The MDR-3 (a.k.a.11) was a long-range flying boat designed and built in the USSR from 1931.
In 1931, Chyetverikov was commissioned to design a new long-range flying boat for MA (Morskaya Aviatsiya – naval aviation).
These commenced in January 1932 after the aircraft was transported to Sevastopol in the Crimea.
Despite fast construction and excellent structural qualities, results of the flight tests were disappointing.
As a result project was transferred to KOSOS (Konstrooktorskiy Otdel Sektora Opytnovo Stroitel'stva – section of experimental aeroplane construction), as there was a lack of faith in Chyetverikov's abilities to rectify the poor performance.