The two-boat seaplane (sea cruiser) MK-1 (ANT-22) is the third flying boat designed and built at TsAGI after ANT-8 (MDR-2) - 1930 - and ANT-27 (MDR-4) - 1934 year of construction.

In July 1931, the Air Force Directorate informed TsAGI of the technical requirements for a "sea cruiser" capable of lifting up to 6000 kg of bombs, having a maximum speed of 300 km / h and a range of 1000 km, and carrying powerful small arms and artillery weapons of four to five defensive, machine guns and two or three small-caliber automatic cannons. Ultimately, for the "sea cruiser" the scheme of an all-metal double-boat seaplane-catamaran was chosen.

The MK-1 design is completely metal, used by TsAGI in other structures: a power set of steel tubular elements, a reinforcing set of duralumin profiles, corrugated wing and tail skin.

A four-spar wing, cantilever of large aspect ratio. The boats, which had a maximum width of 2.5 m, provided the aircraft not only with the required seaworthiness, but also with excellent lateral stability, thanks to the 15 m wide "track" formed by them. The vertical tail assembly is a continuation of the boat hulls. In the lower part it is connected with a narrow fixed stabilizer, in the upper part - with a movable stabilizer sheathed with canvas.

In the upper part of the center section, on special pylons (in the plane of the longitudinal axis of the center section and the axis of each boat), there are three tandem installations of M-34 engines. Wooden propellers, two-bladed, of the same diameter - 4.2 m. The pitch of the pulling screws is 3.35 m, the pitch of the pushing screws is slightly larger - 3.96 m. The total power of the power plant according to the test report is 4950 hp. (6 × 825 hp). Fuel in four gas tanks with a total capacity of 9500 liters, oil 1530 liters.

The flight crew consisted of 4 people (the whole crew is 10-12 people): two pilots, the ship's commander and the navigator. The workplaces of the navigator, two pilots and a flight mechanic were equipped in a central nacelle, fixed on the wing center section along the axis of symmetry and protruding beyond its leading edge.

Armament. ShKAS machine gun, 20-mm cannon, 7.62-mm DA-2 machine gun, 20-mm Oerlikon cannon, 7.62-mm ShKAS machine gun, DA-2 machine gun, 600 shells, 14,000 cartridges, up to 6,000 kg of bombs or 4 aircraft torpedoes with a total mass of up to 4,800 kg, cluster holders for 32 bombs weighing 100 kg each, 6 bombs weighing 1000 kg each, or 4 torpedoes weighing 1,200 kg each.

The construction of the sea cruiser was carried out in the newly built experimental design plant of the TsAGI ZOK (future aircraft plant No. 156), in the center of Moscow on the banks of the Yauza. At the beginning of 1934, the production of MDR-4 (ANT-27) was completed here, and by the middle of the year MK-1. On April 15, 1934, when trying to take off for the first time, MDR-4 suffered a catastrophe, so preparations for the MK-1 tests were carried out especially carefully.

Factory tests of MK-1 began on August 8, 1934, continued until May 8, 1935 and were generally recognized as successful. In terms of flight sensations it was listed: "The controllability of the aircraft with various combinations of engine operation should be recognized as good" . However, such an aircraft could not be put into service for reasons of purely practical use. To maintain it, a large number of technical equipment and ground personnel were required. The preparation for the flight and its very maintenance turned out to be too complicated and time-consuming. For a combat aircraft, such indicators could not be acceptable, and a decision on its further development was not made.

The MK-1 flew until 1937. On December 8, 1936, on an experimental MK-1 aircraft with six M-34R engines, pilots Ryabenko and Ilyinsky set a world record for carrying capacity for seaplanes - lifting a load of 10 tons to a height of 1942 m. According to some reports, in other flights, not registered as a world achievement, it lifted a load of 13,000 kg.

Photo	Description
	Drawing MK-1
	MK-1 in flight

Bibliography

• The history of aircraft designs in the USSR, before 1938 / V.B. Shavrov /
• Black Sea Giant / Polygon. Mikhail Maslov, Vadim Egorov /