The Fl 282 Kolibri was an improved version of the Flettner Fl 265 announced in July 1940, which pioneered the same intermeshing rotor configuration that the Kolibri used. It had a 7.7 litre displacement, seven-cylinder Siemens-Halske Sh 14 radial engine of 150-160 hp mounted in the center of the fuselage, with a transmission mounted on the front of the engine from which a drive shaft ran to an upper gearbox, which then split the power to a pair of opposite-rotation drive shafts to turn the rotors.
The Sh 14 engine was a tried and true design that only required servicing every 400 hours, as opposed to the nearly 27 litre displacement, nine-cylinder BMW/Bramo Fafnir radial engine powering the Focke Achgelis Fa 223, whose outdated design required maintenance every 25 hours. The Fl 282's fuselage was constructed from steel tube covered with doped fabric, and it was fitted with a fixed undercarriage.
The German Navy was impressed with the Kolibri and wanted to evaluate it for submarine spotting duties, ordering an initial 15 examples, to be followed by 30 production models. Flight testing of the first two prototypes was carried out through 1941, including repeated takeoffs and landings from a pad mounted on the German cruiser Köln.
The first two "A" series prototypes had enclosed cockpits; all subsequent examples had open cockpits and were designated "B" series.
In case of an engine failure, the switch from helicopter to autorotation was automatic.
Three-bladed rotors were installed on a test bed and found smoother than the vibrating 2-blade rotor, but the concept was not pursued further. The hover efficiency ("Figure of Merit") was 0.72 whereas for modern helicopters it is around 60%.
After the war, Anton Flettner emigrated to the United States and became the chief designer for Kaman Aircraft, creating the Kaman HH-43 Huskie. Intermeshing rotors have become noted with Kaman helicopters, which continues this concept.
Fl 282 V1/7 : Prototypes.
Fl 282A-1 : Single-seat naval reconnaissance type, for operation from cruisers and other warships. Tested in the Baltic, Mediterranean and Aegean Seas.
Fl 282A-2 : Single-seat reconnaissance type for submarines equipped with special deck hangar, project only.
Fl 282B-1/B-2 : Two-seat land reconnaissance-liaison helicopter