Editing Iowa-class battleship (section)

=== Armament ===
{{main|Armament of the Iowa-class battleship}}

====Main battery====
{{multiple image
| direction= vertical
| width  = 220
| footer =
| image1 = Iowa 16 inch Gun-EN.svg
| alt1   = A multicolor cutaway of a 16in gun turret. Within the cutaway black lines point to various areas and objects of note, at the other end of the black lines English labels are given for identification purposes.
| caption1= Cutaway of a 16"/50 gun turret.
| image2 = Uss iowa bb-61 pr.jpg
| alt2   = An overhead view of a large ship with a teardrop shape firing guns toward the top of the image.
| caption2= {{USS|Iowa|BB-61|6}} fires a full broadside of nine 16-inch and six 5-inch guns during a gunnery exercise (1984)
| image3 = USS Iowa gun load.jpg
| alt3   = A ship deck with blue bullet and six drum shapes lined up behind the bullet
| caption3= 16"/50 gun projectile with six propellant bags (display) aboard USS ''Iowa'' (BB-61)
}}
The primary guns used on these battleships are the nine {{convert|16|in|0|adj=on}}/50-caliber Mark 7 naval guns, a compromise design developed to fit inside the barbettes. These guns fire high explosive- and armor-piercing shells and can fire a 16-inch shell approximately {{convert|23.4|nmi|km mi}}.{{sfn|Thompson|1999|pp=70–81}}<ref name="NavWeaps 16/50">{{Harvard citation no brackets|NavWeaps.com|loc= [http://www.navweaps.com/Weapons/WNUS_16-50_mk7.php 16"/50 Mark 7]}}</ref> The guns are housed in three 3-gun turrets: two forward of the battleship's [[superstructure]] and one aft, in a configuration known as "2-A-1". The guns are {{convert|66|ft}} long (50 times their 16-inch bore, or 50 calibers from [[breechface]] to [[Muzzle (firearms)|muzzle]]). About {{convert|43|ft}} protrudes from the gun house. Each gun weighs about {{convert|239000|lb}} without the breech, or {{convert|267900|lb}} with the breech.<ref name="NavWeaps 16/50" /> They fired {{convert|2700|lb|0|adj=on}} armor-piercing projectiles at a muzzle velocity of {{cvt|2500|ft/s|0|lk=on}}, or {{convert|1900|lb|0|adj=on}} high-capacity projectiles at {{cvt|2690|ft/s|0}}, up to {{convert|24|mi|nmi km}}.{{refn|The actual range of the ''Iowa''-class battleship's 16"/50 caliber guns varies from source to source. The most commonly cited distance for the 16"/50 caliber gun is approximately 20 miles; however, this number does not necessarily take into consideration the age of the gun barrel, the gun barrel's elevation, the projectile variant (armor piercing or high explosive), or the powder charges required to launch the artillery shell, all of which affect the range that a shell fired from a 16"/50 caliber gun can attain. The longest confirmed shot fired against an enemy naval unit using a 16"/50 caliber gun appears to have occurred during the raid against Imperial Japanese Navy units at [[Chuuk Lagoon|Truk Atoll]], when ''Iowa'' straddled a destroyer at 35,700 yards,<ref name="straddle"/> while the longest shot ever fired by a 16"/50 caliber gun in a non-combat situation is alleged to have occurred during an unauthorized naval gunnery experiment conducted 20 January 1989 off the coast of [[Vieques, Puerto Rico]] by ''Iowa''{{'}}s [[Master Chief Petty Officer|Master Chief]] [[Fire Controlman]], Stephen Skelley, and Gunnery Officer, [[Lieutenant commander (United States)|Lieutenant Commander]] Kenneth Michael Costigan, who claimed that one of the 16-inch shells traveled {{convert|23.4|nmi|km|-1}}.{{not in citation given|date=October 2024}} In addition, the standard 20-mile range does not take into account experimental artillery shells that were under consideration for use with the 16"/50 caliber gun in the 1980s, some of which are alleged to have been capable of traveling distances in excess of the often cited 20-mile gun range. One example is the Improved HC shell, which is said to have been test fired from ''Iowa'' at Dahlgren sometime after her 1980s recommissioning and is alleged to have achieved a range of over 51,000 yards.<ref name="NavWeaps 16/50" /> |group=N|name=Distance}} At maximum range, the projectile spends almost {{fraction|1|1|2}}&nbsp;minutes in flight. The maximum firing rate for each gun is two rounds per minute.<ref name="BAW">Poyer, pp. 50–53.</ref>

Each gun rests within an armored turret, but 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 between 85 and 110 men to operate.<ref name="NavWeaps 16/50" /> The original cost for each turret was US$1.4&nbsp;million, but this figure does not take into account the cost of the guns themselves.<ref name="NavWeaps 16/50" /> The turrets are "three-gun", not "triple", because each barrel is individually sleeved and can be elevated and fired independently. The ship could fire any combination of its guns, including a [[Broadside (naval)|broadside]] of all nine. The fire control was performed by the Mark 38 Gun Fire Control System (GFCS); the firing solutions were computed with the Mark 8 rangekeeper, an analog computer that automatically receives information from the director and Mark 8/13 fire control radar, stable vertical, ship pitometer log and gyrocompass, and anemometer. The GFCS uses remote power control ([[Glossary of British ordnance terms#RPC|RPC]]) for automatic [[gun laying]].<ref name="Mk38">{{cite web |url=http://www.dustdevil.com/ppl/billgx/mk38.htm  |title=Mark 38 Gun Fire Control System |access-date=2007-08-01 |archive-url = https://web.archive.org/web/20041028050854/http://www.dustdevil.com/ppl/billgx/mk38.htm |archive-date = 2004-10-28}}</ref>

The large-caliber guns were designed to fire two different conventional 16-inch shells: the {{convert|2700|lb|0|adj=on}} Mk 8 "Super-heavy" [[APCBC|APC]] (Armor Piercing, Capped) shell for anti-ship and anti-structure work, and the {{convert|1900|lb|0|adj=on}} Mk 13 high-explosive round designed for use against unarmored targets and shore bombardment.{{sfn|Sumrall|1988|pp=73–76}} When firing the same conventional shell, the 16-inch/45&nbsp;caliber Mark 6 used by the fast battleships of the ''North Carolina'' and ''South Dakota'' classes had a slight advantage over the 16-inch/50&nbsp;caliber Mark 7 gun when hitting deck armor&nbsp;– a shell from a 45&nbsp;cal gun would be slower, meaning that it would have a steeper trajectory as it descended. At {{convert|35000|yd|mi km}}, a shell from a 45&nbsp;cal would strike a ship at an angle of 45.2&nbsp;degrees, as opposed to 36&nbsp;degrees with the 50&nbsp;cal.<ref name="NavWeaps 16/45">{{Harvard citation no brackets|NavWeaps.com|loc= [http://www.navweaps.com/Weapons/WNUS_16-45_mk6.php 16"/45 Mark 6]}}</ref> The Mark 7 had a greater maximum range over the Mark 6: {{convert|23.64|mi}} vs {{convert|22.829|mi}}.<ref group=N name=Distance/><ref name="NavWeaps 16/45" /><ref>{{cite web|url=http://www.combinedfleet.com/baddest.htm |title=Battleship Comparison |publisher=Combinedfleet.com |access-date=2012-08-07}}</ref>

In the 1950s, the W23, an adaptation of the [[W19 (nuclear artillery shell)|W19 nuclear artillery shell]], was developed specifically for the 16-inch guns. The shell weighed {{convert|1900|lb|0}}, had an estimated yield of {{convert|15|to|20|ktonTNT|GJ|lk=in}},{{sfn|Yenne|2005|pp=132–133}} and its introduction made the ''Iowa''-class battleships' 16-inch guns the world's largest [[nuclear artillery]]{{sfn|Polmar|2001|p=490}} and made these four battleships the only US Navy ships ever to have nuclear shells for naval guns.{{sfn|Polmar|2001|p=490}} Although developed for exclusive use by the battleship's guns it is not known if any of the ''Iowa''s actually carried these shells while in active service due to the United States Navy's policy of refusing to confirm or deny the presence of nuclear weaponry aboard its ships.{{sfn|Yenne|2005|pp=132–33}}{{refn|"Military members and civilian employees of the Department of the Navy shall not reveal, report to reveal, or cause to be revealed any information, rumor, or speculation with respect to the presence or absence of nuclear weapons or components aboard any specific ship, station or aircraft, either on their own initiative or in response, direct or indirect, to any inquiry. [...] The Operations Coordinating Board (part of President Eisenhower's National Security Council) established the US policy in 1958 of neither confirming nor denying (NCND) the presence or absence of nuclear weapons at any general or specific location, including aboard any US military station, ship, vehicle, or aircraft."<ref>{{cite web |last=Morgan | first=J.G. Jr. |date=3 February 2006 |title=Release of Information on Nuclear Weapons and on Nuclear Capabilities of U.S. Forces (OPNAVINST 5721.1F N5GP) |publisher=Department of the Navy&nbsp;– Office of the Chief of Naval Operations |location=Washington, DC |pages=1–2 |url=http://www.fas.org/irp/doddir/navy/opnavinst/5721_1f.pdf |access-date=2012-07-02 }}</ref>|group=N|name=Nuclear}} In 1991, the United States unilaterally withdrew all of its nuclear artillery shells from service, and the dismantling of the US nuclear artillery inventory is said to have been completed in 2004.{{sfn|DeVolpi|Minkov|Simonenko|Stanford|2005|p=VA-13}}

====Secondary battery====

[[File:5-inch 38-caliber cropped.jpg|thumb|220px|alt=A grey turret with two gun barrels pointing forward. A black eagle, globe, and anchor insignia has been painted on the side of the turret.|A 5-inch gun mount emblazoned with the [[Eagle, Globe, and Anchor]] of the [[United States Marine Corps]] aboard the battleship {{USS|New Jersey|BB-62|2}}. In keeping with tradition, a 5-inch gun mount on each ''Iowa''-class battleship was manned by the ship's Marine Detachment.]]
The ''Iowa''s carried twenty [[5"/38 caliber gun|{{convert|5|in|0|adj=on}}/38 caliber]] Mark 12 guns in ten Mark 28 Mod 2 enclosed base ring mounts. Originally designed to be mounted upon destroyers built in the 1930s, these guns were so successful that they were added to many American ships during the Second World War, including every major [[Classification society|ship type]] and many smaller warships constructed between 1934 and 1945. They were considered to be "highly reliable, robust and accurate" by the Navy's Bureau of Ordnance.<ref name="NavWeaps 5/38">{{Harvard citation no brackets|NavWeaps.com|loc= [http://www.navweaps.com/Weapons/WNUS_5-38_mk12.php 5&quot;/38 Mark 12]}}</ref>

Each 5-inch/38 gun weighed almost {{convert|4000|lb|kg}} without the breech; the entire mount weighed {{convert|156295|lb|kg}}. It was {{convert|223.8|in|mm}} long overall, had a bore length of {{convert|190|in|mm}}, and a rifling length of {{convert|157.2|in|mm}}. The gun could fire shells at about {{cvt|2500|–|2600|ft/s}}; about 4,600 could be fired before the barrel needed to be replaced. Minimum and maximum elevations were −15 and 85&nbsp;degrees, respectively. The guns' elevation could be raised or lowered at about 15&nbsp;degrees per second. The mounts closest to the bow and stern could aim from −150 to 150&nbsp;degrees; the others were restricted to −80 to 80&nbsp;degrees. They could be turned at about 25&nbsp;degrees per second. The mounts were directed by four Mark 37 fire control systems primarily through remote power control (RPC).<ref name="NavWeaps 5/38" />

The 5-inch/38 gun functioned as a [[dual-purpose gun]] (DP); that is, it was able to fire at both surface and air targets with a reasonable degree of success. However, this did not mean that it possessed inferior anti-air abilities. As proven during 1941 gunnery tests conducted aboard {{USS|North Carolina|BB-55|2}} the gun could consistently shoot down aircraft flying at {{convert|12000|–|13000|ft|mi km}}, twice the effective range of the earlier single-purpose [[5"/25 caliber gun (United States)|5-inch/25 caliber]] AA gun.<ref name="NavWeaps 5/38" /> As Japanese airplanes became faster, the gun lost some of its effectiveness in the anti-aircraft role; however, toward the end of the war, its usefulness as an anti-aircraft weapon increased again because of an upgrade to the Mark&nbsp;37 Fire Control System, Mark 1A computer, and proximity-fused shells.{{sfn|Stillwell|1996|p=256}}{{sfn|Sumrall|1988|p=80}}

The 5-inch/38 gun would remain on the battleships for the ships' entire service life; however, the total number of guns and gun mounts was reduced from twenty guns in ten mounts to twelve guns in six mounts during the 1980s' modernization of the four ''Iowa''s. The removal of four of the gun mounts was required for the battleships to be outfitted with the armored box launchers needed to carry and fire Tomahawk missiles. At the time of the 1991 Persian [[Gulf War]], these guns had been largely relegated to littoral defense for the battleships. Since each battleship carried a small detachment of [[United States Marine Corps|Marines]] aboard, the Marines would man one of the 5-inch gun mounts.{{sfn|Wass|1984|p=27}}

====Anti-air battery====

[[File:40mm-guns-USS-New-Jersey-194412.gif|thumb|left|alt=A man wearing a military uniform with an open shirt sleeping between two double-barreled guns|upright|A 40 mm quadruple gun mount onboard USS ''New Jersey'' in 1944]]

At the time of their commissioning, all four of the ''Iowa''-class battleships were equipped with 20 quad 40&nbsp;mm mounts and 49 single 20&nbsp;mm mounts.{{sfn|Terzibaschitsch|1977|pp=147–53}} These guns were respectively augmented with the Mk&nbsp;14 range sight and Mk&nbsp;51 fire control system to improve accuracy.

The [[Rheinmetall Air Defence|Oerlikon]] {{convert|20|mm|1|adj=on|sp=us}} gun, one of the most heavily produced [[anti-aircraft gun]]s of the Second World War, entered service in 1941 and replaced the [[M2 Browning|{{convert|0.50|in|1|adj=on}} M2 Browning MG]] on a one-for-one basis. Between December 1941 and September 1944, 32% of all Japanese aircraft downed were credited to this weapon, with the high point being 48.3% for the second half of 1942; however, the 20&nbsp;mm guns were found to be ineffective against the Japanese [[Kamikaze]] attacks used during the latter half of World War II and were subsequently phased out in favor of the heavier Bofors {{convert|40|mm|adj=on|sp=us}} AA gun.<ref name="NavWeaps 20mm/70">{{Harvard citation no brackets|NavWeaps.com|loc= [http://www.navweaps.com/Weapons/WNUS_2cm-70_mk234.php 20&nbsp;mm/70 Oerlikon Marks 2, 3, 4]}}</ref>

When the ''Iowa''-class battleships were commissioned in 1943 and 1944, they carried twenty quad 40&nbsp;mm AA gun mounts, which they used for defense against enemy aircraft. These heavy AA guns were also employed in the protection of Allied aircraft carriers operating in the [[Asiatic-Pacific Theater|Pacific Theater of World War II]], and accounted for roughly half of all Japanese aircraft shot down between 1 October 1944 and 1 February 1945.<ref name="NavWeaps 40mm/56">{{Harvard citation no brackets|NavWeaps.com|loc= [http://www.navweaps.com/Weapons/WNUS_4cm-56_mk12.php 40&nbsp;mm/56 Bofors Mark 1, Mark 2, and M1]}}</ref><ref name="NavWeaps 3/50">{{Harvard citation no brackets|NavWeaps.com|loc= [http://www.navweaps.com/Weapons/WNUS_3-50_mk27-33-34.php 3&quot;/50  Marks 27, 33, and 34]}}</ref>{{refn|In early 1945, the United States Navy determined that these 40&nbsp;mm guns were also inadequate for defense against Japanese kamikaze attacks in the Pacific Theater, and subsequently began to replace the Bofors guns with a [[3"/50 caliber gun|{{convert|3|in|0|adj=on}}/50 caliber gun]] capable of using [[Proximity fuze#CITEREF1946|variable time (VT) charges]].<ref name="NavWeaps 40mm/56" /><ref name="NavWeaps 3/50" /> |group=N}} Although successful in this role against WWII aircraft, the 40&nbsp;mm guns were stripped from the battleships in the jet age&nbsp;– initially from ''New Jersey'' when reactivated in 1968{{sfn|Garzke|Dulin|1995|p=139}} and later from ''Iowa'', ''Missouri,'' and ''Wisconsin'' when they were reactivated for service in the 1980s.{{refn|"As part of their modernizations, the ''Iowa''-class vessels lost their AA batteries in favor of [[Phalanx CIWS|Phalanx Close-In Weapon Systems]] and several of their 5-inch/38cal guns to make room for the launchers for the TLAMs and Harpoons."<ref>{{cite web |url=http://www.nps.gov/nr/feature/july/2012/USS_Wisconsin.pdf |title=National Register of Historic Places Registration Form |author=Nauticus |author-link=Nauticus |publisher=United States Department of the Interior |page=11 |type=Official United States Government Document |access-date=2012-11-28}}</ref>|group=N}}