Iowa class battleship

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Iowa-class battleship
Image:Uss wisconsin bb.JPG
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)
Length:887 ftin (270.43 m)
Beam:108 ft 2 in (32.98 m)
Draft:38 ft (11.6 m)
Speed:33 knots (61 km/h)
Complement:2,800 officers and men
Max. cruising radius9,600 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
Drive:4 screws; geared turbines
Fuel:9,033 tons oil (max)
ArmourTemplate:RefBelt: 12.1 in (307 mm),
Bulkheads: 11.3 in (287 mm),
Barbettes: 11.6 to 17.3 in (295 to 339 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.Template:Ref". 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. 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 2,700lb shell was developed. This lead 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 two Navy Yards: the New York Navy Yard in Brooklyn, New York, and the Philadelphia Navy Yard. 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 New York Navy Yard respectively, and construction on both continued until their cancellation in 1945 and 1947, respectively.

Competition

Since the Iowa-class battleships are frequently referred to as the "ultimate battleships" they have been involved in an ongoing debate over which battleships would have been their "main competition".

The North Carolina-class was the first designated US "fast battleship" class, while the South Dakota-class were the models upon which the Iowa-class were based. Preceding these two classes were the less capable battleships of the Colorado-class, which were the first US battleships to mount 16-inch guns.

The Imperial Japanese Navy had originally planned to build two "Super Yamato"-class battleships, while the United States Navy had drawn up plans for five Montana-class battleships. The Super Yamatos would have had 20-inch guns, while the Montanas would have mounted four turrets with twelve of the 16-inch guns used on the Iowa-class. Both of these battleship classes were cancelled before construction began.

It is important to note that most of the ships named as the "superpower competitors" to the Iowa-class battleships never actually fought the Iowas, the decision to rank such ships along side the Iowa-class battleships as competitors would have been reached by assessing the performance of rival ships against the Iowas based on such factors as battle performance, gun size, and armor. Such assessments are, at best, educated guesses, and should always be taken with a grain of salt.

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 a Phalanx-class Gatling gun system.

Main battery

Image:Uss iowa bb-61 pr.jpg 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 up to 2,700 pounds (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 sideways when a broadside is fired. (For a more scientific exploration of this subject, see the link below.)

The guns can be elevated from −5º to +45º, moving at up to 12º per second. The turrets can be rotated about 300º 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:Template:Ref Image:16-in Battleship Ammunition.JPG

  • The Mk. 8 APC (Armor-Piercing, Capped) shell mentioned in the above text, which weighs in at 2,700 lb (1225 kg) and was designed to penetrate the hardened steel armor carried by foreign battleships. At 20,000 yards (18 km) the Mk. 8 could defeat (penetrate) 20 inch (500 mm) of steel armor plate. At the same range, the Mk. 8 was able to penetrate 21 feet (6.4 m) of reinforced concrete.
  • For unarmored targets and shore bombardment, the 1,900 lb (862 kg) Mk. 13 HC (High-Capacity—referring to the large bursting charge) shell was available. The Mk. 13 shell would create a crater 50 feet (15 m) wide and 20 feet (6 m) deep upon impact and detonation, and was capable of defoliating trees 400 yards (360 m) from the point of impact.
  • "Katie" shellsTemplate:Ref: Around 1953, the United States Navy began a top-secret program to develop Mk. 23 nuclear naval shells with an estimated yield of 15 to 20 kilotons. These shells were designed to be launched from the best seaborne artillery platform available, which at the time were the four ships of the Iowa class. The shells were reportedly ready by 1956; however, it is not known whether they were ever actually deployed on the Iowa-class battleships because the United States Navy does not confirm or deny the presence of nuclear weapons aboard its ships.

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. Image:NJ-06.jpg

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

Image:Missouri Recovers.JPG 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. Image:Iowa drone.JPG

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.Template:Ref

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)Template:Ref 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

Image:Wisconsin museum.JPG Although there are now no active battleships in any navy, the United States Navy still maintains two mothballed battleshipsIowa and Wisconsin—and could recommission one or both of them if needed. Since the 1950s, the United States battle doctrine has called for air superiority, which clearly favors the aircraft carrier, but other weapons such as guided missile ships and destroyers also play a significant role. In addition, cannon-fired shells have become exceedingly accurate thanks to guided shells, as well as longer range due to improved shell technology (including rocket boosting) and better cannons. For targets within range of the ships' cannons, it is cheaper to fire and harder to stop shells than either missiles or aircraft strikes. The 16-inch (406-mm) guns of the Iowa—if equipped with guided shells—would offer a cost-benefit ratio potentially rivaling an aircraft strike for targets along the coast, and even firing the older shells would have similar accuracy to many types of aircraft bombing strikes (but not the currently-favored use of precision guided munitions)

The United States has not manufactured the 16-inch (406-mm) battleship shell ammunition since the 1950s and 1960s, because it has a reserve of nearly 15,000 of the 16-inch (406-mm) shells in case the battleships are reactivated. Until the stocks are depleted below a certain level there will be no need to make more for the ships.

There are some serious issues regarding the reactivation of these battleships, namely the cost involved in reactivating and operating the battleships, which is high when compared to smaller warships, making them prime targets for budget cuts. Also, the Tomahawks carried by the Iowa class are now obsolete; modern U.S. Navy ships use a type of Tomahawk fired from a Vertical Launch System (VLS) launcher. The Iowa-class ships still carry the old Armored Box Launcher (ABL) system which is not compatible with the presently used Tomahawks. As a result, the older-style missiles would have to be used, VLS missiles retrofitted to work with the ABL system, or the ships would need to be refitted with the VLS system. The practicality of any these options would have to be determined by expert analysis.

USS Iowa and USS Wisconsin are maintained in accordance with the National Defense Authorization Act of 1996Template:Ref, 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)

Current plans in the United States Navy call for keeping the battleships on the register until its naval surface fire support gun and missile development programs achieve operational capability, which is expected to occur sometime between 2003 and 2008. If and when Iowa and Wisconsin are removed from the Naval Vessel Register, there is a high probability that interest groups will request that they be placed on donation hold and transferred for use as museums.

The long-term plan to remove Iowa and Wisconsin and donate them as museum ships is not without controversy; the United States Marine Corps has fought to get both battleships reinstated. The USMC believes that the naval surface fire support gun and missile programs will not be able to provide adequate fire support for an amphibious assault or onshore operations; additionally, the USMC does not think that the Navy's DD(X) destroyer program will be an acceptable replacement for the battleships, and points out that the DD(X) will not be available until 2013 in any event.

On the opposite side of the coin, it is argued that few existing shoreside defenses are sufficiently hardened to withstand pre-invasion missile strikes. Amphibious assault techniques have improved since World War II enough that most coastal areas are suitable for amphibious entry, rendering a mass assault against a built-up chokepoint obsolete (and thus the need to smash up the chokepoint with heavy naval artillery), and a single round that destroys an enemy command center so the enemy cannot see that the invasion force is landing somewhere else is just as (or more) effective at protecting the troops as a 100-round bombardment to soften up the enemy shore defenses prior to a full-on rush into the teeth of the enemy. The battleships are disproportionately vulnerable to mine and submarine warfare - though they can absorb heavy gunfire with little damage, heavy explosives pose a severe threat to them; so severe that the operations of Wisconsin and Missouri were heavily limited during the 1991 Gulf War because of Iraqi mining of their costal waters. Some of the most effective shore fires from that war were carried out by 3"-armed Oliver Hazard Perry-class frigates. Most of all, the Navy suffers from a chronic 8,000 billet shortfall in manpower; adding two 1,500 man battleships would only exacerbate this problem.

Refurbishing Iowa and Wisconsin has been priced at either $430 million for a 14-month program or $500 million for a 10-month program.

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 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 Nauticus National Maritime Center. 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 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.

See also

Image:Missouri panama canal.JPG

Notes

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

References

  • Johnston, Ian and McAuley, Rob. The Battleships. Channel 4 Books, London ISBN 0752261886
  • Naval Historical Foundation. The Navy. Barnes & Noble Inc, China ISBN 0767076218X
  • Yenne, Bill. Secret Weapons of the Cold War Berkley Publishing Group ISBN 0-425-20149-X
  • Keegan, John; Ellis, Chris, and Natkiel, Richard. World War II: A Visual Encyclopedia PRC Publishing Ltd. ISBN 1-85585-878-9
  • William H. Garzke and Robert O. Dulin, Jr. Battleships: United States Battleships 1935–1992
  • The Floating Drydock. United States Naval Vessels, ONI 222-US, Kresgeville, PA 18333
  • Sumrall, Robert. "USS Missouri (BB-63) Warship Data 2". Pictorial Histories. ISBN 1-57510-050-49

External links


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

List of battleships of the United States Navy

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