This combination was proposed during 1930s for special attacks against the ships in harbours, especially when direct access to the sea/ocean was not easy or available.

The second TsAGI/Tupolev flying boat, the ANT-22, was conceived in a programme headed by Ivan Pogosski in response to a naval specification for a ‘flying cruiser’, a large amphibious seaplane with long range and endurance to seek out and destroy enemy warships.

Early work for this project was carried out under the programme number ANT-11, but the pressure of work on other projects caused it to be put aside with only the programme outlines being submitted in late 1929. Other design bureaux proceeded with submitting more detailed proposals, but in 1932 the naval authorities came back to TsAGI and requested the project be completed. The designation MK-1 (Morskoi Kreiser = sea cruiser) was applied.

For this, the largest seaplane to be built in the Soviet Union until at least the 1960s, Pogosski chose a twin hull arrangement, with two identical boats. In a design more to be expected from Italy’s Savoia Marchetti, it seems likely that the spectacular long-range flights of Pinedo and the formation flights of Balbo in the S-55 had not gone unnoticed in the Soviet Union. At the rear of each boat was a tail turret with twin DA-2 machine guns of 7.62mm calibre, each pair operated by a gunner. Two similarly equipped turrets were mounted forward, one in each nose. The wing had a 51m/167.3ft span and was mounted on top of the twin hulls; mounted on pylons on the wing were three pairs of Mikulin M-34Rs, with one pusher and one puller in each nacelle. Each engine generated 750 to 830hp. The tail featured a biplane arrangement, supported by a centre strut, with the elevators on the upper surface. The cockpit was mounted on the leading edge of the wing at the centre; here, the two pilots had good forward visibility, but the twin hulls must have seriously impeded most other angles. Once again, the aircraft was constructed of duraluminium, with corrugated surfaces. In addition to the machine-guns listed above, two Oerlikon cannons were mounted in ring turrets behind the wing, one in each hull.

The aircraft was constructed at TsAGI/ZOK. Completed in late 1933, it was disassembled and brought by train to Sevastopol, on the Black Sea coast, where, after reassembly, it made its first flight from Omega Bakt (Bay) on 8 August. It was flown by Timofei Riabenko. Without armaments, in factory tests it achieved a maximum speed of 233kph/145mph, but a disappointing service ceiling of only 3,500m/l 1,484 feet. For state tests the following summer with a full military load, including a six-tonne bomb load, the speed fell to 205kph/127mph and the ceiling to 2,250m/7,382 feet. The poor performance would have left the MK-1 very open to attack. So the Navy did not progress the programme.

But the ANT-22 flew well and performed well on water. So Tupolev and TsAGI built up more knowledge with it, and it proved its load-carrying capabilities by setting a world record. In December 1936, Riabenko and Ilynski carried 10,040kg to l,942m/6,371 feet. Later, they lifted a 13,000kg payload for the first time, but no record was sought. But the programme had ended.

Project APSS

The first Soviet midget submarine built was code named Project APSS (special-purpose autonomous submersible vessel). In other documents and publications this submarine was called a ‘telemechanical submarine’, ‘radio-controlled TV-equipped submarine’ and even a ‘telecontrolled self-propelled vehicle.’ The APSS project was developed in 1934 - 1935 by the 1st Division (the Submarine Division) of the famous Leningrad Ostekhbyuro (The Special Bureau of Unique Military Designs) headed by Chief Designer Fyodor Shchukin. The APSS was his first submarine. A famous defense-industry engineer, V. Bekauri, who was Head of Ostekhbyuro at that time, and the Naval Communications Research Institute, took part in the APSS development work.

APSS was a midget submarine with a surface displacement of 7.2 tons and underwater displacement of 8.5 tons. The submarine was armed with one forward mounted torpedo tube, and could be operated in two basic modes: standard mode (by one man) and remote-control mode. In the latter mode, the possibility of controlling the submarine from surface ships and aircraft (ANT-22 or MBR-2 flying boats--the so-called ‘drivers’) was studied. A remote ‘wave control’ was supposed to be accomplished via a Kvarts system, developed for the purpose by Ostekhbyuro, and installed on board the ‘drivers.’ In the telemechanical mode, the APSS carried a 500-kg explosive charge instead of a torpedo.

In 1935, the submarine design stage was completed and the APSS construction began at the Sudomekh Shipbuilding and Mechanical Plant in Leningrad. Two prototypes were built which underwent manufacturer’s trials in 1936.

However, Ostekhbyuro’s bold technological ideas could not be implemented at that time. An official report on the APSS project stated that ‘the problem of the submarine remote control was far from being solved.’ Although Ostekhbyuro had a whole ‘fleet’ of ships (the Konstruktor destroyer, the Inzhener and Mikula mine sweepers, the Bystry torpedo boat) as well as aircraft (MBR-2 flying boats) to carry out various experiments, the APSS project was never tested with these ships and aircraft being used as ‘drivers’ of these midget submarines. Both submarines were dismantled in 1936.