In 1934, the cadet VMIU them. Dzerzhinsky B.P.Ushakov presented schematically project flying Underwater Boats (LPL), which was later reworked and presented in several different ways to determine the stability and stress on the structural elements of the machine.
In April 1936, in a review of Captain 1st Rank Surin pointed out that the idea is fascinating and deserves Ushakov undeniable realization. A few months later, in July, polueskizny project LPL discussed in the Research Military Committee (NIVKI), and has received generally positive reviews, which contained three extra Fri, one of which said: "… The development of the project better to continue to bring out the reality of its implementation by the production of the respective calculations and relevant laboratory tests … "Among the signatories were the chief Nyvka Military Engineer Grade 1 Grigaytis and head of the department's flagship strategy of combat weapons grade 2 Dr. Potters.
In 1937, the topic was included in the plan of the Department "B" Nyvka, but after reviewing it, which was very typical of the long abandoned. All of the upcoming development was conducted engineer of the "B" military technician 1st rank B.P.Ushakovym off-duty.
January 10, 1938 in the second division Nyvka took consideration of sketches and the main tactical and technical parts of the LPL prepared creator That still was a project? A flying submarine boat intended for the destruction of enemy ships on the high seas and in the waters of marinas, protected by minefields and booms. Small underwater speed and limited progress in store under water LPL is not an obstacle, because in the absence of targets in the square (the area of the act) boat she could seek out the enemy. Having determined its course from the air, she sat down behind the horizon, which excluded the possibility of its early detection, and plunged into strips ship ways. Before the emergence of goal salvo at LPL remained at depth in a stable position without expending unnecessary energy moves.
In the case of the allowable deviation from the strip enemy tion rate of LPL was a rapprochement with him, and at very bolshennom deviation boat missed its target over the horizon, then floated, soared again and getting ready to attack.
The likelihood of recurrence of call on the target was seen as one of the significant advantages of underwater torpedo bomber aircraft before the classic submarines. Especially effective was to be the action of flying submarines in the group, because at the theoretical level, three such apparatus made in the way the enemy impassable barrier to 9 miles wide. LPL could leak into the black time of the day in the harbor and the ports of the enemy, dive, and the days of conduct surveillance, direction finding hidden fairways and comfortable storm event. The design of the LPL envisaged autonomous 6 compartments, 3 of which were placed the aircraft engines AM-34 rated at 1,000 hp each. They were equipped with superchargers, admits speeding at takeoff and 1200 hp Fourth section was living, designed by a team of 3 people. Of it was carried on under the control of the vessel with water. In the fifth battery compartment was in the sixth — rowing electric motor 10 l, p. Strong body LPL is a cylindrical riveted construction of a diameter of 1.4 m width of 6 mm duralumin. In addition to strong compartments, the boat had a pilot's cabin light wet type, which was filled with water when submerged, with all this flight instruments battened down in a special shaft.
The cladding of the wings and tail supposed to be made of steel, and floats from duralumin. These design elements were not designed for excessive external pressure, because when submerged flooded with sea water, flows by gravity through the scuppers (holes for water drainage). Fuel (gasoline) and oil were stored in special rubber tanks, located in the center section. When covered with a supply and return line water cooling system of aircraft engines overlap, which excluded from being damaged by the pressure of seawater. To protect the body against corrosion provided for coloring and varnishing of his skin. Torpedoes were located by the wing panels on special holders. Design desired load the boat was 44.5% of the total flying weight machine that has been commonplace for cars languid type.
The dipping process involved four steps: zadraivanie motor divisions, the overlap of water in the radiators, the transfer of control to the underwater and the transition from the cabin crew in the living compartment (central control).
Flight and tactical characteristics of LPL:
Crew. — 3
Take-off weight, kg — 15000
Flight speed, knots. (Km / h) — 100 (-200)
Range, km — 800
Ceiling, m — 2500
Number and type of aircraft engines — 3xAM-34
Power at takeoff, hp — 3×1200
Max. Perm. excitement during takeoff / landing and dive scores — 4-5
U-sa-Th, knots — 2-3
Depth, m — 45
Progress in store under water, miles — 5-6
Underwater autonomy, h — 48
Power propulsion motor hp — 10
Dive time, min — 1.5
Duration of ascent, min — 1.8
— 18-inch. torpedo units. — 2
— coaxial machine gun, pieces. — 2