Editing GAU-12 Equalizer

{{Short description|25 mm rotary aircraft autocannon}}
{{More citations needed|date=November 2017}}
{{Infobox weapon
| name               = GAU-12/U Equalizer
| image              = A GAU-12 25 mm Gatling gun static display sits outside the Munitions Materiel Handling Equipment Focal Point building at Eglin Air Force Base, Fla., April 24, 2013 130424-F-OC707-003.jpg
| origin             = United States
| type               = [[Rotary cannon]]
<!-- Type selection -->| is_ranged          = Y
| is_bladed          = 
| is_explosive       = 
| is_artillery       = 
| is_vehicle         = 
| is_UK              = <!-- Service history -->
| service            = 
| used_by            = 
| wars               = <!-- Production history -->
| designer           = [[General Electric]]
| design_date        = 
| manufacturer       = [[General Dynamics]]
| production_date    = 
| number             = 
| variants           = <!-- General specifications -->
| weight             = GAU-12: {{convert|270|lb|kg}} with feed system <br />GAU-22: {{convert|230|lb|kg}} without feed system
| length             = 83.2 in (2.11 m)
| part_length        = 
| width              = GAU-12: {{convert|11.5|in|mm}} <br />GAU-22: {{convert|11.1-13.3|in|mm}}
| height             = {{convert|10.2|in|mm}}
| crew               = <!-- Ranged weapon specifications -->
| cartridge          = 25 × 137 mm
| caliber            = 25 mm (0.98 in)
| barrels            = GAU-12: 5-barrel <br />GAU-22: 4-barrel <br />(progressive RH parabolic twist, 11 grooves)
| action             = Hydraulic, Electric, Pneumatic
| rate               = GAU-12: 1,800–4,200 rounds per minute <br />GAU-22: 3,300 rounds per minute
| velocity           = (HEI) 3,400 ft/s (1,040 m/s); (API) 3,280 ft/s (1,000 m/s); (APEX) 3,200 ft/s (970 m/s)
| range              = 
| max_range          = {{convert|12000|ft|m|sigfig =3}}
| feed               = Linked or linkless
| sights             = Lead Computing Optical Sight System (LCOSS)
<!-- Artillery specifications -->| breech             = 
| recoil             = 
| carriage           = 
| elevation          = 
| traverse           = <!-- Bladed weapon specifications -->
| blade_type         = 
| hilt_type          = 
| sheath_type        = 
| head_type          = 
| haft_type          = <!-- Explosive specifications -->
| diameter           = 
| filling            = 
| filling_weight     = 
| detonation         = 
| yield              = <!-- Vehicle specifications -->
| armour             = 
| primary_armament   = 
| secondary_armament = 
| engine             = 
| engine_power       = 
| pw_ratio           = 
| suspension         = 
| vehicle_range      = 
| speed              = 
}}

The '''General Dynamics GAU-12/U Equalizer''' is a five-barrel [[25 mm caliber|25 mm]] [[Gatling gun|Gatling-type]] [[rotary cannon]]. The GAU-12/U is used by the United States, Italy and Spain, which mount the weapon in their attack jets such as the [[AV-8B Harrier II]], airborne [[gunship]]s such as the [[Lockheed AC-130]], and land-based fighting vehicles.
A lighter four-barrel version, designated '''GAU-22/A''', is mounted on [[F-35 Lightning II]] fighter jets.
[[Category:Multiple-barrel firearms]]

==Development==
The five-barrel Equalizer cannon was developed in the late 1970s, based on the mechanism of the 30mm [[GAU-8/A Avenger]] cannon, but firing a new [[NATO]] series of 25&nbsp;mm ammunition. The GAU-12/U cannon is operated by an 11&nbsp;kW (15&nbsp;hp) [[electric motor]], or in external mounts supplied by a [[bleed air]] driven pneumatic system. Its rate of fire is normally 3,600 rounds per minute, with a maximum of 4,200 rounds per minute. For use in the [[AC-130]] gunship, the fire rate is limited to 1,800 rounds per minute in order to conserve ammunition and reduce barrel wear.

===GAU-22/A===
The '''GAU-22/A''' is a four-barrel version of the GAU-12/U designed for use on the [[F-35 Lightning II]].<ref>{{cite web |title=25mm Gun Systems for the F-35 Joint Strike Fighter |url=http://www.dtic.mil/ndia/2006garm/thursday/maher.pdf |publisher=[[National Defense Industrial Association]] |last=Maher |first=Dave |date=2006-03-30 |access-date=2008-10-14 |url-status=dead |archive-url=https://web.archive.org/web/20071029160922/http://www.dtic.mil/ndia/2006garm/thursday/maher.pdf |archive-date=2007-10-29 }}</ref>   
The GAU-22/A's major difference is the use of four barrels, rather than the GAU-12/U's five barrels.  The GAU-22/A is lighter and has a reduced rate of fire of 3,300 rounds per minute, but maintains the same, high accuracy of 5 [[milliradian]]s, 80% circle<ref>[https://www.gd-ots.com/armaments/aircraft-guns-gun-systems/gau22a/ GAU-22/A fact sheet] General Dynamics</ref> of the GAU-12<ref>[https://www.gd-ots.com/armaments/aircraft-guns-gun-systems/gau12u/ GAU-12/U fact sheet] General Dynamics</ref> and A-10's GAU-8.<ref>[https://www.gd-ots.com/armaments/aircraft-guns-gun-systems/gau8a/ GAU-8/A fact sheet] General Dynamics</ref> The weapon is produced by [[General Dynamics]] Ordnance and Tactical Systems.

The [[Nammo]] 25&nbsp;mm PGU-47/U [[High Explosive Incendiary/Armor Piercing Ammunition|APEX]] (Armor Piercing with Explosive)<ref>{{cite web |url=https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2014/armaments/Wed15439Sande.pdf |title=APEX – Armor Piercing with Explosive. The Dual Purpose Round for the F-35 |website=[[Nammo]]}}</ref> projectile has been developed for the GAU-22/A.<ref>[http://www.upi.com/Business_News/Security-Industry/2010/11/29/Norway-contracts-for-F-35-ammunition/UPI-87971291045636/ "Norway contracts for F-35 ammunition."] ''UPI'', 29 November 2010.</ref>
It features a tungsten carbide penetrator in the tip and an explosive fragmentation body, to be multi-purpose against both hardened and soft targets. Also, the presence of a [[Ratchet (device)|clockworking]] inertia-driven mechanical [[fuze]] in the mid-body, protects the round from shocks, misfires and cookoffs, making it safer to handle and fire.

==Uses==
[[File:AV-8B Harrier taking off in Sierra Leone - May 2006 (Defense Visual Information Center, USMC, USDoD) CROPPED.jpg|thumb|right|An AV-8 Harrier II; the two pods on the belly of the aircraft hold the cannon (port side, visible hole) and ammunition (starboard side).]]

The current principal application for the Equalizer is the [[AV-8 Harrier II]]s of the [[United States Marine Corps]], [[Italian Navy]] and [[Spanish Navy]]. The Harrier II carries the Equalizer system in a pair of detachable pods mounted on the fuselage underside, with the cannon in the port pod and 300 rounds of ammunition in the starboard pod, fed through a bridge at the aft ends of the pods that also contains the drive system for the gun (unlike previous Harriers which used dual cannons, with each pod containing a [[30 mm caliber|30mm]] [[ADEN cannon|ADEN gun]] and its own ammunition supply). The complete installation, which includes a double-ended feed system that returns empty cartridges to the [[Magazine (firearms)|magazine]], weighs 900&nbsp;lb (410&nbsp;kg) empty and 1,230&nbsp;lb (560&nbsp;kg) loaded. The detachable pods are located and shaped to be interchangeable with the usual ventral strakes or fences under the Harrier, both serving to help trap a cushion of high-pressure air under the aircraft to add lift while in hover mode. The strakes can easily be removed and the pods attached in their place, serving the same function while adding useful firepower.{{citation needed|date=November 2017}}

[[Royal Air Force|RAF]] and [[Fleet Air Arm]] Harriers did not adopt the Equalizer for their [[BAE Harrier II|Harrier GR7]] and GR9s. The British had originally planned a pair of '''ADEN 25''' guns (using the same ammunition as the GAU-12/U, but based on the 30&nbsp;mm [[ADEN cannon]]). That gun was canceled in [[1999 in aviation|1999]] after protracted development problems, and British Harrier GR7/9s were without gun armament until retirement.{{Citation needed|date=June 2007}}

The Equalizer is also used in the [[Lockheed AC-130|AC-130U Spooky]] [[gunship]], where one cannon is mounted on the port side, and the [[United States Marine Corps|U.S. Marine Corps]] [[LAV-25|LAV-AD]] air-defense vehicle. Other applications have been planned for the GAU-12/U, including a mounting for the [[AH-1 Cobra]] [[attack helicopter]].

The Equalizer was also used as the basis for the '''''Sea Vulcan 25''''', a turret mounted gun for naval ship self-defense, although not as a [[Close-In Weapon System]], as the gun was not automatic nor did it use radar tracking. Instead the gun was manually aimed using a digital gun sight and fire control. Sea Vulcan consisted of a 540-round helical drum magazine, a one-piece aluminum turret that can be opened with just a screwdriver, and the main gun. One unique advantage of the system was that it was capable of operating independently of ship's power; the gun and ammunition magazine were powered by a {{convert|3,000|psi|MPa|abbr=on}} [[pneumatic actuator|pneumatic drive]] and the turret motor by twin [[lead–acid battery|lead–acid batteries]].

Intended as a higher-firepower alternative to conventional deck-mounted machine guns and cannon, the weapon employs the Navy's Mk&nbsp;24 target designator and laser range finder for enhanced accuracy. The gun was developed in the mid-1980s as a cost-effective protection for ships smaller than [[frigate]] or [[corvette]] or patrol boats, but did not enter this service.

The GAU-12 was utilized as the principal armament for the [[Scaled Composites ARES|Rutan ARES]].

The four-barrel GAU-22 is carried internally by the F-35A (the [[CTOL]] version of the F-35) on the port side of the fuselage, with 181 PGU-47/U APEX rounds. In contrast, the F-35B [[STOVL]] and C [[CATOBAR]] aircraft mount the GAU-22 in a stealthy external [[gun pod]] under the fuselage, together with 220 rounds.

==Specifications (GAU-12/U)==
[[File:GAU-12U test firing.ogv|thumb|GAU-12/U gun test firing]]

*'''Type''': Five-barreled [[rotary cannon]]
*'''Caliber''': [[25 mm caliber|25 mm (0.98 in)]]
*'''Operation''': [[Electric motor|electric]]
*'''Length''': 83.2 in (2.11 m)
*'''Weight (complete)''': 270&nbsp;lb (122&nbsp;kg)
*'''Rate of fire''': 3,600–4,200 rounds per minute
*'''Muzzle velocity''': (HEI) 3,400&nbsp;ft/s (1,040&nbsp;m/s); (API) 3,280&nbsp;ft/s (1,000&nbsp;m/s)
*'''Projectile weight''': (HEI) 6.5 oz (184 g); (API) 7.6 oz (215 g)
*'''Muzzle energy''': (HEI) 73,400&nbsp;ft·lbf (99,500 joules); (API) 79,300&nbsp;ft·lbf (107,500 joules)

==Specifications (GAU-22/A)==

*'''Type''': Four-barreled rotary cannon
*'''Caliber''': 25&nbsp;mm (0.98&nbsp;in)
*'''Operation''': electric
*'''Length''': 83.2 in (2.11 m)
*'''Weight (complete)''': 230&nbsp;lb (104&nbsp;kg)
*'''Rate of fire''': 3,300 rounds per minute
*'''Muzzle velocity''': (APEX) 3,200&nbsp;ft/s (970&nbsp;m/s)
*'''Projectile weight''': (APEX) 7.87 oz (223 g)
*'''Muzzle energy''': (APEX) 77,400&nbsp;ft·lbf (104,900 joules)

==Similar systems==
* [[Gryazev-Shipunov GSh-6-23]]
* [[Myriad CIWS]]

==References==
{{Reflist|1}}

==External links==
{{Commons category|GAU-12 Equalizer}}
* [https://web.archive.org/web/20170819143124/http://www.gd-ots.com/armament_systems/mbw_GAU-12U.html General Dynamics Ordnance and Tactical Systems GAU-12/U page]
* [http://www.gd-ots.com/armament_systems/mbw_GAU-22A.html General Dynamics Ordnance and Tactical Systems GAU-22/A page]
* {{usurped|1=[https://web.archive.org/web/20130513133834/http://www.gdatp.com/factsheets/A079_F-35%20Lightning%20II.pdf F-35 JSF gun system page on General Dynamics Armament and Technical Products (manufacturer) site]}}
* [http://www.fas.org/man/dod-101/sys/ac/equip/gau-12.htm FAS.org: GAU-12 Equalizer]
* [http://www.globalsecurity.org/military/systems/aircraft/systems/gau-12.htm Globalsecurity.com's article on the GAU-12]
* [https://www.youtube.com/watch?v=qhA8kGfSV1s Sea Vulcan archive Video]
{{Multiple Barrel Firearms}}
{{Modern Gatling Guns}}

{{DEFAULTSORT:Gau-12 Equalizer}}
[[Category:Rotary cannon]]
[[Category:Multi-barrel machine guns]]
[[Category:Aircraft guns]]
[[Category:Articles containing video clips]]
[[Category:25 mm artillery]]
[[Category:Military equipment introduced in the 1970s]]