The Sovetsky Soyuz-class battleships (Project 23, , ), also known as "Stalin's Republics", were a class of battleships begun by the Soviet Union in the late 1930s but never brought into service. They were designed in response to the s being built by Germany. Only four hulls of the fifteen originally planned had been laid down by 1940, when the decision was made to cut the program to only three ships to divert resources to an expanded army rearmament program.
These ships would have rivaled the Imperial Japanese and America's planned in size if any had been completed, although with significantly weaker firepower: nine guns compared to the nine guns of the Japanese ships and a dozen on the Montanas. The failure of the Soviet armor plate industry to build cemented armor plates thicker than would have negated any advantages from the Sovetsky Soyuz class's thicker armor in combat.
Construction of the first four ships was plagued with difficulties as the Soviet shipbuilding and related industries were not prepared to build such large ships. One battleship, Sovetskaya Belorussiya, was cancelled on 19 October 1940 after serious construction flaws were found. Construction of the other three ships was suspended shortly after Nazi Germany invaded the Soviet Union in June 1941, and never resumed. All three of the surviving hulls were scrapped in the late 1940s.
Design and development Design work began in 1935 on new battleships in response to the existing and planned German battleships,Westwood, p. 202 and the Soviets made extensive efforts in Italy and the United States to purchase either drawings or the ships themselves in the late 1930s.McLaughlin 2003, pp. 362–372 The Italian firm of Gio. Ansaldo & C. proposed a ship of standard displacement with nine 16-inch (406 mm) guns, in size and appearance similar to the then under construction by the company.Ireland, p. 93 The U.S. firm of Gibbs & Cox provided four designs; one for a conventional battleship, and three hybrid designs which combined battleship main armament with a raised flight deck on the central superstructure capable of operating up to 30 aircraft.Ireland, pp. 92–93; Braynard, p. 66 While these projects proved useful to the Soviets, they decided to proceed with their own designs.
The first Tactical-Technical Requirement (abbreviated in Russian as ТТZ) for the large battleship design was issued on 21 February 1936 but proved too ambitious, specifying nine 460 mm guns and a speed of on a displacement of 55,000 tons.Aside from the ship's specifications themselves the type of ton is not specified by McLaughlin. The TTZ was revised in May 1936 by Admiral Vladimir Orlov, Commander of the Soviet Navy, reducing speed to , and weakening the secondary and anti-aircraft batteries. A few months later Admiral Orlov further reduced the size of the battleship to 45,000 tons and set the size of the main guns at 406 mm. Shortly afterward, the Soviet Union signed the Anglo-Soviet Quantitative Naval Agreement of 1937 and agreed to follow the terms of the Second London Naval Treaty that limited battleships to a displacement of 35,560 metric tons (35,000 long tons), although they did add a proviso that allowed them to build ships of unlimited size to face the Imperial Japanese Navy if they notified the British. Yet another TTZ was approved by Orlov on 3 August for ships of 41,500 tons with an armament of nine 406-millimeter, twelve , twelve , and forty guns, a maximum armor thickness of and a speed of 30 knots.McLaughlin 2003, pp. 380–382
The design of KB-4, the surface ship design bureau of the Baltic Shipyard, was selected for further development although the lead designers were convinced that only a larger ship could fulfill the ambitious requirements. They did manage to get agreement on 22 November 1936 for a thickening of the deck armor that raised the displacement to about 47,000 tons. Design work continued on this basis and technical work was completed for a ship of 47,700 tons in April 1937, but the designers continued to press their case for larger ships. The issue was resolved by General Secretary Stalin at a meeting on 4 July when he agreed to increase displacement to about 56,000 tons. This forced the project to begin again.McLaughlin 2003, pp. 383–384
The timing of the redesign proved to be inauspicious as the Great Purge was spreading through the ranks of the military and related industries. The original deadline for completion of design work by 15 October was missed, and an incomplete version was presented to the navy's Shipbuilding Administration the next month. A number of details remained to be worked out, including the final design of the machinery plant, the 152 mm guns and the 100 mm gun mounts. In the meantime, extensive and expensive testing was conducted on the ship's hull form, deck armor and torpedo protection; 27 million rubles were spent on experimental work in 1938 alone. Over 100 models of the hull were tested in a ship model basin to find the best hull form and two one-tenth-scale launches were built at Sevastopol to test the hull's maneuverability. An old German-built steamship, known as S-53, was fitted with a replica of the design's armor decks in late 1936. S-53 was tested against bombs, proving that such ordnance would generally penetrate both the upper and middle decks before exploding on the armored deck. The main armor deck was raised one deck in consequence and a splinter deck added underneath it to stop any bomb or shell fragments that might penetrate the armor deck. The underwater protection system was tested on fifteen one-fifth scale models and two full-sized experimental barges. These tests proved that the torpedo belt system of multiple bulkheads was superior to the Pugliese system of a large tube filled with smaller sealed tubes, but it was too late to incorporate these test results into the design as construction was well underway by the time they were completed in late 1939.McLaughlin 2003, pp. 384–385
A revised design was approved on 28 February 1938 and the first ship was to be laid down on 15 July, but even this design was incomplete and would be revised later. Trials with similarly shaped motor launches suggested that the hull's propulsive efficiency would be less than planned, and this was accepted in the November 1938 revision as a maximum speed of . However, a new propeller design proved to be more efficient and was predicted to increase speed to . Another change was the deletion of the centerline rudder when tests showed that the two wing rudders would not be able to counteract its effects if it jammed. The weight toward the stern of the boat was calculated to be too great, producing a substantial stern-down trim. To remedy this, the two 100 mm turrets mounted on the quarterdeck were deleted and the height of the armor belt abreast the rear turret was lowered, but this decision was reversed and they were restored by a decision of the State Defense Committee on 14 January 1941. This forced a revision of the aircraft arrangements as the aircraft catapult had to be removed from the centerline of the quarterdeck; two catapults were added to the sides of the quarterdeck instead.McLaughlin 2003, pp. 385–386, 389
General characteristics
As designed, the Project 23-class ships, as Sovetsky Soyuz and her sisters were designated, were long overall. They had a beam of and a draft of at deep load. They displaced at standard load and at full load, although weight estimates made in 1940 show that they would have exceeded standard and at full load.McLaughlin 2003, pp. 379, 386
The hull form was very full-bodied, especially at the forward magazines, where the torpedo protection system added width to the beam. Coupled with the relatively low length-to-beam ratio of 7.14:1, this meant that very powerful turbines were necessary to achieve even modest speeds. Stalin's decision that the Project 23-class ships would use three shafts instead of four increased the load on each shaft and reduced propulsive efficiency, although it did shorten the length of the armored citadel and thus overall displacement. Metacentric height was designed at and the tactical diameter was estimated at .McLaughlin 2003, p. 388
The Sovetsky Soyuz-class ships were provided with facilities to handle two to four KOR-2 flying boats which would be launched by the two catapults mounted on the stern. Two hangars were built into the after end of the forecastle deck to house two of them and cranes were provided at the forward end of the quarterdeck to hoist them out of the water.Gribovskii, p. 167
Machinery The machinery arrangement "provided good dispersal of the machinery spaces, but at the cost of very long runs for the wing shafts (ca. ). The turbine compartments for the wing shafts were located forward of boiler room No. 1 and aft of the No. 2 turret magazines. The engine room for the center shaft's turbine was between boiler room No. 2 and No. 3. This meant that the wing propeller shafts had to run underneath the boilers.
The steam turbines, and a license to build them, were originally going to be ordered from Cammell Laird in the United Kingdom, but their £700,000 cost was more than the Soviets wanted to pay. Instead they bought them from Brown Boveri, using the technical information acquired from Cammell Laird in the process, for £400,000. Four single-reduction, impulse-reduction geared turbines were ordered from the Swiss firm, three to equip Sovetskaya Rossiya and one to serve as a pattern for the factory in Kharkov that was to build the remainder. The three produced a total of . Six triangle-type water-tube boilers—two in each boiler room—powered the turbines at a working pressure of and a temperature of .McLaughlin 2003, pp. 393–394
Maximum speed was estimated at 28 knots, using the revised propeller design, although forcing the machinery would yield an extra knot. The normal fuel oil capacity was , giving an estimated endurance of at and at full speed. Maximum fuel capacity was which gave a range of at 14.5 knots and at full speed.McLaughlin 2003, p. 380
Armament
The main armament consisted of three electrically powered MK-1 triple turrets, each with three 50-caliber 406 mm B-37 guns. The guns could be depressed to −2° and elevated to 45°. They had a fixed loading angle of 6° and their rate of fire varied with the time required to re-aim the guns. It ranged from 2.0 to 2.6 rounds per minute depending on the elevation. The turrets could elevate at a rate of 6.2 degrees per second and traverse at 4.55 degrees per second. 100 rounds per gun were carried. The guns fired projectiles at a muzzle velocity of ; this provided a maximum range of .
The secondary armament consisted of twelve 57-caliber B-38 152 mm guns mounted in six twin-gun MK-4 turrets. Their elevation limits were −5° to +45° with a fixed loading angle of 8°. Their rate of fire also varied with the elevation from 7.5 to 4.8 rounds per minute. They were provided with 170 rounds per gun.McLaughlin 2003, pp. 379, 389 The turrets could elevate at a rate of 13 degrees per second and traverse at 6 degrees per second. They had a maximum range of about with a shell at a muzzle velocity of .
Heavy anti-aircraft (AA) fire was provided by a dozen 56-caliber 100 mm B-34 dual-purpose guns in six twin-gun MZ-14 turrets with 400 rounds per gun. The ships began construction with only four turrets, but two additional turrets were restored to the quarterdeck in January 1941. They could elevate to a maximum of 85° and depress to −8°. They could traverse at a rate of 12° per second and elevate at 10° per second. They fired high explosive shells at a muzzle velocity of ; this provided a maximum range of against surface targets, but their maximum range against aerial targets was , the limit of their time fuse.