GAU-12/U 25 mm EQUALISER CANNON
TYPE:
25 mm Gatling aircraft cannon.
DEVELOPMENT:
The GAU-12/U 25 mm lightweight cannon was developed
from the GAU-8/A cannon making full use of the
technology involved. It was developed by General
Electric (now Martin-Marietta Armament Systems) in
parallel with an external pod system to provide the
USMC Harrier V/STOL aircraft with a powerful,
lightweight air-to-air and air-to-ground attack
capability. For details of the pod system see the AV-8B
Armament System entry within this binder. The
five-barrelled cannon, known as the Equaliser, was
designed to be capable of firing the standard NATO 25
mm ammunition, and was the first of the family of
Vulcan cannons to do so. GE also developed a full-bore
armour-piercing incendiary round as part of the AV-8B
armament contract in order to supplement the cannon's
normal Bushmaster family of TP, HEI and APDS ammunition.
DESCRIPTION:
The GAU-12/U is a 25 mm five-barrelled Gatling type
cannon similar in design to the GAU-8/A (for full
details see separate entry) and employing the same
reverse clearing operation of the GAU-8/A. However,
whereas the GAU-8/A is hydraulically operated, the
GAU-12/U can be driven by mechanical, pneumatic
electric or hydraulic means. The bare cannon is 2.11
m
long, has a maximum body diameter of 279 mm and weighs
122 kg. All barrels are rigidly clamped together and
attached to the forward end of the breech rotor which
rotates in a stationary housing.
In the AV-8B armament system the GAU-12/U is driven
by a pneumatic motor turned at 9000 rpm by aircraft
engine bleed air and geared down to the rear of the
cannon to give a normal firing rate of 3600 rds/min.
There are reports that this can be increased to 4200
rds/min.
SPECIFICATIONS:
Calibre: 25 mm
No of barrels: 5
Length: 2.11 m
Weight: 122 kg
Rate of fire: 3600 rds/min
Muzzle velocity: 1036 m/s with API ammunition