XM8 Armored Gun System
The FMC XM8 Armored Gun System
(AGS) is designed to incorporate tanklevel
firepower in a compact, mobile, and
airportable vehicle. The controversial
AGS concept originated in the early
1980s as a means to provide more powerful
direct support to rapidly deployable
forces such as the US Army's light, mountain,
and airborne divisions. Doubts remain
about its ability to avoid engaging
heavy forces while usefully supporting offensive
action.
The M8's profile resembles a conventional
tank, and the vehicle has a typical
tank layout. The high engine compartment
aft limits gun depression to a 270°
arc. The large electrohydraulic, two-axis
stabilized turret is asymmetrically laid out
with the gun left of center in the mantlet
and the turret slightly to the right of the
centerline in the hull. (The combination
of asymmetries repositions the gun on
the vehicle centerline.)
The XMS's main armament is the 105-
mm XM35 tank gun, a modified M68 that
was turned upside down by Rheinmetall
of Germany and fitted with a soft-recoil
system that doubles the recoil length and
buffers it through a rifled, multislotted
muzzle brake that is 35% efficient. A
fume extractor is fitted halfway up the
barrel. When the gun is depressed, its
breech recoils through hydraulically operated
doors in the turret roof.
FMC Naval Systems Division supplies
the 21-projectile autoloader; nine more
rounds are stowed forward near the
driver. The AGS can fire a full range of
105-mm ammunition, including Armor-
Piercing Fin-Stabilized Discarding Sabot
(APFSDS) rounds.
Fire control equipment includes the
Computing Devices Corp. digital fire
control system with 32-bit microprocessors
and MIL-STD-1553B digital
databus. The gunner's primary sensor is
the Hughes Aircraft Co. day/night thermal
sight and integrated laser rangefinder
in a two-axis stabilized mount on
the right side of the turret. A relayed picture
of the gunner's sight image can appear
in the commander's sight.
To balance the contradictory demands
imposed by airportability and the need
for some level of protection, the AGS can
be fitted with four levels of protection:
none, Level 1 against splinters, Level 2
against armor-piercing small-arms and
small-cannon fire, and Level 3 against
cannon up to 30-mm. The crew compartment
is sealed against Nuclear, Biological,
and Chemical (NBC) warfare effects,
even when the gun's recoil doors are
open.
Vehicle mobility is aided by a relatively
high power-to-weight ratio and relatively
low ground pressure. Maintainability is
enhanced by a powerpack that can be
rolled out through a drop-down rear
door for repair or replacement. An essential
feature of the M8's design is its airportability:
three can be loaded into a C-5 or
C-17 transport, two into a C-141, and one
in a C-130. The C-130 can deliver the
"stripped" M8—lacking any armor and
the commander's cupola—in a Low-
Velocity Airdrop (LVAD).
DEVELOPMENT • In its earlier trials
form, the M8 was known as the Close
Combat Vehicle Light (CCVL). Development
of the predecessor CCVL began in
1983, with prototype rollout on August
30, 1985. Interest in the AGS waxed and
waned throughout the 1980s for many
reasons; requirements were difficult to
reconcile—the Army and Marine Corps
had differing ideas.
After several changes and delays, a
$27.7-million contract for Phase I was
awarded on June 4, 1992, to FMC Corp.
Defense Systems Group of San Jose, California
(now United Defense); full Phase I
contract amount was $119.6 million. Approximately
300 vehicles are planned,
with an initial operational capability in
1996-97.
In September 1993, United Defense
and Taiwan's Hwa Fong Industries announced
plans to build several hundred
M8s for Taiwanese service.
COMBAT EXPERIENCE • None.
SPECIFICATIONS •
CREW 3 (commander, gunner, driver)
COMBAT WEIGHT ranges from 36,900 Ib
(16,738 kg) (airdrop) to Level 3 armor
52,000 Ib (23,587 kg)
ground pressure
12.161b/in2 (0.86kg/cm2)
DIMENSIONS
hull length 20 ft (6.1 m), with gun
forward 30 ft IVa in
(9.18m)
extreme width
8 ft 10 in (2.69 m)
height to top of turret
7 ft 9M> in (2.37 m)
ground clearance
16 in (406 mm)
length of track on ground
11 ft 10 in (3.61m)
track width 15 in (381 mm)
MAIN ARMAMENT Rheinmetall/
Watervliet 105-mm/51-cal rifled gun
with 21 ready rounds in autoloader
and 9 stowed in hull
elevation -10°/+20°, traverse 360°
weapons 7.62 coaxial machine gun
and 12.7-mm M2HB
antiaircraft machine
gun
SENSORS AND FERE CONTROL digital fire
control computer, stabilized day/
night thermal sight and laser rangefinder
for gunner, 8 periscopes for
commander, 5 periscopes for driver
with image intensifier in center
ARMOR aluminum hull with steel armor
modules
POWERPLANT Detroit Diesel 6V-921A
550-hp liquid-cooled turbocharged
2-stroke V-6 diesel engine, General
Electric HMPT-500-3EC hydromechanical,
infinitely variable transmission
with 3 forward/1 reverse
ranges
power-to-weight ratio
30.47 hp/metric ton
(Level 1) down to
23.32 hp/metric ton
(Level 3)
SUSPENSION (EACH SIDE) independent
trailing arm torsion bar, 6 road
wheels, rear drive, front idler, 5 linear
shock absorbers, 10-in (254-mm)
wheel travel, no return rollers
SPEED 43.5 mph (70 km/h), acceleration
0-20 mph (0-32 km/h) at Level 3
weight 6.5 sec, range 300 mi (483 km)
OBSTACLE CLEARANCE vertical 2 ft 6 in
(0.76 m), gradient 60%, side slope
40%, trench 7 ft (2.13 m), fording 3 ft
4 in (1.02m)
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