Furutaka class
| Furutaka class | |
|---|---|
|
|
| Overview | |
| Type: | Heavy cruiser |
| Units: | 2 |
| Predecessor class: | no |
| Successor class: | Aoba class |
| Technical data (original planning) |
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| Displacement: | Displacement under test conditions: 7,500 tn. l. |
| Length: | over everything: 185.2 m |
| Width: | 16 m |
| Draft: | Draft: 5.6 m |
| Speed: | Top: 34 kn |
| Crew: | 625 permanent crew |
| Range: | 6,000 nautical miles at 14 knots |
| Drive: | 4 screws over 4 shafts |
The Furutaka class ( Japanese 古 鷹 型 巡洋艦 , Furutaka-gata jun'yōkan ) was a class of two heavy cruisers of the Imperial Japanese Navy , which were built in the early 1920s and used in World War II .
history
Design and construction
As a result of the preliminary negotiations for the fleet contracts of 1922 , the ships of the Furutaka class, based on the Japanese naval doctrine, were designed as rapid attack and reconnaissance units in 1921, which the assumed, but contractually not yet mandatory weight limit of 7,500 at the time of their planning tn. l. not exceeded.
It was supposed to carry out night attacks and surprisingly cover the enemy with gunfire and torpedoes in short skirmishes, only to then withdraw into the darkness. For this purpose, the cruisers were equipped with twelve torpedo tubes (twelve loaded torpedoes and twelve in reserve) and six 20 cm No.1 guns in six individual turrets. So they should be able to fire 681 kg of shells in a single volley of their main artillery.
The weight distribution on the ships posed numerous problems for the planning group around chief developer Yuzuru Hiraga , because the individual turrets of the artillery and the torpedo sets contributed significantly to the top-heaviness of the units. The naval command therefore required the torpedo armament to be installed inside the hull , so that these weapons with their warheads, which could also be dangerous for the own ship, were stored directly above the engine rooms. When calculating the weights of the various components of the ships, however, there was an error that increased the draft of the units of the class by about one meter.
Construction of the two ships of the class was initiated by the Navy in 1922, a year before official approval. It was carried out at the Mitsubishi shipyards in Nagasaki and Kawasaki in Kobe , but its completion was delayed by strikes . Since the Kako was first laid on the keel, the name Kako class was initially used, but this was changed in 1930 by the Minister of the Navy , so that the class was named after the first completed ship, the Furutaka .
Armament
The main artillery of the ships initially consisted of six individual turrets, each with a 20 cm L / 50 No. 1 gun. These guns could fire a shell up to 24,000 meters and were designed for a rate of fire of up to five rounds per minute. However, they only achieved two rounds per minute. The towers had thin armor made of 25 mm steel plates on their front, 19 mm plates on the tower roof and 6.5 mm on their rear. The towers themselves as well as their ammunition supply were designed to save weight. When the six turrets, each with one gun, were finally replaced on both ships by three turrets with two 20.32 cm guns each by 1939, the weight of the main artillery increased by 105 tons due to improved armor and more automated ammunition feed.
The air defense consisted of four open single mounts, each initially equipped with an 8 cm L / 40 Type 3. However, the weapon was replaced by the 12 cm L / 45 Type 10 gun just a few years after the ships were commissioned.
Armor
The armor of the Furutaka class was limited by the weight restrictions in the planning to the protection of the vital ship systems from impacting 15 cm shells. To protect against shells with a flat trajectory, an 80-meter-long 76 mm thick belt armor made of NVNC steel was attached to the sides of the fuselage. Due to the miscalculation in the planning, however, it only reached 2.21 meters above the waterline - almost one meter less than initially planned. The two belt armor were connected at their upper edge at the level of the engine rooms by an intermediate deck armored with 35 mm NVNC steel. In order to protect the weak points - the openings for the chimneys in this deck - the chimney extensions were armored all around with 38 mm steel up to a height of about one meter above the deck and a 48 mm thick ceiling consisting of thinner individual plates of high-strength steel was pulled into it Weather deck a. The horizontal protection was reinforced over the magazines for grenades and propellants with a 51 mm steel cover in addition to the 35 mm deck.
The superstructures, on the other hand, were hardly protected and only had a weak splinter protection made of high-strength steel for the area of the rudder controls, which was nowhere thicker than 25 mm.
The protection against underwater hits from mines or torpedoes was poorly dimensioned. There was only one watertight compartment between the 75 mm belt armor and the engine rooms, which, with its width of about one meter as an expansion space, was supposed to absorb the pressure wave and with its 27 mm thick inner wall the fragments of an explosion. The protection below the belt armor was even weaker, as the outer hull of the ships there was only 22 mm thick and the inner wall of the expansion chamber fell to 10 mm. A torpedo bead was not installed for weight reasons.
modification
The weight problems caused by the armament were ultimately solved at the expense of the stability of the ship's hull, which forced extensive renovations and retrofits years after its completion. The two cruisers of the Aoba class should originally also belong to the Furutaka class , but were rescheduled during construction, so that, for example, the problem of six turrets with one barrel each did not arise here, since three twin towers were built in from the beginning. When building the Myōkō class following the Aoba class , most of the mistakes that were made in the Furutaka class were fixed at the planning stage.
The Furutaka class was modernized in a two-year operation until 1939, with three gun turrets being omitted and only one turret on the stern and two on the forecastle remaining, which, however, carried two tubes each, so that nothing in the overall armament changed. The torpedo tubes in the hull were also eliminated, and two quadruple launchers for 61 cm torpedoes were installed on the weather deck. The boilers were revised and instead of twelve boilers with a total of 102,000 HP (75,021 kW), ten boilers with a total of 110,000 HP (80,905 kW) were installed in 1938/39. The top speed fell from 34.5 to just under 33 knots.
displacement
The water displacement increased as a result of the conversions, so that for different charge states the displacement from the beginning of 1937 was significantly lower than that of 1938/39 after the conversion:
- light: 8,075 t to 8,561 t
- Trials: 9,996 t to 10,507 t
- maximum: 10,761 t to 11,273 t
Furutaka-class ships
Furutaka
The Furutaka was laid down in Nagasaki in December 1922 and launched in February 1925. It was in service until 1931, but was then sent to the shipyard for several renovation and modernization measures. It was not until 1939 that she returned to the fleet and participated in several operations during the Pacific War. On October 11, 1942, during an attempted surprise attack in the dark by American cruisers that were already equipped with radar , she was discovered in the Battle of Cape Esperance and so badly damaged by gunfire that she went under.
Cocoa
The Kako was laid down in Kobe in November 1922 and put into service in July 1926. After a thorough modernization, she was reassigned to the fleet in 1939. She took part in operations in the Pacific War such as the Battle of the Coral Sea and played a pivotal role during the Battle of Savo Island in 1942 . On the march back from Guadalcanal she was attacked on August 9, 1942 by the US submarine S-44 with a torpedo fan and so badly damaged by three hits that she capsized .
Evidence and references
literature
- Eric LaCroix, Linton Wells: Japanese Cruisers of the Pacific War. US Naval Institute Press, 1997, ISBN 0-87021-311-3 .
- Furutaka class / Aoba class. Gakken Pacific War Series, number 44, Gakken, Tokyo, 2003, ISBN 4-05-603323-4 .
Web links
Individual evidence
- ↑ Eric LaCroix, Linton Wells: Japanese Cruisers of the Pacific War. P. 53.
- ↑ Eric LaCroix, Linton Wells: Japanese Cruisers of the Pacific War. P. 55.
- ↑ Eric LaCroix, Linton Wells: Japanese Cruisers of the Pacific War. P. 60.
- ↑ Eric LaCroix, Linton Wells: Japanese Cruisers of the Pacific War. P. 59.
- ^ David C. Evans: Kaigun: Strategy, Tactics, and Technology in the Imperial Japanese Navy, 1887-1941. US Naval Institute Press, 2003, ISBN 0-87021-192-7 , pp. 225 and following.
- ↑ Japanese Cruisers of the Pacific War. P. 804.
- ↑ for 1937 according to Japanese Cruisers of the Pacific War. P. 57.
- ↑ for 1939 according to Japanese Cruisers of the Pacific War. P. 803.
