GAU-12 Equalizer
Encyclopedia
The General Dynamics
GAU-12/U Equalizer is a five-barrel 25 mm
Gatling gun
-style rotary cannon. The GAU-12/U is used by the United States
, Italy and Spain, which mount the weapon in their fighter jets such as the AV-8B Harrier II
, airborne gunship
s such as the Lockheed AC-130
, and land-based fighting vehicles.
, 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 was lowered to 1800 rounds per minute in order to conserve ammunition.
, Italian Navy
and Spanish Navy
. The Harrier II carries the Equalizer system in a pair of pods mounted on the fuselage sides, 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. The complete installation, which includes a double-ended feed system that returns empty cartridges to the magazine, weighs 900 lb (410 kg) empty and 1,230 lb (560 kg) loaded.
RAF
and Fleet Air Arm
Harriers have not adopted the Equalizer for their 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 mm ADEN cannon
). That gun was canceled in 1999
after protracted development problems, and British Harrier GR7/9s were without gun armament until retirement.
The Equalizer is also used in the AC-130U Spooky
gunship
, where one cannon is mounted on the port side, and the U.S. Marine Corps
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
.
. In the CTOL
version of the aircraft it will carry the gun internally, while on the STOVL
and CV
versions an external podded gun will be available. The major difference between the GAU-12/U and the GAU-22/A is the use of a four barrel system, rather than the five barrels on the standard GAU-12/U. The four barrel version is purported to reduce weight and improve accuracy. This system is currently undergoing intensive testing and qualification. The weapon's current contractor is General Dynamics Armament and Technical Products
.
The rate of fire is reduced to 3300 rounds per minute and the accuracy is increased to 1.4 milliradians radius as compared to the GAU-12.
General Dynamics
General Dynamics Corporation is a U.S. defense conglomerate formed by mergers and divestitures, and as of 2008 it is the fifth largest defense contractor in the world. Its headquarters are in West Falls Church , unincorporated Fairfax County, Virginia, in the Falls Church area.The company has...
GAU-12/U Equalizer is a five-barrel 25 mm
25 mm caliber
The 25x137 mm caliber/.98425 inch is one of the standard sizes of cannon and autocannon ammunition for NATO forces. The round itself has a length of approximately 223 mm .-Usage:...
Gatling gun
Gatling gun
The Gatling gun is one of the best known early rapid-fire weapons and a forerunner of the modern machine gun. It is well known for its use by the Union forces during the American Civil War in the 1860s, which was the first time it was employed in combat...
-style rotary cannon. The GAU-12/U is used by the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, Italy and Spain, which mount the weapon in their fighter jets such as the AV-8B Harrier II
AV-8B Harrier II
The McDonnell Douglas AV-8B Harrier II is a second-generation vertical/short takeoff and landing ground-attack aircraft. An Anglo-American development of the British Hawker Siddeley Harrier, the Harrier II is the final member of the Harrier family that started with the Hawker Siddeley P.1127 in...
, airborne gunship
Gunship
The term "gunship" is used in several contexts, all sharing the general idea of a light craft armed with heavy guns.-In Navy:In the Navy, the term originally appeared in the mid-19th century as a less-common synonym for gunboat.-In military aviation:...
s such as the Lockheed AC-130
Lockheed AC-130
The Lockheed AC-130 gunship is a heavily-armed ground-attack aircraft variant of the C-130 Hercules transport plane. The basic airframe is manufactured by Lockheed, while Boeing is responsible for the conversion into a gunship and for aircraft support...
, and land-based fighting vehicles.
Development
The five-barrel 'Equalizer' cannon was developed in the late 1970s, based on the mechanism of the GAU-8/A Avenger cannon, but firing a new NATO series of 25 mm ammunition. The GAU-12/U cannon is operated by a 15 hp (11 kW) electric motorElectric motor
An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...
, in external mounts supplied by a bleed air
Bleed air
Bleed air in gas turbine engines is compressed air taken from within the engine, after the compressor stage and before the fuel is injected in the burners. While in theory bleed air could be drawn in any gas turbine engine, its usage is generally restricted to jet engines used in aircraft...
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 was lowered to 1800 rounds per minute in order to conserve ammunition.
Current uses
The current principal application for the Equalizer is the AV-8 Harrier IIs of the United States Marine CorpsUnited States Marine Corps
The United States Marine Corps is a branch of the United States Armed Forces responsible for providing power projection from the sea, using the mobility of the United States Navy to deliver combined-arms task forces rapidly. It is one of seven uniformed services of the United States...
, Italian Navy
Italian Navy
Italian Navy may refer to:* Pre-unitarian navies of the Italian states* Regia Marina, the Royal Navy of the Kingdom of Italy * Italian Navy , the navy of the Italian Republic...
and Spanish Navy
Spanish Navy
The Spanish Navy is the maritime branch of the Spanish Armed Forces, one of the oldest active naval forces in the world. The Armada is responsible for notable achievements in world history such as the discovery of Americas, the first world circumnavigation, and the discovery of a maritime path...
. The Harrier II carries the Equalizer system in a pair of pods mounted on the fuselage sides, 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. The complete installation, which includes a double-ended feed system that returns empty cartridges to the magazine, weighs 900 lb (410 kg) empty and 1,230 lb (560 kg) loaded.
RAF
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...
and Fleet Air Arm
Fleet Air Arm
The Fleet Air Arm is the branch of the British Royal Navy responsible for the operation of naval aircraft. The Fleet Air Arm currently operates the AgustaWestland Merlin, Westland Sea King and Westland Lynx helicopters...
Harriers have not adopted the Equalizer for their 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 mm ADEN cannon
ADEN cannon
The Royal Small Arms Factory ADEN is a 30 mm revolver cannon used on many military aircraft, particularly those of the British Royal Air Force and Fleet Air Arm...
). That gun was canceled in 1999
1999 in aviation
This is a list of aviation-related events from 1999:-February:* February 16 – Gulfstream II carrying film director Barry Sonnenfeld , slid off runway at Van Nuys, California; Sonnenfeld was uninjured.*February 24 – A China Southwest Airlines Tupolev Tu-154 crashes in Ruian, China while descending...
after protracted development problems, and British Harrier GR7/9s were without gun armament until retirement.
The Equalizer is also used in the AC-130U Spooky
Lockheed AC-130
The Lockheed AC-130 gunship is a heavily-armed ground-attack aircraft variant of the C-130 Hercules transport plane. The basic airframe is manufactured by Lockheed, while Boeing is responsible for the conversion into a gunship and for aircraft support...
gunship
Gunship
The term "gunship" is used in several contexts, all sharing the general idea of a light craft armed with heavy guns.-In Navy:In the Navy, the term originally appeared in the mid-19th century as a less-common synonym for gunboat.-In military aviation:...
, where one cannon is mounted on the port side, and the U.S. Marine Corps
United States Marine Corps
The United States Marine Corps is a branch of the United States Armed Forces responsible for providing power projection from the sea, using the mobility of the United States Navy to deliver combined-arms task forces rapidly. It is one of seven uniformed services of the United States...
LAV-AD air-defense vehicle. Other applications have been planned for the GAU-12/U, including a mounting for the AH-1 Cobra
AH-1 Cobra
The Bell AH-1 Cobra is a two-bladed, single engine attack helicopter manufactured by Bell Helicopter. It shares a common engine, transmission and rotor system with the older UH-1 Iroquois...
attack helicopter
Attack helicopter
An attack helicopter is a military helicopter with the primary role of an attack aircraft, with the capability of engaging targets on the ground, such as enemy infantry and armored vehicles...
.
GAU-22/A
The GAU-22/A is the latest application of the GAU-12/U, which is a four barrel version designed for use on the F-35 Lightning IIF-35 Lightning II
The Lockheed Martin F-35 Lightning II is a family of single-seat, single-engine, fifth generation multirole fighters under development to perform ground attack, reconnaissance, and air defense missions with stealth capability...
. In the CTOL
CTOL
CTOL is an acronym for conventional take-off and landing, and is the process whereby conventional aircraft take off and land, involving the use of runways. The aircraft will taxi along the runway until its rotation speed is reached, then climb into the air...
version of the aircraft it will carry the gun internally, while on the STOVL
STOVL
STOVL is an acronym for short take off and vertical landing.This is the ability of some aircraft to take off from a short runway or take off vertically if it does not have a very heavy payload and land vertically...
and CV
Aircraft carrier
An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...
versions an external podded gun will be available. The major difference between the GAU-12/U and the GAU-22/A is the use of a four barrel system, rather than the five barrels on the standard GAU-12/U. The four barrel version is purported to reduce weight and improve accuracy. This system is currently undergoing intensive testing and qualification. The weapon's current contractor is General Dynamics Armament and Technical Products
General Dynamics
General Dynamics Corporation is a U.S. defense conglomerate formed by mergers and divestitures, and as of 2008 it is the fifth largest defense contractor in the world. Its headquarters are in West Falls Church , unincorporated Fairfax County, Virginia, in the Falls Church area.The company has...
.
The rate of fire is reduced to 3300 rounds per minute and the accuracy is increased to 1.4 milliradians radius as compared to the GAU-12.
Specifications (GAU-12)
- Type: Five-barreled rotary cannonGatling gunThe Gatling gun is one of the best known early rapid-fire weapons and a forerunner of the modern machine gun. It is well known for its use by the Union forces during the American Civil War in the 1860s, which was the first time it was employed in combat...
- Caliber: 25 mm (0.98 in)25 mm caliberThe 25x137 mm caliber/.98425 inch is one of the standard sizes of cannon and autocannon ammunition for NATO forces. The round itself has a length of approximately 223 mm .-Usage:...
- Operation: electricElectric motorAn electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...
- Length: 83.2 in (2.11 m)
- Weight (complete): 270 lb (122 kg)
- Rate of fire: 3,600 - 4,200 rounds per minute
- Muzzle velocity: (HEI) 3,400 ft/s (1,040 m/s); (API) 3,280 ft/s (1,000 m/s)
- Projectile weight: (HEI) 6.5 oz (184 g); (API) 7.6 oz (215 g)
- Muzzle energy: (HEI) 73,400 ft·lbf (99,500 joules); (API) 79,300 ft·lbf (107,500 joules)