YUMA PROVING GROUND, AZ-- For versatility and power, the mortar has been a key indirect fire weapon for generations, and virtually every type and variant of mortar in the ground combat arsenal goes through rigorous developmental testing at U.S. Army Yuma Proving Ground (YPG).
The man portable M224A1 60mm mortar is of particular importance to infantry Soldiers. Consisting of an Inconel cannon attached to a base plate and supported by a bipod, the mortar system provides high-angle fire for close-in support of ground troops. When a mortar cannon is fired for a sustained period of the time the cannon becomes extremely hot, so testing is conducted to determine the rate of fire the weapon system can be fired at without overheating. Overheating of a cannon can result in a failure of the cannon, presenting a safety issue to the crew.
For these reasons, YPG recently conducted a rate-of-fire test to verify that the Army's M1061 60mm mortar round could be used at the specified rate of fire without overheating the weapon system. Most YPG mortar tests are conducted remotely, with weapons operators remotely firing with a lanyard system while under protective cover. The realism necessary for this test, however, made that procedure impossible.
"We're man-firing this test because it is the only way we can achieve the rate of fire we need," said Ken Morrison, test officer. "The purpose of the test is to ensure the M1061 won't overheat the tube at the specified maximum rate of fire."
"It is one of our toughest tests, because it is manned with a very high rate of fire and not a lot of time to react between rounds," added Eddy Patchet, branch chief.
In fact, the test called for the weapons operation crew to fire 320 rounds within 15 minutes, with an initial rate of fire of 30 rounds per minute for four minutes, which means one every two seconds.
To make the test as safe as possible, the team of six operators donned Kevlar vests, helmets and ear protection, and knelt on pads beside the weapon to minimize knee discomfort. Also, within arm's reach was a bucket of water to extinguish any stray burning embers that could fly into the weapon operator's hands or face. The rounds were wax-filled to the same weight of an armed mortar bomb, making the propellant the only explosive part of the test rounds.
Despite the increased risks, the weapons operators were confident of the additional safety measures, and proud that the intense test would help Soldiers in theater.
"It's emotionally moving when we do a test like this and know what it is going towards," said Joe Torres, gun crew leader. "This is for the Soldiers, so we are always highly motivated."
The unique test required a hand from other divisions within the proving ground. The automotive instrumentation branch provided thermocouples at the mortar tube that constantly measured cannon temperature as the firing was in progress. A siren and light was setup that could be activated from within the gun position's bombproof to halt the test immediately if a safety concern was identified. Unlike the typical test, two additional test officers assisted during the test to ensure safety: Mike Barron was stationed with the gun crew and had constant communications with Chad Bloomingdale and Morrison who were monitoring cannon temperature and three live video feeds from inside the bombproof.
Even more special equipment was required: a sensor at the mortar's base plate accurately recorded the rate of fire throughout the test. Then there was the matter of how to stack 320 four-pound mortar rounds for quick access to sustain the extremely rapid rate of fire. Toward that end, YPG's support services constructed a stout two-shelved wooden structure behind the mortar emplacement. As the test moment approached, weapons operators and test officers carefully unloaded ammo can after ammo can of mortar rounds delivered to the gun position by truck, stacking them onto the shelves.
Once the test began, the weapons operators performed flawlessly, feeding weapon operator Matt McDaniel round after round and easily achieving the desired rate of fire while experiencing a mere three cook-offs of the 320 wax-filled mortars at the tube.
YPG testers attribute the flawless performance to careful planning, gun crew expertise, and rigorous adherence to safety procedures.
"It was highly successful," said Patchet. "Even when we had the cook-off at the muzzle, the crew knew to remove the round and keep going. As a result, we met the test objective."
Social Sharing