Northrop Grumman announced that the company was developing 50 mm guided cannon ammunition, primarily for the air defence role. How does it work? The probable answer is more complex than it would initially appear.
At Eurosatory 2026, Northrop Grumman unveiled their as-yet unnamed concept for a mobile short-range air defence (SHORAD) system, alongside providing information on their in-development 50 mm guided projectile.
The SHORAD concept was shown in scale model form, and comprised a palletised turret, fitted with a radar for target acquisition, and an optoelectronic sight for fire control. The turret was armed with the Northrop Grumman XM913 dual-feed automatic cannon, chambered in 50 × 228 mm ‘Supershot’ (this is a ‘necked up’ version of the 35 × 228 mm cartridge), with 400 ready rounds. As part of their air defence offering, the company stated that a guided 50 mm round was in development and could form part of their palletised turret solution.
Guided cannon ammunition development has been known about for many years, and experimental forms have previously been publicly demonstrated. For example, in a previous role, I recall having been shown a presentation by Orbital ATK just before they became part of Northrop Grumman, circa 2018, in which the company presented footage of a guided 30 mm round successfully striking targets.
Yet despite numerous proof-of-concept demonstrations, the technology has yet to enter service at typical cannon calibres. To understand why, consider that many of the typical components necessary for many typical guided weapons – seekers, steering and stabilisation fins, servos, proximity fuzes, and so on – would have to be shrunk down to fit into a comparatively tiny amount of space available on a cannon projectile, while also retaining enough space for enough explosive filler. On top of this, the rounds also need to be cost-competitive with alternatives on a ‘stowed kills’ basis. This is no simple task.
To discuss Northrop Grumman’s developmental guided 50 mm round in more detail, Warsight sat down for an interview with Jon Ferko, Senior Director at Northrop Grumman, and Monty Dellapi, Director of Business Development at Northrop Grumman.
Starting with a bit of history, Warsight enquired what had happened to the original Orbital ATK 30 mm guided munition project, Dellapi noted the “we look at guided ammunition more holistically as sort of a technology, as opposed to really focusing in on a caliber specific application, and I’ll be honest, most recently we’ve been working with the US Navy on a guided concept for a 57 mm, the Mk 110 remote weapon station [RWS] on the littoral combat ship [LCS], and that’s in development with the US Navy, and the technology that we’re using on the 57 guided, we’re going to implement a lot of what we’re learning on that development program in the 50 mm.”
“Lack of a customer requirement for 30 mm, kind of stalled the technology evolution and maturation, and then it wasn’t until the Navy came to us with a problem that they had, where they had a contractor that they were having issues with, and we worked it, they had, they funded us under an OTA [Other Transaction Authority] for a development programme,” he added.
Northrop Grumman declined to go public with the specific seeker type they were aiming for, with Ferko stating simply “we’re exploring all options here still” and adding that current tests had been “very positive,” and added “this is all Northrop Grumman Investment, so it’s all proprietary, we’re putting a lot through.”
Using a seeker would provide a number of advantages over certain other guidance methods. For example, compared to laser beam riding, or command guidance, a seeker-based solution would be less constrained in terms of the number of simultaneous engagements possible, since it would not be limited by the number of targeting channels on the platform, or by the need to maintain targeting within a certain field of regard for each target.
Warsight also enquired into the degree of divert capability that could be expected from a guided 50 mm round. Ferko responded, “We’re talking a 50 mm, so there’ll be some course correction, some guidance that it’ll take, I mean, we’re not going to be swerving this thing like a hypersonic, but there will be some, guidance that guides it towards the threat, and then it’s proximity burst, so you put a few of those guided into the direction, multiple threats at the same time, it’s not single.”
Dellapi added, “one of the biggest advantages to guided ammunition is that it provides you range extension, so larger standoff distances. So, if nothing else, it takes the dispersion out of longer-range engagements.”
In terms of potential procurement decisions, alongside the US Navy, Ferko added, “We’ve got a whole test plan throughout the end of the year. We’ve got some milestones there that we’re talking to the Army and other customers that if things are very successful, that could lead to, I’m hoping, eventual procurements.”
Moving on to force structure, the war in Ukraine has demonstrated how dangerous the persistent drone threat can be, and numerous militaries are looking into modifying force structures to face this reality. With this in mind, Warsight asked where Northrop Grumman saw their guided 50 mm solution fitting into coming doctrinal shifts.
Ferko responded, “I think you’re seeing across all modern militaries is a doctrinal shift on how we do air and missile defence, right? Before, air and missile defence was very separated from the manoeuvre force, covered the manoeuvre force, but with the influx of the of the warfare we’re seeing, it now has to be integrated with the manoeuvre force, especially with UAVs. So I think every military is evaluating their doctrine, and how these different units are down at the individual soldier level defence to organisational units, to full manoeuvre units, to static critical infrastructure defence systems. This [Northrop Grumman’s mobile SHORAD solution] has been designed to do kind of both. We’re showing a mobile system…so two of these on a C-130, you know, drop it on an air base, you could move it with a Chinook…but you can see it’s completely palletised system, you could put four to six of these at a rather large airfield, and you’ve created 360-degree air defence.”
“Remember, this is part of a full-up integrated air defense system, and now you know, as you have your, your mid-tier capability, and you’re tying in, like, an IBCS [Integrated Battle Command System] that’s feeding fire direction to this, and what now you can make decisions. I’m going to use my PATRIOT, my IRIS-T, my NASAMS for those. I’m going to let some through, and I’m going to get them with my shorter range systems…So you capture the leakers on the cruise missiles, and now you’ve got your UAVs coming through, and now you’ve got that whole family of defender systems. Start using your 30 mm, even our PGS [Precision Grenadier System] that we have…we’ve really got to think out of the box to your question about how are we building our CONOPS and our doctrine now,” Ferko added.
On the subject of the steering mechanism used by the guided 50 mm round, the Northrop Grumman representatives remained tight-lipped. However, there’s no reason Warsight can’t do its own homework to figure out what the most likely steering mechanism might be.
Much of the core functionality has previously been hinted at in a Northrop Grumman marketing video around their guided 57 mm projectile. The video showed a visual representation of the rounds, and gave an overview of how it works: “once in flight, the projectile’s onboard seeker powers on, and then searches for, acquires, and tracks the target. The aft manoeuvre system continuously guides the round to the target. This enables pinpoint accuracy no matter how many times the target pivots. Capable of both proximity and point-detonate modes, the 57 mm guided munition will self-select in-flight which mode will maximise probability of defeat.”
In terms of potential contenders, a good place to start is often history, examining some of the solutions that have come before. Looking at the recent past of US attempts to develop guided cannon munitions, some interesting examples can be found in the 2010s-era DARPA Multi-Azimuth Defense Fast Intercept Round Engagement System (MAD-FIRES) programme aiming to develop a guided 57 mm round for the US Navy, as well as the earlier 2000s-era Extended Area Protection and Survivability Integrated Demonstration (EAPS ID), which sought to develop a guided 50 mm round, using the weapon which would later become the XM913.
Starting with EAPS ID in the 2000s, early efforts to develop a guided 50 mm round centred on the use of a lateral thruster system mounted on the mid-body of the projectile, and fixed stabilisation fins in the rear. This system was heavily contributed to by Orbital ATK (now part of Northrop Grumman). However, the problem with this method is that a thruster-based system would have a finite number of impulses, which wouldn’t match the claim of “pinpoint accuracy no matter how many times the target pivots”.
By a similar token, Raytheon’s submission to the MAD-FIRES programme doesn’t seem a good match. This used a front-mounted steering canard assembly, along with rear-mounted stabilisation fins at the rear. These were understood to have been supplemented by small lateral thrusters in the forebody and aft, presumably for yaw/pitch control.
BAE Systems’ ORKA (Ordnance for Rapid Kill of Attack Craft) concept doesn’t seem a close match either. This concept mounted an infrared (IR) seeker at the front of the projectile, with four long steering fins mounted behind it, and six long stabilisation fins in the rear. While a fin-based solution such as this could allow continuous manoeuvre, the steering took place just behind the nose of the projectile, rather than the aft portion.
L3 (now L3Harris) took a fairly different approach for their ALaMO (Advanced Low-cost Munitions Ordnance) projectile. This was steered using a system of jettisonable counterweights fitted to the midbody. By controlling the order in which the weights were jettisoned as the round flew, it was possible to steer the round. However, this method also suffered from the same downside as thruster-based systems, insofar as it provided a finite number of opportunities to steer, since once the weights were jettisoned, that was it.
Outside of US programmes, Leonardo developed the DART 76 mm round, and in 2013 stated that serial production had been started. Alongside this, the company has offered its Vulcano family of guided munitions in 76 mm, 127 mm, and 155 mm. Yet DART and Vulcano all use steering fins in the forward portion, with rear mounted stabilisation fins.
Elsewhere, Russian company TsNII Burevestnik developed the 2A91 57 mm automatic cannon, chambered in 57 × 347SR mm, which has been shown fitted to a variant of T-15, as well as the 2S38 Derivatsiya-PVO system. As part of this development, Russia has shown a range of munitions for the weapon, among them the 3UO7 projectile, which uses a semi-active laser (SAL) seeker for guidance, with pop-out fins behind the seeker for steering and aft fins for stabilisation.
Based on the available evidence, Northrop Grumman’s approach is different to all of the above.
Over the course of examining various papers on projectile steering methods, one quite ingenious type of steering system stood out, and I believe serves as a perfect match for all the statements the Northrop Grumman video made about their guided cannon round technology. If this assessment is correct, then the steering mechanism for their 57 mm and 50 mm is something significantly more interesting than canards, fins, counterweights, squibs, or thrusters. Due to potential sensitivity, the information will not be linked here, but will instead be described with respect to the physical principles by which it operates.
The projectile steering system used is assessed to be a form of active spin control, using a rotating control unit or ‘collar’ mounted to the rear of the projectile, fitted with small aerodynamic structures (strakes and a flap), and with this collar able to be selectively internally coupled to or decoupled from the main body of the projectile. In very simple terms, this steering system works by leveraging the spin stabilisation effect of rifled weapons. This will require some context to understand.
When firing rifled weapons, the rifling imparts spin onto the projectile, which keeps the round stable in flight. However, spin-stabilised rounds normally spin so fast they ‘want’ to keep moving along their normal ballistic path, which can in turn can make them ‘stubborn’ to attempts to steer them. This is known as very high gyroscopic stability. On the other hand, if a round spins too slowly, it will have a tendency to tumble in flight and so will become very inaccurate. This is known as very low gyroscopic stability.
However, if you can slow down the round’s spin rate in a controlled manner, you can decrease the gyroscopic stability to a ‘sweet spot’, where the round remains stable enough not to tumble, while also becoming easier to steer. You can then use aerodynamic structures present to steer the projectile. This is the basic principle by which the rear-mounted steering system is understood to work.
Going into more depth on how the projectile actually steers in flight requires getting a bit more technical. Assuming the physics at work has been understood correctly, it should operate roughly like so:
When the projectile needs to turn, the rear collar becomes internally coupled to the main body of the projectile. This harnesses the air resistance acting on the collar’s strakes and transfers it to the main body of the projectile. This acts as a brake on the projectile spin rate, inducing a torquing motion opposite the direction of spin, transferred via the internal coupling, to slow down the projectile spin rate to the desired level. As this spin rate slows, the projectile reaches the desired level of gyroscopic stability, and becomes more susceptible to having its direction changed. At this point, the flap on the collar can be ‘locked’ into a stable position relative to the Earth, to induce an aerodynamic moment (turning force) on the projectile, acting as a rudder, and thereby allowing the projectile to be steered in the desired direction. This same operating principle can also be used to extend the projectile’s range.
This is an extremely clever piece of engineering, and on paper looks to have a number of advantages over various other types of steering system. Unlike single-use thrusters, or jettisonable weights, it can be used to change the projectile’s direction multiple times over the course of its trajectory. Unlike fin-guided projectiles, it takes full advantage of the projectile’s spin stabilisation. Additionally, mounting the entire steering mechanism in the rear is more space- and weight-efficient than most pop-out fin designs, which must sacrifice more of their available volume to accommodate the fins. While the technology is still some ways from being fielded, it nonetheless looks like a highly promising approach.
