“The Bratukhin Omega (also known as the 2MG) was an early Soviet helicopter, the first product of a new Soviet design bureau, OKB-3 that was created from within TsAGI specifically to develop rotary-wing aircraft. Bratukhin’s design was a side-by-side twin rotor machine, with each rotor carried on a long outrigger truss. The Omega’s rotors were each powered by a separate engine carried in a nacelle also at the end of the truss. Captive trials commenced in August 1941 and revealed severe problems with engine vibration and overheating. Before these could be addressed, however, OKB-3 was evacuated ahead of the German advance into the Soviet Union.
Flight testing recommenced in mid 1942, with the Omega still flying on a tether until early the next year. Free-flight trials confirmed the design as basically sound, so although the engine difficulties were never fully resolved, Bratukhin was convinced that further development along the same general lines would prove fruitful. Development of the Omega helicopter was incremental with progressively more powerful engines, stronger structure and more reliable dynamic components, such as gearboxes and transmission shafts.
The ultimate iteration of the Omega was the Bratukhin B-11 which was used to compare characteristics of the products of the three competing helicopter designers. Completed in 1948 this was probably the most successful of the breed up to that time but still exhibited some of the short-comings of the configuration; mis-match between fixed wing and rotor and reliability of the complex dynamic components.
Source: Wiki, X-planes, blogrolled here