USS Thresher (SSN-593)

The USS Thresher (SSN-593) was an American fast attack submarine, which was powered by one S5W nuclear reactor. She sank by implosion during deep-diving tests on April 10, 1963, off the coast of Massachusetts, killing 129 officers and sailors. Extremely quiet, she had been designed to hunt Soviet submarines during the Cold War.

The USS Thresher had been launched on July 9, 1960, and commissioned on August 3, 1961. Built at Portsmouth Naval Shipyard, she was the lead submarine of her class of 14 boats. The other subs were Permit (SSN-594), Plunger (SSN-595), Barb (SSN-596), Pollack (SSN-603), Haddo (SSN-604), Guardfish (SSN-612), Flasher (SSN-613), Greenling (SSN-614), Gato (SSN-615), Haddock (SSN-621).

Below, the Thresher on sea trials in July 1961. It had a better hardened hull against explosive shock and introduced new sensors.

Technical Description

The design of USS Thresher (SSN-593) featured major advantages in five vital areas: depth, quieting, sonar, shock hardening, and weapons. She had a greater operating depth than her predecessors of the Skipjack class. Her pressure hull was made of HY-80 steel. Although it was the same type of steel used to produce the Skipjack submarines, to build the Thresher, the American engineers used improved welding techniques and piping, giving her a test depth of 400 m (700 feet).

To reduce the coolant piping and turbine noises, the sub machinery was isolated from the hull using a technique called "rafting", which the Royal Navy had developed for the Ton-class minesweeper. This arrangement decreased the sound transmission through the hull into the sea water. Thus, the twin steam turbines and related gearing were set up on a sound-isolating raft, not directly attached to the hull.

The most advanced electronic feature of the USS Thresher was her AN/BQQ-2 sonar system, which replaced the old BQR-2 and BQR-4 passive sonars. The BQQ-2 revolved around a 15-foot diameter sphere which was fitted with 1,241 hydrophones. Thus, it was capable of greater passive detection than older types of sonars as it could distinguish target noise from own ship and background sea noises. It also had an active acoustic pinging component.

Specifications

Type: attack nuclear submarine

Displacement: 4,369 tons (submerged), 3,810 tons (surfaced)

Length: 84.86 m (278 feet, 5 inches)

Beam: 9.63 m (31 feet, 7 inches)

Draft: 7.67 m (25 feet, 2 inches)

Propulsion: one pressurized water reactor S5W, which produced 11 MGW, with two steam turbines and one shaft, which generated 15,000 SHP.

Maximum Speed: 28 knots (submerged), 15 knots (surfaced).

Range: unlimited propulsion; food supplies for up to 90 days.

Compliment: 113 sailors and officers.

Armament: four 533-mm torpedo tubes, eighteen Mk-37 torpedoes.

Below, the AN/BQQ-2 sonar, the most advanced sonar of the time.

Front view of the SSN-593 on September 20, 1961.

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Charlie Class Submarine

A Charlie class submarine (Project 670 Skat) was one of a series of seventeen Soviet, cruise missile submarines, which were powered by one nuclear reactor. The first boat of the class, the K-43, was launched in 1966 and commissioned in 1967. She was the world's first submarine with an underwater-launch cruise missile capability. The last one, the K-209, entered service in 1980. All boats were built at the State-run Krasnoye Sormovo Shipyard No. 112 (Gorkiy) on the Volga River.

The last six boats of the series were improved subs and they were designated Project 670M by the Soviet Navy. NATO called them "Charlie II class". They were built from 1973 and 1980. The upgrade included a longer hull for the incorporation of electronic equipment and a new launch system to be able to use the P-120 Malakhit anti-ship missile, thus posing a major threat to NATO warships. All seventeen boats of the class were phased out from 1990 to 1994.

A Charlie class submarine cruising in the South China Sea in 1974.

Technical Description

The Project 670 submarine was developed and built exclusively as a cruise missile boat. She had a streamlined, double-hull design, which consisted of seven compartments. The inner and the outer hull were made of steel. The sail was of aluminum construction to save weight. The eight missile tubes were built in the bow section between the inner and outer hull, with four on each side; they lay slantingly, with a 32 degrees angle of inclination. The six torpedo tubes, on the other hand, were horizontally arranged; four 533-mm, and two 400-mm in diameter.

Compared to other cruise missile submarine designs, the Charlie class was a relatively smaller and compact boat. However, the Project 670M was 8 m (26 feet, 3 inches) longer. She was powered by one pressurized, water-cooled VM-4 nuclear reactor. Her OK-350 steam turbine generated 18,800 horsepower to drive a single shaft propeller. She had a test depth of 350 m (1,150 feet) and could sail at the maximum speed of 26 knots (submerged).

Specification

Type: nuclear-powered, cruise missile submarine.

Displacement: 4,900 tons (submerged); 4,300 tons (surfaced).

Length:  95 m (312 feet); Charlie II: 103 m (338 feet)

Beam: 10 m (32 feet, 10 inches)

Draft: 8 m (26 feet, 3 inches)

Propulsion: one VM-4 nuclear reactor; one OK-350 steam turbine, with one shaft.

Maximum Speed: 26 knots (submerged); 20 knots (surfaced.

Range: unlimited, but she had to moor after 80 days for food supply.

Crew: 100 sailors and officers.

Armament: 8 P-70 Amethyst anti-ship, cruise missiles; Charlie II: 8 P-120 Malhkit anti-ship missiles. Six torpedo tubes.

Below, a Charlie II class submarine (Project 670M) sailing in the Atlantic Ocean in 1984.

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November Class Submarine

The November class submarine (Project 627) was the first nuclear-propelled submarine design of the Soviet Union. The first boat of the series was the K-3, which was commissioned in 1959, three and half years after the USS Nautilus. However, the design of these attack submarines had begun in 1952, under Vladimir N. Peregudov, at the Research Institute of Chemical Machine-Building, which would build the nuclear reactor for the Project 627 led by physicist N. A. Dollazhal.

The November class submarine was the first nuclear-powered boat to have a torpedo-shaped hull in naval history, since the USS Nautilus had a modified Type-XXI configuration. Vladimir Peregudov asserted that the submarine should resemble a torpedo in shape to fully exploit the power of her reactors. However, this new design in Soviet Navy was based on the USS Albacore (AGSS-569), which was a diesel-electric research submarine. According to Russian engineers, the Soviets had obtained details of the American submarine from a magazine photos.

Below, aerial view of the K-8, a Project 627A sub. Here, it was already in trouble off the coast of Spain in 1970. She would sink soon after this photo was taken. You can see her forward diving planes on the bow section are extended.

The first submarine of the series, the K-3, had been launched on August 9, 1957. She had gone to sea for the first time on July 4, 1958. Due to safety concerns, her nuclear twin reactor power plant first operated at only 60% until the completion of the test runs, reaching a speed of 23.3 knots. Later, her maximum speed would be 30 knots. Until then, the Project 627 was highly secret, with the last sub being retired in 1990.

Technical Description

The Project 627 submarine had a torpedo-shaped, double-hull configuration, with a reserve buoyancy of 30%, roughly twice that of the Nautilus, and internal pressure bulkheads. Internally, the November class submarine contained nine compartments (three more than the Nautilus): torpedo (bow); battery/crew; officers; reactor; turbine; two machinery compartments, and the stern compartment. The reactor compartment was located amidships and was fitted with two VM-A reactors, each supplying 70 megawatts thermal power.

The Project 627 boat was also equipped with electric motors for quiet low-speed operation, and in an emergency, they could drive her at 8 knots. Her inner pressure hull was built with the new AK-25 high-tensile steel, which provided the boat increased test depth. Thus, she would have a test depth of 300 m (985 feet), deeper than US Navy's contemporary submarines. The AK-25 steel had first been used in the Project 641/Foxtrot class submarine.

A coating of classified special material was applied to the inner hull to absorb own ship machinery noise to reduce the acoustic signature of the boat. Nevertheless, her noise levels increased at higher speeds. Although the first generation of Soviet nuclear attack submarines had a good speed quality and atomic installation two times more powerful than the US Navy's submarines, they significantly lacked in stealth at maximum speed.

Specifications (Project 627A)

Type: nuclear attack submarine

Displacement: 3,118 tons (surfaced); 4,750 tons (submerged)

Length: 107.4 m (351 feet)

Beam: 7.9 m (26 feet)

Draft: 6.4 m (20 feet)

Propulsion: two VM-A water-cooled reactors, producing 70 megawatts.

Maximum Speed: 30 knots (submerged); 15 knots (surfaced)

Range: 20 years, but limited to 70 days for food supplies.

Armament: eight 533-mm torpedo tubes, with 20 SET-65 torpedoes.

Below, the K-3 November class submarine. The photo was taken in 1964.

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Victor Class Submarine

A Victor class submarine (Project 671) is one of a series of nuclear attack submarines developed and built by the Soviet Union during the Cold War. With the first one being commissioned in 1967, a total of 48 subs were produced in three variants; Victor I, II, and III. Today 3 of them still remain in active service with the Russian Navy. When it was introduced, it was the first Soviet attack boat featuring a single-propeller shaft.

Technical Characteristics

Made of AK-29 steel, the Project 671 submarine has a double-hull configuration. The pressure hull comprises seven compartments: torpedo/berthing/battery; command center; reactor; turbine; auxiliary equipment; berthing and diesel generators; and electric motors. The ballast tanks are located along her sides, between outer and inner hull, as well as in forward and aft. The Soviet AK-29 steel is the equivalent to the American HY-100 steel, which has a high yield and high impact strength used in marine defense. This extremely hard steel enables the Victor class submarine to submerge to a maximum depth of 450 m (about 1,400 feet).

In order to reduce self-generated noise, the Project 671 is fitted with limber hole covers, which close automatically the deeper it sails. Thus, they reduce flow noise over the hull. The versions Victor II and III (Project 671RT and 671RTM respectively) have anechoic (anti-sonar) coating on the outer hull, and dampening coating on the inner hull. The purpose of the dampening coating is to reduce the transmission of machinery noises.

The Project 671 is powered by a twin VM-4P pressurized-water nuclear reactor, and twin OK-300 turbine. The submarine was designed with a streamlined sail, which has contributed to her excellent underwater performance. The first version, the Victor I, had a two-reactor plant, with a single steam turbine rated at 31,000 shaft horsepower. The single propeller is situated 4.5 m (15 feet) aft of the stern control surfaces.

Below, a Victor III (Project 671RTM) submarine in 1983. You can see the large sonar array pod on top of her vertical fin. Her electronic surveillance mast is raised.

Armament

The Victor class submarine features six bow torpedo tubes; four 533-mm tubes, and two 650-mm tubes to launch the VA-111 Shkval and the Type-65 torpedo as well as the SS-N-16 Stallion anti-submarine missiles. The VA-111 Shkval is a fast and lethal supercavitating torpedo, which can travel underwater at 225 knots, which means more than 380 km/h (305 mph).

Specifications

Type: nuclear-powered attack submarine

Displacement: 7,250 tons (submerged); 6,990 tons (surfaced).

Length: 102 m (334 feet)

Beam: 10 m (32 feet, 10 inches)

Draft: 7 m (23 feet)

Propulsion System: a twin VM-4P nuclear reactor; two OK-300 turbines.

Maximum Speed: 32 knots (59 km/h - 37 mph)

Range: limitless but must moor after 90 days for food supply.

Radar:  one MRK-50 Albatros; Skat sonar system

Crew: 37 men

Below, a Victor II (Project 671RT) at sea in 1980.

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IJN Hosho

The IJN Hosho had been laid down as a mixed sea plane carrier/aircraft carrier in 1920. However, she would be modified during construction and was completed as a full-deck aircraft carrier. She was launched in November 1921 and commissioned in December 1922. Thus, she was the Imperial Japanese Navy's first aircraft carrier.

Technical Description

As built, Hosho had a small starboard-side island, but this was removed in 1923 and it was never replaced. The three funnels were originally hinged, being normally vertical but it was swung to the horizontal position during flying operations. However, it was found to be unnecessarily complicated and they were permanently fixed in the upright position in 1934.

The flight deck of the IJN Hosho was originally 158.2-m (519-ft) long, but it would be extended aft in 1944 to give it a length of 176.6-m (579.4-ft). Thus, it stretched completely from bow to stern. The original aircraft compliment was 26, but as aircraft became larger and heavier, this number was progressively reduced to 21 in 1934, and to 11 in 1942.

Operational History

Between 1937 and 1940, the IJN Hosho was active in operations off the China coast, providing close fire support, through their aircraft, to the Japanese ground troops. By the time the war against the United States of America broke out, she had already been relegated to the training role and other secondary duties. She would continue to function as a trainer carrier until the end of the armed conflict in 1945. Finally, she was scrapped in 1947.

Specifications

Type: aircraft carrier

Displacement: 7,470 tons; 10,000 tons full load.

Length: 176.6 m (579.4 ft)

Beam: 18 m (59 ft)

Draft: 6.2 m (20.3 ft)

Propulsion: two geared steam engines, with two shafts, fed by twelve boilers, developing 30,000 SHP.

Maximum Speed: 25 knots

Range: 8,680 nautical miles

Armament: four 5.5-in guns outboard of hangar; two 3-in AA guns.

Crew: 550 sailors and officers

Below, the IJN Hosho in 1922 after it had been commissioned

Below, the Japanese carrier in August 1945

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IJN Ryujo

The IJN Ryujo was a light aircraft carrier used by Japan during the Sino-Japanese War and WW2. Built by Mitsubishi in Yokohama shipyard, she was laid down in 1929 and launched in 1931. After two years of sea trials, she was commissioned in service of the Imperial Japanese Navy on May 9, 1933. However, the ship would be rebuilt one year later, between 1934 and 1936.

Like other Japanese carriers, the IJN Ryujo had no island on her flight deck. The bridge was located below the forward part of flight deck on the bow section of ship. Although it had originally been designed to carry 24 aircraft in a single hangar, the Imperial Japanese Navy determined that such small group of aircraft would not be effective as a fighting force. As a result, a second hangar was added, giving her the capacity to carry 48 aircraft. This modification increased her tonnage from 8,000 to 10,600 tons.

In August 1934, Ryujo was sent back to the yards to address stability problems. Thus, the work was mainly intended to reduce instability and improve sea-keeping. To achieve this, the hull was strengthened, the underwater bulges were enlarged, and the armament reduced as more ballast was added. It was fitted with two geared steam turbines, with two shafts, as a propulsion system, which was fed by twelve boilers.

Below, the IJN Ryujo sailing in the Pacific after modifications

Operational History

During the Japanese invasion of China, the IJN Ryujo was used to provide fire support to the Japanese Army with her dive bombers. When World War II broke out, she was employed extensively during the initial period of the Pacific war. Ryujo's aircraft also provided close support to the Japanese landings in the Philippines in December 1941 as well as to the invasion of Java in February 1942.

Ryujo also took part in the Japanese Navy Aleutians diversionary attack, thus avoiding the Battle of Midway. Being part of the Japanese fleet assigned to counter the American invasion of Guadalcanal in August 1942, she participated in the Battle of the Eastern Solomons, during which she was sunk by four bombs and one torpedoes dropped from the USS Saratoga's aircraft.

Specifications

Type: light aircraft carrier

Displacement: 10,600 tons

Length: 179.9 m (590.3 feet)

Beam: 20.8 m (68.2 feet)

Draft: 7.1 m (23.3 feet)

Propulsion: two geared turbines, with two shafts, twelve water-tube boilers, generating 65,000 SHP.

Maximum Speed: 29 knots

Range: 10,000 nautical miles

Aircraft: 48 fighters, dive-bombers and torpedo-bombers

Armament: eight 127-mm and four 25-mm AA guns

Compliment: 924 sailors and officers

Below, Ryujo in 1937.

Aerial view of Ryujo

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IJN Soryu

The IJN Soryu was an aircraft carrier used by the Imperial Japanese Navy during World War II. It was the first Japanese fleet carrier which was entirely designed as such, from the keel up, as older ones had been converted from battlecruisers into carriers, such as Hosho and Kaga. Powerful modern machinery and a cruiser-type hull gave her a very high speed.

Soryu was the basis for all subsequent Japanese fleet carriers. It was intended for the attack role, as it was fast and lightly built, with a large air group composed of 63 aircraft. It was laid down in 1934 and was completed three years later in 1937. To carry such large number of aircraft, two hangars were provided. It was also fitted with three elevators. Exhaust gases were vented through two downward-venting stacks on the starboard side.

Below, a photo of the IJN Soryu in 1937.

Operational History

Together with IJN Hiryu, Soryu formed the First Air Fleet's Carrier Division 2. She would see extensive service before her loss early in the war. Both carriers took part in the attack on Pearl Harbor on December 7, 1941. Later, her dive bombers would provide fire support to the Japanese invasion of Dutch East Indies, also participating in the devastating attack on Port Darwin, Australia.

In April 1942 IJN Soryu took part in the Japanese raid into the Indian Ocean, attacking Colombo and Trincomalee in Ceylon. Along with Hiryu, she would be sunk during the Battle of Midway on June 4, 1942. She was attacked by US Navy dive bombers and hit by three bombs from USS Yorktown aircraft. As soon as she was hit, the carrier became ablaze as the fire spread quickly from fueled and armed aircraft.

Specifications

Type: fleet carrier

Displacement: 15,900 tons

Length: 227.5 m (746.5 feet)

Beam: 21.3 m (69.9 feet)

Draft: 7.62 m (25 feet)

Propulsion: 4 geared steam turbines, with 4 shafts, fed by 8 boilers, generating 152,000 HP.

Maximum Speed: 34.5 knots

Range: 7,680 nautical miles

Armament: twelve 127mm (5-in) guns; twenty eight 25mm AA guns mounted in double turrets.

Compliment: 1,100 sailors and officers

Below, Soryu aircraft carrier during the last stage of construction

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