The General Electric GAU-12/U Equalizer is a 25 mm, five-barrel Gatling gun used by the United States and several other NATO nations.

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 25mm ammunition.

The GAU-12U cannon is operated by a 15 hp (11.1 kW) electric motor, in external mounts supplied by a bleed air-drive pneumatic system. Its rate of fire is normally 3,600 rounds per minute, with a maximum of 4,200 rounds per minute.

The Equalizer normally uses PGU-20/U armor-piercing incendiary (API) or PGU-22 or PGU-25 high-explosive incendiary (HEI) ammunition. With a harder-hitting projectile and comparable muzzle velocity, it is more lethal than the older M61 Vulcan, and more effective than the older 30mm ADEN cannon it replaces.

The current principal application for the Equalizer is the AV-8 Harrier IIs of the USMC, Italian Air Force and Spanish Air Force . 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 (408.2 kg) empty and 1,230 lb (557.9 kg) loaded. RAF and Fleet Air Arm Harriers have not adopted the Equalizer for their Harriers. The British had originally planned a pair of ADEN 25 guns (using the same ammunition as the GAU-12/U, but based on the 30mm ADEN cannon). That gun was cancelled in 1999 after protracted development problems, and British Harriers and Sea Harriers have been forced to rely on the older 30mm gun.

The Equalizer is also used in the ACU-130U 'Spooky' gunship (where one cannon is mounted on the port side) and the US 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 helicopter.

The GAU-12 will be the cannon armament of the F-35 Joint Strike Fighter. The USAF F-35A CTOL will have an internal GAU-12 with 180 rounds of ammunition, while the F-35B STOVL version for the USMC and Royal Navy and the F-35C for the USN will carry the same weapon in a streamlined centerline pod with 220 rounds of ammunition.

The weapon's current contractor is General Dynamics Armament Systems .

Specifications

• Type: five-barrel rotary cannon
• Caliber: 25 mm (0.98 in)
• Operation: electric
• Length: 83.2 in (2.11 m)
• Weight (complete): 270 lb (122.5 kg)
• Rate of fire: 3,600 - 4,200 rounds per minute
• Muzzle velocity: (HEI) 3,400 ft/s (1,036 m/s); (API) 3,280 ft/s (1,000 m/s).
• Projectile weight: (HEI) 6.5 oz (184 g); (API) 7.58 oz (215 g)

External link

• FAS.org: GAU-12 Equalizer