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USS Baltimore (CA-68).jpg
USS Baltimore (CA-68)
Class overview
Name: Baltimore class cruiser
Operators: US flag 48 stars.svg United States Navy
Preceded by: Wichita-class cruiser
Succeeded by: Oregon City-class cruiser
In commission: 1943–1971
Completed: 14
Retired: 14
Preserved: 0
General characteristics
Type: Heavy Cruiser
Displacement: 14,500 tons standard
17,000 tons full load
Length: 205.3 m (673 ft 7 in)
Beam: 21.6 m (70 ft 10 in)
Height: 34.4 m (112 ft 10 in) (mast)
Draft: 7.3 m (23 ft 11 in)
Propulsion: Geared steam turbines with four screws
Speed: 33 knots (61 km/h)
Complement: 61 officers and 1085 men
Armament:

The Baltimore class cruiser was a type of heavy cruiser in the United States Navy from the last years of the Second World War. Fast and armed with artillery, ships like the Baltimore cruisers were mainly used by the Navy in World War II to protect the fast aircraft carriers in carrier battle groups. With their strong anti-aircraft armament, Baltmores could contribute especially in air defenses of these battle groups. Additionally, their 8-inch main guns and smaller medium guns were regularly used to bombard land targets in support of amphibious landings. After the war, the ships were, for the most part, moved to the reserve fleet but then reactivated for the Korean War. By 1971, all ships based on the original design were decommissioned. However, four Baltimore class cruisers were refitted and converted into some of the first guided missile cruisers in the world, becoming Albany class and Boston class cruisers. The last of these was decommissioned in 1980. No example of the Baltimore class still exists.

Contents

History

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Planning and construction

USS Bremerton in drydock

Immediately after the outbreak of World War II in September, 1939, the US Navy initiated studies regarding a new class of heavy cruiser, which eventually led to the construction of the Baltimore class. With the start of the war, the limitations instituted by the Second London Naval Treaty, which had completely banned the construction of heavy cruisers, became obsolete. The Baltimore class was based partly on the Wichita-class cruiser, a heavy cruiser from 1937, which represented the transition from inter-war to Second-World-War designs. It was also based partly on the Cleveland-class cruisers, a light cruiser that was then being built. In profile the Baltimores looked very much like the Cleveland-class light cruisers, the obvious difference being that the larger Baltimores carried nine 8-inch (203 mm) guns in three triple turrets, compared to the 12 6-inch (152 mm) guns in four triple turrets of the Clevelands.

The construction of the first four ships of the Baltimore class was launched on July 1, 1940 and four more were ordered before the year was out. A second order, which consisted of 16 more ships, was approved on August 7, 1942. The completion of the ships was delayed, because the Navy gave priority to the construction of the lighter Cleveland-class ships, as more of the lighter ships could be completed more quickly for deployment in carrier groups. With the construction of the first eight Baltimore class ships moving slowly, the US Navy used the time to review the initial plans and improve them. The new, modified design was itself delayed, so that construction had begun on a further seven ships--for a total of 15--using the original design before the revisions were completed. The final 9 ships ordered were converted to the second, modified design. Between 1943 and 1946, 14 ships of the Baltimore class entered the service of the US Navy. Construction of the fifteenth ship, which would have been the Norfolk, was stopped at then end of the war, after 8 months of work had already been done and the half-completed hull was scrapped.

The largest contractor for the construction of the Baltimore class ships was Bethlehem Steel, which produced eight ships at the Fore River Shipyard in Quincy, Massachusetts. New York Shipbuilding in Camden, New Jersey built four and the Philadelphia Naval Shipyard in Philadelphia completed one in addition to working on the final, uncompleted ship. The ships were named after cities in the United States, the only exception being the USS Canberra, which was named in honor of the sunk HMAS Canberra which had been named after the Canberra, the Australian capital. The classification "CA" originally stood for "armored cruiser" but was later used for heavy cruisers.

Service

USS Baltimore during her reactivation

Of the fourteen completed ships, twelve were launched before the Japanese capitulation on September 2, 1945, though only seven took part in the battles of the Pacific Theater and one in the European Theater. The other ships were still completing their testing in the final days of the war. By 1947, ten of the Baltimores had been decommissioned and placed in the reserve fleet, while four remained in service. However, at the start of the 1950s, six were reactivated, making ten available for deployment in the Korean War. Six of these were used for escort missions and coastal bombardment in Korea, while the other four reinforced fleets in other areas of the globe. The remaining four remained out of service: the Fall River was never reactivated, the Boston and Canberra were refitted as Boston Class Cruisers, and the Chicago was reactivated after being converted to an Albany Class.

After the Korean War, beginning in 1954, the Baltimores were decommissioned for good. By 1963, only one unmodified ship, the Saint Paul, remained active to serve in the Vietnam War. It was finally decommissioned in 1971. All fourteen of the original Baltimores were sold for scrap after being decommissioned, the refitted Chicago being the final one destroyed in 1991.

Damage and Casualties

The USS Pittsburgh with its bow ripped off

In World War II, only the Canberra was damaged through enemy fire, when she was struck with a compressed air torpedo on October 13, 1944, which cost 23 men in the engine room their lives. A year later, repairs were completed at the Boston Naval Shipyard and it was assigned to the Atlantic Fleet. In June, 1945, the Pittsburgh had her entire bow ripped off in a typhoon, but there were no casualties. The ship struggled through 70-knot winds to Guam, where provisional repairs were made before sailing to the Puget Sound Naval Shipyard for a full reconstruction.

During the Korean War, a fire in a forward turret on April 12, 1952 killed 30 men on the St Paul. Then, in 1953, the same ship was hit by a coastal battery, though without injury to the crew. The Helena in 1951 and the Los Angeles in 1953 were also struck by coastal batteries without injuries during the war.

In June 1968, the Boston, along with its escort, the Australian cruiser HMAS Hobart, were victims of friendly fire when planes of the US Air Force mistook them for enemy targets and fired on them with AIM-7 Sparrow missiles. Only Hobart was seriously damaged; although the Boston was hit, the warhead of the missile failed to detonate.

Refittings (Albany and Boston classes)

The USS Boston, the template for the later Boston-class

By the latter half of the 1940s, the navy was planning warships equipped with missiles. In 1946 the battleship USS Mississippi and in 1948 the seaplane tender USS Norton Sound were converted to test this idea. Both were equipped, among other weapons, with RIM-2 Terrier missiles, which were also used after 1952 on the first series of operational missile cruisers. Two Baltimore-class cruisers were refitted in this first series, the USS Boston and the USS Canberra. These were the first operational guided missile cruisers in the world. The two ships were designated Boston-class and returned to service in 1955 and 1956 respectively, reclassified as CAG-1 and CAG-2--"G" for "guided missile" and maintaining the "A" because they retained their heavy guns.

The USS Chicago refitted as an Albany-class cruiser

In the following years six ships of the Cleveland class were equipped with guided missiles and in 1957 the first ship designed from the start to be a missile cruiser was completed (the USS Long Beach). Ships also continued to be converted, so starting in 1958, two Baltimore-class cruisers, the USS Chicago and the USS Columbus, along with an Oregon City-class cruiser, the USS Albany, were converted to the new Albany class. These were launched in 1962 and 1964. Two more ships were planned to be refitted as Albanys, the Baltimore-class USS Bremerton and another Oregon City-class cruiser, the USS Rochester but these conversions were cancelled on financial considerations. As opposed to the Boston-class refit, the Albany-class refit required a total reconstruction. Both entire weapons systems and the superstructure were removed and replaced with new ones, which explains the high cost of one refit: $175 million. Because no high-caliber weapons were used, the Albany class ships received the designation CG.

Engineering and Equipment

Hull

Side-view of the Los Angeles
Side-view of the Columbus, refitted as an Albany-class

Baltimore-class cruisers were 205.3 (673 ft 7 in long) and 21.6 m (70 ft 10 in) wide. Since the hull was not altered in either the Albany or the Boston class, these numbers were the same for those ships as well, but the alterations differentiated them in all other categories.

Original Baltimores, fully loaded displaced 17,031 long tons of water. It's draft was 7.3 m (23 ft 11 in). At the bow, the top level of the hull lay 10.1 m (33 ft) above the water, at the stern, 7.6 m (25 ft). The funnels were 26.2 m (86 ft) high and the highest point on the masts was at 34.2 m (112 ft). The superstructure occupied about a third of the ship's length and was divided into two deckhouses. The gap between these housed the two thin funnels. Two masts, one a bit fore and the other a bit aft of the funnels, accommodated the positioning electronics.

The vertical belt armor was 152 mm (6 in) thick and the horizontal deck armor was up to 76 mm (3 in) thick. The turrets were also heavily armored, between 76 and 152 mm thick, while the command tower had the thickest armor, at 203 mm (8 in).

The ships of the Boston class lie about half a meter (20 in) deeper in the water, and displace about 500 long tons more water than their former sister ships. Because the Bostons were only partially refitted, the forward third of the ship remained virtually untouched. The first serious change was the combination of what were two funnels on the Balitmores to just one, thicker funnel, which still stood in the gap between the two deckhouses. Because the missiles required more guiding electronic systems, the forward mast was replaced with a four-legged lattice mast with an enlarged platform. The most conspicuous change was of course the addition of the missile-launching apparatus and the magazine of missiles, which took up the entire back half of the ship and replaced the guns which had been there.

The three Albanys were completely rebuilt from the deck level up, to the point that they bear very little resemblance to their former sister ships. The deckhouse now took up nearly two thirds of the ships length and was two decks high for almost the entire length. Above that lay the box-shaped bridge which was one of the most recognizable markers of the class. The two masts and funnels were combined into the so-called "macks--a portmanteau word combining "mast" and "stack" (smokestack)--where the electronics platforms were attached to the tops of the funnels rather than attached to masts rising all the way from the deck. The highest points on the forward mack was more than 40 m (130 ft) above the water line. Such heights could only be achieved with the use of aluminum alloys, which were used to a great extent in the construction of the superstructures. Despite this the fully loaded displacement of the Albanys grew to more than 17,500 long tons.

Propulsion

The Baltimore cruisers were propelled with steam power. Each ship had four shafts, each with a propeller. The shafts were turned by four steam turbines, the steam produced by four boilers, which at full speed reached pressures of up to 615 psi. The Baltimores each had two engine rooms and two funnels, though this was changed in the Bostons, which only had one funnel for all four turbines, as noted above. The high speed was around 33 knots (61 kph) and the performance of the engine was around 120,000 horsepower.

The original Baltimores could carry up to 2250 tons of fuel, putting the maximum range at a cruising speed of 15 knots, was about 10,000 miles (18,500 km). The increased displacement of the modified Boston and Albany classes meant their range was reduced to about 9000 and 7000 miles respectively, despite increases in fuel capacity to 2600 and 2500 tons.

Armament

Salvo by both forward turrets on the St Paul during the Vietnam War

The main armament of the Baltimore class consisted of three turrets, each with three barrels, a caliber of 8 in, and an effective barrel length of 440 in. Two of these were located fore and one aft. The range of these guns was 27.8 km (17.3 mi). The secondary weapons were six twin-turret guns 5 in caliber and 190 in long. Two were located on each side of the superstructure and two behind the main batteries. These guns could be used against aircraft, ships, and for coastal bombardment. Their range for surface targets was 16 km and they could reach airplanes at altitudes of up to 9.8 km (6 mi). In addition, the ships had very strong purely anti-aircraft defenses: 12 quadruple mounts of Bofors 40 mm (or 11 quadruple mounts and 2 twin mounts on ships with only one rear airplane-crane) as well as between 20-28 20mm machine guns, depending on when a given ship was commissioned. The small-caliber weapons were soon removed. The 20mm anti-aircraft guns were removed without replacement shortly after the war because they had been ineffective against the Japanese planes. The 40mm Bofors were replaced with 3"/50 caliber guns over the course of the 1950s.

Four ships, the USS Toledo, USS Macon, USS Helena, and USS Los Angeles, were also each equipped with three nuclear cruise missiles of the type SSM-N-8 Regulus between 1956 and 1958. Ultimately, though, the deployment of such missiles on surface ships remained an experiment, which was only undertaken until the 1960s. The successor UGM-27 Polaris was only carried by nuclear submarines.

Electronics

USS Pittsburgh with the SPS-8 on the aft mast, and the SPS-6 on the forward mast

Initially, the Balitmores were equipped with SG radar systems for surface targets and SK systems for airborne targets. The range of these systems for surface targets, depending on the size of the target was between 15 and 22 miles (28 and 40 km). The SK could detect bombers at medium altitudes from 100 miles (180 km). The radar systems were replaced in the Korean war with the more effective SPS-6 (built by Westinghouse Electric or later with the SPS-12 (from the Radio Corporation of America combined with a SPS-8 as a height-finder. With these systems the detection range for bombers was increased to 145 mi (235 km). The ships in active service longer received further upgrades in their final years: the SPS-6 was replaced with the SPS-37 (also from Westinghouse) and the SPS-12 was replaced with the SPS-10 from Raytheon. With this equipment planes could be detected at over 250 miles (400 km) away.

The Baltimore-class was equipped from the start with electronic fire control systems to determine the fire-parameters by which targets over the horizon could be hit. The main guns were controlled by a Mark 34 fire control system connected to an MK 8 radar. The AA guns were guided by Mk 37 systems with Mk-4 radar. Later, the fire control radars were replaced along with the main radar systems. The fire control systems remained the same except that the new 3 in guns were fitted upgraded to Mk 56 with Mk 35 radars.

Aircraft

Two Kingfishers on their catapults on board the USS Quincy

The onboard flight systems of the Baltimore-class cruisers during World War II consisted of two aircraft catapults on the side edges of the aft deck. Between the catapults was a sliding hatchway which was the ceiling of an onboard hangar. The first four ships of the class had two cranes each, while the later models had only one.

At full speed Vought OS2U Kingfisher could be launched from these catapults and later Curtiss SC-1 Seahawk as well. These planes were used for reconnaissance, anti-submarine, and rescue missions. The planes were seaplanes and after their missions would land in the water near the cruiser and be lifted back up into the ship by the crane or cranes in the rear and reset upon their catapults. In the 1950s, the catapults and the accompanying capacity to launch airplanes were removed, though the cranes were left.

On the USS Macon, in 1948, had a slightly elevated helipad installed instead of the catapults. Because of the helipad, the available firing angles and the experiment was for this reason quickly abandoned and not attempted on any other ships of the class. The ships of the Albany-class did have an area on the deck for helicopters to land, but no platform.

Later designs

The hull of the Baltimore-class was used for the development of a number of other classes. The Oregon City-class cruisers differ only slightly from Baltimores. This is because they were originally planned as Baltimore-class cruisers but were constructed based on modified plans. Though nine ships were planned, only three were completed. The main differences between the two classes is the reduction to a single-trunked funnel and an alteration of the body, primarily to decrease top-heaviness. A somewhat enlarged design resulted in the Des Moines-class. While the basic deck layout was unchanged, this class carried the first fully-automated high-caliber guns on a warship, though none was constructed in time to take part in World War II. The plans for the Saipan class-light aircraft carrier were adapted from the drafts of the Baltimore hull design, and, for example the layout of the engines was transferred as well. The bodies of these ships were, however significantly widened. The Saipan-class ships were completed in 1947 and 1948, but by the mid 1950s, they proved too small for the planes of the jet age and were converted for use as communication and command ships.

Crew

Crew of the Canberra plotting target data

The size of the crew of a Baltimore-class cruiser varied by era and by tactical situation. Different sources also differ about the numbers. Naturally, the crew sizes were larger during wartime and furthermore, some cruisers--including all three of the modified Albany-class--were used as flagships and therefore housed an admiral and his staff.

At launch, during and shortly after the war, the crews consisted of around 60 officers and about 1000 rank and file crewmen. When an admiral's staff was aboard during wartime, this number could swell to 80 officers and 1500 crewmen. On the Bostons, the standard crew, even in peacetime and without and admiral's staff, was 80 officers and around 1650 crewmen. Because the Albany-class was equipped almost exclusively for guided-missiles, it required less crew than the Bostons, and was roughly comparable numerically to the basic Baltimore.

Compared to today's crew sizes, these numbers seem high. The modern Ticonderoga-class is manned by about 400, a sign of the advances of automation and computerization on warships through the Navy's Smart Ship program.

Quarters for the crew lay mostly below deck as the superstructure was the site of the Combat Information Center (CIC) and possibly the Admiral's headquarters.

List of Baltimore class heavy cruisers

See also

External links

This article incorporates information from the revision as of January 4, 2009 of the equivalent article on the German Wikipedia.


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