Boeing has offered the best look yet of its 155mm artillery shell, with a ramjet engine actually sent into the depths. The company also says a recent test of this design, which it is developing in collaboration with Norway’s Nammo, broke the existing range record for a ramjet-propelled artillery shell. However, the exact distance the grenade traveled is unknown.
A press release issued by Boeing today included the image of the Ramjet 155 cartridge at the top of this story, as well as details about the milestone test and other future plans for this ammunition. Nammo first introduced the 155mm ramjet bullet design in 2018. The two companies are currently developing the projectile as part of the U.S. Army’s Extended Range Artillery Munitions Suite (ERAMS) program.
Boeing and Nammo also announced last year that they had conducted a test of the Ramjet 155, which set the previous range record for a missile of this type. In this case too, the two companies did not want to say how far it had been traveled.
An image released by Boeing and Nammo after the 2022 test of the Ramjet 155 shell, which took place at the Andøya Test Center in Norway. Boeing
Boeing has said in the past that the goal is for the ramjet to be able to hit 155 targets at a distance of more than 70 kilometers (~43.5 miles). Nammo said the ramjet-powered round could ultimately be able to reach a range of up to 150 kilometers (just over 93 miles), depending on the weapon used to fire it.
Typical 155 mm artillery shells are fired with separate propellant charges. There are also extended-range models that integrate a small rocket booster into the base of the projectile and are now in use worldwide.
A Nammo graphic showing the comparative maximum ranges of various types of existing and under development 155mm munitions, including advanced rocket-launched types and the Ramjet 155. Nammo
The Ramjet 155 has an air-breathing ramjet engine. Detailed design information is limited. The general concept, which companies around the world have been experimenting with for decades, is to increase range through a combination of sustained supersonic flight and the fact that the engine actively pulls the projectile through the air.
The Ramjet 155’s guidance package will also include the same “mission computer” component found on the Joint Direct Attack Munition (JDAM) precision-guided air-dropped bombs. This suggests a GPS-based guidance method suitable for encountering static targets. There is still the possibility that some type of seeker or a combination of seekers will be integrated in the future to be able to hit moving targets.
Boeing and Nammo hope to demonstrate the Ramjet 155’s precision guidance capabilities in another test soon.
Although the original design is only capable of attacking specific fixed target coordinates, the Ramjet 155 could represent a significant leap in performance for existing 155mm howitzers. Historically, the expected range of the ramjet-powered cartridge is closer to that of large-caliber artillery rockets.
A 2018 U.S. Army graphic showing the ranges of various existing ground-based artillery and missile systems, as well as planned future developments, compared to those of Russian threat systems. United States Army
For example, the latest A6 and A7 versions of the venerable M109 155mm self-propelled howitzer now in service with the US Army can hit targets at ranges of 22 kilometers (~13.6 miles) and 30 kilometers (~18 .6 miles) with existing unpowered and rocket-assisted weapons hit ammunition. With Ramjet 155, the range of these howitzers would at least double, if not expand.
A 155 mm M109A7 self-propelled howitzer. United States Army
This additional range also gives the 155 mm howitzer batteries significantly greater flexibility. With a range of 30 kilometers, one of these weapons can hit anything within a circular area of about 2,827 square kilometers (nearly 1,092 square miles). If their range is expanded to 70 kilometers or 150 kilometers, the area in which they can hold vulnerable targets without having to relocate them increases to 15,394 square kilometers (5,944 sq mi) and 70,686 square kilometers (27,292 sq mi), respectively.
Howitzers already have the inherent ability to easily shift focus from one target area within their range to another in response to new developments on the battlefield.
However, it remains to be seen whether or not the U.S. Army or any other world military ultimately acquires stocks of the Boeing/Nammo Ramjet 155 or another 155mm ramjet-propelled grenade design. Boeing and Nammo are just one team working on an advanced 155mm cartridge as part of ERAMS. The Army already refers to the cartridge it ultimately decides to purchase as the XM1155.
Teams led by Raytheon and BAE Systems are also working on competing designs. Raytheon’s projectile is another type of ramjet propulsion that the company is developing in collaboration with the Netherlands Organization for Applied Scientific Research, also known by its Dutch acronym TNO.
The BAE Systems grenade is a so-called sabotaged concept, in which, after firing, a smaller projectile is fired, which then flies at very high speed. The expected maximum range of this design is at least 110 kilometers (just over 68 miles). It is based on the ammunition the company developed for the US Navy’s failed electromagnetic railgun project. According to BAE, the XM1155-SC (SC stands for Subcaliber) round holds the current record for the longest precision-guided shot from an Army M109 series howitzer, another of the company’s products that uses any type of ammunition.
A now-dated slide from a briefing on the U.S. Navy’s railgun program, showing other potential applications of the central high-velocity projectile (HVP), including a cartridge for 155mm howitzers. USN A previously released image of the BAE Systems XM1155-SC cartridge during test firing. BAE Systems
For the U.S. Army specifically, a new ramjet-powered or other long-range 155mm grenade is just one part of a much larger initiative to expand the range of its units tactically and strategically. This includes a variety of other programs focused on developing new ground-launched cruise and ballistic missiles, drones, prowling munitions and more.
A graphic depicting various roles and missions of future U.S. Army air-launched drones and loitering munitions, including use in conjunction with long-range artillery. United States Army
At the same time, the Army’s future artillery strategy, particularly with regard to advanced 155mm howitzers and their ammunition, appears to be currently undergoing a period of change. For some time, the service has been pursuing a new 155mm self-propelled tracked howitzer called the XM1299, which is designed to make optimal use of ERAMS ammunition and features improvements including an automatic loader.
A briefing slide showing various elements of the U.S. Army’s Extended Range Cannon Artillery (ERCA) artillery initiative, including the XM1155 ERAMS projectile and the XM1299 self-propelled howitzer. United States Army
However, senior Army officials have now raised questions about whether this is necessarily the most cost-effective option and whether other options now available on the open market could potentially provide similar capabilities sooner.
“If we go in a different direction, it really becomes a fiscal year 2025 budget decision,” Doug Bush, assistant secretary of the Army for Acquisition, Logistics and Technology, recently told Defense News. “However, I think the requirement still exists. We still need greater reach in a more affordable way, which is an important caveat.”
Another problem is that the heavily armored XM1299 is not really suitable for lighter forces such as Army airborne and airmobile units, for which lighter howitzer designs may be better suited. In 2021, the service tested a number of 155mm wheeled self-propelled howitzers, including several foreign types, but did not pursue any of them further.
The Archer from BAE Systems Bofors in Sweden, seen in the video below, was one of the foreign 155mm self-propelled howitzers that the US Army had previously tested.
“The [Army artillery] “The strategy is to consider a combination of factors,” Bush told Defense News back in September. “Where do you need towed artillery versus tracked artillery or maybe wheeled artillery? What can you do with ammunition to gain range instead of building new guns?”
Regardless, “the general lesson is that you still need artillery,” he added at the time. “She is the No. 1 killer on the battlefield, still in this conflict.” [in Ukraine].”
Overall, it is clear that the Army continues to view expanding the range of its artillery units as an important focus. Boeing and Nammo’s ramjet-propelled artillery projectile or one of the other ERAMS projectile designs are expected to play a key role in realizing this capability.