US Army Wants 120mm Guided Mortars for the Front Lines

The US Army is pushing to get precision mortars developed and deployed to the field in Afghanistan as soon as possible. Mortars are lighter and can be towed by a HMMWV or MRAP, or carried and fired from inside M113 or Stryker APCs, making them easier to deploy than heavier cannon artillery.

When indirect fire support is needed against enemies who are dug in along mountain ridgelines and other high positions, or in an urban area where which building you hit matters a great deal, getting the job done requires precision artillery. That capability has already come to MLRS rockets (M30/31 GMLRS, ATACMS), and 155mm artillery shells (Excalibur), and has been deployed to great effect on the front lines by American forces and their allies. Now it is coming to the USA’s 120mm mortars as well.

The Accelerated Precision Mortar Initiative (APMI)

M120 in Afghanistan

The US army has been experimenting with guided mortar development efforts since the 1980s, but the technologies required have only recently become small enough and reliable enough for use. An effort to field a laser-guided mortar began in earnest in 2004, but eventually the Army decided to change its guidance focus.

The Army’s Operational Needs Statement from Afghanistan specifies a GPS-guided 120mm mortar, with a circular error probable (CEP) of 16.4 feet or less and a 4.3 mile range, said Maj. Jeffrey Hilt, the APMI program lead for the Army, in an interview with Greg Grant of DoD Buzz. The mortar must also be compatible with existing fire control systems, such as the Lightweight Hand-held Mortar Ballistic Computer, be compatible with Soltam’s M120/M121 fin-stabilized smoothbore system, and have the same multi-option fuze as the current M734A1 fuze.

Maj. Hilt told DoD Buzz that GPS guidance is preferable to laser guidance because insurgents in Afghanistan frequently duck down behind ridges and rock outcroppings; laser guidance would require a laser marker almost on top of them, buts a soldier on the ground can accurately target a GPS round against an enemy taking cover behind obstacles, or in dead ground.

Three companies were competing to develop a 120mm precision mortar compatible with the M120 system under the Accelerated Precision Mortar Initiative (APMI): Raytheon, General Dynamics, and Alliant Techsystems (ATK). The 3 companies tested GPS guided versions of the precision mortar in May 2009. The first phase would conclude with flight tests and a competitive “shoot off” amongst industry designs in January 2010, after which the Army would select the winning design.

In April 2010, ATK’s design won.

ATK explains that its Mortar Guidance Kit converts mortar bodies into precision mortar rounds by replacing standard fuzes in the mortar’s fuze well with a guidance kit that includes fins, guidance, and fuze. The design owes much to the firm’s Precision Guidance Kit for 155mm artillery. While PGK lost out to Raytheon’s Excalibur in the USA, Alliant Techsystems also has 105mm offerings, and MGK has more than 90% commonality with PGK. ATK’s MGK has demonstrated its ability to accurately and reliably guide a 120mm mortar to within 10 meter CEP (Circular Error Probable) at ranges in excess of 6,500 meters.

Their offering will join a growing list of global 120mm mortar competitors, including the Russian Gran system, and Raytheon/ Israeli Military Industries’ 120GM DAGGER. When combined with similar advances for 155mm and 105mm artillery, and for longer-range 227mm+ rockets, the net effect is to make precision firepower widely available, even when aircraft or UAVs aren’t nearby. If successful, precision mortars in particular would be a “70% solution” that would severely undercut the Army’s rationale for “missiles in a box” projects like the Army’s recently-canceled NETFIRES NLOS-LS.

Contracts & Key Events

M1129 Stryker MCV

April 21/09: US Army APMI program lead Maj. Jeffrey Hilt reportedly tells a Precision Strike Association conference that ATK had been picked for APMI, following a competitive shoot-off.
Maj. Hilt says that APMI is not a program of record, but may become one if it performs well. Should that happen, however, ATK is not guaranteed to win – another shoot-off and selection would take place.

Nov 30/09: ATK announces a $5 million contract to proceed with APMI Phase 1. The firm used its Mortar Guidance Kit (MGK) to provide GPS guidance to the 120mm mortar during the testing.

Before winning the award, ATK successfully concluded a Cooperative Research and Development Agreement (CRADA) flight test program of its Mortar Guidance Kit (MGK) design.

Raytheon and General Dynamics also won phase 1 contracts, although the value of their contracts were not disclosed.

Jan 12/06: Alliant Techsystems announces completion of the laser-guided PGMM’s Preliminary Design Review. During the PDR, all elements of the system design were thoroughly vetted to ensure the design has the performance capability to meet requirements and the program remains on schedule and on cost.

The PDR is one of 2 critical milestones prior to a Milestone C production decision, and the next milestone is the Critical Design Review later in 2006. ATK intended to begin low rate initial production in 2008 and field the system by 2010, while the Army pushed for an earlier fielding date of 2009. In the end, field requirements overtook those intentions, and the Army opted for a GPS/INS guidance solution instead.

Jan 5/04: ATK announces that it has been picked by the U.S. Army to design and develop the XM395 Precision Guided Mortar Munition (PGMM), and could begin low-rate initial production if an option award is made. Initial terms of the pending contract were not disclosed, but ATK said that the contract could lead to production with total sales of more than $500 million.

The PGMM projectile flies ballistically to a laser-designated target, maneuvers in flight, and delivers its warhead. It is designed to defeat targets at distances beyond 7 km, with 1 meter CEP accuracy, and its modular design will allows enhancements to meet future combat soldier requirements in range and lethality.

ATK Ordnance and Ground Systems in Plymouth, MN, will manage the PGMM program and lead system integration with program support provided by ATK Missile Systems in Woodland Hills, CA; and ATK Tactical Systems in Rocket Center, WVA. The US Army’s Product Manager for Mortar Systems, reporting to the Project Manager, Combat Ammunition Systems, Picatinny Arsenal, NJ, is the material developer for PGMM, and played a critical role in the development of smooth-bore, cannon-launched technology adopted by ATK’s PGMM concept.

This article can be found in its original entirety here.