Heavy attack flying boat First flight: 1934 Tupolev

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

Naval heavy bomber Project Bartini

At the late 1920s, R.L. Bartini began working on the MTB-2 (Naval Heavy Bomber-Second) flying boat, designed by Plant No. 22. The design was developed in 1929-30 in accordance with the requirements for the "MBB-2 heavy naval torpedo bomber, boat-type, metal construction, powered by six M-34 engines with a total output of 5,000 hp."

The aircraft's purpose was defined as "...Destruction and annihilation of enemy ships at anchor and while at sea. Destruction of enemy naval bases and fortified coastal areas. Assistance in the landing of friendly troops and support of friendly forces operating along the coast."

Method of use: "...Flight both in a group and alone, combat - defensive, based on maximum use of the firepower of one's own weapons."

The order of requirements, in order of importance, is quite in keeping with the spirit of the time: payload capacity, range, fire "independence" (i.e., spherical fire), seaworthiness, and, lastly, horizontal speed.

Bomb load of up to 3,200 kg, crew of up to 10. The drop load consisted of various combinations of bombs of 100, 250, 500, 1,000, and 2,000 kg caliber. The requirements specifically stipulated the placement of bombs of up to 250 kg caliber inside the boat in cassettes, with release through hatches in the bottom or sides of the boat. In addition, "...In place of the bomb load, provision must be made for the placement of special drop loads, each weighing 1,000, 1,600, or 2,000 kg. The installation of these loads must be coordinated with the Ostekhbyuro."

The MTB-2's defensive armament consisted of a 20-37mm automatic cannon on the nose turret, a pair of DA machine guns on the rear turret, and another DA machine gun in the tail turret.

The MTB-2, under normal load, was expected to have the following flight characteristics: a horizontal speed of at least 200 km/h at an altitude of 3,000 m with rated engine power.

Flight range of 2,400 km at a combat altitude of 3,000 m with a maximum operating speed of 0.8 times.

Landing speed - no more than 100 km/h. Takeoff time - no more than 40 seconds. The permissible glide angle is at least 20°. The ability to continue flight with one or even two engines stopped was specifically stipulated.

Interestingly, the preliminary crew arrangement diagram depicted the MTB-2 as a conventional single-boat monoplane. The choice of a two-boat configuration arose due to the Ostekhbyuro's requirements for the suspension of large-sized equipment; one option was a jettisonable (detachable after landing on water) radio-controlled mine boat.

R.L. Bartini's final design was proposed in 1930 as a development project for Aircraft Plant No. 22. In many ways, its size and purpose are similar to the later TsAGOV MK-1 (ANT-22). The question of whether further development and construction of the MTB-2 was possible can be answered in the negative, and here's why. To achieve the construction of such a huge aircraft, it was first necessary to "grow into" the aviation industry. Organize your own design bureau, establish a production base (i.e., gain a foothold at an aircraft factory), establish a reputation for successfully implementing smaller designs, and secure the support of some Soviet bigwig. R.L. Bartini, after several years of aviation service on the Black Sea, had only recently arrived in Moscow by this time (although he had worked there before his Black Sea assignment!). In 1930, he lacked both the necessary connections and resources.

Photo	Description
	Drawing MTB-2 Bartini

Bibliography

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