The Flettner FI 339 was designed as a light, two-seat aircraft, developed from Autumn 1944 on. The helicopter was basically an improved FI 282, which had a BMW 132 radial engine instead of the Bramo 314 engine and, due to its compact design, was very close to today's helicopters. Due to greater engine power, the rotorcraft should be able to transport higher offensive drop loads in order to be able to intervene successfully in anti-submarine warfare. For example, it was planned to take two SC 50s or corresponding depth charges. The FI 339 had a calculated empty weight of 950 kg, and an average flying weight of between 1,300 kg, with top load of around 1,500 kg. On December 20, 1944, 30 Fa 339s were initially ordered. From the summer of 1945 onwards, up to 30 of the light helicopters were to roll off the production line every month. At the end of the war, however, only one prototype in an advanced state of construction was captured by the Allies.On June 29, 1945, Anton Flettner asked to further develop the FI 339 for the Allies and suggested involving the VDM works in Frankfurt. According to the designer, since the drawing sets were still available, it would easily be possible for him to upgrade four of the helicopters from existing parts and to practically test two each in England and the United States. However, the project was rejected, and parts of the development team went to France.