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Iowa class battleship

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Iowa-class battleship

USS Wisconsin, the fourth ship of the class.
Class Overview
Class type: Battleship
Class name: The State of Iowa
Preceded by: South Dakota class
Succeeded by: Montana class
Ships of the line: Iowa (BB-61), New Jersey (BB-62), Missouri (BB-63), Wisconsin (BB-64) (not completed: Illinois (BB-65), Kentucky (BB-66))
General Characteristics (USS Iowa)
Displacement: 45,000 tons (standard);
56,500 tons (mean war service);
52,000 tons full load.
Length: 861 1/4 ft between Perpendiculars; [[890 ;ft overall (271.27 m)
Beam: 108 ft (32.92 m)
Draft: 36 ft (10.97 m)Maximum.
Speed: 33 knots (61.12 km/h nominal);35 knots (64.82 km/h maximum);
Complement: 2,700 officers and men
Max. cruising radius 9,600 miles (15,000 km) @ 25 knots (46 km/h);
16,600 miles (27,000 km) @ 15 knots (28 km/h)
Power: 212,000 shp (158 MW) forward; 44,000 shp (33 MW) reverse; 12 Babcock & Wilcox Boilers.
Drive: 4 screws; geared turbines; G.E. (BB-61;BB-63); West. (BB-62; BB-64; BB-66).
Fuel: 9,033 tons oil (max)
Armour Belt: 12.1 in (307 mm),
Bulkheads: 11.3 in (287 mm),
Barbettes: 11.6 to 17.3 in (295 to 439 mm),
Turrets: 19.7 in (500 mm),
Decks: 7.5 in (191 mm)

The Iowa-class battleships were the biggest, the most powerful, and the last battleships built for the United States Navy. Four were built in the early 1940s for World War II. All were decommissioned, then recommissioned in the 1980s and decommissioned again in the 1990s.

Two more were laid down but were scrapped prior to completion. Built with cost as no object, "The Iowa class fast-battleships were arguably the ultimate capital ship in the evolution of the battleship."[#endnote_quote] Their true rival, however, was the aircraft carrier, which proved its title as the most important naval vessel during World War II naval battles in the Pacific.

The Iowa-class battleships improved upon the earlier South Dakota class with more powerful engines, longer caliber guns giving greater range and an additional 200 feet (60 m) of length for improved seakeeping. The Iowas are widely considered to be amongst the most attractive battleships ever built, with a long, narrow, elegant bow and three powerful gun turrets. While excellent sea boats, the ships are quite wet forward due to the long bow, and the narrow forecastle made armoring No. 1 turret difficult. Like all American battleships of her generation, her armament was laid out in two turrets before the superstructure and one after ("2-A-1"), with the 5-inch dual-purpose secondaries (anti-ship and anti-aircraft) flanking the superstructure.

The Iowas were unique for several reasons. First, these ships were designed as "fast" battleships, able to rely on an even mix of speed and firepower and capable of sailing at the same speed as the carrier force. Secondly, although they had to be designed to fit through the Panama Canal, they took that to the limit with less than a foot (30 cm) to spare on either side. Third, all four of the Iowa class battleships were recommissioned and refitted under the Reagan Administration as part of Navy Secretary John F. Lehman's "600-ship Navy" plan, particularly in response to the Soviet Navy commissioning the Kirov class battlecruisers/missile cruisers. Fourth, these ships were active, if intermittently, throughout the latter half of the 20th century. Lastly, all four of the ships still exist, which is unusual because the US Navy typically scraps older, decommissioned ships or scuttles such ships in weapons tests.

Contents

Design history

The Iowa-class began in response to the need for fast escorts for aircraft carriers The design process began in early 1938 on the basis of creating an extended South Dakota class. A study was conducted indicating that a 45,000 ton Extended-South Dakota would be capable of 33 knots. In addition to the 33-knot speed, another feature of the design was to be the Mark II 16-inch(406 mm) / 50-caliber gun. This was originally intended to be the main armament of the cancelled battleships and battlecruisers of 1922. However, this gun was rejected in favor of the new Mark VII 16-inch(406 mm) / 50-caliber gun because of its lighter weight. The Mark VII was intended to fire the same 2,240 lb shell as the 16-inch/45-caliber gun but as the design was being completed a new 2,700 lb shell was developed. This led to problems with armor protection since the current armor was only designed to resist 2,240-lb shells. It was too late in the development to solve the problem of increasing the armor and it was decided that the increase in weight from the increased armor would have pushed the ship over the 45,000 ton weight limit. The design was then finalized and a contract was signed with the ship yards in July 1939. Originally BB-61, BB-62, and BB-63 were to be of the same design while BB-64, BB-65, and BB-66 were intended to be larger, slower ships mounting 12 16-inch guns. But by late in 1939, it was apparent that the navy needed as many fast battleships as possible and it was decided that BB-64, BB-65, and BB-66 would follow the same lines as the previous 3 ships.

Construction

The Iowa-class battleships were constructed at three Navy Yards: the New York Navy Yard in Brooklyn, New York, the Philadelphia Navy Yard in Philadelphia, Pennsylvania, and the Norfolk Navy Yard in Norfolk, Virginia. The New York Naval Yard built Iowa and Missouri, while the Philadelphia Navy Yard built New Jersey and Wisconsin. The last two ships, Illinois and Kentucky, were laid down in the Philadelphia Navy Yard and Norfolk Navy Yard respectively, and construction on both continued until their cancellation in 1945 and 1947, respectively.

  1. Iowa was laid down on June 6, 1940, and was completed on February 22, 1943.
  2. New Jersey was laid down on September 16, 1940; and completed on May 23, 1943.
  3. Missouri was laid down on January 6, 1941; and completed on June 11, 1944.
  4. Wisconsin was laid down on January 25, 1942; and completed on April 16, 1944.
  5. Illinois was authorized in 1940, and ordered from the Philadelphia Navy Yard in December, 1942; but was cancelled when 22% complete on August 11, 1945.
  6. Kentucky was laid down on December 6, 1944; suspended in August, 1946; and was cancelled sometime after the first Nuclear tests.

Armament

The Iowa-class ships were among the most heavily armed ships the United States ever put to sea. The main battery of 16-inch guns could hit targets nearly 24 miles (39 km) away with a variety of artillery shells, from standard armor piercing rounds to tactical nuclear charges called "Katies" (from "kt" for kiloton). The secondary battery, of much smaller caliber and shorter range, could inflict severe damage upon smaller ships. The ships were built with many 40 mm anti-aircraft guns, which were gradually replaced with missiles, electronic-warfare suites, and Phalanx anti-missile Gatling gun systems.

Main battery

USS Iowa fires a full broadside of nine 16-inch (406 mm) / 50-caliber and six 5-inch (127 mm) / 38-calibre guns during a target exercise. Note concussion effects on the water surface, and 16-inch (406 mm) gun barrels in varying degrees of elevation.
Enlarge
USS Iowa fires a full broadside of nine 16-inch (406 mm) / 50-caliber and six 5-inch (127 mm) / 38-calibre guns during a target exercise. Note concussion effects on the water surface, and 16-inch (406 mm) gun barrels in varying degrees of elevation.

The primary armament of an Iowa-class battleship is nine 16-inch (406 mm) / 50-caliber guns in three 3-gun turrets—two forward and one aft. The guns are 66 feet (20 m) long (50 times their 16-inch bore, or 50 calibers, from breechface to muzzle). About 43 feet (13 m) protrudes from the gun house. Each gun weighs about 239,000 pounds (108 000 kg), roughly the weight of a space shuttle. The gun fires projectiles weighing from 1,900 to 2,700 pounds (850 to 1,200 kg) at a maximum speed of 2,690 ft/s (820 m/s) up to 24 miles (39 km). At maximum range the projectile spends almost 1½ minutes in flight.

Only the top of the turret protrudes above the main deck. The turret extends either four decks (Turrets 1 and 3) or five decks (Turret 2) down. The lower spaces contain rooms for handling the projectiles and storing the powder bags used to fire them. Each turret required a crew of 77 to 110 men. The turrets are not actually attached to the ship, but sit on rollers, which means that if the ship were to capsize the turrets would fall out. (Underwater photos of the Bismarck show empty barbettes, vacated as the ship sank.)

The turrets are "three-gun," not "triple", because the guns can be elevated independently; they can also be fired independently. The ship could fire any combination of its guns, including a broadside of all nine. Contrary to myth, the ships do not move much sideways when a broadside is fired. (For a more scientific exploration of this subject, see the link below.)

The guns can be elevated from −5° to +45°, moving at up to 12° per second. The turrets can be rotated about 300° at about four degrees per second and can even be fired back beyond the beam, which is sometimes called over the shoulder. The guns are never fired directly forward.

The big guns were designed to fire the standard 16-inch (406 mm) artillery shells, but later advances brought more types of shells, including:[#endnote_ammo1]

16-inch naval gunfire shells
Enlarge
16-inch naval gunfire shells

Secondary battery and anti-aircraft batteries

The secondary battery of the ship consists of 5-inch (127 mm) / 38-caliber guns in a series of twin mounts. Originally the secondary battery was intended to be part of the anti-aircraft defenses, but as aircraft became faster their effectiveness in that role decreased. Their use increased again toward the end of the war with the development of proximity-fuzed 5-inch shells that burst near the target rather than requiring a direct hit. By the time of the Gulf War the secondary battery was largely relegated to shore bombardment and littoral defense. Until the modernization in the 1980s there were ten twin mounts, five on each side of the ship. In the modernization the two mounts farthest aft on each side were removed to make room for missiles, leaving the ship with just six twin mounts. The guns have an effective range of 9 miles (14 km) and can be fired as fast as the crew can load and fire them. A good crew could run 16 to 23 rounds per minute through them.

The British attack at Taranto and the Japanese attack at Pearl Harbor made it clear that airpower was going to play a substantial role in the war. The Iowas were designed to be a fearsome anti-aircraft platform. When launched they carried twenty quad Bofors 40 mm gun mounts, and forty-nine Oerlikon 20 mm cannon single mounts. By the end of WWII, the single 20 mm had stopped being a very effective anti-aircraft weapon: it did not have enough punch to stop the bigger, heavier aircraft they were seeing, in particular the kamikazes. By 1950, almost all of the single 20 mm guns had been removed. In the modernization in the 1980s, the Navy realized that it is difficult to shoot down a jet with a 40 mm anti-aircraft gun, so all of the 40 mm gun mounts and the last of the 20 mm guns were removed in the modernization. In their place, the Navy installed four of the Phalanx Close-In Weapons Systems.

USS New Jersey displays the three weapons systems installed under her 1982 modernization (from upper left to lower right): the Phalanx CIWS for anti-aircraft/anti-missile defense, the Harpoon missile launchers for use against enemy ships, and the Armored Box Launcher (ABL) for use against land-based targets.
Enlarge
USS New Jersey displays the three weapons systems installed under her 1982 modernization (from upper left to lower right): the Phalanx CIWS for anti-aircraft/anti-missile defense, the Harpoon missile launchers for use against enemy ships, and the Armored Box Launcher (ABL) for use against land-based targets.

Missiles

During the modernization in the 1980s, three important weapons systems were added to the Iowa-class battleships. The first was the CIWS anti-aircraft/anti-missile system discussed above. The other two were missile systems for use against both land and sea targets.

The Iowa class were fitted with an anti-ship cruise missile, the AGM-84 Harpoon, in 16 launch tubes. The tubes are located alongside the aft stack with eight on each side of the ship in two pods of four. The Harpoon has a range of up to approximately 85 nautical miles (157 km) depending upon how it is fired. For increased range and accuracy against land targets the Iowa class gained 32 BGM-109 Tomahawk missiles located in eight Armored Box Launchers. The TLAM or Tomahawk Land-Attack Missile was used extensively in the Gulf War by USS Missouri and USS Wisconsin. During the war Wisconsin served as the TLAM strike commander for the Persian Gulf, directing the sequence of launches that marked the opening of Operation Desert Storm. RIM-7 Sea Sparrow was planned but had to be scrapped because no shock absorbing mounting could be designed that would protect the missiles' radar from damage when the guns fired.

Aircraft

USS Missouri recovers a Vought OS2U Kingfisher during her 1944 shakedown cruise. Note the catapult below the plane, which was used to launch the planes off the battleship.
Enlarge
USS Missouri recovers a Vought OS2U Kingfisher during her 1944 shakedown cruise. Note the catapult below the plane, which was used to launch the planes off the battleship.

Like most later battleships, the Iowas used aircraft for reconnaissance and gunnery spotting.

The early aircraft were floatplanes launched from catapults on the ship's fantail. Upon completion of their mission, they landed on the water, taxied up to the stern of the ship, and were lifted by a crane back to the catapult. Initially, the Iowas carried the Vought OS2U Kingfisher, a lightly armed two-man aircraft used exclusively for reconnaissance and gunnery spotting. Typically an Iowa-class battleship would carry three: two on the catapults and a spare on a trailer nearby. At the beginning of 1945, the Kingfisher was replaced by the single-seat Curtiss SC Seahawk floatplane.

Around 1949, the Iowa class no longer had to conduct the dangerous work of launching and recovering floatplanes, as helicopters were brought aboard for reconnaissance, gunnery-spotting, and search-and-rescue missions. The first helicopters were operated from the top of Turret 2; the fantail was still too crowded. Presently, the catapults were removed and helo ops moved aft to the fantail.

As the Iowa class entered the 1990s, they had a new tool available for reconnaissance and gunnery-spotting; as many as eight RQ-2 Pioneer unmanned aerial vehicles (UAVs). Sometimes referred to as remote piloted vehicles (RPVs), these were unmanned aircraft piloted by remote control. Launched from the fantail using a rocket-assist booster that was discarded shortly after takeoff, a Pioneer used an aft-mounted, push-propeller engine to achieve speeds of up to 90 mph (40 m/s) with a mission endurance of about four hours. Because it is difficult to land the Pioneer without damaging itself or the ship, a large net is strung up for recovery as for a volleyball game, and the aircraft is flown into it.

Crewmen recover an RQ-2 Pioneer Unmanned Aerial Vehicle aboard USS Iowa. Pioneer drones launched from the Iowa-class battleships were steered into a large net on the ships, where they were recovered by the crew.
Enlarge
Crewmen recover an RQ-2 Pioneer Unmanned Aerial Vehicle aboard USS Iowa. Pioneer drones launched from the Iowa-class battleships were steered into a large net on the ships, where they were recovered by the crew.

The Pioneer carries a video camera in a pod under the belly of the aircraft, which transmits live video back to the ship so that the operators can observe enemy actions or fall of shot during naval gunnery. The Pioneers saw extensive use by the USS Missouri and USS Wisconsin during the Gulf War. The latter became the first ship ever to have enemy forces surrender to a remotely controlled observation drone.[#endnote_drone]

Engineering plant

The Iowa-class battleships are the fastest battleships ever launched by any nation, capable of sustained speeds of 33 knots (61 km/h) or better. This is made possible by her engineering plant which consists of 4 General Electric double-expansion steam turbine engines. Each engine feeds a single shaft which turns one of the ship's four screws. The two outboard screws on the Iowa class are four bladed and just over 18 feet (5.5 m) in diameter. The two inboard screws are five bladed and approximately 17.5 feet (5.3 m) in diameter. The engines receive the steam that turns the turbines from eight Babcock and Wilcox M-Type boilers which heat the water in tubes to a temperature of more than 800 °F (430 °C), which produces 650 lbf/in² (4500 kPa) of steam pressure.

The double-expansion engines consist of a high-pressure (HP) turbine and a low-pressure (LP) turbine. The steam is first passed through the HP turbine which turns at up to 2100 rpm. The steam, largely depleted at this point, is then passed through a large conduit to the LP turbine. By the time it reaches the LP turbine it has no more than 50 lbf/in² (300 kPa) of pressure left. The LP turbine acts somewhat like a turbocharger, increasing the efficiency and power output of the engine by squeezing the last little bit of energy out of the steam.

After leaving the LP turbine the exhausted steam goes into a condenser where it is recondensed back into water and sent back to the boilers. There is some loss during the process, so the Iowa class requires its evaporators to continue making more fresh water to replenish the boilers. The Iowa class have three evaporators on board which make a combined total of 60,000 US gallons per day (3 liters per second) of fresh water. After the boilers have had their fill of water, the remaining fresh water from the evaporators is fed to the ship's potable water systems for crew drinking, showers, hand washing, cooking, etc. All of the urinals and all but one of the toilets on the Iowa class flush with saltwater in order to conserve fresh water.

The turbines, especially the HP turbine, turn at high speeds, much higher than one would want to try to feed back to the screws. In order to reduce those rpm to a more manageable rate, the shafts that come out of the turbines go into a set of reduction gears which reduce the 2000+ rpm speeds down into a more manageable rate, generally in the under-225 rpm rate—depending upon the desired speed of the ship.

Electricity

Modern warships are heavily dependent upon electricity and the Iowa class are no exception. Much of what happens on the ship, including rotating the turrets and elevating the guns, is done by electric motors. To generate electricity each of the four engine rooms has a pair of Ship's Service Turbine Generators (SSTGs)[#endnote_sstg] manufactured by Westinghouse. Each SSTG generates 1.25 MW of electrical power for a total of 10 MW of electricity. The SSTGs are steam powered and get their steam from the same boilers that feed the engines. For backup the ship also has a pair of 250-kW diesel generators.

During battle it is possible that electrical circuits could be damaged and so it is essential to be able to repair or work around that damage as quickly as possible in order to restore electrical power to crucial systems. To that end throughout the lower decks of the ship there is a Casualty Power System consisting of large 3-wire cables and wall outlets called biscuits which the cables plug into. By using these cables electrical power can be dynamically rerouted around damaged circuits and electrical power restored to the ship if necessary.

Reactivation potential

USS Wisconsin is one of three Iowa-class battleships opened to the public as a museum, and one of two maintained in the US Mothball fleet for potential reactivation.
Enlarge
USS Wisconsin is one of three Iowa-class battleships opened to the public as a museum, and one of two maintained in the US Mothball fleet for potential reactivation.

The United States maintains Iowa and Wisconsin in reserve and could recommission one or both of them. The cost has been priced at $430 million for a 14-month program or $500 million for a 10-month program. #redirect Among other things, fitting the ships to fire Tomahawks would be costly. Their Armored Box Launchers cannot fire today's Tomahawks, which are designed for modern ships' Vertical Launch System (VLS) launcher.

The Navy has nearly 15,000 16-inch (406 mm) shells, but has not manufactured them since the 1960s.

The two ships are maintained in accordance with the National Defense Authorization Act of 1996[#endnote_NDAA'96], which includes the following battleship readiness requirements:

  1. List and maintain at least two Iowa-class battleships on the Naval Vessel Register that are in good condition and able to provide adequate fire support for an amphibious assault;
  2. Retain the existing logistical support necessary to keep at least two Iowa-class battleships in active service, including technical manuals, repair and replacement parts, and ordnance; and
  3. Keep the two battleships on the register until the Navy certified that it has within the fleet an operational surface fire support capability that equals or exceeds the fire support capability that the Iowa-class battleships would be able to provide for the Marine Corps' amphibious assaults and operations ashore. (Section 1011)
The U.S. Navy had originally planned to keep the two battleships on the Naval Vessel Register until new naval surface fire support guns and missiles enter service between 2003 and 2008.

On March 17, 2006, the Secretary of the Navy, acting with the authority granted by the 2006 defense appropriations act, officially struck Iowa and Wisconsin from the Register. They are likely to be transferred, as were Missouri and New Jersey to a museum association.

Reactivation debate

Some have argued that the U.S. military needs the battleships and their 16-inch guns.

Some United States Marine Corps leaders have fought to get both battleships recommissioned. They argue that adequate fire support for an amphibious assault or onshore operations cannot be provided by existing weapons, the Navy's planned naval surface fire support guns and missiles, or the DD(X) destroyer, which will not arrive until 2013.

Battleship proponents argue that cannon-fired shells would be more cost-effective at hitting coastal targets than missiles or bombs dropped from aircraft. They say guidance packages and rocket boosters make today's shells more accurate and longer-ranged than their predecessors.

Detractors say:

Locations

Currently, three of the ships are on display at the following locations:

USS New Jersey
On October 14, 2001, USS New Jersey opened as a museum at Camden, New Jersey.
USS Missouri
Located 1,000 yards (about 1 km) from USS Arizona at Pearl Harbor, Missouri was opened as a museum on 29 January 1999. The museum is operated by the USS Missouri Memorial Association, a non-profit organization.
USS Wisconsin
Berthed in Norfolk, Virginia as a museum ship at the Hampton Roads Naval Museum. Wisconsin was originally struck from the naval register, but her name was restored 12 February 1998. Her weather decks are currently open to the public; however, the ship is still owned and operated by the Navy, and maintained as part of the United States' mothball fleet.
The fourth ship of the class, USS Iowa, is currently part of the Naval Reserve Fleet and is currently berthed at Suisun Bay near San Francisco. In 2005, San Francisco's city council members, citing opposition to the Iraqi war and the U.S. Governments requirements on the Navy's policies regarding homosexuals, voted 8-3 against maintaining Iowa, paving the way for Stockton, California, to acquire the battleship. Currently, Iowa is the only ship of her class not open to the public as a museum.

Competition

Historians and ship buffs debate which of the world's battleships might have been the closest competitors to the Iowa class, assessing performance using such factors as battle history, gun size, and armor.

Some U.S. contenders include the Colorado class battleships, the first U.S. vessels to mount 16-inch guns; the North Carolina class, the first U.S. ships designated as "fast battleships"; and the South Dakota class, from which the Iowas were developed.

Three other contenders were never built:

See also

Missouri moves through the Panama Canal en route to the United States in October 1945.
Enlarge
Missouri moves through the Panama Canal en route to the United States in October 1945.

Notes

  1. ↑ The Battleship, p. 120, "General Characteristics: USS Iowa"
  2. ↑ Found on page 11 in the book The Battleships by Ian Johnston and Rob McAuley.
  3. ↑ Ammunition data is taken from "Battleships: United States Battleships 1935–1992"
  4. ↑ Additional info taken from Secret Weapons of the Cold War
  5. ↑ [Federation of American Scientist report]
  6. ↑ [Diagram and statistics for the Ship’s Service Turbine Generator]
  7. ↑ [Federation of American Scientists Military Analysis Network: BB-61 IOWA-class]

References

External links


Iowa-class battleship
Iowa | New Jersey | Missouri | Wisconsin | Illinois | Kentucky

List of battleships of the United States Navy

 

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