XM32 Lightweight Handheld Mortar Ballistic Computer
Gourley, Scott R., Army
In response to an urgent need from U.S. Army warfighters serving in Iraq, the U.S. Army's Research, Development and Engineering Center at Picatinny Arsenal, N.J., has developed and recently fielded the first 36 XM32 lightweight handheld mortar ballistic computers (LHMBCs).
According to David Super, deputy product manager for Mortar Systems (under project manager for Combat Ammunition Systems at Picatinny Arsenal), the new XM32 lightweight handheld mortar ballistic computer is a joint service Marine Corps/Army system that calculates the ballistic solution for the entire family of fielded U.S. mortars and their complete inventory of ammunition.
U.S. mortar systems include the 60 mm, 81 mm and 120 mm mortar weapons. The 60 mm and 81 mm mortars are dismounted systems with the 120 mm fielded in both dismounted and vehicle-mounted configurations. Vehicle-mounted 120 mm mortar configurations include the tracked M1064A3, a variant of the M113A3 armored personnel carrier, and the soon to be fielded wheeled M1129, a Stryker mortar variant.
"The current [dismounted] mortar ballistic computer is the M23," Super explained. "It was built in the 1970s and is the equivalent of a Commodore 64. It is obsolete, unsupportable and cannot be repaired anymore."
Perhaps most serious, the M23's memory capabilities are exhausted, meaning that recently fielded ammunition options could not be included in the system.
"The memory is depleted," Super said. "We cannot expand it any further."
In addition to supporting all of the currently fielded mortar ammunition, the XM32 also provides warfighters with a more accurate solution, based on a ballistic algorithm that accounts for wind speed, wind temperature and propellant temperature. Moreover, the system features software growth potential to allow incorporation of any future mortar rounds.
"The XM32 also automates a number of different procedures, such as determining ammunition requirements for a given target and calculating firing orders for large target areas in terms of traverse. We do computations much faster and the entire system weighs less than two pounds," Super added.
By contrast, the obsolete M23 weighs approximately eight pounds.
The requirement for the XM32 was derived from an umbrella operational requirements document (ORD) for the M95/M96 mortar fire control system (MFCS), which is the current heavy mortar fire control system fielded in the M1064A3 and M1129.
The main computer in the MFCS is the commander's interface computer, which weights almost 14 pounds.
"There was also a requirement in the mortar fire control system ORD for a lightweight commander's interface computer," Super added, "so, Fort Benning [Ga.], who is our user, developed a user's functional description for the XM32 to formalize the requirement."
"The XM32 is strictly a ballistic calculator," he said. "It does not do weapon pointing like the mortar fire control system does. What we need to do is be able to take that heavy mortar fire control system and develop a dismounted [lightweight] mortar fire control system for dismounted applications. The first step in doing that is the XM32 lightweight handheld mortar ballistic computer. It does not give us weapon pointing/weapon laying capability, but it does give us that exceptional lightweight ballistic calculator. …