By Ann Roosevelt
ABERDEEN PROVING GROUND, Md.–The 120mm XM360 gun that will provide the firepower for the Army’s Future Combat System (FCS) Mounted Combat System (MCS) is firing for safety certification, according to officials.
“Once certification is completed, then troops can be near the gun and fire it,” Dave Smith, U.S. Army Benet Laboratories, Watervliet, N.Y., the Integrated Product Team Design Team Leader, told reporters visiting the Aberdeen Test Center range here March 14. Before soldiers get near the gun, some seven to 10,000 rounds will be fired. The safety certification is tied to NATO standardization agreement (STANAG) 4110, which links to allied interoperability.
“As far as I can tell it’s the most technologically advanced, lightweight 120 in the world,” Bob McCallister, General Dynamics [GD] MCS primary weapon assembly integrated product team leader, said. The XM360 has all the capabilities of the current Abrams tank M256 gun in a smaller, lighter more durable package.
Army Lt. Col. Robert Hannah, product manager for Mounted Combat Systems, said, “Everything you see is about the soldiers, adding capability for soldiers.”
The XM360 will be the primary weapon on the MCS, one of eight FCS Manned Ground Vehicle variants. General Dynamics and BAE Systems are teamed to develop these vehicles for FCS Lead System Integrator Boeing [BA] and SAIC [SAI].
Several advances allow the 120mm to provide the capability of an Abrams in a lighter package.
For example, the unmanned gun turret provides a smaller silhouette and volume. “You can’t see or touch” it from the crew compartment, McCallister said. Embedded sensors offer prognostics and diagnostics providing information on the gun’s behavior and can predict failure, but, more importantly, anticipate problems.
The gun is more than 2,000 pounds lighter than the Abrams M256 120mm, Smith said. Benet Laboratories works under a Cooperative Research and Development Agreement with General Dynamics on this. Benet does the acceptance testing, both firing and non-firing.
The gun tube itself is comprised of new, ultra high strength steel and composites. There are many new steels, but Smith said this is one of the first in the cost range the military can afford. There is a composite overwrap in several areas, the first gun in the world where the overwrap is part of the tube.
The lightweight XM360 has some “whip” to it, so a muzzle brake reduces shock and vibration on the crew and vehicle. A lot of study went into how many holes and where they should be on the brake, Hannah said.
Emory Thompson, Aberdeen Test Center director of MCS, said the forces at work are tremendous. In some instances, when the Sheridan tank fired, it would roll up on its side and back. Here, the XM360 is designed with the vehicle to cut those forces.
For example, a muzzle reference sensor predicts and communicates with the fire control system to pinpoint where the muzzle is pointing and when to fire.
Additionally, the gun mount has a compact cradle, titanium recoil rails, modular recuperators and recoil brakes compared to an Abrams coil system. The maximum recoil is 23.5 inches, Smith said.
The traditional hydraulic-actuated breech on the Abrams is replaced in the MCS by a 600V DC electric actuation system. This is smaller and removes weight and volume from the overall vehicle. Advanced smart rounds communicate with the gun by a secure and reliable ammunition data link.
The XM360 is backward-compatible with 120mm ammunition now in the Army inventory, and has proven it can fire new ammunition, such as the beyond-line-of-sight Mid-Range Munition (MRM), developed by Raytheon [RTN] teamed with General Dynamics. The MRM extends the defended space out to 12 kilometers. This munition allows the future brigade combat team the ability to fire from beyond an enemy’s lethal range, “stripping off” an adversary’s combat capability, Hannah said. In turn, this allows U.S. forces to fight in a totally different way.
As early as this fall, some inert MRMs will be available and integrated into the ammunition handling system for characterization, Hannah said.
The MCS offers line-of-sight and beyond-line-of-sight fire. On the move, the MCS can fire out to eight kilometers, stationary, out to 12 kilometers with the MRM.
The MCS XM360 will carry 27 rounds in a carousel loaded by the automated ammunition handling system (AHS) built by Meggitt Defense Systems Inc. (MDSI). This increases the rate of fire, he said.
MCS carries a crew of three compared to the Abrams four. The AHS provides sort of a robotic fourth crewman.
The AHS will be delivered this quarter to General Dynamics for integration into the MCS Firing Fixture, which will then undergo Turret Motion Based simulator testing. Firing tests will follow, with the unit returning to the Aberdeen Test Center in November for three months of firing.
The MCS network firing capability is “an evolutionary step to the way we want to fire,” Hannah said. The MCS will be able to use all on-and off-board sensors through the FCS network where data is fused and pushed through to the common operating picture.
This architecture is in development testing now, Hannah said. “MCS will be a consumer of data and have on-board sensor data [that] will populate to associates [other MCS] and to the brigade, and redistribute target lists.”
Here at Melvin Jackson Barricade 1, Thompson said the gun is mounted on risers at the height it would fire from the vehicle. Sensors can monitor just about every part of it, to include blast overpressure, so designers know what to expect.
At one side of the range is a mockup of the MCS front end, showing 27 sensor sites.
After all, Hannah said, with communications and sensor systems on top of the MCS, no one wants cannon fire to blast them off.
It’s possible to collect 90 some channels of data on each shot that “may be the most ever collected on a gun system before,” Thompson said. That doesn’t happen every shot, though. But since crew members are not expected to interact with the gun and are in their own compartment, it’s vital that all the electronics be accurate.
Clearing the range with whistles, sirens, and a broadcast voice countdown, the XM360 shot a M1002 training round three kilometers downrange. It’s the Army’s newest training round, the one troops train with. The test center keeps the rounds in temperature controlled boxes and can simulate various environmental conditions. The two shots fired were set at 70 degrees.
Inside, the small data control building has rooms full of computers and a large screen showing dozens of categories of information in a spreadsheet. The data, arriving about a minute after the shot, is also ported to Benet labs. Cameras catch the action from the rear, side and front of the gun, the round in flight and the target and can give near- instant replay.
There is discussion now on the possibilities of retrofitting the gun into the Abrams, Smith said. Hannah added it would take some engineering; it’s not as simple as pulling out one gun and dropping in the other.