Changing tracks – the future of European MBTs

Outside of Russia and Ukraine, other European countries are investing significant resources into the procurement of main battle tanks (MBTs), including upgrades for legacy vehicles, production of new types, and the development of next-generation systems. Examining how these designs differ from a technical perspective indicates how the technological capabilities of MBTs may evolve in the long-term future.

Russia’s invasion of Ukraine has helped to resuscitate the development of MBTs across Europe by injecting a new sense of urgency into the procurement of heavy armour. This has been channelled into multiple lines of development ranging from extensive upgrades for legacy MBT families, to the creation of technology demonstrators that give a preview of the capabilities the MBTs of the 2040s may come to possess.

MBT development in Europe can be divided into current and next generation designs. The current generation centres on upgrade programmes for MBT families that have their origins in the latter stages of the Cold War or – in a handful of cases – the production of new-design MBTs that incorporate similar technology. Some of these have begun to be delivered, while others are on the cusp of entering service.

Looking to the next generation, a Franco-German programme led by the multinational Krauss-Maffei Wegmann + Nexter Defense Systems (KNDS) is leading the development of the Main Ground Combat System (MGCS). Slated to ultimately replace the Leclerc and Leopard 2 families in French and German service, it is being billed as a revolutionary leap in technology that will challenge the conventional understanding of the MBT as a single platform.

More tangible indications of some of its possible technological capabilities have been shown by Rheinmetall’s KF51 Panther and KNDS’ Enhanced Main Battle Tank (EMBT), both of which were unveiled at Eurosatory in June 2022. Straddling the threshold between the existing state of the art and the conceptual realm of the MGCS, these demonstrators showcase which technology is mature enough for use in the near future.

The points at which the various MBT families that comprise the current generation converge and diverge in their technological capabilities, as well as where the next generation may depart from its predecessors, indicate how European MBTs will continue to evolve through the 2020s and into the 2030s. The implications of this for European MBT development can be appreciated by comparing the current- and next-generation designs through four main lenses: firepower, situational awareness, protection, and mobility.

A growing arsenal: Firepower

The current generation of European MBTs has coalesced around 120 mm smoothbore guns of more than 50 calibres in length for their main armament. This includes the Challenger 3, which will replace the L30A1 120 mm rifled gun of the Challenger 2 with the Rheinmetall L55A1 120 mm smoothbore. Unlike the rifled gun, the L55A1 will be compatible with NATO-standard 120 mm one-piece ammunition, including armour-piercing fin-stabilised discarding sabot (APFSDS) rounds with longer penetrators than the two-piece rounds designed for the L30A1. Some of the current generation of 120 mm smoothbore-equipped European MBTs have recently introduced the capability to fire programmable natures of high-explosive fragmentation (HE-FRAG) ammunition. This includes the Leclerc XLR, which can fire the KNDS M3M round, and the German Leopard 2A8, which will be compatible with the Rheinmetall DM11 round.

Alongside these, Poland received approval from the US Defense Security Cooperation Agency (DSCA) in December 2022 to procure the M1147 Advanced Multi-Purpose (AMP) round for its M1A2 SEPv3 Abrams. These programmable rounds incorporate a programming device that allows the MBT’s fire control system (FCS) to instruct the round’s fuze to detonate the HE charge at the optimal time, whether on impact or after a certain time delay. Using the latter, the round can be programmed to airburst above targets in defiladed position or to detonate inside a structure it has penetrated. Recent adoption of this ammunition may be indicative of the need to counter the threat posed by infantry, particularly anti-tank guided missile (ATGM) teams, to MBTs operating in dense urban environments.

With the exception of the South Korean K2GF (known as the K2 ‘Gap Filler’) received by Poland and the French Leclerc XLR, all of Europe’s current generation of MBTs eschew autoloaders in favour of a fourth crew member to manually load their main gun. Widely employed by the Soviet Union and later Russia, autoloaders were adopted to make MBTs lighter and more compact, since a two-person turret would result in less volume required to be protected by armour. A similar design philosophy appears to have led to the use of an autoloader in the K2GF, which was designed to be used in Korea’s mountainous terrain where an MBT with a low silhouette and light combat weight would be advantageous. In certain circumstances, autoloaders can also offer a rate of fire advantage over human loaders, although this can be dependent on whether or not the loader is loading from the most accessible stowage racks. However, as with two-piece ammunition, the use of an autoloader can limit the length of an APFSDS penetrator, as space constraints within the vehicle and within the autoloader’s mechanism may preclude the use of longer ammunition without substantial modifications.

Despite the absence of autoloaders in most contemporary European MBTs, the technology demonstrators shown as Eurosatory in June 2022 suggest that they will become a standard feature of the next generation of MBTs. This will be required due to the adoption of larger-calibre smoothbore guns, such as the Rheinmetall 130 mm L51 Future Gun System (FGS) and the KNDS 140 mm Autoloaded and SCALable Outperforming guN (ASCALON), of which the former has been shown on the KF51 Panther and the latter is proposed as an option for the EMBT. Compared to the typical weight of circa 20 kg for a 120 mm one-piece round, a one-piece 130 mm or 140 mm round will weigh more around 30-35 kg, making them impractical for manual loading. Able to accommodate heavier penetrators and more propellant, the APFSDS rounds fired by these larger-calibre guns will have greater muzzle energy than their predecessors, providing more armour penetration and increased range, with Rheinmetall aiming for an effective range against armoured targets of at least 1,000 m further than its 120 mm gun family.

The initial APFSDS designs in these large guns also seem to have higher muzzle velocities than many of the more recent 120 mm APFSDS projectiles, with Rheinmetall reported to have reached muzzle velocities of 1,700-1,900 m/s using their 130 mm L51 FGS design. Similar speeds have previously been obtained with smaller calibres, but have decreased on newer APFSDS designs as projectiles have become longer and heavier. While higher speed is not necessarily a factor of increased bore diameter, it is possible on designs such as the Rheinmetall 130 mm L51 FGS due to these having a larger chamber volume than the 120 mm L55, permitting a more favourable ratio of propellant to projectile weight, and a very slightly longer barrel (6,630 mm on the 130 mm L51 versus 6,600 mm on the 120 mm L55), giving propellant gasses a bit more time to interact with the projectile.

Due to their heavier penetrators, these projectiles will also be more difficult for active protection systems (APS) to intercept and degrade. However, these advantages come at a substantial cost in ammunition stowage capacity. For example, when armed with a 130 mm gun, the KF51 Panther can only accommodate 20 rounds in the two drum magazines of its turret bustle, less than half of the 42 rounds stowed inside the Leopard 2A8. Although this can be partially offset by the use of larger-calibre secondary armament that can engage targets that would have previously been reserved for the main gun, this limits their longevity in a protracted firefight. That this is a compromise European users may be unwilling to accept at present is shown by the Hungarian contract awarded to Rheinmetall in December 2023 for the development of another KF51 Panther demonstrator with an L55A1 120 mm main gun.

The secondary armament of the European MBTs is also evolving. A remote weapon station (RWS) is now a standard feature on the current generation of MBTs, with the exception of the Challenger 3 and K2GF, although the K2PL variant is expected to remedy this shortcoming for the latter. Typically armed with a 12.7 mm M2 heavy machine gun (HMG), these can provide a relatively close-in self-defence capability for the MBT. Moreover, as they have a higher range of elevation than the main gun and its coaxial armament, they can be used to engage targets at high altitudes, such as the upper stories of buildings in urban areas. If their FCS software is modified accordingly and linked to an appropriate detection system such as a radar, RWS could potentially also offer very short-range air-defence (VSHORAD) against small unmanned aerial vehicles (UAVs), although this avenue has not yet been implemented with the current generation of MBTs. Should RWS come to take on these additional roles, it is possible that they will come to be armed with heavier weapons. This was hinted at with the EMBT, which featured two RWSs, one of which was armed with the KNDS 30M781MPG automatic cannon chambered in the 30×113 mm cartridge.

The KF51 Panther and the design concepts for the MGCS also indicate that the future generation of European MBTs may come to possess an expanded arsenal of indirect fire weapons to complement their existing armament. This was demonstrated by the option to replace one of the KF51 Panther’s 130 mm drum magazines with a launcher for a pod of UVision Hero 120 loitering munitions. Fitted with a 4.5 kg warhead, the Hero 120 can strike targets at least 40 km away, substantially enlarging the Panther’s engagement envelope. By contrast, the German vision for MGCS envisions a separate variant armed with launchers for longer range indirect-fire munitions that will be networked to an MBT variant armed with a large-calibre gun in a mutually supportive system of systems. In the absence of any concrete user requirements for this capability, it remains unclear whether an indirect fires capability will become a standard element in the arsenal of the next generation of European MBTs.

Seeing over the hill: Situational awareness

The ability of MBTs to employ their armament effectively is reliant on the crew having sufficient situational awareness to be able to detect and accurately engage targets. Optoelectronic sights packaging a day camera, thermal imager, and a laser rangefinder have therefore become a standard feature on the current generation of European MBTs. At least two of these sights are provided for all of the European MBTs examined in this article, one for the gunner and one for the commander. Both of these sights have independent two-axis stabilisation, but whereas the gunner’s sight is usually fixed in position, the commander has a panoramic sight that can rotate through 360°. This enables hunter-killer operations, in which the gunner engages a target while the commander actively searches for the next target to pass on to the gunner, shortening the target engagement process.

Each of these sights is complemented by a digital FCS, which takes inputs from a variety of sensors to calculate a firing solution with a high probability of a first-round hit. This will also contain software for automatic target tracking, increasing the chance of an accurate hit on a moving target and reducing the cognitive burden on the crew. As each European MBT has a different combination of sights and its own FCS, there are differences in the capabilities of each system, such as the ranges and conditions in which it can detect, recognise, and identify a tank-sized target.

The situational awareness of the current generation of Western platforms is also enhanced by the provision of battle management systems (BMS). Accessed via a separate display normally installed in the commander’s position, the BMS can receive data from the vehicle’s own navigation and radio systems, as well as from other platforms that it is networked to. This enables it to show information such as the location of friendly and enemy forces on a digital map, and a visual representation of orders or battle plans. These systems are thus intimately connected with wider army-level networking programmes designed to increase data sharing across a range of platforms and units. For example, the Leclerc XLR is equipped with the Atos Scorpion Combat Information System (SICS) and the Thales Contact software-defined radio, meaning that it will be able to exchange information with other French Army vehicles procured under the Scorpion programme, their dismounts, and potentially the Tiger attack helicopter.

As European MBTs enter their next generation, there will be a proliferation of optoelectronic sensors both on and off the platform. This will increase the information burden on the crew and lead to increased reliance on form of artificial intelligence (AI), such as pattern recognition algorithms, to process and prioritise information. The growth in the number of sensors can already be seen on the Altay, which will come equipped with the Aselsan Örümçek (Spider) camera system. Based on modules containing a charge-coupled device (CCD) camera and an uncooled long-wave infrared (LWIR) thermal imager, it is designed to provide each crew member with a close-in view around the perimeter of the MBT. Images from each sensor can also be fused together and warnings of threats detected by other sensors such as the Akkor APS can be overlaid on the images. Similar see-through armour systems delivering a panoramic view to the crew are envisioned for the KF51 Panther and EMBT. These could incorporate AI-based software using machine learning algorithms to automatically alert the crew to possible targets or threats.

An even greater volume of information could be provided to next-generation MBTs via external sensors, such as unmanned aerial vehicles (UAVs) or unmanned ground vehicles (UGVs). These can extend the ranges at which the platform can observe their surroundings to well beyond the visual range of the MBT itself, a capability that could be particularly useful if they are required to operate in a more dispersed manner. Consequently, the KF51 Panther was displayed at Eurosatory with an inbuilt compartment for launching the BärDrones Stinger, a short-range quadcopter UAV with an endurance of 50 minutes. In the MGCS concepts, UAVs and other networked sensors will upload their data to a combat cloud which can be accessed by the MGCS MBT and its other supporting platforms. The MGCS will then exploit AI to fuse together the various sources of data and present actionable intelligence that the crew can act upon. However, both the KF51 Panther and the EMBT have a position for a fourth crew member dedicated to operating linked unmanned systems, reflecting the reality that such systems would impose a cognitive burden on a small crew, and that neither AI nor the necessary networks are regarded as sufficiently reliable to perform these tasks unsupervised. Indeed, a representative of the German Army’s procurement office explained at the International Armoured Vehicles 2024 conference that provision of a high-bandwidth network with a reliable connection in a contested environment is a significant technological hurdle that must be overcome to realise the potential of a combat cloud.

Hiding in plain sight: Protection

The proliferation of sensor technology is not a trend unique to Western militaries, with even non-state actors employing UAVs to extend their situational awareness and attack targets. This is expanding the range of threats that a European MBT must be able to contend with and leaving them with few places to hide from the eyes of the enemy. Yet the passive and reactive armour used on the current generation of European MBTs is predominantly focused on countering the threat from other tank guns, ATGMs, and under-hull blasts from mines or improvised explosive devices (IEDs).

A good example of this is the Challenger 3’s armour package. Although most details of its projected performance are classified, it will have a new ‘Epsom’ armour package containing passive and reactive elements installed on its hull and its new welded turret, the option to install additional hull armour on its hull sides and underneath the hull, and blow-out panels in its rear turret bustle. This reflects a preference for a modular armour system that can be adjusted to suit the threat environment of a specific theatre and shows an emphasis on crew survivability at the cost of greater weight. This compromise is less apparent on the lighter K2GF procured by Poland, which – unusually for a European MBT – can be fitted with explosive reactive armour (ERA) on its turret roof and sides, but Polish defence media has reported that the K2PL will accept a heavier weight for increased passive protection.

The most significant departure from traditional protection practices in the current generation of European MBTs is to make provision for the installation of a hard-kill APS a standard feature. Rafael’s Trophy family is the most common option, but Turkey has designed the indigenous Akkor for use on the new Altay. While the K2GF has provision for the Korean Active Protection System (KAPS), this is not installed on Polish K2GFs, although the K2PL is slated to receive an APS. Since the current generation of MBTs were not originally designed to accommodate these systems, the integration of these APS is more parasitic in terms of size, weight, and power (SWaP). In contrast, an APS will likely be an integral component of the next generation of MBTs. This thinking is evidenced by the integration of the Rheinmetall Strikeshield on the KF51 Panther, which has its modules encased within the passive armour to reduce its weight and make the sensors less susceptible to damage. Yet while APSs can effectively defeat many ATGMs and other anti-tank weapons operated by infantry, most remain vulnerable to top-attack munitions. This is a particularly glaring vulnerability, given how the first-person view (FPV) UAVs that have become ubiquitous in Ukraine have demonstrated how they can strike the vulnerable roof armour. It may be possible to modify the software of the radars and optical sensors used by an APS to allow them to detect UAVs, but this will also require effectors to be appropriately positioned to deal with threats at high angles and at sufficient range to avoid any risk of penetration.

Reducing their signature is another avenue by which MBTs can increase their survivability in a sensor-rich battlespace. Large and noisy, they are difficult to conceal, particularly when the electromagnetic emissions caused by the radars of their APS and their communications systems can broadcast their position. In recognition of this threat, some current-generation European MBTs have the option to fit a multispectral camouflage net, such as the Saab Barracuda that can be fitted to the Leopard 2A8 or the TDU Defence Systems Mobile Camouflage System (MCS) that covers the new Altay. Signature management technology has also been mentioned as a technical feature of the MGCS. Yet, outside of statements, little else has been demonstrated that can address this problem, suggesting that there is a gap between aspirations for the technology and its capabilities. This could mean that European MBTs will need to rely on new tactics, techniques, and procedures to minimise their chances of being detected, such as by operating in less concentrated groupings.

Going on a diet: Mobility

The survivability of an MBT is connected to its mobility, which is constrained by its weight. With the exception of the K2GF, which has a combat weight of 56 tonnes, the current generation of European MBTs weigh in excess of 60 tonnes. They therefore require engines that are capable of generating approximately 1,500 hp in order to maintain a power-to-weight ratio of at least 20 hp/tonne. Diesel engines remain the most popular option for generating this power, although the M1A2 SEPv3 has a gas turbine engine instead. Only the Challenger 3 will maintain a 1,200 hp diesel engine in the form of the overhauled CV12-8A, meaning that if it has a similar maximum combat weight to the Challenger 2 of 72 tonnes, its power-to-weight ratio could slip to as low as 15 hp/tonne. The importance of having access to a reliable powerpack is also illustrated by considering the impact of difficulties procuring suitable engines and transmissions had on delaying the development of the K2 and Altay MBTs. Lacking access to the MTU and Renk components used on the original prototypes due to a German embargo on Turkey, the initial production batches of the new Altay will utilise a South Korean engine and transmission before this is replaced by an indigenously-developed powerpack. As long as MBTs remain at weights of 50 tonnes or more, developing the appropriate powerpacks will remain a major barrier to entry in the future development of MBTs.

Rather than attempt to provide further uplifts in power, the next-generation of European tank development aims to restore mobility through weight reduction. This was a key aim behind the development of the 59 tonne KF51 Panther and the 61.5 tonne EMBT. It will be of paramount importance for the MGCS, which is planned to consist of multiple platforms not exceeding 50 tonnes. This weight reduction will be achieved through multiple means, including the system of systems approach to the MGCS design that will distribute capabilities across multiple platforms, and the adoption of a hybrid-electric drive. The latter can theoretically aid weight reduction by giving the designers the freedom to distribute the automotive components around the vehicle, although this will be dependent on massive strides in the improvement of the power density of the batteries that these systems rely on. Driving home this point, it is noteworthy that a hybrid-electric drive has not been demonstrated on the KF51 Panther or the EMBT. This indicates that the technology is still considered immature in this weight class, and is not anticipated to be feasible until the next-generation MGCS is due to enter service.

Coming together: The future of European MBTs

In all four aspects of European tank development, there is a significant degree of convergence within the current generation of vehicles that have recently entered or will soon enter service. Though they may differ in the exact type of subsystem that they use, their capabilities are broadly similar. This consolidation is likely to harden during the next generation, as a project as technologically ambitious as the MGCS will only be feasible if endowed with the budget of a multinational development programme.

Of all the technology required, the next generation of armament is the most mature. Large calibre guns have already been trialled and could soon enter service, while secondary armament is evolving to keep pace with new threats. However, there appears to be little demand for the step-changes in capability offered by a larger calibre main gun, at least for the short term.

A more significant and more sought-after leap in the design of next-generation European MBTs will come from the sensor fusion and increased networking enabled by AI. If it can live up to its promises, this could go a long way towards compensating for the lack of mass in many European armies and facilitate a new style of dispersed operations. This is ultimately a long-term aspiration that will necessitate significant technological investment, but the creeping presence of this technology even within the current generation suggests that there is at least a clear path to its progression.

The issue of balancing vehicle survivability, mobility, and weight appears to be a more vexing conundrum. As APSs proliferate and efforts to tailor them to a local C-UAV role become more advanced, MBTs may become less reliant on their passive amour. Crew reduction through the exploitation of AI may also allow for the shedding of weight. However, what has been seen of the next generation so far does not provide a clear answer as to how MBTs will deal with the problem of being detected in the first place, nor as to how hybrid-electric drives can supersede conventional diesel engines. If MGCS is to be successful, future MBT developments will have to begin addressing these pressing issues with concrete solutions.

Jim Backhouse