Beriev MBR-2

The Beriev MBR-2 was a Soviet multi-purpose (including reconnaissance) flying boat which entered service with the Soviet Navy in 1935. Out of 1,365 built, 9 were used by foreign countries including Finland and North Korea. In Soviet Union it sometimes carried the nickname of "Kорова" (cow) and "Амбар" (barn).
Design.
The MBR-2 was designed by Georgy Mikhailovich Beriev and first flew in 1931, powered by an imported 373 kW (500 hp) BMW VI.Z engine. Production models, which arrived in 1934, used a licence-built version of this engine, the Mikulin M-17 of 508 kW (680 hp), and could be fitted with a fixed wheel or ski undercarriage.
Beriev also designed a commercial airliner derivation, the MP-1, which entered airline service in 1934, and a freighter version, which followed in 1936.
In 1935, an improved version was developed, the MBR-2bis, powered by the Mikulin AM-34N engine, and fitted with an enclosed cockpit, dorsal gun-turret and enlarged vertical tail. In this configuration, the machine remained in production until 1941. As with the MBR-2, the bis spawned a commercial derivative and the MP-1bis entered service in 1937.