September 2020

Bratukhin “Omega II”/G-2 Lateral-Twin Helicopter

2020-September

Early Soviet rotary-wing activities generally followed a similar development path as European and US pioneers by designing and experimenting with autogyros. This led to early helicopter experiments by numerous designers and the Central Aero- and Hydrodynamic Institute (TsAGI) with single-rotor helicopters, and by Nikolai Kamov with co-axial helicopters. Later, Mikhail Mil’s design bureau would also specialize in single-rotor development and production.

Soviet designer Ivan Bratukhin (1903-1985) and his 1940 OKB-3 department, part of the Aviation Institute of Moscow, chose a different approach and were influenced by the success of Germany’s Focke-Wulf Fw 61 lateral-twin helicopter.

Since the aircraft was developed during the Second World War, the original design mission for the Omega II was artillery spotting with the hovering aircraft adjusting the ground-based gunfire via radio.

The Omega II was Bratukhin’s second lateral-twin design and was powered by two Kossov MG-31F 9-cylinder radial engines with 350 HP (261 kW) each mounted outboard on the uncovered steel tube truss. The engines were connected by a synchronizing shaft. The fuselage and T-tail were fabric covered. The first Omega encountered severe engine overheating problems so the second version incorporated front-mounted engine cooling fans.

After prolonged delays due to higher priority war efforts, the helicopter made its first tethered flight in September 1944 and its first public appearance during the Tushino Air Display on Soviet Aviation Day on Aug. 18, 1946.

Improved OKB-3 Bratukhin lateral-twin helicopter variants followed the Omega II with increased horsepower engines and improved performance but overall, persistent vibration problems consistent with the lateral-twin configuration continued and by 1950, Soviet leadership had determined that the Mil single-rotor and Kamov co-axial rotor types held better promise.

Characteristics:

  • Rotor diameter: 23 ft (7 m)
  • Max. gross weight: 5,070 lb (2,300 kg)

Sources:

Text by Ken Bartie

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