Aviation of World War II

Before the start of World War II, the USSR Navy received several types of flying boats, including the MDR-6 (Che-2) long-range sea reconnaissance aircraft. It was developed by a group of engineers led by Igor Vyacheslavovich Chetverikov. For the first time in domestic practice, a "gull" wing was used on an experimental naval aircraft, and the engine nacelles were installed in places where the wing was bent. Later, during operation, this innovation fully justified itself: such a wing layout and the adopted arrangement of engines created a sufficient distance between the propellers and the water surface.

Structurally, the MDR-6 was an all-metal boat-type monoplane. The cantilever wing of the "gull" type had hydraulically controlled flaps. According to its data, the MDR-6 was superior to the Beriev's close scout MBR-2M-34, already in service with the seaplane, and had a significant resource for improving flight characteristics.

Before the production of the serial aircraft, various modifications of the aircraft with different power plants were produced.

Most of the production aircraft, designated Che-2, were produced with M-63 engines (further development of the M-62 with a compression ratio increased to 7.2 and a power of 1,100 hp each). The car, despite its large size, was light enough. The empty weight of the Che-2 did not exceed 4100 kg, the takeoff weight was 6700 kg. In the reloading version, the flying boat weighed 7200 kg. Due to its aerodynamic shape, the aircraft had good flight and seaworthiness data. Its maximum speed reached 360 km / h, the ceiling was 9 thousand meters.

To improve the flight qualities of the MDR-6 aircraft, so that the flying boat could more or less be equal to the serial DB-3 bomber, it was decided to release modifications designated "A", and then "B" with increased power plants and improved aerodynamics , retractable floats from electric motors with worm gear.

The operation of weapons on naval aircraft has some peculiarities. At temperatures below minus 20-25°, the number of failures of the locks of the DER-19 bomb racks increased on aircraft with a low wing location (MDR-6 type).

Contact with salty seawater required frequent complete disassembly and cleaning of the locks, which increased the aircraft's combat readiness. On the seaplane, it was necessary to have mechanization that could provide the suspension of bombs in any weather.

The experience of operating weapons in sea conditions shows that poor processing of parts, lack of good access for inspection and cleaning contribute to severe corrosion and an increase in the number of failures.

Photo	Description
	Drawing MDR-6 with M-25
	Drawing MDR-6A
	Drawing MDR-6B-4
	MDR-6A on the water

Modifications

• MDR-6 - the first aircraft with two M-25E engines (M-25 - radial nine-cylinder Shvetsov engine - Soviet metric version of the American Wright R-1820-F3 of the Perm plant.) The non-serial M-25E had a rated power of 710 hp. s, rated speed - 2100 rpm, altitude - 5400 meters, takeoff power - 635 hp, weight - 453 kg. The power of the engines was insufficient and, in the future, in case of successful tests, serial production with a more powerful power plant was supposed.
• MDR-6A - seaplane with in-line engines Klimov M-105 with a capacity of 2 × 1050 hp.
• MDR-6B-1 - a seaplane powered by Klimov M-105 engines, the wing consoles are significantly reduced (in favor of speed). The plane was executed very cleanly and was rightfully considered the most beautiful of the seaplanes. The speed reached 454 km / h at an altitude of 6000 m. Armament: three ShKAS machine guns and four bombs of 100 - 250 kg.
• MDR-6B-2 of 1943 release had the same engines, size and wing design as B-1. The floats were increased in size and the takeoff weight of the seaplane increased. There was still a lack of range.
• MDR-6B-3 release of 1943 with M-105PF engines, take-off power 2 × 1270 hp, wing size and design as in B-1. The armament was strengthened: in the rear fuselage, two blisters were mounted under the UB machine guns. The crew was increased to 5 people. The weight of the aircraft increased in the normal version to 7200 kg, and in the reloading version to 8200 kg (the mass of fuel in both versions is 1100 kg).
• MDR-6B-4 release in 1944 with VK-107 engines. The boat was broadened from 1.9 to 2.2 m and made higher on average by 0.4 m, with a raised tail and plumage. The floats were made non-retractable, the fuel supply was increased to 2150 kg. The vertical tail area has been increased by adding a third (middle) keel. The weight of the aircraft increased to 10 tons.
• MDR-6B-5 of 1945 release with VK-107A engines with a capacity of 2 × 1650 hp. The weight of the empty B-5 without removable equipment increased to 5610 kg. The seaplane was not submitted for state tests. The flight qualities of the seaplanes of variants 4 and 5 were leveled out by the low reliability and low resource of the VK-107 engine.

Bibliography

• "The history of designs of planes in USSR 1938-1950" /Vadim Shavrov/