Soviet Submarine Troop Transport Designs

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While the Soviet Union built no Project 607 submarines, the concept of cargo-transport submarines continued to occupy the thoughts of Soviet submarine designers into the post-World War II era. The Soviets may also have considered ocean-going cargo submarines in this same period. According to the memoirs of the U.S. ambassador to the USSR, Admiral William H. Standley, while discussing with Josef Stalin the problems of shipping war materiél to Russia, Stalin asked:

Why don't you build cargo submarines? Cargo submarines could cross the ocean without interference from Nazi submarines and could deliver their supplies directly to our own ports without danger of being sunk.

Admiral Stanley responded that he was "sure that the question of building cargo submarines has received consideration in my country." Stalin replied, "I'm having the question of cargo submarines investigated over here."

In 1948 the design bureau TsKB-18 (later Rubin) developed a draft design for Project 621 - a landing ship-transport submarine to carry out landings behind enemy lines. This was to be a large submarine with a surface displacement of some 5,950 tons. This underwater giant - with two vehicle decks - was to carry a full infantry battalion of 745 troops plus 10 T-34 tanks, 12 trucks, 12 towed cannon, and 3 La-5 fighter aircraft. The troops and vehicles would be unloaded over a bow ramp; the aircraft would be catapulted, with the launching device fitted into the deck forward of the aircraft hangar. Both conventional diesel-electric and steam-gas turbine (closed-cycle) powerplants for both surface and submerged operation were considered for Project 621.

TsKB-18 also developed the draft for Project 626, a smaller landing ship-transport ship intended for Arctic operations. The ship would have had a surface displacement of some 3,480 tons and was intended to carry 165 troops and 330 tons of fuel or four T-34 tanks for transfer ashore.

Simultaneously, interest in specialized mine-laying submarines was renewed. In 1956, the Soviet Navy's leadership endorsed a TTE for a large minelayer capable of carrying up to 100 of the new PLT-6 mines and transporting 160 tons of aviation fuel (gasoline or kerosene) in fuel-ballast tanks. This was Project 632 at TsKB-18.

Preliminary designs addressed carrying mines both "wet" and "dry" (i.e., within the pressure hull). Soon the heavy workload at TsKB-18 led to the transfer of design work on Project 632 - estimated to be 33 percent complete at the time - to TsKB-16 (later Volna/Malachite). The design was completed in two variants - with wet storage for 90 mines or dry storage for 88 mines. A combined wet/dry configuration could carry 110 mines. A further variant of Project 632 showed a small increase in dimensions that would permit 100 troops to be carried in the mine spaces, with the mine-laying gear designed to be removable. The latter feature was a consequence of the Sevastopol experience, which suggested that these and other large submarines should also be able to transport aviation fuels and to be reconfigurable at naval bases to transport combat troops or wounded (with medical attendants) in place of mines.

Project 632 was approved for construction in February 1958. Significantly, in October 1958, the design for a nuclear-propelled variant of the minelayer was also approved - Project 632M, employing a small O-153 reactor plant. This ship would have been some 100 to 200 tons heavier than the basic 632 design. The nuclear variant would have a submerged cruising range estimated at 20,000 nm compared to 600 to 700 nm for the conventional propulsion plant. But when the Central Committee and Council of Ministers approved the seven-year shipbuilding program in December 1958, the Project 632 submarine was missing.

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Graphic courtesy of A.D. Baker III, from Cold War Submarines The Soviet's Project 621 was designed as a landing ship-transport submarine that could carry out landings behind enemy lines. This underwater giant had two vehicle decks, and was designed to carry a full infantry battalion of 745 troops plus 10 T-34 tanks, 12 trucks, 12 towed cannon, and three La-5 fighter aircraft.