In 1934, a cadet of the V. I. Dzerzhinsky B. P. Ushakov presented a schematic design of a flying submarine (LPL), which was subsequently revised and presented in several versions to determine the stability and loads on the structural elements of the apparatus.
In April 1936, in the review of Captain 1st Rank Surin, it was indicated that Ushakov's idea was interesting and deserves unconditional implementation. A few months later, in July, the LPL semi-sketch project was considered by the Military Research Committee (NIVK) and received generally positive feedback, containing three additional points, one of which read: “… It is advisable to continue the development of the project in order to reveal the reality of its implementation production of appropriate calculations and the necessary laboratory tests …”Among the signatories were the head of the NIVK, military engineer 1st rank Grigaitis and the head of the department of tactics of combat weapons flagship 2nd rank professor Goncharov.
In 1937, the topic was included in the plan of department "B" of NIVK, but after its revision, which was very typical for that time, it was abandoned. All further development was carried out by an engineer of the "B" department, military technician of the 1st rank, BP Ushakov, during off-duty hours.
On January 10, 1938, in the 2nd department of the NIVK, a review of the sketches and the main tactical and technical elements of the LPL, prepared by the author, took place. What was the project? The flying submarine was intended to destroy enemy ships on the high seas and in the waters of naval bases protected by minefields and booms. Low underwater speed and limited underwater cruising range of the LPL were not an obstacle, since in the absence of targets in a given square (area of action), the boat could find the enemy itself. Having determined its course from the air, it landed behind the horizon, which excluded the possibility of its early detection, and sank in the line of the ship's path. Before the target appeared at the point of the salvo, the LPL remained at a depth in a stabilized position, without wasting energy with unnecessary moves.
In the event of a permissible deviation of the enemy from the line of the course, the LPL went to a rapprochement with him, and with a very large deviation of the target, the boat missed it over the horizon, then surfaced, took off and again prepared for an attack.
The possible repetition of the approach to the target was considered one of the significant advantages of an underwater-air torpedo bomber over traditional submarines. The action of flying submarines in a group should have been especially effective, since theoretically three such devices created an impassable barrier up to nine miles wide in the enemy's path. The LPL could penetrate into the harbors and ports of the enemy at night, submerge, and during the day, conduct observation, direction finding of secret fairways and, if the opportunity arises, attack. The design of the LPL provided for six autonomous compartments, three of which housed AM-34 aircraft engines with a capacity of 1000 hp each. each. They were equipped with superchargers that allowed forcing up to 1200 hp in takeoff mode. The fourth compartment was residential, designed for a team of three. From it, the ship was controlled under water. In the fifth compartment there was a rechargeable battery, in the sixth - a rowing electric motor with a capacity of 10 liters, with. The robust body of the LPL was a cylindrical riveted structure with a diameter of 1.4 m made of duralumin 6 mm thick. In addition to strong compartments, the boat had a wet-type pilot's light cabin, which was filled with water when immersed, while the flight instruments were battened down in a special shaft.
The covering of the wings and tail unit was supposed to be made of steel, and the floats were made of duralumin. These structural elements were not designed for increased external pressure, since during immersion they were flooded with seawater supplied by gravity through scuppers (holes for water drainage). Fuel (gasoline) and oil were stored in special rubber tanks located in the center section. During submersion, the inlet and outlet lines of the water cooling system of the aircraft engines were blocked, which excluded their damage under the influence of seawater pressure. To protect the body from corrosion, it was envisaged to paint and varnish its casing. The torpedoes were placed under the wing consoles on special holders. The design payload of the boat was 44.5% of the total flight weight of the device, which was usual for heavy vehicles.
The diving process included four stages: battening down the engine compartments, shutting off the water in the radiators, transferring control to underwater control and transferring the crew from the cockpit to the living compartment (central control post).
Flight and tactical characteristics of LPL:
Crew, people - 3
Takeoff weight, kg - 15,000
Flight speed, knots (km / h) - 100 (~ 200)
Flight range, km - 800
Ceiling, m - 2 500
Number and type of aircraft engines - 3xAM-34
Takeoff power, h.p. - 3x1200
Max. add. excitement during takeoff / landing and diving, points - 4-5
Underwater sk-th, knots - 2-3
Immersion depth, m - 45
Cruising under water, miles - 5-6
Underwater autonomy, h - 48
Rowing motor power, h.p. - ten
Dive duration, min - 1, 5
Ascent duration, min - 1, 8
Armament
- 18-inch. torpedo, pcs. - 2
- coaxial machine gun, pcs. - 2
