Army’s Cannon, Propellant Updates Reflect Lessons Learned in Ukraine
U.S. Army photo
Combat operations in Ukraine over the last two years have highlighted the importance of modern field artillery systems.
From longer cannon tubes for increased range, to extreme long-range projectile accuracy, to restarting production of legacy subsystems, several industry efforts are focused on enhancing capabilities of field artillery systems for use in Ukraine and future possible conflicts.
Vendors at the 2023 Association of the United States Army’s annual conference highlighted a range of efforts to meet both current battlefield needs and projected future demands.
One sea change has happened at the Watervliet Arsenal in New York, which has been making cannon tubes for the Army since the late 1880s. Today, it represents the government’s central repository of metallurgy equipment and knowledge necessary to blast 100-pound explosive projectiles 18 miles and beyond.
The war in Ukraine has demonstrated a significant need to extend those distances through technologies ranging from longer tube length to range assisted projectiles, experts at the conference said.
In the case of cannon tube length, which is generally expressed as a multiple of projectile diameter, longer tubes feature greater chamber ignition volume and longer rifling — the lands and grooves inside the barrel — resulting in longer projectile ranges.
The Army’s M109A7 self-propelled howitzers, for example, feature a 39-caliber length M284 155 mm tube manufactured at Watervliet Arsenal. The arsenal also developed a 58-caliber 155 mm tube for the Extended Range Cannon Artillery systems.
More recently, 52-caliber length 155 mm tubes have been proving their effectiveness in Ukraine on systems like the Nexter Systems CAESAR and Rheinmetall/KMW PzH 2000.
One potential U.S. Army cannon tube enhancement highlighted at AUSA featured a new hybrid prototype incorporating a 52-caliber length 155 mm tube on a U.S. Army M109A7 self-propelled howitzer.
Significantly, the new barrel was not produced at Watervliet Arsenal.
“I’m not certain that Watervliet has a ‘52 cal’ right now,” said Jim Miller, vice president of business development for combat mission systems at BAE Systems. “We actually talked to just about every artillery producing company that we could reach to ask about a 52-caliber tube, and we selected the Rheinmetall L52, which has already been bought by nine NATO and other allied countries. It’s the gun that’s on the PzH 2000 in Ukraine right now. So, if a cannon can have combat experience, this one has it.”
The idea to prototype a new 52-caliber tube on the M109A7 was originally focused on potential upgrades for international M109 series of self-propelled howitzers, Miller said.
“We wanted to make sure we had a capability to mount ‘a buyer’s choice’ of a 52-cal tube,” he said. The U.S. Army then said it was interested also in upgunning the M109A7 Paladin Integrated Management at some point, Miller said. “So, we thought, why not bring it to AUSA?” he added.
“What we’re trying to show is that we can take the already fielded and fully qualified base chassis and take a system that’s very mature, like the L52, and put them together to give customers — whether they’re international customers or the U.S. Army — [upgrade] options that could go fairly fast if they wanted to.”
Miller noted that the prototype performed “a quick live fire” at Camp Ripley, Minnesota, in late September to prove the new design could manage the recoil impulses of the new cannon.
“We have taken a combat-proven, mature technology and integrated it on the M109 to provide the Army an option to get after [its] range challenges and provide some tactical overmatch, once again, back to the field artillery,” Miller said.
Jon Milner, director for business development, weapons and munitions, American Rheinmetall Defense Inc., said, “We’re going to spend most of the rest of 2024 doing deeper characterization firings to showcase range and compatibility with different things. But we at Rheinmetall think that this barrel — combined with propellants and U.S. projectiles — is really a winning combination for the Army to get after some of [its] challenges.”
He added: “This [L52] cannon is performing in Ukraine right now, with both Germany and Netherlands having donated PzH 2000s. We’ve gotten direct feedback from the Ukrainian chief of artillery. … They love the howitzer mobility and the accuracy of both the weapon and the SMArt 155 sensor-fused top attack anti-armor munition that has been really proving itself in the Ukraine.”
Inspections of tubes on PzH 2000 systems that have left the field for refurbishment have shown surprisingly little barrel wear, despite many of the systems having fired between 4,000 and 9,000 rounds, he added.
“The L52s still have significant rifling — lands and grooves — left,” he said. “That speaks to our technology because we chrome plate the barrel and we also laser harden the rifling, which again, gives you a very long barrel life.”
In terms of new barrel availability, the L52 on the howitzer prototype came off the “hot production line” at Rheinmetall Waffe Munition, Unterlüß, Germany, Milner said.
“Because of Ukraine and other things, that production line has basically doubled in capacity. We currently make both large caliber tank and 155 mm howitzer barrels on the same line at a rate of approximately 200 per year,” he said.
“If the Army likes the prototype [it sees] over at the BAE booth, and we hope they do, and if they want more prototypes for testing, certainly those barrels are going to have to come out of Germany,” he said.
“We’re prepared for that. We’re already planning in future years for some numbers of barrels to potentially come out of there,” he said.
However, that is not a permanent solution due to the 1920 Arsenal Act, which requires production in U.S. government-owned factories or arsenals.
“We’re also not fooling ourselves that Germany is going to be the source of any L52 barrel for the United States,” he said.
Rheinmetall would be happy to industrialize in the United States and be a second source to Watervliet Arsenal, but it’s a congressional issue that would have to be resolved, he noted.
In addition to highlighting the performance of the SMArt 155 projectile in Ukraine, Milner also referenced several ongoing Rheinmetall projectile production activities, emphasizing a significant increase in production capability following last summer’s purchase of Spain’s Expal and the subsequent creation of Rheinmetall Expal Munitions, S.A.U.
Along with projectile efforts focusing on base bleed and rocket assisted designs, other recent industry activities have been directed toward the precision delivery of sub-caliber guided projectiles at extremely long ranges.
As one example, BAE Systems’ Miller pointed to the company’s partnership with the U.S. Army Combat Capabilities Development Command Armaments Center, which recently resulted in firing the XM1155-SC sub-caliber guided projectile to the farthest distance an M109 Paladin has ever fired a guided projectile. It successfully guided to and impacted the target area using GPS, demonstrating the added capability the round can deliver to the U.S. Army’s current howitzer fleet, he said.
The firing tests are exploring two specific issues. The first is doubling the range of standard 155 mm howitzers, regardless of tube length. The second is whether they can achieve a hit at those ranges against poorly defined or moving targets, he said.
“We’re hitting where we want to hit. So, we’re pretty excited,” he said.
In terms of distance bragging rights, representatives from a Boeing-Nammo team outlined their recent efforts to fire a ramjet-powered projectile from a 58-caliber Extended Range Cannon Artillery cannon tube at the Army’s Yuma Proving Ground in Arizona.
Erland Ørbekk, technical director for engineering and development in the missile products division at Nammo, said company efforts have optimized a ramjet combuster design in which the ramjet engine ignites approximately 20 meters outside the barrel, with terminal guidance design efforts reflecting some of Boeing’s Joint Direct Attack Munition technology.
Future efforts will be directed toward adapting the technology for use in shorter cannon tubes, he said.
Another contributor to projectile range involves the propellant that ignites in the cannon chamber.
Once focused on different types of powder bags, U.S. artillery has moved to the Modular Artillery Charge System, or MACS. Consisting of the M231 and M232 series propelling charges, it uses an incremental-based design reflective of target range and is compatible with all current and planned 155 mm artillery weapons.
A recent test of the XM1155-SC precision-guided munition conducted at Yuma Proving Ground used the MACS “Zone 5” charge to prove compatibility with current artillery systems, Ørbekk noted.
Rheinmetall’s Milner asserted the importance of using a propellant optimized for a specific weapon system. In the case of the L52, he said the range benefits could be further optimized through the adoption of the DM92 propellant used with the German-built PzH 2000 armored self-propelled howitzer.
The MACS was designed for the Army’s now canceled Crusader artillery system, he said. “And it’s a solvent-based propellant. We’re solvent-less. It’s better technology, and the Army needs to move on from MACS. And we’re ready to bring [DM92] over and work with the Army at Radford Army Ammunition Plant.”
Another representative example of the influence of the Ukraine war on U.S. artillery production activities was reflected in the mid-September 2023 contract award to Nammo Perry Inc. of Nammo Defense Systems and General Dynamics Ordnance and Tactical Systems. The five-year award covers production of the M119A2 “red bag” propelling charge used in howitzers containing the 39-caliber length M185 and M199 cannon tubes.
The M185 tube was previously used on U.S. M109 models A1–A4 while the M199 was used on the U.S. towed M198.
“The M119A2 is a legacy propelling charge that has not been manufactured in the United States since the 1980s,” said Elizabeth Eastman, president and general manager, Nammo Perry/Nammo Defense Systems. The production is being split between the two companies and “is in direct support of the Ukraine conflict,” she said.
Since the charge hasn’t been produced since the 1980s, both companies would likely require some level of facility preparation, she said. “The requirement is for deliveries 12 months from award, so September 2024 is when we will be entering into the first article and low-rate production.”
Eastman added the biggest challenge stems from the fact that the M119A2 propellant bags use a “legacy propellant” that is no longer in active manufacture and will have to be “ramped up” as well.
The government-owned, contractor-operated Radford Army Ammunition Plant in Virginia is going to make the propellant and provide it to both companies, who will then dose it, bag it and sew it, she said.
The five-year production award will likely have uses beyond Ukraine, Eastman said, noting that the propellant for artillery stock is low.
“This is something that we understand the government can have for its own use as well, should it need to. I don’t think it will go to waste,” she said. ND