High-Speed Nuclear Submarines – Project 705

Alfa_class_submarine

An Alfa on the surface, showing how her sail blends into her hull. A mast is raised forward of the windshield. When the masts were retracted they were covered over to minimize water flow disturbance over the sail structure. Although a titanium-hull submarine, the Alfa-like the Papa SSGN-was not a deep diver. (U. S. Navy)

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The Remarkable Alfa

The direct successor to the Project 627/November SSN would be the second-generation Project 671 (NATO Victor). This was a relatively conservative design intended primarily for the ASW role. The near-simultaneous Project 705 (NATO Alfa) was a major step forward in submarine development.

The design team for Project 705 at SDB- 143/Malachite was led by Mikhail G. Rusanov, who had just completed work on Project 653, a missile submarine intended to carry the P-20 missile. Project 705 was to be a high-speed ASW submarine, intended to seek out and destroy Western missile and attack submarines in Soviet defensive areas. 40 The endurance of the ASW submarine was to be 50 days. From the outset Project 705 was to have had minimal manning.

The titanium hull, advanced fittings and ballast system, and other features would give the submarine a test depth of 1,300 feet (400 m), comparable to U. S. second-generation SSNs of the Thresher and later classes. While titanium would lower the hull’s magnetic field, the submarine’s acoustic signatures were higher than contemporary U. S. submarines. A streamlined sail was “blended” into the advanced hull shape. The submarine would prove to be highly maneuverable.

Armament of the submarine consisted of six 533-mm torpedo tubes with 12 reloads. In addition to standard torpedoes, the submarine could carry the RPK-2 Vyuga (blizzard) ASW missile, given the U. S.-NATO designation SS-N-15 Starfish. This was a ballistic missile carrying a nuclear warhead, similar to the U. S. Navy’s SUBROC (Submarine Rocket). The torpedo complex, including rapid reloading, was totally automated. Advanced sonars and fire control system were provided to support the armament.

In some respects the most futuristic aspect of Project 705 was the propulsion plant. Although the Project 645/modified November SSN as well as the USS Seawolf (SSN 575) had liquid-metal reactor plants, neither submarine was considered successful. The Project 705 reactor plant would use a lead-bismuth alloy as the heat exchange medium. This would provide increased efficiency (i. e., a more dense power plant) with a single reactor and single OK-7 turbine providing 40,000 horsepower.

Two types of nuclear plants were developed simultaneously for the submarine: the OK-550 for Project 705 was modular, with branched lines off the first loop, having three steam lines and circulating pumps; the BM-40A for Project 705K was a modular, two-section reactor, with two steam lines and circulating pumps.

There were significant drawbacks to both plants because the use of a liquid-metal heat carrier required always keeping the alloy in a liquid (heated) condition of 257°F (125°C) and, in order to avoid it “freezing up,” the plant could not be shut down as was done on submarines with a pressurized-water plant. At Zapadnaya Litsa on the Kola Peninsula, the base for these submarines, a special land-based complex was built with a system to provide steam to keep the liquid metal in the submarine reactors from solidifying when the reactors were turned off. In addition, a frigate and floating barracks barge supplied supplemental steam to the submarines at the piers. Because of the inherent dangers of using these external sources of heat, the submarine reactors were usually kept running when in port, albeit at low power.

Like previous Soviet submarines, the craft would have a two-reactor plant, but with a single propeller shaft. The decision to provide a single shaft in this design followed considerable deliberations within the Soviet Navy and at SDB-143 (similar to the discussions within the U. S. nuclear program). The single screw was adopted for Project 705/Alfa almost simultaneous with the Project 671/Victor second-generation SSN design. To provide these submarines with emergency “come-home” propulsion and, in some circumstances, low-speed, quiet maneuvering, these submarines additionally were fitted with small, two-blade propeller “pods” on their horizontal stern surfaces.

The Project 705/Alfa made use of processes and technologies previously developed for Project 661/Papa. The K-64 was launched at Sudomekh on 22 April 1969 (V. I. Lenin’s birthday anniversary). She was then moved by transporter dock through the Belomor- Baltic Canal system to Severodvinsk, where her fittingout was completed and her reactor plant went critical. The K-64 was accepted by the Navy in December 1971, with Captain 1st Rank A. S. Pushkin in command.

The submarine underwent trials in the Northern Fleet area beginning in mid-1972. That same year the K-64 suffered a major reactor problem when the liquid metal in the primary coolant hardened, or “froze.” She was taken out of service, and her hull was towed to Sverodvinsk, where she was cut in half in 1973-1974. The forward portion of the submarine, including control spaces, was sent to Leningrad for use as a training device. The reactor compartment was stored at the Zvezdochka yard in Severodvinsk. (Because of the distance between the two hull sections, Soviet submariners joked that the K-64 was the world’s longest submarine!)

As a result of this accident, in 1974 Rusanov was relieved of his position as chief designer, although he remained at Malachite. The project was continued under his deputy, V. V. Romin. Solving the engineering problem that plagued the K-64 delayed the completion of the other submarines of the class. Seven additional units were ordered-four from Sudomekh (705) and three from Severodvinsk (705K), with six units laid down from 1967 to 1975.48 They were launched from 1969 to 1981, and the first to commission was the K-123, built at Severodvinsk, on 26 December 1977. The remaining five operational units were completed in 1978-1981.

Beyond the lead submarine, other Project 705/Alfa SSNs suffered problems. In the lead operational submarine, the K-123, liquid metal from the primary cooling circuit leaked and contaminated the reactor compartment with almost two tons of metal alloy. The compartment was removed in 1982 and a new reactor installed. It took almost nine years to replace the reactor, with the submarine being launched again in 1990 and placed back in commission the following year. The other Project 705/705K submarines operated until the end of the Cold War, being decommissioned in 1990-1991.

The U. S. and Soviet Navies initially developed high-speed submarines for different reasons. The U. S. Navy-like the Royal Navy-became interested in high submerged speed to train ASW forces to counter “enemy” submarines based on Type XXI technology. Subsequently, the Soviet Navy sought speed to enable attack submarines (SSN/SSGN) to close with Western aircraft carrier groups, a part of their homeland defense strategy to counter nuclear strike aircraft from the carriers.

The USS Albacore was a revolutionary undertaking, the next major step in submarine hull form and supporting systems developed after the Type XXI. This test craft reportedly attained an underwater speed of 37 knots. The subsequent USS Barbel marked the rapid transition of the Albacore hull form to a combat submarine. But the Albacore was too revolutionary for the U. S. Navy’s leadership; although her basic hull design was adopted for the Barbel, and that submarine was more capable than the previous Tang design (based on the Type XXI), many performance features of the Albacore were not applied to the Barbel.

The subsequent step in the development of advanced submarines-from the American perspective- was the USS Skipjack. That submarine combined two underwater revolutions: the Albacore hull form with nuclear propulsion. The Skipjack went to sea in 1959, the same year the three submarines of the Barbel class were completed. Earlier, the Navy’s leadership had made the decision to produce only nuclear-propelled combat submarines.

That historic decision was made by 1956- only a year after the Nautilus went to sea. This commitment contradicts the later myth that “the Navy” opposed nuclear submarines and, even after the Nautilus proved the efficacy of nuclear submarines, persisted in wanting to construct diesel boats.

Similarly, the early Soviet government decisions to procure advanced submarines so soon after completion of the first Project 627/ November (K-3) must be applauded. The use of titanium, very-high-power density reactor plants, advanced hull forms, and improved weapons and sensors made Projects 661/Papa and 705/Alfa significant steps in submarine development. Although titanium was used in the construction of these submarines, they did not have a greater-than-normal test depth for their time (a characteristic that was attributed to them by Western intelligence).

Further, while Project 661 was a one-of-a-kind submarine, Project 705 was produced in numbers. Despite major problems with the prototype Project 705 submarine and a major reactor problem with another submarine of that class, Project 705 was in many ways a highly successful design.

Essentially simultaneous with the advanced Projects 661 and 705 high-speed submarines, the Soviet design bureaus and shipyards were producing “conventional” SSN/SSGN designs.

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