The last design authorised from OKB-3 was to provide comparision against Mil and Yak single-rotor submissions to VVS requirement for a three-seat all-weather communications helicopter. Dynamic parts were as previous Bratukhin except for hydraulic rotor-hub dampers and faired masts with oil-cooler inlets. Wing of lifting section are set at zero incidence. The fuselage had improved form, with round instead of polyhedral top and bottom. The tail was basically as the B-5. The pilot was in B-5 type nose, main cabin for two seats, with space at rear for freight ot two stretchers (in lieu of passengers) loaded through enlarged door. Improved differential rotor controls with reduced friction were fitted. The B-11 was equipped for blind flight.
Two prototypes were completed in April 1948, flying in June and September. Progress was made with measured performance, sustained (47 min) single-engine flight, autorotative landings and in eradication of various faults stemming mainly from vibration was achieved. One problem was lack of wing lift resulting from incidence setting, causing the rotors to stall at high forward speeds. A further snag was hydraulic leaks difficult to rectify. On 13 Decemeber 1948 first machine shed a blade from the right rotor, killing Ponomaryov and I.G.Nilus.
After several modification, including installation of new engines (same series), it was presented on an Aviation Parade.
The favored scheme of twin-rotor helicopter became “The Flying Banana” (due to less drag), and the transversal scheme was not used again until the Mil Mi-12.

B-11
Engine: 2 x AI-26GRF, 575hp
Rotor diameter: 10.0m
Take-off weight: 4150kg
Empty weight: 3398kg
Max speed: 155km/h
Service ceiling: 2550m
Range: 328km
Crew: 3
Passengers: 1-3

Also designated VNP (Vozdushni Nabludatyelnii Punkt – aerial observation point), its original role was to replace the AK in artillery spotting. The Bratukhin helicopter had become larger and potentially more capable and the VNP was to be a multi-role machine able to fly recon, tactical supply and even casevac missions. Engines were fully boosted AI-26 version, and dynamic parts were essentially the same as the B-9. Wings were of the same plan and section as the B-9 but with a pair of bracing struts from the bottom of two main-spar frames in the fuselage to the spar booms at 60% semi-span, and two bracing struts from the upper spar booms at same location to the top of rotor masts. The fuselage was an entirely new dural monocoque with a glazed nose seating the pilot on the left and navigator on the right under a large observation dome. An was also in the tail, again with large observation dome. A new tail with a variable-incidence tailplane mounted on the fuselage carrying endplate fins(latter possibly rudders). Usual four-wheel landing gear. The central fuselage was available for additional loads: three passengers, or two stretchers (room for more but weight-limited) or 200kg cargo or various radio or photographic equipment. Entrance door on left.
A single example was built and flown 1947. Behaviour was satisfactory, and complete performance measurements were taken. Later fitted ShKAS at nose and tail. At the time on the ‘decision-making level’ attention was shifted to competing schemes of helicopters (under influence of Western designs). Despite B-10 was performing well, it failed to catch any interest in the ‘High Circles’.
According to Shavrov 1947-48 saw general disillusionment with helicopters and especially with twin lateral rotor configuration.

B-10
Engine: 2 x AI-26GRF, 575hp
Rotor diameter: 10.0m
Take-off weight: 3900kg
Empty weight: 3019kg
Max speed: 218km/h
Service ceiling: 6550m
Hovering ceiling: 2200m
Range: 440km
Crew: 3
Passengers: 2-3

A scaled-up derivative of the G-4, with slightly more powerful model of same engines.
The first helicopter designated for Bratukhin himself, the transmission and other dynamic parts were identical but the new airframe had a lifting aerofoil wing instead of space-frame outriggers and large passenger fuselage.
Designed as a duralumin semi-monocoque (not steel tube as has been reported) with a level floor and door on the right side. A total of 7 seats, intended as two crew and 5 passenger seats, with an aisle along the right wall. Wings were also of light-alloy stressed-skin construction with lifting profile to carry about 25% of the weight in cruise. Fixed tricycle gear with bumber tail-wheel.
A single example was completed in 1947 powered by supercharged version of the AI-26GR engine, but only limited testing was undertaken because of inadequate wing stiffness.

B-5
Engines: 2 x AI-26GRF, 550hp
Rotor diameter: 10.0m
Take-off weight: 4032kg
Empty weight: 2932kg
Max speed: 236km/h
Service ceiling: 6400m
Hovering ceiling: 2280m
Range: 595km
Crew: 2
Passengers: 5

The first Soviet helicopter with the engines purposely designed, with cooling fan and front gearbox giving vertical and lateral outputs for the rotor and for transverse coupling shaft. The transmission was provided with centrifugal clutch; overall drive ratio 0.27 (540 rotor rpm). The main rotor had an inbuilt twist of 6 deg 45 min along the blade, and blade spar were extruded instead of folded sheet. Two prototypes were built, the first flown in October 1947 by M.K.Baikalov and second a month later. In January 1948 the first G-4 was damaged in the course of autorotational descents and deadstick landings typically at 12 m/s descent along 15.5-16 deg glide path.
The first prototype did not meet expectations (some calculated parameters were not reached). The second prototype had an improved rotor blade airfoil passed the extended test program without problems. Gliding (autorotation) rate was 12m/s, with gliding angle 16°. In this case landing speed was 80-90km/h with 10-15m roll.
The second G-4 was the first helicopter in the Soviet Union to meet its stipulated life for dynamic parts (in this case 100h). A small series constructed 1947-48, according to one account four flying out of ten ordered.
A G-4 and two G-3s participated in Aviation Parade in 1947.

G-4
Engine: 2 x AI-26GR pistone engine, 370kW
Rotor diameter: 7.7m
Take-off weight: 3002kg
Empty weight: 2364kg
Max speed: 148km/h
Ceiling: 2400m
Range: 233km
Crew: 1