Artillery: U.S. Replaces Old M-109 With New M-109


October 10, 2011: The U.S. is selling Chile twelve refurbished M109 155mm self-propelled howitzers. This effort will upgrade the older M-109A2s to the M-109A5 standard and return the M-109 to "like new" condition. The upgrade includes a new howitzer barrel, with 25 percent more range, new electronics and fire control systems. This will cost about $1.3 million per vehicle. Chile already has 12 of these refurbished M-109s, plus 24 that were upgraded by a Swiss firm earlier (to something roughly similar to the A5 standard).

Despite the popularity of the M-109, the U.S. (where the M-109 originated in the 1960s) has been seeking a replacement, without much luck. For example, two years ago, the U.S. Army cancelled its second attempt (the XM1203 NLOS-C) to develop a M-109 replacement. The third attempt will consist of the PIM (Paladin Integrated Management program). That means the army is going to rebuild many of its existing 900 M-109s, rather than trying to come up with another new design. But PIM will be a quite extensive upgrade. It will use the same chassis as the M-2 Bradley infantry vehicle, and a new engine control system. Added to that will be the cab and gun mounts from the Paladin. From the XM1203, the automatic rammer, but not the automatic loader, will be used. So troops will still have to manually load the propellant and 41 kg (90 pound) shell, but the semi-automatic rammer will then push the propellant and shell into the firing chamber and close the breech. Automating this part of the process improves accuracy somewhat, because when troops manually shoved (rammed) in the propellant and shell, they often applied too much, or too little, pressure and left the shell out of position by a tiny bit, just enough to hurt accuracy. PIM will get new electronics, and numerous small improvements, many based on user suggestions. This will make the M-109 PIM competitive with some new European self-propelled 155mm howitzers.

The NLOS-C was to have been the first of the eight MGV (Manned Ground Vehicle) systems to enter service two years ago as part of the FCS (Future Combat System) program. But the FCS lost its focus, budget discipline and Congressional support. It was cancelled in 2009.

Nine years ago, the prototype NLOS-C was cobbled together in six months, after the new (and very high tech and high priced) Crusader SP artillery system was cancelled. The 45 ton Crusader used an autoloader and an engine similar to the one used in the M-1 tank. It was deemed too heavy and too expensive. The NLOS-C used the Crusader autoloader and some of its electronic components.

Although the M-109 has been frequently updated, the NLOS-C incorporated many more new technologies. This included an auto-loader (from the Crusader) and a more modern 155mm gun and an APC chassis with a hybrid-electric engine (to reduce fuel consumption.) This all weighed 23 tons, about the same as the M-109. But the NLOS only had a two man crew, compared to five in the M-109.

The final version of the NLOS-C was to be heavier (about 27 tons), because more defensive systems were added, to reflect experience in Iraq. The NLOC-C also got a lot of new electronics. The vehicle carried 24 rounds of 155mm ammo. Congress originally demanded that NLOS-C be in service by 2008, but development needed a few more years. Field testing (operating as one would in combat), began four years ago with the six prototypes.

One problem the brass were concerned about was the ability of the two man crew to hold up during 24/7 operations. The M-109, with a five man crew, has enough people to take care of maintenance, standing guard and, basically, always having one or two people rested and alert. Not so easy when you only have two guys. One solution was to have two or more crews per vehicle, as combat aircraft (and some warships) have done for years. The off-duty crews would be back with the support troops. PIM will have a crew of four, compared to five in the Paladin M-109.

One of the things that helped kill the NLOS-C was the new GPS guided Excalibur shell. This smart shell entered service four years ago, and changed everything. Excalibur has worked very well in combat, and this is radically changing the way artillery operates. Excalibur means 80-90 percent less ammo has to be fired, meaning less wear and tear on SP artillery, less time needed for maintenance, and less time spent replenishing ammo supplies, and more time being ready for action.

In the current war on terror, even the M-109 has not been used much. The lighter, towed, M777 has proved more useful, especially when using the Excalibur shell. Currently, the army plans to keep PIM versions of the M-109 around until 2050. The M-109 was a solid design, which is pretty clear from how difficult it's been to come up with a replacement. So, in the end, the army replaced the M-109 with another M-109 upgrade.

The army plans to acquire at least 600 PIMs, reflecting the impact of the Excalibur shell, and the number of older M-109s that are still fit for service.

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