Atlanta class

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Atlanta- class
USS Atlanta 1941
USS Atlanta 1941
Overview
Type Light cruiser
units 11 built, 0 in service
Namesake Atlanta , Georgia
period of service

1941-1956

Technical specifications
Information applies to the type ship, later construction lots showed deviations
displacement

6718 ts

length

164.9 m

width

16.1 m

Draft

6.1 m

crew

35 officers, 683 men

drive

4 boilers, 2 steam turbines , 2 shafts , 75,000 sHP = approx. 76,000 wPS

speed

33  kn

Range

3475  nm (6437 km) at 25 kn

Armament

1941:

  • 8 5 ″ twin guns
  • 3 1.1 ″ quadruple guns
  • 6 20 mm MK
  • 8 21 ″ torpedo tubes
  • 2 WaBo drainage racks
  • 3 WaBo throwers

1943:

  • 8 5 ″ twin guns
  • 8 40 mm quadruple guns
  • 13 20 mm MK
  • 8 21 ″ torpedo tubes
  • 2 WaBo drainage racks
  • 3 WaBo throwers

The Atlanta-class , sometimes referred to as the Atlanta-Oakland-class , was a class of light cruisers of the United States Navy . The eleven ships completed in three construction lots between 1941 and 1946 were the smallest and most lightly armed and armored cruisers of the US Navy from the Second World War ; they were in service until 1956. The most famous ships in the class were the USS Juneau , largely because of the tragic story of the Sullivan brothers , and the USS San Diego , which with 18 Battle Stars was the ship in the class with the most deployments in the Pacific.

history

USS Flint , the third ship in the second assembly, about to be launched

Planning and construction

The planning for the Atlanta class began after the London Naval Conference of 1936 , the ships of the class were planned to replace the technically outdated light cruisers of the Omaha class from the early twenties, whose armament no longer met modern requirements. The primary task of the new ships should be to secure the naval units from enemy air attacks, and as destroyer leaders they should also support the fight of destroyer units against enemy units. The original design from 1938, which was created by the New York engineering firm Gibbs & Cox , provided for the ships to be armed with nine 6-inch guns as primary and six 5-inch guns as secondary and anti-aircraft armament. Problems with the radar fire control of the 6-inch guns made it necessary to change the plans, so that the first four ships of the class were laid down between March and May 1940 with 16 5-inch guns in eight twin towers. The first ship of the class, the USS Atlanta , was put into service on Christmas Eve 1941, the other three followed by the end of February 1942. In the second construction lot of the class, the two side turrets were removed. They only had a restricted fire area and were superfluous as there was only a single fire control device in the aft area for what were originally five turrets with ten tubes. The four ships of the group , also known as the Oakland class after the first ship, the USS Oakland , were put into service between June 1943 and February 1945. A third group of three vessels to reduce Topplastigkeit had a lower arrangement of the turrets, it was after the first ship, the USS Juneau (CL-119) which, after the sinking of the USS (-52 CL) Juneau also received the name , referred to as the Juneau class . The ships were only put into service between February and November 1946 after the end of World War II. The construction cost per ship was about 23.2 million US dollars.

commitment

Until about the beginning of 1943, the ships of the class were mostly used in accordance with their role as destroyer leaders with smaller destroyer units and operated independently against Japanese units. With the shift in American strategy to large combat units around aircraft carriers, the ships were then mostly used as anti-aircraft ships to protect the carriers from Japanese air and kamikaze attacks. In this role they continued to be used after the war, in 1949 the ships that were still active were given the identification CLAA (cruiser light, anti air) to illustrate this role.

Whereabouts and fate

Two ships of the class were lost, the Atlanta and the Juneau (CL-52) sank after heavy torpedo hits during the sea ​​battle of Guadalcanal on November 13, 1942. The USS Reno took off on October 24, 1944 during the sea ​​and air battle in the Gulf of Leyte participated in the unsuccessful rescue operation for the badly hit light aircraft carrier USS Princeton , but was no longer in the immediate vicinity for anti-aircraft security when the carrier exploded. However, the Reno had the unpleasant task of sinking the wreckage of the carrier with two torpedoes after a corresponding attempt by a destroyer had failed. A few days later, on November 3, the Reno was severely damaged by a torpedo hit by the Japanese submarine I-41 and could only be towed to Ulithi with great difficulty, where it was temporarily restored. The final repair in Charleston took until the end of the war.

The two remaining ships of the first batch were decommissioned in November 1946, the four ships of the second batch between November 1946 and July 1949. The three ships of the Juneau sub-class were also decommissioned between May 1949 and July 1956 despite their young age. All ships remained in the reserve fleet for a few years , until 1973 they were then gradually scrapped.

technology

Side view of the San Diego

Hull, superstructure and armor

The hull of the Atlanta-class cruiser was 164.9 meters long and 16.1 meters wide. The draft was 6.1 meters, the construction displacement 6718 ts and the operational displacement about 8300 ts.

The deckhouse was divided into two areas, the front bearing two gun turrets, the bridge and a chimney. The aft deck structure carried most of the light armament and a second funnel.

The armor was very weak compared to comparable cruiser classes of the time, its maximum thickness was 89 mm in the armored belt on the ship's side. The deck armor and the armor of the gun turrets were 32 mm thick, the command tower was protected with 64 mm armored steel. Inside the ship, the magazines were additionally reinforced with 32 mm steel.

drive

It was powered by two combined high-pressure and low-pressure turbines from Westinghouse Electric with a downstream reduction gear, which drove two propellers. The Atlanta class was the only cruiser class of the US Navy from the time of the Second World War that did not have four propellers. The steam for the turbines came from four steam boilers from Babcock & Wilcox at a pressure of 45 bar . The total output was 75,000 sHP, corresponding to approx. 76,000 wPS.

At the time, American and British sources unofficially stated that the speed was exaggerated ("40 kn" or "38 kn and more") to deceive. The transparent maneuver did not get caught, however, both the contemporary German and French fleet manuals correctly identify them with the 33 knots , which corresponded to the actual design. The test drive result was 33.67 kn and 78,985 hp for the Atlanta then also in the expected range. The fuel supply of 1360 tons allowed a range of 3475 nautical miles (6437 kilometers) at 25 knots or 8500 nautical miles (15740 kilometers) at 15 knots.

For emergencies, the ships originally had a 250 kW emergency generator , which by one eight-cylinder diesel engine from General Motors was driven. After 1943 the ships were equipped with a second emergency generator.

Armament

Main armament

The San Juan 1942, seven of the eight 127 mm twin towers can be seen

The main armament of the cruisers consisted of 16, in the last two construction lots twelve guns, caliber 5 inches (127 mm), caliber length 38, which were housed in Mark 29 twin towers . Six of the turrets were set up in the keel line, three each in front of and three aft of the superstructure. The first construction lot also had two more turrets to starboard and port side of the aft structure, the so-called "waist turret" (literally: hip towers, German designation: wing towers), which, however, had a restricted fire area. On the cruisers of the third batch, the four middle turrets were placed one deck level lower in order to reduce the top-heaviness of the ships.

The gun turrets, which weighed 49 tons, were electrically operated and had a crew of 27 men. The cadence was usually 15 to 20 rounds per minute, well-rehearsed teams achieved up to 30 rounds per minute. Either Mark 49 fragmentation grenades for air defense or armor-piercing Mark 46 grenades were fired. At a distance of 10 km, the 24.5 kg armor-piercing shells, which left the gun barrel at 792 m / s, could penetrate up to 51 mm of hull armor, the maximum range was at 45 ° barrel elevation over 8 nautical miles. The 25 kg flak shells had a muzzle velocity of 762 m / s and a peak height of almost 12 km. When fired, the pipe ran back up to 38 cm before it was hydraulically dampened.

Anti-aircraft armament

The anti-aircraft armament was reinforced in the course of the war, originally it consisted in the first series of three to four 28 mm quadruples and six to eight 20 mm Oerlikon automatic cannons . The 28 mm guns had a rate of around 100 rounds per minute, and the maximum range was around 6.7 km. The quadruple carriage could be rotated 360 ° and swiveled up to 110 ° upwards and 15 ° downwards. The 20-mm cannons fired between 250 and 320 rounds per minute, the range was about two nautical miles. The summit height was almost 3000 m. The number of 20-mm cannons was increased to up to twelve per ship in the course of the war, and in some cases the older single mounts were replaced by double mounts, which further increased the firepower.

View over the aft armament of the San Juan , you can see three of the 5-inch twin towers, a 1.1-inch anti-aircraft gun and the depth charges

The 28-mm quadruplets were replaced on the surviving ships of the first series from 1943 by four 40-mm twins ; the second series came directly into service with eight twins of this type. On San Diego and San Juan , the twin on the Schanz was replaced by a quadruplet in 1944, as was the case on Oakland and Reno in 1945 , where the three 40mm twins in the area of ​​the aft superstructure were also carried through - partly after the torpedo tubes were handed over 40 mm quadruplets were exchanged (final endowment with 40 mm weapons: San Diego 1x4 and 3x2, San Juan 1x4 and 5x2, Oakland and Reno 4x4 and 4x2, Flint and Tucson 8x2). The cadence of the 40-mm cannons was up to 160 rounds per minute, the maximum range was 4 kilometers. The maximum achievable height of the 0.9 kg explosive shells was 6797 meters. The number of 20-mm weapons was also partially increased in various ways.

At the end of the 1940s, the three units remaining in active service were equipped with four 76.2 mm twin guns, which replaced the 40 mm Bofors cannons. The 3-inch guns had a rate of between 45 and 50 rounds per minute. The 5.9 kg explosive shells had a range of over seven nautical miles and the maximum height of fire was over 9,000 meters. Fire control was carried out using a Mark 56 radar.

Torpedo tubes

For use against ships, there were eight 21-inch (533-mm) torpedo tubes in two rotatable groups of four on both sides of the superstructure in front of the two hip towers. The torpedoes weighed 1,004 kg and had a 353 kg warhead with an impact fuse. The range was about 7.5 nautical miles, the maximum speed of the torpedoes was 45 knots. Course, depth and speed were set before the weapon was fired. In 1945 the torpedo tubes were removed from the cruisers of the later series, except on the Flint .

Anti-submarine armament

On the stern were to ASW three water bomb thrower for 300-lb (136-kg) bombs with a total of 30 water bombs and two delivery rails for up to 26 600 lb (272-kg) -Wasserbomben. The originally used, barrel-shaped Mark 7 "ash can" (ash bucket) charges were replaced from 1943 by streamlined Mark 9 "tear drop" (tears), which sank faster and were easier to control thanks to their stabilizing fins.

electronics

View of the front deck of the San Diego , the SC radar and the Mk.37 fire control system can be seen on the right edge

The main radar of the cruiser was the SC radar from General Electric in various versions, the antenna of which was about 4.6 × 1.4 meters in size at the top of the front mast. The radar could locate airplanes at a distance of up to 30 nautical miles, later versions had a range twice as long. The detection range for ships was between 5 and 20 nautical miles, depending on the size of the target. In the course of the war, the ships were then additionally equipped with a system for friend-foe recognition , the antenna of which was located on the radar antenna. To locate surface targets, the ships had an SG radar from Raytheon with a range of up to 22 nautical miles, which could also be used to a limited extent for locating aircraft. The antenna was on the aft mast.

The Atlanta-class ships were the only US Navy cruisers to have a sonar system for underwater location .

As a fire control system for the heavy artillery, two Mark 37 systems were used on the ships, which were located on the superstructure. They consisted of the rotating structure, which carried the optical detection systems and the Mark-4 fire control radar , as well as the part below, which housed the electromechanical Mark-1 fire control computer . Twelve crew members were required to operate each.

Air targets could be pursued in level flight up to speeds of 400 knots, in dive flight up to 250 knots. The square, 1.8 × 1.8 meter measuring Mark 4 antenna was later replaced by a slightly smaller Mark 12/22 dual antenna, which enabled improved tracking of aerial targets.

The 40 mm guns were partly equipped with Mark 63 blind fire control devices during the war, and the system was also used in the 7.62 cm guns.

Additional information

literature

  • Norman Friedman, US Cruisers. An Illustrated Design History . Arms & Armor Press, London 1985, ISBN 0-85368-651-3 .
  • Al Adcock: US Light Cruisers in action (Warships No. 12) . Squadron / signal publications, Carrollton (Texas) 1999, ISBN 978-0-89747-407-8 .
  • Stefan Terzibaschitsch : US Navy cruiser. From the Omaha class to Long Beach . Köhler, Herford 2nd edition 1984, ISBN 3-7822-0348-8 , reprinted several times.

Web links

Commons : Atlanta class  - collection of pictures, videos, and audio files

Individual evidence

  1. ^ A b c d e Al Adcock: US Light Cruisers in action (Warships No. 12) . P. 27
  2. ↑ Terzibaschitsch: US Navy cruiser. From the Omaha class to Long Beach . P. 157.
  3. ↑ James C. Fahey, The Ships and Aircraft of the US Fleet , year 1942 (War Edition), New York 1942, p. 14.
  4. ^ Francis E. McMurtrie, Jane's Fighting Ships 1941 , London 1941, p. 468.
  5. ↑ Alexander Bredt: Weyers Taschenbuch der Kriegsflotten 1941/42 , Munich / Berlin 1941, p. 196.
  6. ^ P. Vincent-Bréchignac, Les Flottes de Combat 1940 , Paris 1940, p. 339.
  7. ^ Norman Friedman, US Cruisers , London 1985, pp. 219, 233.
  8. ^ Norman Friedman, US Cruisers , London 1985, p. 477.
  9. ^ Norman Friedman, US Cruisers , London 1985, p. 477; also Stefan Terzibaschitsch, cruiser of the US Navy - From the Omaha class to Long Beach , 2nd edition Herford 1984, p. 320.
  10. ↑ Terzibaschitsch: Combat systems of the US Navy . Koehler Verlagsgesellschaft, Hamburg, 2001, ISBN 3-7822-0806-4 , p. 16 ff.
  11. ↑ Terzibaschitsch: Combat systems of the US Navy . P. 33 f.
  12. ↑ Terzibaschitsch: Combat systems of the US Navy . P. 29 f.
  13. ↑ Information based on the official description of the USN in ONI-222, 1945
  14. ↑ Terzibaschitsch: Combat systems of the US Navy . P. 93f
  15. ↑ Terzibaschitsch: Combat systems of the US Navy . P. 97.
  16. ↑ Terzibaschitsch: Combat systems of the US Navy . P. 153

Remarks

  1. ↑ Usually, American sHP = Shaft Horsepower and German wPS = Wave Horsepower are adopted 1: 1, but with a precise calculation, 1 HP = 735.5 W and 1 HP = 745.7 W, see Horst Stöcker, Taschenbuch der Physik , 4 Frankfurt am Main 2000 edition, p. 1036.


This version was added to the list of articles worth reading on April 14, 2008 .