The XM1203 NLOS-C

I noticed that the XM1203 ("FCS NLOS-C") never got publicity with the appropriate emphasis, describing its true nature. Most who wrote about it were distracted by the vehicle mass. Even I commented - if at all - rather disparagingly about it, focusing on the by today's standard short barrel (38 calibres) and its thus hardly satisfactory range.

The XM1203 was - as its equally gold-plated and just as cancelled predecessor project, the XM2001 Crusader - equipped with a special feature: A liquid cooling of the gun.

Liquid cooling is traditionally only applied if the associated high weight is acceptable; this was accepted with Maxim-style heavy machine guns, and is still accepted with some naval gun designs (example). Evaporation cooling with water enables a gun to maintain its maximum rate of fire well beyond what its thermal mass would allow for (air cooling is weak and reduces the sustained rate of fire of howitzers to about 1-3 rpm). A SPG such as PzH 2000 can sustain its highest rate of fire for approximately a minute. The XM1203 was able to do so at least until it ran out of ammunition (24 shells at 10 rpm ~ 138 seconds). Its liquid cooling was relatively light weight:

"Following firing, the breech opens and the Automated Cooling and Cleaning System (ACCS) sprays a water/glycol mixture to extinguish residual propellant embers, clean the laser window, wet the breech seal and cool the propellant chamber."*

THIS was the most defining feature, not the by now ordinary networking stuff, by now ordinary maximum rate of fire, the obsolete barrel length or the 'only 50% too heavy for C-130J' weight.

What kind of army would define requirements for such a capability?

Well, I can tell what kind of army would NOT pay much attention to such a capability: An army that expects to face counterfires by long-range artillery. Such an army would expect its own artillery to change positions often, typically after firing a short burst of smoke shells or a MRSI strike** of maybe four HE shells. There is rarely going to be an opportunity to fire multiple MRSI missions on different targets before the "scoot" part of "shoot & scoot".***

Furthermore, an army that expects very high expenditures of munition per day - typical planning would be 200/day and barrel, Ukraine fighting reached peaks of 450/day and barrel!) would likely insist on a larger onboard munition supply, such as 60 shells.

What kind of army is left? I suppose an army that expects to beat up small 3rd rate or worse armies that pose little artillery counterfires threat, possibly after a quick deployment by (heavy) airlift. And one can read this off the design!


*: They used a laser to ignite the propellant, not some percussion cap. 
**: Multiple shells arriving within few seconds because they were fired at different elevation angles with different quantity of propellant modules. This is relevant for lethal shells (not smoke) and meant to exploit the surprise effect. All shells arrive before the targeted troops can leave the area or find cover. This is more lethal per shell (more efficient) than long bombardments with regular intervals between explosions. 
***: The SPG (or classically the entire battery) fires a few shells, then leaves the area in haste before counterfires arrive. The firing of shells can be measured by hostile radars and hostile fire control can calculate the point of origin. That's why artillery locations are very dangerous after firing commenced from there.


  1. There are South African G5 and G6 howitzers. In Europe, there is Panzerhaubitze 2000 or Polish Krab or Turkish Firtina. - Until this day, that`s all. In the realm of barrel artilery we will wait for any really new system for years.

  2. In this case I disagree. If you go back to the former future of the US artillery, the Crusader° the liquid cooling of the whole barrel was an "integral part" of the firepower package needed to finally substitute the obsolete M109. As it's end neared there were desperate attempts to downsize it to 40 tons and at last it was tried to carry over at least some technologies to the supposed future in form of the XM1203 NLOS-C.

    "During the late 1990s, the Crusader program was envisioned as the greatest leap forward in completing the process of automating the fire support chain. When the program was terminated in mid-2002, a short-term bridge contract was put in place to migrate the technological developments and workforce into the FCS program, which was approaching Milestone B in mid 2003. This proved valuable as the NLOS-C has remained the leader in terms of FCS MGV variant development."

    Your Source, page 44

    It seems that they limted the liquid cooling to the chamber area to save weight which did indeed drive all design, but could not resist to implement technology with considerable tradeoffs which fitted far better into the overall Crusader package. Basically institutional imperative instead of a insight into the overall aim. However overall the military focus was not a capable conventional opponent.

    "ECC Weight/C130 Requirements Are “The Eye Of The Needle*” For All MGVs"

    Major Darby McNulty, 2004, page 10.

    All in all it is rather amusing to read about the perceived shortfalls of the M109 around 1998, especially concerning rate of fire and range and then almost two decades later hear about the artillery great leap forward thanks to the latest iteration of the '60 design with same basic cannon hardware^.



    *The Babylonian Talmud applies the aphorism to unthinkable thoughts, according to Wikipedia. Rather apt, I have to say.


    1. The XM1203 NLOS-C was supposed to deliver PZH 2000 ranges (30km+) precisely because the barrel cooling, or more accurately chamber cooling, feature would enable it to use more powerful, less sensitive explosives. The cannon design was intended to be a step on the road to liquid propellant howitzers and guns.

      GAO-05-428T provides a nice summary of why the program failed, the BLUFF was typical: too many immature, untested technologies (75%!), shoe horned into a vehicle chassis that, itself incorporated too many immature technologies, and was likely too small. The total package was supposed to be C-130 transportable and weigh under 18 tons, which is unrealistic.

      It is a gross mischaracterization to say that the “barrel cooling” was a design feature to beat up 3rd rate militaries – even PZH 2000 literature sensationalizes ROF.

      On a separate note; PzH 2000 gets many things wrong, mostly its price.

      A better strategy is save the money from not buying PzH 2000 to buy: more SPHs, a separate ammunition vehicle per SPH retro fit existing SPHs with the larger caliber/bigger chamber volume guns, and add a mechanically simple loading rack that enables 3-4 rounds to be fired in quick succession.

      The counter battery mission is really the job of missiles now, or loitering drones; so even the larger gun is a luxury.


    2. "It is a gross mischaracterization to say that the “barrel cooling” was a design feature to beat up 3rd rate militaries – even PZH 2000 literature sensationalizes ROF."

      There is a huge difference between mcuh effort for 2 minutes high RoF and a little less effort for 1 minute high RoF.
      To leave the place takes approx 30 seconds, and a little more if the choice of routes is limited. Return fire can impact as quickly as 2 minutes after the first shot if the opposing force is very well drilled, well equipped, in position and alert.

      The slightly longer time of firing can make a huge difference.

      Also note PzH 2000 marketing also tells about even higher RoF with higher voltage autoloader - that higher RoF can be maintained for an even shorter time, obviously. That's a whole different thinking than the XM1203's which was about much sustained firepower or many MRSI fire missions without relocating.

    3. The key feature of the XM1203 NLOS-C, and the proceeding crusader program, was the *ammunition propellant* not rate of fire.

      The ability to use extremely stable propellants that, when ignited, release much greater energy than conventional propellants would be as great an advantage as going from muzzle loading to breach loading weapons. This is lost to cursory examination, but is very much the heart of US artillery design if you follow the documentation and briefings.

      Sustained rate of fire was a secondary consideration, the cooling was needed to promote safe, reliable, and consistent ignition of the propellant, which required ridiculous levels of energy to start the reaction.


  3. Moreover, the XM1203 had the ability to load completly different kind of ammunition extremly fast so it could fire different kind of ammo faster than any other system as far as i know.

    1. I doubt that. The simple autoloaders like the Serbian one require to have the shells and propellant modules loaded manually for the next fire mission. Full autoloaders as the one in PzH 2000 choose the shell type and qty of propellant automatically.

  4. Looking at numbers, the M109 is supposed to be 4 rpm maximum ROF. The XM1203 shot for 10 rpm. You could say that (assuming same range as the M109) the XM1203 was eminently suitable for shoot and scoot missions.

    1. That wasn't the point. They added an unusual requirement /capability that points away from MRSI and shoot&scoot even though both were possible.
      This was about reading intent out of an unusual requirement.

  5. SPG have evolved along a somewhat similar line as ship cannons. First a gun was simply put in some fashion* on a carriage, now a specialized, semi- or fully automated system quickly feeds the howitzer.

    Obviously a larger and heavier vehicle offers for the same technology the specific gun-system more space and mass plus more storage. So if the XM1203 was able to achieve firepower x a heavier XM - or indeed a 'new' Crusader - should do it faster, longer and better with more rounds. Robotics has overall come a longish way since the PzH was designed.


    P.S: What do you think about that?


    Seems to carry roughly the same amount of HE as the predecessor. In any case with the guided fuze, which makes increasing sense for those longer ranges, less HE shouldn't matter too much for certain targets. Still a longer barrel would help considerably.

    *https://www.youtube.com/watch?v=wWi2JQ1tjSo and https://www.youtube.com/watch?v=q8bK-7TY0Fw

    1. https://defense-and-freedom.blogspot.de/2008/05/technology-creeps-according-to-patterns.html