Future Combat System (FCS)
The new conception of the Future Combat Systems [plural] as a
distributed battlefield system of systems [in the 20-ton class]
represents a rather dramatic departure from the previous concept of
the Future Combat System [singular] which was focused on a 40-ton
tank.
The US Army Tank-automotive and Armaments Command's future land
combat system vehicle is a 40-ton concept based on evolutionary
tank design and technology which pushes the two-person crew down
and forward into the hull with a remote turret. The crew receives
information from on-board target acquisition and hit avoidance
sensors. Target acquisition sensors are the gunner's primary sight,
a panoramic sight and an auxiliary sight. Hit avoidance sensors are
mounted in the four corners of the turret. A high pressure, 120mm
gun (XM291) is mounted on the turret.
Variable height suspension presents a lower, smaller target and
makes the tank more survivable. The height can be lowered to 64
inches or raised to 79 inches. At its maximum height, the tank has
a 19-inch ground clearance equal to the M1 fleet. Other
survivability technologies include a hull front with 40 inches of
armor that uses advanced passive with integral reactve armor for
large caliber kinetic energy and chemical energy protection. The
hull flanks and turret front and flanks have electromagnetic armor.
The armor will be supplemented by signature management, hit
avoidance and active protection. Eighty smoke grenade launchers are
buried under the skin of the turret armor. Increased cross country
mobility could be provided by an electric drive transmission and
semi-active suspension which would enable the vehicle to obtain
speeds of about 45 miles per hour. Its light weight increases
strategic deployability by allowing two to three vehicles per C-5
cargo plane and increasing the number of vehicles that can be
transported by ship, rail or highway.
The Future Combat System (FCS) Integrated TD (200006) will
demonstrate the maturity of the FCS candidates revolutionary
technologies in the vehicle configuration required for operation in
the Army After Next. Leapahead lethality in vehicles 50 percent
lighter is required to employ strategic mobility throughout the AAN
vision. Using the M1A2 Abrams as a baseline, it will demonstrate
50% reduced crew workload, 40% reduced GVW, 20% increase in fuel
economy, and a 40% increase in cross-country speed, and leap ahead
lethality. Critical issues to be addressed are the acceptance of
two crew vehicle operation, leap ahead mobility, non traditional
survivability (replacing ballistic protection with signature
management, countermeasures, and active protection), and
indefensible lethality (both direct and indirect fire).Critical
issues to be addressed are the acceptance of twocrewvehicle
operation, leapahead mobility (60 mph cross country),
nontraditional survivability (replacing ballistic protection with
signature management, countermeasures, and active protection), and
indefensible lethality (both direct and indirect fire). Virtual
prototypes will be constructed and evaluated, and a system
integration laboratory (SIL) will be implemented with laboratory
hardware to validate electronics integration.
The Future Combat System will be a revolutionary system providing
greater mobility while achieving an overall system weight
approaching 40 tons (
The gun will be a derivative of XM291 tank gun developed originally
for the future Abrams upgrades in a 120mm configuration. The XM291
gun design consisted of an integral cannon, mount, and recoil
mechanism that could be installed, as one integrated unit, in a
combat vehicle from the front of the vehicle. Technology
application to the XM291 configuration will include a composite gun
tube for reduced weight and balance of the gun at the trunnion, and
Electro-Thermal Ignition and pulse-forming network transitioned
from the ElectroThermal-Chemical technology program being conducted
by the Army Research Laboratory, providing higher velocity through
controlled burning of propellant as well as very reproducible
ignition cycles. The gun design will also include an integral
muzzle brake to reduce recoil forces on the vehicles lighter
weight structure, smart barrel actuator to actively control the
position of the muzzle at projectile exit enhancing accuracy, and a
composite gun tube thermal shroud configuration significantly
reducing gun tube signature by enemy radar.
The 120 mm XM291 Gun used enhancements developed by Watervliet
Arsenal (WVA) and Benet Laboratories to improve gun performance.
Compatibility for refit to the M1A1 or M1A2 Abrams Main Battle Tank
was another design requirement. Gun enhancements include improved
breech design, thermal shroud, modular recoil design, and improved
firepower. The cannon can be increased in caliber, if required, to
140mm with a simple tube change.
The 120mm/140mm XM91 Autoloader was designed, fabricated,
installed, and successfully tested in the Advanced TAnk Cannon
(ATAC) System vehicle testing. The Autoloader automatically takes
rounds from tank storage areas and loads them into the breech of
the tank gun -- previously a manual operation. The Autoloader can
be upgraded to support automated replenishment of the tank's
ammunition from a resupply vehicle. Development has involved
mechanical design and analysis, writing of control algorithms, and
control system design. The project also involved extensive
prototype testing, both in the laboratory and at proving grounds.
An innovative feature of the Autoloader is control of projectile
loading velocity by gripping the shell and adjusting (in real time)
its acceleration and deceleration.
The latest tanks are already well armed with guns of 120mm or
125mm, which are capable of defeating heavy armor, and their
performance can be stretched further. However, there are
indications that, even at their best, these guns will not be able
to defeat the kinds of armour that are being developed for future
tanks. In that situation, it is necessary to resort to guns of
larger calibre, and several countries have been working for some
time on 140mm guns that fire APFSDS projectiles with twice the
muzzle energy of those fired by the current 120mm tank guns. As
part of this development, the German firm of Rheinmetall has
mounted its 140mm gun in a Leopard 2 tank. The Swiss Federal
Construction Works has also mounted its 140mm gun in a Leopard
2.
These experiments indicate that the retrofitting of 140mm guns in
the existing tanks is possible. But it presents a number of major
problems. In particular, 140mm rounds are large and heavy, which
makes them difficult, if not impossible, to manhandle. As a result
they require automatic loading systems, and this implies major
changes to tank turrets and a reduction in the size of tank crews
from four to three men.
The UK, Germany and France are working on a 140mm tank gun. While
these can be fitted to tank turrets, the size of the rounds and the
need for an autoloader make the practicality of this doubtful. One
option may be to adopt an assault gun configuration capable of high
elevation fire. A 140mm high velocity gun could be at least equal
in range to a 155mm howitzer [5.5" (140mm) were the standard medium
field piece of the British Army in the Second World War]. A 140mm
gun on an assault gun body could be a useful weapon system both for
divisional artillery and to reinforce armored or infantry attacks.
The only problems with this idea at present is that the prototype
140mm gun is smoothbore, and no 140mm Guided projectiles currently
exist.
The only type of automatic loading system which may readily be
installed in existing tanks is one installed in the turret bustle.
In consequence, the configuration of tanks rearmed with 140mm guns
should resemble that already adopted for the Japanese Type 90 and
the French AMX Leclerc. In fact, this configuration has actually
been adopted for CATTB, the Component Advanced Technology Test Bed
built recently in the US to explore the future form of tanks. Thus
CATTB has a three-man crew and a bustle auto loader for its XM-291
gun, which can be fitted with either a 120mm or a 140mm
barrel.
Because of the problems they pose and the absence of a threat which
would urge their adoption, the development of 140mm tank guns is
proceeding slowly. The problems they pose are also encouraging
people to consider potential alternatives to conventional 140mm
guns. One of them is liquid-propellant guns, which were seriously
considered for tanks.
The second potential alternative is electromagnetic guns. Their
main attraction is that they can launch projectiles at more than 3
000m/s, or twice the muzzle velocity of APFSD projectiles fired by
current tank guns. The size, weight and other problems associated
with electromagnetic guns do not make them a practical proposition
for tanks. Nevertheless, there is a belief in the defence
ministries of the US and the UK that, given further development,
electromagnetic guns might become the main armament of tanks by the
year 2015 or so.
The third alternative is hybrid electrothermal-chemical guns. They
have been considered a more immediate proposition for tanks than
electromagnetic guns because they only require part of the
projectile propulsion energy to come from the electrical equipment,
which can therefore be smaller. In fact, electrothermal-chemical
guns were being proposed in the US five years ago as the main
armament of the next version of the Ml Abrams tank. However, they
are now seen to require much further development before they can be
seriously considered for tanks.
The term electrothermal chemical propulsion applies to propulsion
techniques (typically applied to gun propulsion, but with some
potential applications to space propulsion) wherein the burning
characteristics of a chemical propellant are enhanced with an
electrically induced plasma. ETC fits into a group of kinetic
energy weapons (KEWs) technologies aimed at enhancing lethality by
increasing velocity. In order of increasing electrical power
requirements, ETC falls between true EM launchers (rail guns and
coil guns) and pure chemical propulsion.
In the late 1980s, there was also some interest in pure
electrothermal (plasma-driven) weapons. However, these weapons have
extremely high electrical power requirements. While ETC continues
to be an area of interest, the functional goals of the technology
have been scaled back substantially in recent years, again because
of primary power considerations. Initially, researchers envisioned
ETC as a way to increase muzzle energy by sustaining the design
pressure over the full length of the barrel. However, current
estimates indicate that this would require on the order of 10 MJ of
electrical power.
The FCS ammunition demonstrated will incorporate novel penetrators
and high performance propellant formulations for enhanced target
defeat capability without reduced gun tube wear life or increase in
vehicle vulnerability, and axial/radial thruster mechanisms to
compensate for system errors increasing accuracy. It is expected
that a 100%+ increase in armor penetration could be realized over
the M829A2 at extended ranges with up to 70% increase in system
accuracy (Ph) at 3km under stationary conditions over the
M829A2/M1A2. The cartridge envelope will be determined from a
number of 6.2/6.3 technology programs including the Target Destruct
TD, Advanced KE Cartridge, and the feed of results to the Advanced
Future Cannon Systems work package which will conduct the virtual
prototyping studies of FCS Armament systems meeting the goals of
FCS.
A compact autoloader mechanism will be required to facilitate
expected vehicle configurations where the crew station is in the
hull, separated from gun/ammunition compartment. The specific
autoloader configuration will be defined in conjunction with the
TARDEC FCS contractor vehicle concept activity and will leverage
early 6.2 compact autoloader efforts that resulted in the
demonstration of high density magazine storage capacities, improved
fratricide protection, and weight savings. Sensor technology to
detect and resolve loader anomalies under operating conditions will
be incorporated
The fire control system will leverage commercially based open
electronic architecture developed by TACOM-TARDEC and that which
may be pursued for the Future Scout Cavalry System ATD program.
Promising technologies such as linear and non-linear lead solution,
improved ballistics, dynamic cant sensor, down-range wind sensor,
auto-zero, direct "gearless" drive, smart barrel actuators,
electronic image stabilization and modern digital servo control
will be developed for the specific armament system characteristics.
These fire control technologies will provide an additional 30%
increase in system accuracy at 3km under stationary conditions but
will provide over 500% increase in accuracy during moving
conditions.
The combined effects of accuracy improvement in ammunition and fire
control will provide an estimated increase in system accuracy of
100%+ at 3km under stationary conditions, and 500% under moving
condition as compared to the current Abrams tank.
