Flettner Fl 282 The Flettner Fl 282 Kolibri ( " Hummingbird " ) is a single - seat open cockpit 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 . Design and development . The Fl 282 " Kolibri " was an improved version of the Flettner Fl 265 , announced in July 1940 , which had the same intermeshing rotor configuration as the earlier helicopter . It had a 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 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 Focke Achgelis Fa 223 , which needed 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 . 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 . Operational history . Intended roles of Fl 282 included ferrying items between ships and reconnaissance . However , as the war progressed , the Luftwaffe began considering converting the Fl 282 for battlefield use . Until this time the craft had been flown by a single pilot , but now a position for an observer was added at the very rear of the craft , resulting in the B - 2 version . During the Battle of the Bulge a formation of five of these aircraft conducted the world ' s first helicopter strike against armour . Operating low over the Ardennes Forest they destroyed two American tanks at a loss of two of their own , one to a British Spitfire , the other to groundfire . Later the B - 2 proved a useful artillery spotting aircraft and an observation unit was established in 1945 comprising three Fl 282 and three Fa 223 helicopters . Good handling in bad weather led the German Air Ministry to issue a contract in 1944 to BMW to produce 1 , 000 units . However , the company ' s Munich plant was destroyed by Allied bombing raids after producing just 24 machines . Towards the end of World War II most of the surviving Fl 282s were stationed at Rangsdorf , in their role as artillery spotters , but gradually fell victim to Soviet fighters and anti - aircraft fire .