Iowa class battleship
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| Iowa class battleship | |
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| Class Overview | |
| Class Type | Battleship |
| Class Name | Iowa |
| Preceded By | South Dakota-class |
| Succeded By | Montana-class |
| Ships of the Class: | Iowa, New Jersey, Missouri, Wisconsin, Illinois, Kentucky |
Four battleships of the Iowa-class battleships (BB-61 through BB-64) were built in the early 1940s in the United States. Two other Iowa-class ships, Illinois and Kentucky, were scrapped prior to completion. The Iowa-class was preceded by the South Dakota class battleships and would have been succeeded by the Montana class battleships if the Montana's had not been cancelled prior to construction. These were the last battleships built by the U.S. Navy and were removed from service in the 1990's.
The Iowa class were constructed at two Navy Yards:
- Iowa (BB-61), built at the New York Navy Yard, Brooklyn, New York;
- New Jersey (BB-62), built at the Philadelphia Navy Yard;
- Missouri (BB-63), built at the New York Navy Yard;
- Wisconsin (BB-64), built at the Philadelphia Navy Yard;
- Illinois (BB-65), keel laid at Philadelphia Navy Yard. Cancelled 12 August, 1945;
- Kentucky (BB-66), keel laid at New York Navy Yard. Cancelled 17 February, 1947.
All four of the completed ships were recommissioned in the 1980s, only to be decommissioned in the 1990s after the Cold War ended. Built as cost-no-object gunships, the Iowas are arguably the finest battleships ever built (their only serious competition were the British Vanguard and the Japanese Yamato class). The Iowa design was based upon the South Dakota's but with more powerful engines, larger guns and an additional 200 feet of length for improved seakeeping. The Iowas are also among the most attractive battleships ever built, with a long, narrow, elegant bow and three powerful gun turrets.
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 (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. Wisconsin was originally struck from the naval register, but her name was restored 12 February 1998. Her weather decks currently opened to the public; however the ship is still owned and operated by the Navy, and maintained as part of the United States's 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 in San Francisco.
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General characteristics (USS Iowa)
- Displacement: 45,000 tons (stand); 56,500 (mean war service)
- Length: 887 ft 3 in (270 m)
- Beam: 108 ft 2 in (33 m)
- Draft: 37 ft 9 in (11.5 m)
- Speed: 33 knots (61 km/h)
- Complement: 2,800
- Armament: 9 x 16 in (406 mm) guns; 20 x 5 in (127 mm) guns; 20 x 40 mm quads; 47 to 52 x 20 mm (WWII); 32 Tomahawk Cruise Missiles; 16 Harpoon Anti-Ship Cruise missiles; 4 Phalanx Close-in weapon system anti-aircraft/anti-missile. (1991)
- 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
- Drive: 4 screws; geared turbines
- Fuel: 9,033 tons oil (max)
Engineering plant
The Iowa-Class battleships are the fastest battleships ever launched by any nation, capable of sustained speeds of 33 knots 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 4-bladed and just over 18 feet (5.5 m) in diameter. The two inboard screws are 5-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 degrees Fahrenheit (430 degrees Celsius), which produces 650 lbf/in² (4,500 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 L/s) 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 salt water in order to conserve fresh water.
The turbines, especially the HP turbine, turn at high speeds, much higher than you want to try to feed back to the screws. In order to reduce those RPMs 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 dependant 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) 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 kilowatt 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.
Armament
The Iowas were among the most heavily armed ships the United States ever put to sea and over time their armament evolved to keep pace with the times.
Main battery
The primary armament of the Iowa-class battleships are their 9 x 16 in (406 mm) 50 caliber, guns located in three, 3-gun, turrets -- two forward and one aft. The guns are 66 feet (20 m) long each, with approximately 43 feet (13 m) of it protruding from the front of the gun house, and each gun weighs approximately 239,000 pounds (108,000 kg). For perspective that is roughly the weight of a space shuttle; so the Iowa-class ships are carrying the weight of 9 space shuttles just in the guns.
The gun fired projectiles weighing 2,700 pounds (1,200 kg) at a maximum speed of 2,690 ft/s (820 m/s). Maximum effective range was 24 miles (39 km). At that range the projectile spent almost one and a half minutes in the air.
The gun house that is visible above deck is only the very top of the turret. The turret extends either 4 decks (Turrets 1 & 3) or 5 decks (Turret 2) beneath the main deck. The lower spaces contain projectile handling rooms and a powder handling room where the powder bags used to fire the guns are stored. Each turret required a crew of between 77 and 110 men. One interesting fact about the turrets is that they are not actually attached to the ship. The turrets are simply sitting on rollers which means that if the ship were to capsize the turrets would fall out. For a good demonstration of this see the recent underwater photos of the Bismarck which show her barbettes empty because her turrets fell out as the ship sank.
The turrets are 3-gun turrets and not triple turrets because the guns can be elevated independently. The guns can also be fired independently if desired; the ship could fire any combination of its 9 guns, including all 9 at once which is known as a broadside.
Contrary to popular myth, the ship does not move sideways when a broadside is fired. The Iowa-class battleships displace 58,000 tons. It is too heavy to move sideways just by firing the guns. For a more scientific exploration of this subject, see the link below.
The guns can be elevated from -5 degrees to 45 degrees depending upon the range to the desired target and they elevate at 12 degrees per second.
The turrets can be rotated through approximately 300 degrees at approximately 4 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.
Ammunition
The main battery of the Iowa-class battleships were designed fire the standard 16 in artillery shells, but in later years the art and science of sea-born artillery improved greatly, resulting in several different types of shells, some of which are listed below:
16-in_Battleship_Ammunition.JPG
- The Mk. 8 APC (Armor-Piercing, Capped) shell mentioned in the above text, which weighs in at 2700 lbs. (1225 kg) and was designed to penetrate the hardened steel armor carried by foreign battleships. At 20,000 yards the Mk. 8 could defeat (penetrate) 20" (500mm) of steel armor plate. At the same range, the Mk. 8 was able to penetrate 21 feet (6.4m) of reinforced concrete.
- For unarmored targets and shore bombardment the 1900 lbs. (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 (15m) wide and 20 feet (6m) deep upon impact and detonation, and was capable of defoliating trees 400 yards (360m) from the point of impact.
- Guided shells, which could offer a cost benefit ratio rivaling that of missile and aircraft strikes.
- "Katie" shells: In or about 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.
NOTE: Ammunition data is taken from "Battleships: United States Battleships 1935-1992" By William H. Garzke and Robert O. Dulin,Jr.
Secondary battery
The secondary battery of the ship consists of 5 in (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. 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 aft-most two mounts from each side were removed to make room for the missiles leaving the ship with just six twin mounts.
The guns have a 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.
Anti-aircraft
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 40 mm Bofors mounts, and 49 x 20 mm 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 and 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 all of their enemies were going to be flying jet aircraft and 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.
Missiles
Missouri_missile.JPG
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 immediately above. The other two were missile systems for use against both land and sea targets.
AGM-84 Harpoon
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 8 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.
BGM-109 Tomahawk
For increased range and accuracy against land targets the Iowa-class gained 32 BGM-109 Tomahawk missiles located in 8 armored box launchers. The TLAM or Tomahawk Land-Attack Missile was used extensively in the Gulf War by USS Missouri and USS Wisconsin.
Aircraft
Reconnaissance and gunnery-spotting are a crucial role on any battleship and most of the later classes of battleship utilize aircraft to facilitate those missions. The Iowa-class battleships use the fantail of the ship as their flight deck and over time their aircraft complement has varied and evolved.
The early aircraft were floatplanes launched from catapults on the fantail and recovered through a complicated process of landing on prepared water, taxiing up to the stern of the ship and then being recovered by a crane which lifts the aircraft out of the water and returns it to the catapult.
Vought OS2U Kingfisher
Initially the Iowa-class were equipped with Vought OS2U Kingfishers. The Kingfisher is a two-man aircraft which, despite having a light weapon package, was used exclusively for reconnaissance and gunnery-spotting.
Typically an Iowa-class battleship would carry three of these aircraft on board; two on the catapults and a spare on a trailer nearby.
Curtis SC1 Seahawk
At the beginning of 1945 the Kingfisher was replaced by the SC1 Seahawk, a single-seat floatplane which conducted the same missions as the Kingfisher.
Typically an Iowa-class battleship would carry three of these aircraft on board; two on the catapults and a spare on a trailer nearby.
Helicopters
Around 1949 the Iowa-class no longer had to conduct the dangerous work of launching and recovering floatplanes as helicopters were brought aboard for the reconnaissance and gunnery-spotting roles and also added the ability to carry out search and rescue missions as necessary. The first helicopters were operated from the top of turret 2 as the fantail was still too crowded prior to the removal of the catapults.
Later the helicopters operated from the fantail of the ships.
Unmanned Aerial Vehicles (UAV)
As the Iowa-class entered the 1990s they had a new tool available for the reconnaissance and gunnery-spotting missions; the RQ-2 Pioneer Unmanned Aerial Vehicle or UAV. Sometimes referred to as a Remote Piloted Vehicle (RPV) these were unmanned drones that were piloted via remote control. Launched from the fantail using a rocket-assist booster which was discarded shortly after take-off they used a push propeller engine located at the rear of the aircraft to achieve speeds of up to 90 MPH (40 m/s) with a mission endurance of approximately 4 hours.
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.
Recovering the aircraft is an unusual maneuver. Though the Pioneer is equipped with wheeled "landing gear" it is rather difficult to land the aircraft on the ship without damaging the aircraft or the ship. Therefore a large net is employed for recovery. The net is strung up in a manner not entirely unlike a volleyball net and the aircraft is flown into the net.
As many as 8 Pioneers would be carried by an Iowa-class battleship. The Pioneers saw extensive use by the USS Missouri and USS Wisconsin during the Gulf War.
Class history & Re-activation potential
Missouri_panama_canal.JPG
Mark_48_Torpedo_testing.jpg
The Iowa class was the last battleship line built by the United States, as Naval power had shifted to being primarily aircraft carrier-based. These ships were launched during the Second World War, and all of them saw action throughout the twentieth century. The Iowas were unique for several reasons. First, these ships were designed as "fast" battleships, able to rely on an even mix speed and firepower. Secondly, all of them were designed to fit through the Panama Canal with less than a foot to spare on either side. Third, all four of the Iowa class battleships were recommissioned and refitted under Ronald Reagan's administration as part of Reagan's "600-ship Navy" plan, particularly in response to the Soviet Navy commissioning the Kirov class. Fourth, these ships actively participated in the U.S. Navy throughout the latter half of the twentieth century. Lastly, all four of the ships are still in existence, which is unusual because the Navy usually uses derelict (http://en.wiktionary.org/wiki/Derelict) ships to test weapons on before scuttling them or selling them for scrap.
Although there are no active battleships in any navy as of 1992, the United States Navy still maintains two mothballed battleships — Iowa 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 thanks improved shell technology such as rocket-boosting in addition to better cannons. For targets within range of ships' cannon, it is cheaper and harder to stop shells then 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.
The United States has not manufactured the 16 inch (406 mm) battleship shell ammunition since the 1950s and 1960s because a reserve of nearly 15,000 of the 16 in (406 mm) shells are in storage, 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 retro-fitted to work with the ABL system, or the ships would need to be re-fitted with the VLS system. The practicality of any these option would have to be determined by expert analysis.
External links
- Historic Naval Ships Association (http://www.hnsa.org/)
- USS Missouri Memorial Association (http://www.ussmissouri.org/)
- The 16" Mark 7 gun from NavWeaps.com (http://www.navweaps.com/Weapons/WNUS_16-50_mk7.htm)
- Do battleships move sideways when they fire? (http://www.navweaps.com/index_tech/tech-022.htm)
- Frequently Asked Questions about the USS Missouri (http://home.hawaii.rr.com/schorr/Politics/MightyMoFAQ.htm)
Further Reading
- Yenne, Bill. Secret Weapons of the Cold War Berkley Publishing Group ISBN 0-425-20149-X
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