One of many tactical lessons reinforced by recent combat operations is the need to accurately deliver long-range artillery fires against a broad spectrum of target types and to do so from mobile, survivable and maintainable platforms.

The current Army system used for these mission sets is the Paladin, a combination of the M109A6 155 mm self-propelled howitzer and its associated M992A2 ammunition supply vehicle. The supply vehicle is sometimes called “The Cat” because it is part of the Carrier, Ammunition,

Tracked category of Army vehicles.

As the A6 howitzer designator indicates, the Paladin reflects multiple major improvement packages that have been applied to a weapon system with roots going back to the 1960s. While these packages have introduced massive improvements in tactical capabilities over the subsequent decades, a number of available maintainability, survivability and technology enhancements were not incorporated in the platform. Those enhancements are now being introduced through an upgrade known as Paladin Integrated Management (PIM). Recently redesignated as the

M109A7/M992A3, the upgrade entered low-rate initial production in October 2013.

Unlike many Army systems that have entered production over the past decade, the Paladin upgrade is noteworthy because it followed standard development procedures and not the process for urgent operational needs used in many other systems. As such, it is seen as offering a number of lessons that can be applied to other acquisition programs in a post-Operation Enduring Freedom environment.

Adam Zarfoss, director of artillery programs at prime contractor BAE Systems, said the M109A7/M992A3 upgrade solves the problems that Paladin had with space, weight and power.

“We were already maxed out on electrical power generation,” he said. “We consumed more power than we generated. So initially we are going to solve those problems that the soldiers have today. We are also going to address the other obsolescence problems they had, which goes to the long-term viability and sustainability of the platform.”

For comparison purposes, the M109A6 generates 18.5 kilowatts (kW) of electrical power, while the new system will generate 70 kW, resulting in approximately 40 kW of reserve power that can be applied to future command, control, communications and computer equipment or other electronic growth.

The upgrade will also provide logistics benefits derived from commonality with the Bradley platform. Although they do not share the same hull structure, the new system will have components like the engine, transmission, road arms, road wheels, torsion bars and final drives in common with the Bradley engineering change proposal (ECP) 2 configuration.

“As an example, we have the new, electronically controlled, 675-horsepower version of the V903 engine from Cummins,” Zarfoss said. “We have the HMPT [hydro-mechanical power transmission] 800 series transmission from L3. We have newly designed final drives to account for the higher weights that we will be running at and Bradley will be running at, and they have all been designed in an environment to be common between the two series vehicles.”

Along with the new hull designs, Zarfoss pointed to a number of significant changes to the M109A7 howitzer turret.

“We have kept the same basic turret structure that was designed during the Paladin days, but we have significantly improved its force protection and survivability through a series of modular “We were already maxed out on electrical power generation,” he said. “We consumed more power than we generated. So initially we are going to solve those problems that the soldiers have today. We are also going to address the other obsolescence problems they had, which goes to the long-term viability and sustainability of the platform.”

For comparison purposes, the M109A6 generates 18.5 kilowatts (kW) of electrical power, while the new system will generate 70 kW, resulting in approximately 40 kW of reserve power that can be applied to future command, control, communications and computer equipment or other electronic growth.

The upgrade will also provide logistics benefits derived from commonality with the Bradley platform. Although they do not share the same hull structure, the new system will have components like the engine, transmission, road arms, road wheels, torsion bars and final drives in common with the Bradley engineering change proposal (ECP) 2 configuration.

“As an example, we have the new, electronically controlled, 675-horsepower version of the V903 engine from Cummins,” Zarfoss said. “We have the HMPT [hydro-mechanical power transmission] 800 series transmission from L3. We have newly designed final drives to account for the higher weights that we will be running at and Bradley will be running at, and they have all been designed in an environment to be common between the two series vehicles.”

Along with the new hull designs, Zarfoss pointed to a number of significant changes to the M109A7 howitzer turret.

“We have kept the same basic turret structure that was designed during the Paladin days, but we have significantly improved its force protection and survivability through a series of modular armor kits,” he said. “In one of the other big changes, we have gone away from hydraulic drives to 600-volt electric drive systems.”

The new electric drive systems are just one example of applying technology developed under the Non-Line of Sight-Cannon (NLOS-C) element of the Army’s terminated Future Combat Systems program, which had its legacy in the earlier terminated Crusader program, Zarfoss said.

Another subsystem that is almost a direct lift from NLOS-C and Crusader is the semi-automated projectile loader/ rammer. Not only is the new electric system more reliable than the old hydraulic stroke rammer it is replacing, but its ability to provide more consistent “seating” of the projectile in the tube translates to improved system accuracy.

“So we are leveraging the Army’s investment in past programs and actually bringing it to bear in a real-time application that is going to be put into the hands of soldiers in the near term,” he said.

The only hydraulics remaining in the upgrade design are in areas like the recoil mechanism. “We still have a requirement, and we still have the ability to elevate and traverse manually,” Zarfoss said. “We’ve also kept all of the manual backups—the optical fire sights are all still in there—so the system has a ‘soft failure mode.’”

The  M109A7/M992A3  PIM  program will feature work at three major sites. Through a public/private partnership, Anniston Army Depot in Alabama will perform the induction, teardown and disassembly of existing M109A6 howitzers and M992A2 ammunition support vehicles. The depot will also rebuild cannons and mounts, and it will overhaul the components that are going to be reused.

BAE Systems’ facility in York, Pennsylvania, will be the site where new chassis structures—”new aluminum boxes”—are built and automotive assembly work performed. For the howitzers, the drivable automotive platforms, cab structure and gun mount will then be shipped to Elgin, Oklahoma, for final assembly, integration and testing at nearby Fort Sill.

The M992A3s, with brand new structures, will be completely fabricated in York. “The goal is to buy 66.5 sets,” Zarfoss said. “The extra ‘half set’ is because they are going to buy one more howitzer than they are ammo carriers, and that extra howitzer is going to full-up system live-fire test. They are actually going to take two howitzers and one ammo carrier through [full-up system-level live-fire test and evaluation] and ‘blow them up.’”

The production plan is structured as a base award plus three options. Army representatives, however, have recently indicated to BAE Systems that they intend to award options two and three simultaneously, effectively making it a base plus two options.

The first production deliveries are scheduled for March 2015, with a projected build rate of approximately 1.5 howitzers and 1.5 supply vehicles per month through the low-rate initial production base plus initial option, Zarfoss said.

“The Army’s plan is to ‘pure fleet’ with a single configuration of M109A7s and M992A3s,” he said, noting that future funding profiles and build schedules would determine how long the complete build out will take.

Although Zarfoss declined to identify any possible long-term growth paths beyond the new upgrade package, it is believed future directions could range from new add-on armor packages and electronic subsystems to possible reductions in crew size.

“The real key for this program is that we have solved the immediate problem that the Army had and we have given them a platform they can grow with over time,” he said. “The Army has been trying to ‘eat the elephant in one bite,’ but in this particular program, they said, ‘Let’s solve our immediate problems and then put a growth path together for the future.’ So we’ve got trade space for weight, we generate lots and lots of electrical power, and we have the ability to grow in the longer term.”