Pensacola class

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Lead ship USS Pensacola in September 1935
Lead ship USS Pensacola in September 1935
Overview
Type Heavy cruiser
units 2 completed, none in service
1. Period of service flag
period of service

1929-1948

Technical specifications
to Whitley: Cruiser in World War II
displacement

Standard: 9,243 t
Use: 11,696 t

length

Construction waterline : 173.7 m
over all: 178.5 m

width

19.9 m

Draft

medium: 5.9 m

crew

631 men

drive

8 White Foster boilers
4 geared turbines
4 screws over 4 shafts
107,000  shaft horsepower

speed

32.5 kn

Range

13,000  nm at 15 kn

Bunker quantity

1524 tons of oil (2150 tons maximum)

Armament

10 x 20.3 cm (8 in ) L / 55
4 x 12.7 cm (5 in) L / 25
6 x 53.3 cm (21 in) torpedo tubes

Armor

Side: 76mm – 102mm
Deck: 45mm – 51mm

The two naves in Pensacola class was the first class heavy cruiser of the US Navy . The ships were built in the late 1920s, used in World War II, used in the atomic bomb tests in Bikini Atoll in 1946 , and used up as target ships in 1948.

draft

The Pensacola class was the first class of cruisers built by the US Navy under the restrictions of the Washington Naval Agreement , and after the Omaha class, it was the second modern class of cruisers ever built. As with other navies, the design displacement limitation of 10,000 ts was found very restrictive in the design. The maximum permitted gun caliber of 20.3 cm and a high speed were not wanted, and a long range was necessary for use in the Pacific. Therefore, for reasons of weight, armor protection against equally armed opponents was not possible. Since it was assumed that the ships armed with 15 cm guns could keep cruisers at a distance through their heavier armament, the armor protection was actually only designed against hits from 12.7 cm guns (destroyer caliber).

In the design stage, it was determined that weight-saving measures would make the ships lighter than originally expected, which would make another 250 tons available for armor protection. In fact, the water displacement at the time of completion was well below the contract limit, a weakness that was only addressed with the Portland class .

Initially, the ships had an identifier beginning with "CL" ("Cruiser Light", literally "Light Cruiser"). Shortly after commissioning, the US Navy changed its identification system so that, as is common today, the caliber of the main armament was decisive for distinguishing between "CA" (heavy cruiser) and "CL" ( light cruiser ).

Technical specifications

The water displacement was 9,243 tons standard (corresponds to 9097 ts). The ships were 178.5 m long, 18.9 m wide and had an average draft of 5.9 m.

The drive system consisted of four sets of Parsons geared turbines, which were fed by eight White Foster boilers and operated on four shafts. The drive system was arranged in two boiler rooms and two machine rooms according to the unit principle, i.e. H. Boiler and engine rooms alternated along the ship. This increased the chances that at least half of the propulsion system could still be used in the event of combat damage. The boilers were oil-fired and their flues were brought together in two chimneys.

The ships had an armored belt 76 mm thick over the propulsion system. The thickness of the armored deck was 51 mm. The front ammunition chambers had a side protection of 102 mm, the rear of only 89 mm, as it was assumed that in combat the enemy would be more ahead than abeam. The ceilings of the ammunition chambers were protected by 45 mm thick armor. The armor of the turrets was 25–38 mm.

The main armament consisted of 10 8 "guns in two triple and two twin turrets. What was unusual was that the heavier triple towers raised the twin towers. Such an arrangement is unfavorable for reasons of stability, but was necessary because the hull at the bow was too narrow for the larger barbette of the treble tower. In addition, four 12.7 cm L / 25 guns were installed in open single mounts on the aft superstructure for medium artillery and anti-aircraft defense. The light anti-aircraft gun consisted of eight 12.7 mm machine guns due to a lack of suitable weapons . The ships had six torpedo tubes in two sets of three on the upper deck on either side of the stern funnel.

Between the chimneys, the ships carried a catapult on either side. Up to four aircraft could be carried. As the only heavy cruiser in the US Navy, the Pensacola class did not have a hangar.

Conversions

Since the ships lurched heavily due to their underweight, they were given larger bilge keels .

In the mid-thirties, the torpedo tubes were removed because it was assumed that the cruisers would not be able to use them in the event of a battle. Even before the war, the heavy flak was doubled by setting up four more guns in individual mounts on both sides of the command bridge.

During the war, the light and medium flak was continuously strengthened. First 8, then 16 28 mm guns were installed in quadruple mounts on the ships, which were replaced from 1943 by up to 28 40 mm Bofors guns in quadruple mounts. In addition, the ships received a growing number of 20 mm Oerlikon cannons .

In 1941, the aft heavy tripod mast on both ships was shortened and equipped with a guide device for the heavy artillery. To save weight, the front heavy tripod mast on the USS Pensacola was shortened in 1945 and the rear one completely removed, and the starboard catapult was also removed. The same changes were planned for the USS Salt Lake City , but were no longer implemented because the war ended.

history

Both ships were used in the Pacific.

Location of the ships:

  • USS Pensacola (CA-24) (launched April 25, 1929): Used in July 1946 as a test ship in the atomic bomb tests at Bikiniatoll, sunk as a target ship on November 10, 1948.
  • USS Salt Lake City (CA-25) (launched January 23, 1929): Used as a test ship in the atomic bomb tests at Bikiniatoll in July 1946, sunk as a target ship on May 25, 1948.

literature

Individual evidence

  1. ↑ a b Terzibaschitsch, p. 78
  2. ↑ a b Whitley, p. 268
  3. ↑ The information follows Whitley here; Terzibaschitsch obviously shows printing errors in this regard.
  4. ↑ Terzibaschitsch, p. 320
  5. ↑ a b c Whitley, p. 269
  6. ↑ Terzibaschitsch, p. 323
  7. ↑ Terzibaschitsch, p. 78ff; Whitley, p. 269
  8. ↑ Whitley, p. 269; Terzibaschitsch states that the last event was the decommissioning on August 26, 1948.
  9. ↑ Whitley, p. 269; Terzibaschitsch, p. 84