Kongō-class battlecruiser
The Kongō-class battlecruiser was a class of four battlecruisers built for the Imperial Japanese Navy immediately before World War I. Designed by British naval architect George Thurston, the lead ship of the class,, was the last Japanese capital ship constructed outside Japan, by Vickers at Barrow-in-Furness. Her sister ships,, and, were all completed in Japan.
During the late 1920s, all but Hiei were reconstructed and reclassified as battleships. After the signing of the London Naval Treaty in 1930, Hiei was reconfigured as a training ship to avoid being scrapped. Following Japan's withdrawal from the treaty, all four underwent a massive second reconstruction in the late 1930s. Following the completion of these modifications, which increased top speeds to over, all four were reclassified as fast battleships. The threat of the Kongō-class on American lines of communication and logistics leading up to World War II highly influenced the U.S. Navy's decision to order the fast battleships.
The Kongō-class battleships were the most active capital ships of the Japanese Navy during World War II, participating in most major engagements of the war. Hiei and Kirishima acted as escorts during the attack on Pearl Harbor, while Kongō and Haruna supported the invasion of Singapore. All four participated in the battles of Midway and Guadalcanal. Hiei and Kirishima were both lost during the Naval Battle of Guadalcanal in November 1942, while Haruna and Kongō jointly bombarded the American Henderson Field airbase on Guadalcanal. The two remaining Kongō-class battleships spent most of 1943 shuttling between Japanese naval bases before participating in the major naval campaigns of 1944. Haruna and Kongō engaged American surface vessels during the Battle of Leyte Gulf in late October 1944. Kongō was torpedoed and sunk by the submarine in November 1944, while Haruna was sunk at her moorings by an air attack in Kure Naval Base in late July 1945, but later raised and scrapped in 1946.
Design
The design of the Kongō-class battlecruisers came about as a result of the IJN's modernization programs, as well as the perceived need to compete with the British Royal Navy.In April 1907, the Royal Navy launched at Newcastle upon Tyne. Armed with eight main guns, Invincible rendered all current—and designed—Japanese capital ships obsolete by comparison. In 1911, the Japanese Diet passed the Emergency Naval Expansion Bill, authorizing the construction of one battleship and four armoured cruisers, to be designed by British naval architect George Thurston. In his design of the class, Thurston relied on many techniques that would eventually be used by the British on.
Under the terms of the contract signed with Vickers in November 1910, one member of the Kongō class—the lead ship Kongō—was to be built in Britain and Vickers was to maximize the transfer of naval technology to Japan. The design of the ships was from Vickers Design 472C. The original design featured ten 12-inch 50-calibre guns, sixteen guns, and eight torpedo tubes.
Commander Katô Hirohasu pushed for the adoption of a new /45 calibre gun that was currently under development. After trials of the new gun, which were witnessed by both the Japanese Navy and Royal Navy, the Japanese made the decision on 29 Nov 1911 to use the new gun despite the keel having already been laid down on 17 January 1911, and the resulting need to quickly make a large number of alterations to the design, so as to not prolong the construction. Due to the size of the guns, only 8 were installed
The final design of the battlecruisers resulted in an improved version of the, displacing an estimated 27,940 tonnes. It also called for eight 14-inch guns mounted in four twin gun turrets with a top speed of.
To ensure transfer of the latest design knowledge to Japan more than 100 technical specialists were sent on 18 months secondments from Japan to Vickers during the construction phase of Kongō. If superintendents, supervisors and trial witnesses are also included then about 200 Japanese spent time in Britain.
Description
The ships had a length of overall and a beam of. They had a draft of and displaced at normal load.Propulsion
The Kongō-class ships had two sets of Parsons direct-drive steam turbines, except for Harunas Brown-Curtis turbines, each of which drove two propeller shafts. The high-pressure turbines drove the wing shafts while the low-pressure turbines drove the inner shafts. The turbines were arranged in two compartments, separated by a centerline longitudinal bulkhead; both compartments were situated between turrets No. 3 and 4. They were designed to produce a total of, using steam provided by 36 Yarrow or Kampon water-tube boilers, with working pressures ranging from. The boilers, arranged in eight compartments, were mixed-firing with fuel oil sprayed onto the coal for extra power. The ships had a stowage capacity of of coal and of oil, giving them a range of at a speed of. The battlecruisers were designed to reach a speed of and all of them exceeded that speed on their sea trials. The Kongō and Hiei attained and with and, respectively.In their first reconstruction during the late 1920s, the ships were reboilered with 10, 11 or 16 Kampon boilers, and their fuel stowage was rearranged to accommodate of coal and of oil. This increased their range to at 14 knots and allowed the fore funnel to be removed, which greatly decreased smoke interference with the bridge and fire-control systems. Coupled with the addition of external torpedo bulges, this reduced their speed to and caused the IJN to reclassify them as battleships. During their 1930s reconstructions into fast battleships, the existing boilers were removed and replaced with eleven oil-fired Kampon boilers. These upgraded boilers gave the Kongō and her sister ships much greater power, with the ships of the class capable of speeds exceeding. This made them the only Japanese battleships at the time fully suited to operations alongside fast aircraft carriers.
Armament
The primary armament of the Kongō class consisted of eight 14"/45 guns, mounted in four superfiring twin-gun turrets. The turrets had an elevation capability of −5/+20 degrees, except in Kongō, whose turrets had a maximum elevation capability of +25 degrees. The shells could be loaded at any angle and the guns had a firing cycle of 30–40 seconds. These guns and their turrets underwent multiple modernizations throughout the ships' careers. During the first reconstruction of the class during the 1920s, the elevation of the main guns was increased to a maximum of +33 degrees. The recoil mechanism of the guns was also changed from a hydraulic to pneumatic system, which allowed for a faster firing cycle of the main guns.By World War II, the guns used Type 91 armor-piercing, capped shells. Each of these shells weighed and had a muzzle velocity of. They had a maximum range of at +20 degrees of elevation and at +33 degrees after modernisation. Also available was a high-explosive shell that had a muzzle velocity of. A special Type 3 Sanshikidan incendiary shrapnel shell was developed in the 1930s for anti-aircraft use.
As built, the Kongō class was fitted with a secondary armament of sixteen 15 cm/50 guns mounted in single casemates along the sides of the hull at the level of the upper deck. Eight guns were mounted per side, and each had an arc of fire of 130 degrees and a maximum elevation of +15 degrees. Each gun could fire a high explosive projectile a maximum distance of at a rate of between four and six shots per minute. During their reconstruction in the 1930s, the maximum elevation of the guns was increased to +30 degrees, which increased their maximum range by approximately.
The ships also mounted four 76 mm/40 anti-aircraft guns. The high-angle guns were in single mounts. Each of these guns had a maximum elevation of +75 degrees, and could fire a projectile with a muzzle velocity of to a maximum height of. Both ships were equipped with eight submerged torpedo tubes, four on each broadside.
The Kongō class's secondary armament changed significantly over time. During the modernizations of the 1930s, all of the 76 mm guns were replaced with eight /40 dual-purpose guns. These guns were fitted on both sides of the fore and aft superstructures in four twin-gun mounts. When firing at surface targets, the guns had a range of ; they had a maximum ceiling of at their maximum elevation of +90 degrees. Their maximum rate of fire was 14 rounds a minute, but their sustained rate of fire was around eight rounds per minute. During reconstruction, the two foremost 152 mm guns were also removed.
The light AA armament of the Kongō class changed dramatically from 1933 to 1944. During the second reconstruction, the ships were fitted with four to eight twin machine-guns, later replaced by gun mounts. Both weapons were license-built French Hotchkiss designs. The 25 mm guns were mounted on the Kongō class in single, double, and triple mounts. This model was the standard Japanese light anti-aircraft gun during World War II, but severe design shortcomings rendered it largely ineffective. The twin and triple mounts "lacked sufficient speed in train or elevation; the gun sights were unable to handle fast targets; the gun exhibited excessive vibration; the magazine was too small, and, finally, the gun produced excessive muzzle blast". Haruna ultimately carried 118 guns in 30 triple, two twin, and 24 single mounts.
Armour
The Kongō-class battlecruisers were designed with the intention of maximizing speed and maneuverability, and as such were not as heavily armoured as later Japanese capital ships. Nevertheless, the Kongō class possessed significant quantities of armour, and were heavily upgraded during their modernizations. In their initial configuration, the Kongō class possessed an upper belt that was thick, and a lower belt with a thickness of. Vickers Cemented was used in the construction of the Kongō, while the original armour of the other three was constructed of a variation of Krupp Cemented Armour, designed by the German Krupp Arms Works. Subsequent developments of Japanese armour technology relied upon a hybrid design of the two variations until drastic changes were made during the design of the Yamato-class battleship in 1938. The armoured belt near the bow and stern of the vessels was strengthened with an additional of cemented armour. The conning tower of the Kongō class was very heavily armoured, with variations of Krupp Cemented Armour up to thick. The turrets were lightly armoured compared to later designs, with a maximum plate thickness of. The deck armour ranged from.During the reconstructions that each ship underwent during the interwar period, most of the armour of the Kongō class was heavily upgraded. The main lower belt was strengthened to be a uniform thickness of 8 inches, while diagonal bulkheads of a depth ranging from reinforced the main armoured belt. The upper belt remained unchanged, but was closed by 9-inch bulkheads at the bow and stern of the ships. The turret armour was strengthened to, while were added to portions of the deck armour. The armour upgrades increased the displacement by close to 4,000 tons on each ship, violating the terms of the Washington Treaty. Even after these modifications, the armour capacity of the Kongō class remained much less than that of newer capital ships, a factor which played a major role in the sinking of Hiei and Kirishima at the hands of U.S. Navy cruisers and battleships in 1942.