FI 282 CALIBRI HELICOPTER - 3rd COLOR German Newsreel 1945

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Episode 217

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The Flettner Fl 282 Kolibri (Hummingbird) is a single-seat intermeshing rotor helicopter, or synchropter, produced by Anton Flettner of Germany. According to Yves Le Bec, the Flettner Fl 282 was the world's first series production helicopter.

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 110–120 kW (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 venerable, tried-and-true design with low specific power output and low power/weight ratio (20.28 hp/L, 0.54 hp/lb) which could (anecdotally) run for up to 400 hours without major servicing, as opposed to the more powerful 27 litre displacement, nine-cylinder BMW/Bramo Fafnir 750 hp radial engine powering the larger Focke Achgelis Fa 223 helicopter, whose higher output (27.78 hp/L, 0.62 hp/lb), more modern design required moderate maintenance as often as every 25 hours (such as changing spark plugs, etc., well within the norm for modern radial engines of that era). While such a heavy and low-powered engine would work well in a very small craft like the Fi 282, to try and scale it up and use an engine of equivalent power/weight ratio in the 700-1000 hp class would result in a massive and heavy engine leaving little excess capacity for cargo or passengers. 750 hp was the lowest rating that the Fafnir was available in - indeed, it was a low-power, low maintenance design compared with many other engines of this era. The Fl 282's fuselage was constructed from steel tube covered with doped fabric, and it was fitted with a fixed tricycle 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%.