 185, the Fl 265, believed to be the pioneering example of a synchropter, had two intermeshing rotors 12 m in diameter. Power was provided by a 160-horsepower BMW-Bramo Sh 14 A radial engine. Six helicopters were constructed. Series production was curtailed in favor of the Flettner Fl 282.