General Dynamics demonstrates tactical version of 120mm Roll-Controlled Guided Mortar


General Dynamics has successfully demonstrated a tactical version of its GPS-guided 120 mm Roll Control Guided Mortar (RCGM) for the US Army as the service moves to introduce precision guided artillery and mortar shells.

General Dynamics Ordnance and Tactical Systems announced on May 2 that it had tested the mortar at the Yuma Proving Grounds in Arizona. The testing was conducted under a Cooperative Research and Development Agreement (CRADA) with the US Army Armament Research, Development and Engineering Centre (ARDEC), at Picatinny Arsenal in New Jersey.

The 120mm RCGM is a low-cost, guided mortar that provides precision-strike capability using standard M934A1 mortar components, GPS guidance, M734A1 fuse components and patented Roll-Controlled Fix Canard (RCFC) technology.

Live, tactical 120mm RCGM rounds were used in the demonstration and all of the rounds were successfully guided to within 10 meters of their target at ranges of 1,000 to 5,000 meters, General Dynamics said. The test demonstrated the RCGM capability in height-of-burst, point detonation and delay fuse modes, and demonstrated the rounds’ ability to perform at hot, ambient and cold temperatures.

Michael S Wilson, president of General Dynamics Ordnance and Tactical Systems, said, “These tests fully demonstrate the viability of our system with respect to accuracy, fuse reliability and enhanced lethality for the warfighter. By using existing warheads and fusing, in concert with our innovative low-cost control and guidance system, we can offer a truly affordable precision mortar round for less than US$10,000 per unit.
“This demonstration proves that the General Dynamics low-cost guided mortar is a viable competitive alternative which meets the Army’s requirements for affordable precision munitions,” Wilson said.

The US Army is pushing for the fast development and deployment of precision guided mortars for use in Afghanistan as they are lighter, cheaper and more mobile than artillery. In 2004 the Army began developing laser-guided mortars but switched to GPS guidance.

Under the Accelerated Precision Mortar Initiative (APMI), initiated by the field commander in Afghanistan in February 2009, three companies competed to develop a 120 mm guided mortar for the M120 mortar system. These were Raytheon, General Dynamics, and Alliant Techsystems (ATK). They tested GPS guided versions of the precision mortar in May 2009. After a shoot off in January last year, ATK’s design won the competition that April. American soldiers in Afghanistan fired GPS-guided mortars for the first time in March this year.

Current Circular Error Probable (CEP) for 120 mm mortars at their maximum range is 136 meters (if you drew a circle around a target at 136 metres radius, the rounds fall inside the circle 50 percent of the time). GPS guided mortars have a required CEP of 10 metres, but it is often much less.

The APMI shell is the XM395, which uses the standard M934 high-explosive 120mm projectile body. In the nose, a GPS receiver and computer controlled aerodynamic directional fins keep the round on its programmed trajectory. Folding fins in the tail provide stability. APMI also has a multi-functional fuse, which allows the round to be programmed to explode in the air, once it hits a hard surface or after it penetrates inside a target. In order for the autonomous flight and fuse control to function properly, operators must input mission and GPS data from a fire control computer into the round using a setting device.

The US Army has also developed the GPS-guided 155 mm M982 Excalibur artillery round. These shells are built by Raytheon and cost around US$100 000 each, according to DefenseIndustryDaily. Over the past year, the US Army and Marine Corps have fired more than 300 Excalibur shells. Canada also uses them in Afghanistan, where their precision accuracy is useful in built-up areas.