By Ann Roosevelt
The long search for “insensitive” munitions to replace TNT that don’t detonate when they are dropped, fired into or set off by a nearby detonating round may be coming to an end, with BAE Systems‘ development of a new family of explosives that only detonate as mission-required.
The Army has approved the [Insensitive Munition Explosive] IMX-101, as the first safer and effective alternative to replace TNT in artillery. It is slated as a TNT replacement for the new IM M795 155 mm artillery shell.
TNT was first used in artillery shells by the German army in the very early 1900s.
IMX-101 has the same explosive or energetic power as TNT, but greatly increases the safety of the munition for those who work around it.
“IMX-101 explosive has the potential to revolutionize military ordnance,” said Jerry Hammonds, vice president and general manager of Ordnance Solutions for BAE. “This transformation will help save lives on and off the battlefield.”
BAE is producing small quantities of IMX-101 now and expects to ramp up work in 2011, increasing production in 2012 and 2013.
Throughout history, numerous incidents with the handling and use of TNT-loaded munitions have caused death and injury, Hammonds said.
Thus, it became a Defense Department initiative to try to find systems–explosives and the end-item systems–that could be manufactured and handled more safely. That was the start of the term “insensitive munition.”
“It is becoming a reality” that munitions are becoming insensitive to external stimuli that can cause these particular accidents, he said.
BAE, which had been researching insensitive munitions for nearly a decade anddeveloped IMX-101 in partnership with the Army at the Holston Army Ammunition Plant in Kingsport, Tenn.
“One of the first [munitions] that we attacked was the 155 artillery round and the replacement of TNT in that round,” Hammonds said. “We’ve been very successful.”
IMX-101 is manufactured “with a whole new host of chemicals that are different than what’s been used before, but we’ve got the technology here on site at Holston to do that and we came up with formulations and so forth and then worked with the Army to prove them out,” he said.
Mike Ervin, director of research and development at Ordnance Solutions at BAE, said, TNT, an explosive itself, it can be used alone, such as in a 155 artillery round, or in a formulation. The most common formulation, and what Holston was originally designed to manufacture, is an explosive formulation called Composition B (Comp B). It consists of TNT and RDX explosive–also made at Holston. This goes into mortar rounds and grenades, for example.
IMX -101 is a formulation like Comp B, Ervin said. The Army wants the equivalent performance for what it’s replacing while increasing the safety margin for those who have to handle the munition.
The Army sets aggressive test criteria for insensitive munitons. One test is firing a .50 cal. bullet into an explosive-loaded munition. Another test is fragment impact, where a high velocity fragment will be driven into the munition. Other tests include slow cook-off and fast cook-off done with fires, sympathetic detonation–equivalent to having two munitions beside each other, with one detonating–and the “mother of all” a shape jet charge.
“TNT fails each insensitive munition test the Army has across the board,” Ervin said, while IMX-101 passes all the tests.
In fact, the Army and BAE realized the legacy, traditional explosives themselves–TNT, RDX and others–would not meet the criteria.
“We at Holston in working with the Army established robust manufacturing processes for new insensitive ingredients, such as DNAN, a TNT replacement, he said.
The company put together a team that Ervin said was so successful because it approaches research while thinking about production, making the transition from lab to manufacturing more successful.
Hammonds also noted that BAE allowed it to make its own investments in some formulations and research, making the process move more rapidly.
“The bottom line is by mixing these together you can match the performance of TNT or Comp B but they are much safer,” Ervin said.
Ervin said the Program Manager, Combat Ammunition Systems at Picatinny Arsenal, N.J., shared a story about a team of Marines in Iraq some months ago. The Marines were in a truck hauling 60mm mortars, filled with a first generation insensitive explosive. called PAX-21, also manufactured at Holston. An RPG was shot into the truck and fragments went through the mortar rounds.
“They said if they had been the legacy round filled with Composition B it would have gone high order (detonation) and there would have been seven fatalities,” Ervin said. Because of the insensitive explosive in the mortars they didn’t detonate, but caught on fire. Everyone was able to get out of the truck, and there was only one injury.
“That’s just an example, but it’s only one of several where these insensitive munitions are saving warfighters lives out in the field,” Ervin said.
Hammonds said Holston is producing insensitive munition products now, and various formulations are being tested and will be fielded.
“We have a product called IMX-104, a replacement for Composition B with the intent of that flowing into the mortars, the 60-80-120 mm mortar systems. We’re very far along on that path,” he said.
BAE is already providing PAX-21 for the 60mm mortar program, and has for some time provided CMXM-7 that is part of the fill in the JDAM bomb.
Additionally, BAE is currently producing some other formulations that are in some Air Force and Navy bombs, such as the Mark 80 series bombs already fielded.
Additionally, BAE is working with Picatinny in examining the potential to provide some of the formulations to NATO allies.
The Army also has deemed IMX-101 a suitable replacement for any large-caliber munitions requiring the energetic performance equivalent to TNT.
BAE, then Royal Ordnance, won the contract in 1998 to operate the 6,000 acre Holston Army Ammunition Plant over ATK [ATK]. BAE replaced incumbent Holston Defense Corp., which had operated the plant for the Army since 1943. The plant now produces more than 80 explosive products or formulations the government needs to support its munitions base.
The company is in year 11 of the 25-year contract that expires in 2023.