The Flettner Fl 185 was an experimental German

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 helicopter

Helicopter

A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...

 developed by Anton Flettner

Anton Flettner

Anton Flettner was a German aviation engineer and inventor. He made important contributions to airplane and helicopter design...

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This helicopter was developed in 1936 with support of the German Navy. It was powered by a 160 hp BMW-Bramo Sh 14 A

Siemens-Halske Sh 14

-References:* Becker, E. Siemens Jahrbuch 1928: Flugzeugmotoren der Siemens & Halske AG, reproduced on * http://www.oldengine.org/members/diesel/Duxford/germaer1.htm...

radial piston engine with forced-air cooling, mounted at the nose. The engine drove a 12 m diameter main rotor and two auxiliary propellers mounted on outriggers attached to the fuselage.

The auxiliary propellers worked in opposition to each other and served to cancel the torque of the main rotor, a function handled by a single, variable-pitch tail rotor on contemporary helicopters. The landing gear consisted of a nosewheel, two smaller stabilising wheels under the outriggers and a tail skid. Only one prototype was constructed.