Nonlethal mortar program

Nonlethal mortar program

Robert Worth

In 1998, the Department of Defense’s Joint Nonlethal Weapons Directorate (JNLWD) recognized the need for a weapon system capable of delivering nonlethal (NL) payloads at a distance in excess of 100 to 200 meters. To meet this need, they solicited private-sector contract bids using a broad agency announcement. Of the many responses received, only two companies won contracts: M2 Technologies (M2) and United Defense. Both companies proposed mortar solutions, and the contracts were awarded in May 1999.

The biggest design challenge facing M2 and United Defense was a contract requirement stipulating that no portion of the payload or mortar cartridge could impact the ground with kinetic energy (KE) greater than 58 foot-pounds. Since existing mortars weigh several pounds and typically impact at greater than 100 meters per second, positive design features reducing the KE had to be considered. M2’s initial approach was to make the cartridge case combustible by using compressed felt fiber (CFF), a material readily available in ammunition.

United Defense, teaming with two Army research laboratories (ARLs) and the Soldier and Biological Chemical Command, looked for ways to reduce the cartridge weight by substituting composite parts for metal ones and deploying parachutes that slow the spent cartridge’s descent. M2 concluded that CFF would not survive launch without significant structural enhancement via doping agents (agents added to a pure material to alter a physical property of the material), and even that would be a marginal improvement.

In a series of proof-of-principle firings at Edgewood Arsenal in June 2000, United Defense and the ARLs demonstrated that an 81-millimeter mortar cartridge (weighing about 50 percent as much as existing mortars of that caliber) could be flown over 1,500 meters. However, they encountered difficulties with the two parachutes that controlled their descent.

A short time later, the JNLWD asked the Tank-automotive and Armaments Command-Armament Research, Development, and Engineering Center (TACOM-ARDEC) to assume responsibility for subsequent NL mortar efforts. An integrated product team (IPT) was then formed, and the work continued. The IPT considered several KE-reduction techniques, and prototype hardware was built and lab-tested.

A new series of firings was held from November 2002 to January 2003; not only KE reduction but also payload deployment was evaluated. The TACOM-ARDEC IPT established pre-Milestone A exit criteria (such as range, accuracy, and ability to deliver different types of payloads with an appreciable area coverage) and demonstrated that they could meet or surpass the criteria in the firing test programs. The next step of the development program is Milestone A.

Mr. Worth retired from TACOM-ARDEC in 2001. Before that, he was a development project officer in ARDEC’s Mortars Team that was responsible for mortar weapons and new systems. He headed the Nonlethal Mortar Pre-Milestone A Program. Mr. Worth now serves as a program consultant and has a bachelor’s in aeronautical engineering and a master’s in mathematics.

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