[1] The B-11 was similar to the design bureau's earlier B-5, a twin-rotor helicopter, with each rotor driven by an Ivchenko AI-26 radial engine.

[2] In August 1948 the first prototype was grounded for investigation, but limited testing carried on with the second to find the causes of the problems.

[2] On 13 December 1948 a blade on the right-hand rotor of the second prototype broke, and the subsequent crash killed the two crew.

[2] The prototype was then re-designed and re-built to overcome the problems, but when flying resumed in 1949 the stall occurred again.

[2] Bratukhin further modified the helicopter in May 1950 with new rotor blades, but development was soon abandoned, and soon after the design bureau was closed down.