A Soldier from the 4th Engineer Battalion handles an M320 grenade launcher during weapon qualification at Fort Carson, Colorado. Engineers at Picatinny Arsenal have developed an improved pyrotechnic formulation for the infrared illumination cartridge used by the M320 and M203 grenade launchers.

Picatinny researchers develop safer, less expensive variation of infrared illuminant cartridge

The 40mm M992 Infrared (IR) Illuminant Cartridge is a type of a pyrotechnic flare, but unlike the standard flare, the IR cartridge produces a type of light that is invisible to the naked eye yet can be seen through night-vision goggles.

“The cartridge brought the infantry squad the ability to enhance infrared night vision without providing visible light and exposing friendly positions,” said mechanical engineer Anthony Amoroso.

“Without it, the ability to see in the dark was something that previously was only available with a call for fire from field artillery or aircraft,” added Amoroso, who is with the Medium and Cannon Caliber Munitions Division at Picatinny Arsenal. The division is part of the larger Armament Research, Development and Engineering Center, or ARDEC.

The new pyrotechnic formulation was for the 40mm M992 Infrared Illuminant cartridge. This new formulation, called RG-1155, resolves logistical issues with procurement and improves the overall manufacturing process.

The illuminant cartridge is fired from various 40mm grenade launchers — the M203, and M320, and is managed by the Project Manager Maneuver Ammunition Systems, which is part of the Program Executive Office Ammunition.

The first 40mm IR illuminating munitions were developed and fielded in 2002 by ARDEC. In 2010, the project won an award as of the Army’s Greatest Inventions, which is commonly referred to as the “Soldier’s Choice Award.”

Later, the IR cartridge was approved for full materiel release on October 8, 2010 and then fielded in 2011.

MOVING AWAY FROM SINGLE SOURCE

But the pyrotechnic composition was a proprietary mixture, meaning that it was only made and provided by one supplier: ATK Corporation, Brigham City, Utah. The composition also had to be shipped and stored frozen, which raised potential safety issues throughout the transportation of hazardous materials.

By developing a new composition for RG-115, ARDEC engineers minimized potential safety problems and eliminated what is called a “single-point failure” or having to rely on a single source.

As an added benefit, the new composition also saves about $4 per cartridge, which is roughly 5–10 percent of the cost of each cartridge.

Without infringing on the supplier’s intellectual property, Robert Gilbert and Gary Chen of the Pyrotechnic Technology and Prototyping Division successfully developed and proved out a new pyrotechnic formulation.

“Originally, the contractor who bought the composition would have to have it shipped refrigerated, store it refrigerated at a certain temperature, and then use it within a certain amount of time,” said Gilbert. “So, it was pricey and logistically cumbersome. With this new fill, we can make the composition as needed, versus buying and storing it and then having it expire.”

The effort to improve the infrared cartridge began in 2011. By working with Battelle Memorial Institute and Chemring Ordnance, Picatinny developed formulations that matched the previous IR cartridge’s performance capability.

Although different formulations were tested before RG-1155, Amoroso says that the previous compositions didn’t perform as well when they were scaled down to fit the 40mm form factor.

With laboratory development and prototyping success in hand, it was time to scale-up to a production level. “What works when one person diligently makes five samples doesn’t always work when a production line produces 5,000” Amoroso noted.

Working with partners Battelle Memorial Institute and Chemring Ordnance, every step of the production process was developed, optimized, and documented to ensure producibility of the new system.

Some testing included a drop test and transportation/vibration test, which simulates what the material may experience in a moving vehicle. More than 2,000 cartridges were built and tested to ensure that the required performance and reliability were maintained in this new version of the M992.

“Our goal is to ensure that the Soldier gets a proper function every time he pulls the trigger,” said Christopher Summa, an ARDEC mechanical engineer, who spent weeks testing the formulation at Aberdeen Proving Ground in Maryland.

Recently, the ARDEC team completed its engineering change notice, which is a document that records or authorizes the change to a specific design. As a result, the new composition has been verified and will be fielded inside the 40mm M992 IR Illuminant Cartridge starting in 2017. 
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The U.S. Army Armament Research, Development and Engineering Center is part of the U.S. Army Research, Development and Engineering Command, whose mission is to provide innovative research, development and engineering to produce capabilities that provide decisive overmatch to the Army against the complexities of the current and future operating environments in support of the joint warfighter and the nation.