The GAU-13/A is a four-barreled rotary cannon based on the mechanism of the larger GAU-8, sharing the same massive 30 mm ammunition. Like the Avenger, it has a double-ended feed system with reverse clearing to remove unfired rounds. Unlike the GAU-8, however, it is pneumatically driven, giving it arate of fire of 2,400 rounds per minute. Minimum time between stoppages is estimated at 32,000 rounds, making it a very reliable weapon.
The GAU-13/A uses the same range ofPGU-13 High Explosive Incendiary (HEI) andPGU-14 Armor-Piercing Incendiary (API) rounds (which contain adepleted uranium penetrator) as the Avenger. Despite its somewhat lower rate of fire compared to the seven-barreled Avenger, it is an immensely powerful weapon.
The principal application for the GAU-13/A was theGPU-5/A gun pod (originally marketed as theGEPOD 30). The pod is 4.3 metres (14 feet 1 inch) long and can be mounted on any standardNATO 762 mm (30.0 in) suspension lugs. It holds 353 rounds of ammunition, enough for approximately nine seconds of continuous fire. The GPU-5/A weight is 600 kg (1,300 lb) empty and 841 kg (1,854 lb) fully loaded. The pod is completely self-contained.
The GPU-5/A was intended for carriage on a wide range of U.S. tactical aircraft, including theF-15 Eagle andF-16 Fighting Falcon. In the mid-1980s theUSAF considered a specialized variant of the F-16 for theclose air support (CAS) mission, using the GPU-5, as a substitute to or adjunct for theA-10 Thunderbolt II.
The GPU-5 pod, however, proved unsatisfactory in service. It was briefly tried on someAir National GuardF-16 Fighting Falcons during the 1991Gulf War, but was removed from service after barely a day of combat use because of its very poor accuracy. Despite the cannon's impressive ballistic characteristics, the pylon mounting was not sufficiently rigid to prevent deflection, and the weapon's heavy recoil exacerbated the problem by causing pylon misalignment. Further, the GPU-5 was not integrated into the F-16's sighting system. The GPU-5 is no longer in U.S. service, although someThaiF-5E Tiger II aircraft still carry the weapon; it was also tested on theF-20 Tigershark.
In mid/late 1995, the U.S. Marine Corps conducted a trial of the GPU-5 on theLCAC-66, as a potential weapon to providesuppressive fire for landing forces. The pod was mounted on a standard MAU-12 bomb rack, itself mounted in a standard cargo container. It was believed that four such containers could then be carried on the LCAC. The resulting combination was referenced as the Gun Platform Air Cushion (GPAC). By 1997, the Marines had reportedly acquired the USAF's entire stock of GAU-13/A cannons and GPU-5 pods as surplus. Besides the GPAC, the GAU-13/A was also touted as possible armament on ships and ground vehicles such as theLAV-25.[1]
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