By Josh Rasmussen

Grenades come in many shapes and sizes, and have varying designs, but not everyone understands exactly how they work, how many parts are involved, or what happens to those parts after detonation. A research team funded by the Environmental Security Technology Certification Program (ESTCP) has been developing environmentally friendly grenade components and has successfully demonstrated them with no performance loss.

An Integrated Product Team (IPT) focused its development on the M213 fuze, used on the M67 fragmentation grenade and the M69 practice grenade. The M213 is a pyrotechnic delay, striker-release fuze. It includes a primer, a delay, and a detonator. The team’s goal is to replace all three with green materials that meet the performance requirements and are better for the environment as well as warfighter health.

ESTCP issued a statement of need around this in 2012 and funded a suite of projects designed, in part, to address “delay elements in high-use, multi-item fuze systems, including but not limited to” the M213. This was one such project.

Other, related projects funded under that SON include:

• Eliminating Lead, RDX, and AP in a Castable EMMS-Configured Propellant While Maintaining Performance (WP-2143)

• 105mm M67 Propelling Charge Improvement Program: Eliminate Lead by Propellant Replacement with PAP7993-Modified Green Propellant (WP-201413)

• Medium Caliber Lead Free Electric Primer (WP-1331)

• Novel Lead-Free Ballistic Modifiers for Improved, IM-Compliant Minimum Signature Propellants (WP-2142)

A Soldier prepares to throw a practice M67 fragmentation grenade as part of Expert Infantryman Badge testing at Camp Buehring, Kuwait, May 29, 2019.

This project’s official focus, and title, is the development of “Environmentally Sustainable Gasless Delay Compositions for Fuzes.” Delay compositions used in modern hand grenade fuzes are gasless, or nearly gasless. This is a preferable (and necessary in some instances) property of delays loaded in sealed housings, but certain delay compositions may contain constituents of concern, such as potassium perchlorate, barium chromate, and lead chromate.

“I’ve been working on green primary explosive for years,” Neha Mehta, senior lead chemical engineer, said. “Around 2009, I started looking at different materials to replace lead components. The M67 work started closer to 2017.”

In 2018, Mehta attended a Strategic Environmental Research and Development Program (SERDP) conference, where she started to have conversations with IMP Aerospace & Defence and other DEVCOM AC members on the idea of replacing lead with DBX-1 in Grenade—a green primary explosive developed by Pacific Scientific under a Navy contract. DBX-1 is expensive right now and only produced in small quantities, she said, but the team is actively working to secure funds to set up a production facility.

At this time, Mehta was focused on replacing individual fuze components, but decided it made more sense to consider a developing a full, green fuze, which led her to the current project.

During mini arena tests, researchers tape a string to the grenade so they can start the initiation process remotely.

It is divided into three phases. During the now-complete Phase I, the team tested four configurations of delay and primer options. Had these not been successful, the project would have ended there, but all configurations met performance standards.

“We went back to Robin Nissan, ESTCP former Weapons and Platforms Program manager,” Mehta said, “and told him all four worked fine. We don’t know which to eliminate. His advice was to continue with all four using the C70 detonator. Everything was successful. We tested the green fuze by the end of Phase II, and Phase III was the full-up grenade body testing with green M213 fuze.”

Following the overwhelming success through the first three phases, the research team’s next step is to qualify the detonator—the biggest challenge yet.

“We have to test more than 550 detonators,” Mehta said,” which involves all sorts of tests – environmental conditioning, transportation, rough handling, etc. and generally takes 8-12 months, but we have a test plan together and have the funds. Airborne Led Reduction is supporting us.”

The team is working to qualify the green fuze against the detailed spec held by PM (project manager) CCS (close combat systems). The team has already submitted a proposal for funding to develop a mortar fuze (M734 for PMCAS) along the same lines, to be able to prove that DBX-1 will work with other munitions fuzes that need green alternatives.

Visit ESTCP’s website for overview of the Green M213 fuze project (WP20-5045) along with conference posters and the technical presentation.

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