More or less in parallel with the construction and development of the KOR-1 floatplane, the Beriev bureau was working on the design of a small flying-boat. This was intended to fulfil the same requirement as the hastily developed KOR-1, but was intended to provide much improved performance.

A Beriev MBR-2 flown by the Soviet Navy

First flown in 1940, this new and basically attractive flying-boat was of all-metal construction. The term 'basically attractive' is used judiciously, for without its wing-mounted powerplant this new aircraft had superb lines. The giant engine, however, rather like the disfigurement of a hunchback, dominated all else to spoil the aesthetic lines of Beriev's design. In configuration the Beriev KOR-2, as the new aircraft was designated, was a parasol-wing monoplane, the wing itself being pylon-mounted above the stepped flying-boat hull, and braced by two streamlined struts on each side. An unusual feature was the selection of an inverted gull wing, but almost certainly this was chosen to raise the wing-mounted engine as high as possible to provide adequate clearance for the three-bladed controllable-pitch propeller and, at the same time, to ensure that the mounting struts for the underwing stabilising floats could be kept as short as possible. The tail unit was similar in configuration to that of the KOR-1, except that the high mounted tailplane was a strut-free cantilever structure.

Built in a factory at Taganrog, on the shore of the almost enclosed Sea of Azov, only a small number of these aircraft had been completed and delivered to the Soviet navy before the Taganrog area was over-run by the invading Germans in the autumn of 1941. Production of the KOR-2, or Beriev Be-4 as it had then been redesignated, was resumed at a Central Asian factory during 1942, but no records of the number constructed have so far been discovered.

Variants

Beriev MBR-2M-17 - Deliveries of the MBR-2M-17, intended for use in the short-range bombing and maritime reconnaissance roles, began in 1934. It was a shoulder-wing cantilever monoplane, with its 680 hp (507 kW) Mikulin M-17B engine mounted on a pair of N-struts over the wing. It had a two-step wooden hull with plywood covering, and the pilot's cockpit located just in front of the wing. A strut braced horizontal tailplane was set high on the single fin. Bow and midships gunners each had a single 7.62 mm (0.30 in) PV-1 machine-gun.

Beriev MBR-2AM-34 - In 1935, with the first production version already in service, Beriev carried out a radical redesign of the MBR-2, the pilot's cockpit was fully enclosed, and the midships gunner's position protected by a glazed cupola; the M-17B engine was replaced by the M-34NB (redesignated AM-34NB in 1937) of 830 hp (619 kW). An entirely new curved fin and rudder replaced the original angular vertical tailplane and ShKAS machine-guns supplanted the obsolete PV-1s. The new version was soon placed in large-scale production, which continued until 1942, when some 1,300 of all variants had been built. The maximum speed of the MBR-2AM-34 was 152 mph (245 km/h), a considerable improvement over the initial production version. Range was 497 miles (800 km), and service ceiling was raised to 23,460 ft (7150 m); weight empty increased to 5,992 lbs (2718 kg) and loaded weight was 8,818 lbs (4000 kg); the MBR-2AM-34 served with all four main Soviet fleets and saw considerable service, first during the Winter War of 1939-40 with Finland, and then throughout the Great Patriotic War of 1941-45. It was tough, reliable and acquitted itself well and it could be fitted with wheel or ski landing gear. Post-war, the MBR-2 served for nearly a decade on fishery' patrol duties; it received the NATO codename 'Mote'

Beriev MBR-2M-103 - In 1937 a standard MBR-2AM-34 was modified to take a more powerful M-103 engine, but no production of this version was undertaken.

Beriev MP-1 - This was a civil passenger version of the MBR-2M-17. It carried six passengers in an enclosed cabin or an equivalent weight of freight. It was used in some numbers by Soviet Civil Aviation.

Beriev MP-1bis - A 1937 civil development of the MBR-2AM-34, with similar capacity to that of the MP-1. One MP-1bis, piloted by Paulina Osipenka, established a number of women's world records. Between 22 and 25 May 1937 she attained respectively 24,905 ft (7605 m) with a 1,102 lbs (500 kg) payload and 22,966 ft (7000 m) with a 2,204 lbs (1000 kg) payload. On 2 July, in the same year she made a non-stop flight of 1,501 miles (2416 km) between Novgorod and Archangelsk.

Beriev MP-2bis - The outbreak of World War II triggered hurried efforts to develop a new version, the MBR-2bis, which was powered by an 860 hp (642 kW) AM-34NB engine in place of the earlier 680 hp (507 kW) Mikulin M-17B engine. Increased fuel tankage raised the range from 597 miles (960 km) to 870 miles (1400 km), for the purposes of maritime reconnaissance over the confined waters of the Baltic and Black Seas, as well as the northern Artic seaboard. The new version was seen as an ideal interim aircraft pending the arrival in service of the Chetverikov MDR-6 (Che-2). In 1942 about 1,500 aircraft had been delivered, making the MP-2bis the most widely used short-range flying boat during the first three years of the war. Its principle task was that that of Air-Sea Rescue. Mediocre performance and poor defensive armament made it easy prey to Luftwaffe aircraft. 

Specifications (Beriev MBR-2M-17)

Type: Four Seat Short Range Coastal Reconnaissance Bomber Flying Boat

Design: Designer General Georgij Mikhailovich Beriev

Manufacturer: State Industries (Prototype) Menschinsky Factory in Moscow but production aircraft were built at the Beriev Factory in Taganrog

Powerplant: One 680 hp (507 kW) Mikulin M-17B 12-cylinder inline engine.

Performance: Maximum speed 124 mph (200 km/h); service ceiling 14,435 ft (4400 m)

Range: 404 miles (650 km) on internal fuel.

Weight: Empty equipped 5,456 lbs (2475 kg) with a maximum take-off weight of 9,039 lbs (4100 kg).

Dimensions: Span 62 ft 4 in (19.00 m); length 44 ft 3 1/2 in (13.50 m); height 15 ft 8 3/4 in (4.82 m); wing area 592.03 sq ft
(55.0 sq m).

Armament: One 7.62 mm (0.30 in) ShKAS machine-gun on bow and midship ring mountings, plus up to 1,102 lbs (500 kg) of bombs or depth charges on underwing racks.

Variants: Beriev MBR-2M-17, Beriev MBR-2AM-34, Beriev MBR-2M-103, Beriev MP-1 (civil), Beriev MP-1bis (civil), Beriev MP-2bis.

Avionics: None.

History: First flight 1931.