The Military’s Lengthy-Vary Howitzer Has Met Its Achilles Heel

Funds paperwork launched in March present that the Military’s bold plans to double the vary of its M109 Paladin armored howitzer artillery have ignominiously bit the mud, regardless of supply of functioning prototypes that fired take a look at photographs at targets out to 61 miles away.

The prototype M1299 Prolonged Vary Cannon Artillery (ERCA) sported an extended 58 caliber barrel that might generate the mandatory inner stress to spit out 155-millimeter shells at targets dozens of miles away. But it surely couldn’t execute these long-distance photographs with out breaking its barrel sooner than ordinary.

Six years in the past, the U.S. Military unveiled its Lengthy Vary Precision Hearth program, which sought to dramatically lengthen the vary of its artillery and land-attack missile forces. That might give floor commanders higher assault choices whereas decreasing dangers of enemy artillery with the ability to retaliate. In any case, nothing is safer than attacking the enemy from such a protracted vary that they merely can’t attain you.

ERCA was a key merchandise in these plans, searching for to just about double the utmost vary of the mainstay M109 Paladin self-propelled howitzer from the present 24 miles (utilizing rocket-assisted projectiles) to over 40 miles.

This vary improve was to be achieved via the usage of a brand new pressure-tolerant XM1113 rocket-assisted projectile (which entered service in 2016), mixed with juiced up propellant referred to as the XM654 SuperCharge, and a lengthened 58 caliber XM907 gun tube (up from the M109’s ordinary 39-caliber gun) mounted on a automobile referred to as the M1299.

The M1299 mated the XM907 gun to the chassis of the most recent variant of the M109 armored howitzer referred to as the M109A7 PIM (for ‘Paladin Built-in Administration’), which launched the hull of the Bradley fighting vehicle. A real Ship of Theseus, the M1097A7PIM not has both turret or hull in widespread with the unique M109 Paladin, which was launched to service within the Nineteen Sixties.

The XM907 gun’s 29.5-meter tube might improve the stress pushing the shell out of the barrel at as much as 3 times the velocity of sound, thereby growing the vary.

Already, in 2018, the XM907 achieved a 38.5-mile take a look at shot firing from the carriage of an M777 towed howitzer. Two years later, in March of 2020, an M1299 automobile additionally carried out take a look at photographs—together with one which exactly landed on a van 40.4 miles away.

Then, in December—after two vary photographs—it blasted a goal from 43 miles away utilizing an M982 Excalibur GPS/inertial-guided smart shell. On common M109s, that shell is confined to a most vary of 25 miles.

A full battalion of 18 M1299 prototypes—plus two extra for harmful testing—was delivered to for operational testing by 2023. From there, the Military hoped for a manufacturing order to resurrect a retired tier of very-long vary artillery within the type of M107 weapons and M110 howitzers. These are used for hitting high-value targets deep behind enemy traces similar to air defense systems, command posts, bridges and naturally enemy artillery.

Ramjet and sabot shells

The Military additionally deliberate to double the vary of the M1299 once more to 70-80 miles by taking pictures much more unique 155-millimeter Prolonged Vary Artillery Projectile (ERAP) shells—to be designated the XM1155, as soon as procured.

Each Boeing/Nammo and Raytheon/TNO are providing shells powered by a stable gasoline ramjet engine, that are very environment friendly for propelling autos already shifting at supersonic speeds (because the onrushing air is used for compression). That’s problematic for an airplane making an attempt to takeoff from the bottom at a beginning velocity of 0 miles per hour, however not an artillery shell propelled out of a gun barrel at supersonic speeds. Moreover, ramjets are light-weight and don’t want to hold oxidizer like conventional rocket-propelled shells.

Boeing’s Ramjet 155 shell fired by an M1299 apparently attained record-breaking range in a take a look at final fall.

BAE Methods can be competing with a non-ramjet munition referred to as the XM1155-SC—initially derived from the HVP-ER hypervelocity projectile, developed for a canceled Navy railgun. This ‘sabot’ design concentrates the power of an enormous shell right into a smaller, lighter, sub-caliber munition launched after firing to realize superior thrust-to-weight ratio and allow a max vary of 68 miles.

This shell—dubbed the XM1155 and fired from a modified XM907E2 gun—achieved a variety of 68 miles.

Supposedly, XM1155-SC could cost “less than $85,000”. That’s not low-cost sufficient for use casually en masse—no less than, in comparison with ‘dumb’ shells costing $3,000 every. But it surely’s lower than the Excalibur spherical’s present value, and thus could fall inside the realm of viability as a silver-bullet weapon for selecting off useful level targets (particular person armored autos, radars, command posts, depots, and many others…)

The Army was additionally growing an Superior Autoloader, which is able to cut back the crew on its armored howitzers and greater than triple the ‘surge’ fee of fireside from 3 shells per minute to 10 per minute. Nonetheless, balancing the lengthy ERCA gun was already tough, and have become much more so with a full-sized autoloader. This compelled engineers to cut back the autoloader’s journal from 31 shells to only 23.

Downfall of the M1299

However 2023 got here and went, and the M1299s proved to be the solely program—out of the 24 that the Military promised to subject by 2023—that went undelivered. The issue turned out to be considered one of barrel put on: the highly effective gun taking pictures highly effective shells was powerfully sporting via its gun barrel.

Repeated firing progressively wears down all artillery weapons, and that put on is accelerated throughout each excessive fireplace charges (which quickly overheat the barrel and trigger warping) and long-range photographs (utilizing the utmost variety of costs which inflict maximal kinetic stress on the barrel).

Worn barrels change into increasingly more inaccurate, and people over-used past security tolerances threat exploding, which may hurt crew and trigger the barrel to ‘petal’ dramatically. Such overuse is particularly widespread in high-intensity conflicts just like the one in Ukraine.

Whereas there is no such thing as a escaping the necessity to change the barrels of artillery techniques and tanks, producers nonetheless attempt to optimize barrel life to final via as many photographs as attainable. They do that via the usage of metallurgical improvements and design options, like thermal sleeves to control barrel temperature.

The issue with the XM907 gun, apparently, was that the stress produced by its shells was sporting via the XM907’s barrel far too quickly, that means {that a} new and costly barrel must be swapped in with impractical regularity. The straightforward repair of accelerating barrel thickness would trigger an excessive amount of weight achieve, which risked unbalancing the already precariously balanced automobile.

Specifically tempered barrels aren’t low-cost, and having to drag weapons off frontline fight operations for re-barreling is clearly lower than ultimate. Combating in Ukraine has proven huge artillery utilization charges that too quickly exceed the barrel lives of the NATO 52-caliber howitzers donated to Ukraine.

So, whereas the M1299 might belt out some spectacular long-distance photographs, it could too quickly must be pulled out of operational service for an costly and time-consuming barrel substitute.

The Military had not discovered an answer to the extreme put on by the point prototypes have been delivered. The Authorities Accountability Workplace issued a report warning that this system had already inflated by $78 million over estimated funds, and was delayed. That result in the 2024 choice to drag the plug on what had as soon as appeared like a promising, quick, and inexpensive venture.

Maybe just a few extra years and tens of millions of {dollars} of spending might have mounted the issue, however there was a threat ERCA would suck down an excessive amount of extra cash with out producing a cost-efficient resolution. The service most well-liked to return to the drafting board, and is requesting proposals for different solutions.

Whereas lack of lengthy barrel weapons is a blow to the Military’s artillery department, the service nonetheless needs its 40-mile strike functionality. And going by program rhetoric, it now seems extra inclined to select a relatively mature, off-the-shelf solution than threat making an attempt to develop a brand new design once more. That will contain becoming a future M109 variant with the 52-caliber size 155-millimeter barrels already utilized in a number of Euroupean howitzers just like the Panzherhaubitze 2000.

The XM1155 shell, when mixed with 52- and even the present 39-caliber howitzers, may nonetheless attain spectacular ranges—even when they nonetheless fall wanting these achieved with the M1299 and XM907 gun.

The Military additionally has a number of different avenues via which they will carry out deeper oblique strikes, together with MLRS rocket artillery, drones, new helicopter-launched missiles, and tactical ballistic missiles like the brand new Precision Strike missiles. Whereas shells are cheaper and theoretically extra sustainable than these weapons, the expense of the R&D and unit prices of the prolonged vary artillery should not rise so excessive as to obviate the worth benefit. clear amount and sustainability have confirmed the decisive elements in Ukraine’s artillery wars to date.

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