The first Gulf War saw the introduction of a new generation of airborne precision munitions. In the second Gulf War, precision has moved to land forces, with a primary emphasis on significantly reducing collateral damage, while also reducing the time U.S. and allied forces are exposed to enemy fire.

“God is on the side with the best artillery.”

– Napoleon Bonaparte

Responsibility for the development and fielding of cannon-launched precision munitions falls under the Program Executive Office (PEO)-Ammunition. Within PEO-Ammunition, as the Single Manager for Conventional Ammunition (SMCA), the Project Manager-Combat Ammunition Systems-Indirect Fire (PM-CAS) procures all cannon-launched, indirect fire munitions and mortar weapons systems for all military services. These include near-precision and precision-guided munitions (PGMs), conventional artillery and mortar munitions, mortar weapon systems, mortar fire control systems, propellants, fuzes, and fuze setters.

The only cannon-launched PGM currently fielded is the XM982 Excalibur 155 mm precision-guided artillery round, which is in service in Afghanistan. That is planned to change significantly in the near future. PM-CAS expects to field the XM395 Accelerated Precision Mortar Initiative (APMI), a 120 mm GPS-guided mortar round, in the second quarter of FY 11. Additionally, the XM1156 Precision Guidance Kit (PGK) Increment 1, a GPS-guided fuze that can be installed in the fuze well of a standard 155 mm high explosive (HE) round, is still in development and moving toward initial operational capability (IOC) in 2012.

With greater accuracy enabling first-round target engagement without the need for adjusting onto the target, initial expectations were that the increased use of precision and near-precision artillery also would mean fewer rounds needed overall, thus reducing the logistics tail and associated costs. Instead, greater accuracy with less collateral damage may lead to a higher demand as field commanders are able to increase the number of targets they can attack.

“Because Excalibur has only been fielded in small numbers [189 had been fired in combat through late September 2010], we don’t really have enough data to date to know the actual operational behavior versus what we theoretically believe [it may be],” noted PM-CAS, Col. Scott Turner. “We felt there should be logistics burden advantages because we need fewer rounds to get the same effect. But in [scenario-driven] modeling and simulation, because you can service more targets, we’ve also seen the opposite effect, using more to attack more targets effectively. So the potential is there to reduce the logistics burden, but we will know a lot more once we field APMI and PGK.”

Turner also is careful to draw a distinction between precision and near-precision capabilities in these new munitions. Excalibur, with a range-independent, required circular error probable (CEP) of less than 10 meters – meaning at least half of all shots will strike within at least 10 meters of the intended target and more than 90 percent within 30 meters – is classed as a precision munition, as is APMI. PGK, however, has a required CEP of 50 meters, making it a near-precision capability.

“Think of Excalibur as a cannon-launched missile; it flies a fin-stabilized ballistic trajectory at launch, then becomes a guided missile from apogee to target with deployment of its four-axis canards. PGK, on the other hand, is really just a GPS-guided trajectory assist capability to maintain the ‘should fly’ spin-stabilized ballistic trajectory of a standard HE projectile once launched,” Turner explained.

“The real takeaway is that to have true precision on artillery platforms, you currently have to have significantly greater complexity in munition guidance and flight controls to have sufficient maneuver authority to get to less than a 10-meter CEP. The purpose of the PKG is low cost, so we had to use a simpler technique to provide assisted guidance correction to the ballistic trajectory.”

APMI is also a PGM and will add a level of user access to precision capabilities and increased responsiveness beyond Excalibur today.

“APMI, for the first time, will provide an organic, precision capability to the battalion/company level within Infantry Brigade Combat Teams. Currently, maneuver battalions within Infantry BCTs and Stryker BCTs have 120 mm, 81 mm, and 60 mm mortars as organic indirect fire support to those tactical formations,” he said. “Each BCT also has a fires battalion – equipped with the M119A2 105 mm towed howitzer in IBCTs or the M777A2 155 mm towed howitzer in SBCTs – under the direct control of the brigade commander, but with no guarantee a battalion commander or his company commanders would have direct control over any of those for fire mission planning and execution. That’s why this is an important capability.

“Like Excalibur, APMI provides responsive, first-round precision attack against targets in defilade [behind intervening crests], where you need to employ high angles of attack or high angle fires to avoid hitting intervening ridge lines. So, this can go after enemy mortars or folks emplacing improvised explosive devices (IED). When fielded, APMI will provide range-independent, 10-meter CEP precision out to about 90 percent of standard 120 mm HE maximum range – that is, about 6,500 meters. APMI has a special fin stabilization tail kit and a guidance section similar to the PGK that increase drag that reduces the range to less than 6,500 meters but does not affect the required minimum range of about 1,000 meters.”

While overall accuracy is a significant advantage, the most important element of PGMs for the warfighters firing them is abandoning the age-old need for several targeting rounds to adjust onto the target and going instead for a first-shot kill.

“For the near-precision PGK and precision Excalibur and APMI, the guidance capability provides first-round fire-for-effect, which is a significant increase in capability against targets,” Turner said. “Often, with conventional artillery or mortar munitions, although we try to be precise, there are things that cannot be entirely accounted on the first shot.

“So, given weapon system and target location, we compute a technical firing solution to point the cannon or mortar tube with required charge and fuze function but often will be off the target on the first round and have to adjust due to unaccounted for inherent weapon system errors and exterior ballistics factors. The problem becomes that if we are off the target on the first round with adequate effects, whatever was there can take cover or move, so we lose the opportunity to effectively attack many targets unless we use very large volumes of fire to account for that first shot probable error. With these near-precision and precision projectiles, we have a much higher percentage of lethal effect on the first round.”

These capabilities provide the ability to attack targets more effectively, offering less opportunity for the enemy to continue firing or to escape to attack U.S. or allied forces another day – underscoring field commanders’ calls for more Excaliburs, rapid deployment of APMI, and future fielding of PGK.

The Excalibur rounds fired in theater to date are the initial version fielded in response to operational needs statements in 2007 and 2008, with a demonstrated reliability of 85 percent and accuracy of 6-meter CEP – exceeding its 10-meter CEP requirement. Additionally, test firings of PGK to date have also exceeded its 50-meter CEP requirement.

With APMI still in the qualification phase of development with initial fielding to begin in early 2011 and PGK completing development with full rate production and IOC planned for 2012, how well those two will perform in combat is yet to be determined.

“The plan is to procure about 3,475 Excalibur Increment 1A configured projectiles from both LRIP [low rate initial projection] and full rate production buys,” according to Excalibur product manager Lt. Col. Michael Milner. “We ultimately will buy 6,264 total projectiles – about half the Increment 1A-1 version [the increment currently in use in Afghanistan] and 1A-2 version and the other half the Increment 1B version.”

In addition, the Marine Corps already has acquired 344 Excalibur Increment 1A-1s and has planned an additional buy of 1-A2s in FY 11, although no numbers have yet been specified.

“Excalibur also is a cooperative development and production program with Sweden, which plans to buy 1,000-2,000 projectiles. We will deliver some of those this Fall and some in Spring 2011. They are awaiting the Increment 1B release for the vast majority of their purchases,” he added, noting Excalibur Increment 1B Foreign Military Sales (FMS) potential may be significant given it will likely be half the cost of the Increment 1A variant.

As for what may come next, the only certainty at this point is continued improvements in Excalibur.

“These improvements will focus mainly on making Excalibur more reliable, employing a simpler design with greater inherent reliability,” Milner said. “It is also very important to have an accurate target location when employing Excalibur and systems are being employed to ensure that.”

PM-CAS will continue to work with the Armament Research, Development and Engineering Center and  other elements of JM&L LCMC, to advance the implementation of current precision technologies across a broader range of weapons while also seeking to resolve some ongoing concerns.

“We’re looking at common form factors, so once you come up with the technology or solution, you can apply it as a common capability across munitions families – 155 mm and 105 mm artillery projectiles and 120 mm and 81 mm mortar rounds. In the cannon world, if we can develop once and apply components across more domains, the cheaper it should be, theoretically,” noted Paul Manz, director of the Technical Management Division of PM-CAS. “We’re also looking at other things that reduce cost like simplifying guidance and control given it is probably one of the largest cost drivers in precision munitions.”

“A lot of PGMs [precision-guided munitions] use GPS to navigate, so if there are threats to that signal, what can you do to provide anti-jam capability? The Air Force GPS Wing has developed the M-code [a new GPS military signal], so how do we upgrade our GPS-based precision guidance systems to take advantage of that? Also, Excalibur has an IMU INS [Inertial Measurement Unit Inertial Navigation System] in addition to GPS, so to have that in a much smaller and more manufacturable package, we’re looking at MEMS [Micro-Electro-Mechanical Systems] IMU devices.”

One enabling component for that would be a MEMS gyroscope, which would reduce cost, but Manz considers development of that capability as requiring considerable addition research aptly suited for the Defense Advanced Research Projects Agency (DARPA). DARPA programs typically are years, even decades, away from fielding, so PM-CAS is also pursuing more near-term answers.

“With GPS-guided or assisted projectiles, you’re ability to set the guidance system and its accuracy is a function of the number of satellites you see, so we are looking at how to harness the capability of the Army’s expanding battlefield network – the Mobile Tactical Internet – in assisting us in providing maximum visibility and acquisition of those satellites,” he said. “Another effort involves PGK compatibility not only with HE projectile types but also cargo projectiles like illumination and smoke as well as the potential for use with cluster munition replacement projectiles so we will be in compliance with DoD’s recently issued cluster munition policy.

“You probably can never replace the current cluster munitions capability on a round-per-round basis, but you can get a lot closer with fewer rounds if you can guarantee you can precisely place them. But the goal also is to increase the effect of the weapon itself, for each individual munition being employed – but without violating the tenets of DoD policy. In this case, policy says if we have submunitions, whatever we wind up fielding as a replacement must achieve 99 percent or greater reliability – that is, 1 percent or less unexploded ordnance (UXO) permitted. That also goes back to increasing the amount of targets you can engage or the combat lethality of your existing combat load.”

The Army’s current investment in precision munitions has been a direct response to commanders in the field, Turner said. They were calling for a responsive, precision capability in tactical formations to attack targets in defilade or in very tight build-up spaces where the probability for civilian collateral damage was very high – but where they still needed to get to the enemy.

“At this point, I don’t have any specifics regarding any additional capabilities being requested for precision effects. We do have three operational needs statements to put 155 mm IR [infrared] illumination rounds in theater for the Marine Corps and the Army,” he added. “We’re in the middle of doing that right now.

“We’re also working an initiative to provide a follow-on, less toxic, less incendiary smoke projectile. The issue is you don’t want to harm non-combatants with toxic fumes or burn down their dwellings. Many of our legacy smoke munitions were developed for high intensity conflict against large formations in open terrain and not optimized for use in urban terrain where there could be unintended consequences. So we’re starting an effort to come up with a different kind of smoke chemistry with less toxic effects and less incendiary than our current white phosphorus [WP] and hexachloroethane [HC] smoke rounds.”

Another area of interest is creating artillery and mortar rounds that not only are more accurate, but also offer the field commander a range of lethality.“More accuracy and more range and more lethality all are great, but if they could tailor lethality round-to-round, that would be even better,” Turner said.

“We also have an annual event at Picatinny [Arsenal, N.J., where PM-CAS is based] where we bring in  E-6s, 7s and 8s, non-commissioned officer field artillerymen who have been in combat, to get their insights and input into how we can improve products or capabilities from what they have seen in combat in Afghanistan and Iraq. So not only are we getting the institutional combat developer inputs from Fort Sill [Oklahoma – the Fires Center of Excellence] and Fort Benning [Georgia – the Maneuver Center of Excellence], but another perspective directly from the end user to help inform us of what we need to work on.”

The future of cannon-delivered precision munitions also is part of a recently completed internal Army review and evaluation of the right mix of non-precision, near-precision, and precision conventional munitions.

“We just went through a precision fires capability portfolio review [CPR], where really for the first time, the Army institutionally looked at the precision munitions enterprise in terms of what capabilities are out there and where the overlaps, seams and gaps are,” Turner concluded. “One of the messages out of that – several programs were adjusted, including reduced quantities for Excalibur and APMI – was the Army is still grappling with trying to determine the right mix of precision, near-precision, and conventional ammunition we ought to have in our inventories. And the reason, frankly, is because precision, relative to conventional, is much more expensive.

“So one thing the Army hopes to benefit from is having a mix of true precision munitions provided by something like Excalibur or APMI, in combination with near-precision such as what PGK will offer, combined with some quantity of our current stockpile of non-precision conventional artillery and mortar munitions that does not have inherent first-round accuracy.

“One could conclude, based on the decisions from this CPR, that the Army had previously invested in too many precision munitions across the indirect fire portfolio and even too many conventional weapons. So, what they started to do was right-size the precision piece – 10-meter CEP or less – decrease the number of conventional munitions, and invest in more near-precision munitions like PGK that can decrease the logistics burden.”

This article was first published in Army Materiel Command: The Army’s Premier Provider of Materiel Readiness, 2010-2011 Edition.