8×8 armoured fighting vehicles (AFVs) now make up a sizable proportion of many military AFV fleets. However, pressures to integrate more protection and heavier armament are leading to greater compromises in mobility that will have an impact on their operational utility.

8×8 armoured fighting vehicles (AFVs) have played a significant if underappreciated role in the conflicts in Ukraine and Gaza. During the fighting around Mariupol in April 2022, Ukrainian BTR-4s were able to exploit their speed and manoeuvrability to pop up in unexpected positions and knock out heavily armoured Russian main battle tanks (MBTs). Similarly, the Israel Defense Forces’ Eitan 8×8 was used to rapidly respond to the 7 October 2023 attacks on Israel by Hamas – in one case, an Eitan rushed down a highway to neutralise a Hamas landing party on the coast, despite having only entered service with the Nahal Brigade in May 2023.

The Eitan APC variant has been deployed by the IDF in Gaza.
Credit: Israeli MoD

On the other hand, footage of wheeled vehicles bogged in Ukraine’s thick winter mud reminds observers of the inferior trafficability of wheeled vehicles when traversing fine-grained soils with a high moisture content. A near constant stream of footage of these vehicles being hit by anti-tank guided missiles (ATGMs) or the increasingly ubiquitous first-person view (FPV) unmanned aerial vehicles (UAVs) fitted with high-explosive anti-tank (HEAT) munitions also illustrates the vulnerability of wheeled AFVs with large signatures and comparably less passive and active protection than some heavier tracked vehicles.

These advantages and disadvantages of 8×8 AFVs are the result of a perennial problem encountered in AFV development: designs must balance sufficient mobility to be able to get to where they are needed, while also maintaining a level of survivability and lethality that will make them useful in the battlefield circumstances for which they are expected to be used. This presents a serious issue that will need to be addressed for 8×8 vehicles: while recent conflicts have reinforced strong and immediate pressures to increase the lethality and survivability of 8×8 AFVs, the means to arrest their concomitant weight increase and restore their mobility are still very much in their nascent stages.

Putting on the pounds

The pressure to increase the protection of 8×8 AFVs is closely related to their employment as infantry fighting vehicles (IFVs). Since they need to accompany the infantry into the battlespace and support them in the close fight, IFVs need to be protected against the most prolific threats in their theatre of operations so that they have sufficient survivability to remain in action for a useful period of time. Whereas other AFVs that must operate in similar circumstances can concentrate this protection around the crew or vital mission systems, this protection must be extended to the dismount compartment in an IFV, or otherwise the operator runs the risk of losing a significant chunk of an infantry formation’s combat power to one strike.

With the majority of operators requiring their 8×8 IFVs to support the full spectrum of operations ranging from counter-insurgency (COIN) to conventional warfare against a peer opponent, the range of threats that they need to protect against is similarly vast. For use in COIN, the passive armour must be able to provide all-round protection against armour-piercing small-arms fire, heavy machine gun (HMG) projectiles of up to 14.5 mm in calibre, and close-range shell fragments, while conventional warfighting is likely to require armour that can resist medium-calibre cannon projectiles across the vehicle’s frontal arc. In addition to this, the hull needs a high degree of underbelly blast protection, as otherwise mines and improvised explosive devices (IEDs) can otherwise result in catastrophic casualties. This is not just a problem for COIN; Russia’s use of minefields in defending its territorial gains against Ukrainian attacks, including those sown by mine-laying multiple launch rocket systems, shows that this is also an important factor in conventional operations.

The N-WAV IFV is considerably heavier than the K808 APC, with a gross vehicle weight of up to 35 tonnes.
Credit: Hyundai Rotem

The implications of this on 8×8 AFV design can be demonstrated by comparing Hyundai Rotem’s K808 armoured personnel carrier (APC) with its Next-Generation Wheeled Armoured Vehicle (N-WAV). Unveiled in prototype form at the ADEX exhibition in October 2023, the N-WAV is intended to interest potential export clients by offering the basis for a family of vehicles centred around an IFV. This contrasts with the K808, which was aimed at a narrower set of South Korean requirements framed around resisting a North Korean invasion. The K808 is therefore comparatively lightly armoured because its purpose is to protect infantry while they are being transited across friendly territory to respond to enemy incursions. Conversely, the N-WAV has a hull tailored towards resisting underbelly blasts and an adaptable armour package that enables the user to modify the ballistic protection to meet their expected threat environment. The upshot of this is that whereas the K808 has a combat weight of 20 tonnes, the N-WAV can weigh up to 35 tonnes.

Even the Russian Military Industrial Company’s Improved BTR-82A (which has also been referred to as the BTR-22), which was developed as a successor to the legacy BTR-82A, trades a four-tonne weight increase for greater blast and ballistic protection. First shown in public at the Armiya exhibition in August 2023, the 20 tonne vehicle is constructed from a new grade of steel designed to offer all-round protection against 12.7 mm projectiles, while the hull is raised and reinforced to be able to resist a blast equivalent to 6 kg of TNT, meeting NATO STANAG Level 2a and 2b standards for blast protection.

Alongside these traditional blast and ballistic threats, the conflicts of the previous ten years have demonstrated that the threat from ATGMs and small, cheap, strike-capable UAVs has proliferated to such an extent that non-state actors can be expected to have these systems in their arsenals. While these can present a threat to even the most heavily armoured MBTs by either overmatching their passive armour or striking vulnerable areas, they are especially dangerous to 8×8 IFVs, which are a large, conspicuous target, carrying a valuable infantry payload. Recognising this threat, more and more militaries are attempting to integrate hard-kill active protection systems (APS) capable of neutralising ATGMs into their vehicles. Efforts are also underway to modify APS radars to enable them to take on the counter-unmanned aerial vehicle (C-UAV) role too. Although no 8×8 AFV with a hard-kill APS has been fielded at the time of writing, they are planned for integration on nearly all high-end 8×8 platforms, including the N-WAV. Not only does this further increase weight (an APS can weigh up to 1,000 kg depending on its configuration), but it also demands more electrical power from the vehicle.

The Pars Alpha has several design features aimed at reducing its weight and volume, including the option for mounting the Teber-II 30/40 unmanned turret and a front-mounted engine.
Credit: FNSS

This additional weight has negative ramifications for the mobility and manoeuvrability of 8×8 AFVs. Bulkier vehicles will struggle to navigate the tight confines of urban areas or mountain passes. This led Turkish company FNSS to debut its Pars Alpha 8×8 IFV at the World Defense Show in February 2024. Featuring a revised internal layout that dispenses with the Pars family’s traditional mid-engined layout, it has a lower, front-mounted engine designed to reduce its overall dimensions. It also features all-wheel steering as standard, providing a tight turning circle.

Weight plays an important role in mobility and has knock-on effects for survivability. The heavier a wheeled vehicle, the more restrictions it will face operating cross-country. This is particularly noticeable when traversing fine-grained soils such as clay, which have a tendency to shear after repeated passes by wheeled vehicles, especially when saturated with moisture. This leads to the formation of thick mud that can cause heavy wheeled vehicles to become bogged down and stuck. Heavy 8×8 IFVs may face further limitations on their terrain passability by needing to sacrifice their amphibious capability for adequate protection. This compromise is shown by ST Engineering’s Terrex s5 (the s5 denoting Serviceability, Smartness, Superiority, Survivability, and Sustainability), which can weigh up to 35 tonnes without an amphibious capability or 32 tonnes with an amphibious capability. All of these factors combine to constrain 8×8 IFVs to a more restricted set of terrain. This in turn makes them less survivable, as they do not have the flexibility to operate dispersed and must follow more predictable routes across the battlespace.

Bringing out the big guns

Just as the use of 8×8 AFVs in the IFV role is widening the number of threats that they must contend with, it is also broadening the range of threats that their armament must be able to neutralise. Unlike APCs, which are not designed to participate in the close fight, an IFV is an integral part of its infantry squad’s firepower and must therefore be armed appropriately. Hence vehicles used in this role tend to have a turret armed with a cannon of between 25 mm and 40 mm in calibre (although 8×8 IFVs with cannons of up to 57 mm have been prototyped) and a coaxial rifle-calibre MG. This can be used to engage infantry, light AFVs, and low-flying aircraft.

That there is a trend towards equipping 8×8 AFVs with the armament necessary to perform as IFVs is shown by both the Polish and the US armies, which have operated 8×8s in the APC role since the early 2000s, opting to retrofit a turreted armament onto older vehicles. In Poland’s case, the ZSSW-30 turret armed with a Mk44S Bushmaster cannon is being installed on 70 of its Rosomak 8×8 AFVs under a contract in July 2022. Around the same time as this contract was finalised, the US Army took delivery of the first a Stryker Infantry Carrier Vehicle Double V Hull (ICVVA1) fitted with the Rafael Medium Caliber Weapon System (MCWS) unmanned turret armed with XM813 30 mm cannon. Both the Mk44S and XM813 are compatible with programmable air-burst munitions (PABM). The latter can increase the lethality of the weapon against UAVs and infantry in defiladed positions by ensuring that the round’s explosive filler detonates at a time that is optimal for showering the target with shrapnel.

The next generation of 8×8 AFVs being developed is sporting an even greater variety of armament that includes ATGMs for engaging heavy armour or fortified positions in an emergency, and heavy machine guns mounted in remote weapon stations (RWSs).

The Polish Army is retrofitting some of its Rosomak AFVs with the ZSSW-30 unmanned turret to provide them with the firepower to operate in the IFV role.
Credit: HSW

In order to offset the weight increase associated with adding heavier armour and armament, it is becoming more common to package a wheeled AFV’s armament and its sensors into an unmanned turret. Indeed, nearly all of the new 8×8 platforms unveiled in 2023 and 2024 were shown with an unmanned turret. This includes the aforementioned Terrex s5 and N-WAV, but also includes a Chinese 8×8 vehicle that entered service in November 2023. Dubbed ‘Type 19’, it appears to have an unmanned turret armed with a 30 mm cannon, coaxial MG, and a pop-up launcher for ATGMs.

The primary advantage of unmanned turrets is that they offer considerable weight savings. Since the turret crew can be located within the hull, the turret can be smaller, less well-armoured, and lighter than a manned equivalent. This is demonstrated by the Pars Alpha, which is marketed with a choice of either the manned two-person Teber 30 turret or the unmanned Teber-II 30/40. Both can be armed with a similar range of weaponry, but the Teber-II 30/40 is 850 kg lighter. Furthermore, the lack of a turret basket protruding into the hull increases the usable volume inside the troop compartment, meaning that more dismounts can be carried for a given volume. Consequently, it is predominantly 8×8s that do not need to prioritise carrying dismounts which now feature manned turrets, such as the Australian Army’s Boxer Combat Reconnaissance Vehicle (CRV) and its German Boxer Heavy Weapon Carrier derivative that was ordered for the German Army in March 2024.

A more radical divergence from the traditional configuration of an 8×8 IFV has been envisioned for the Terrex family by Singapore’s ST Engineering. Although the Terrex s5 displayed at the Singapore Airshow in February 2024 appeared to have a conventional layout with the driver and commander seated in tandem at the front of the hull and a gunner for the unmanned turret at the front of the dismount compartment, the company also displayed a concept for a two-person crew seated side-by-side. Using display screens and console-style controllers to monitor and control the vehicle’s subsystems, the crew would be reliant on artificial intelligence (AI) to autonomously perform many of the core tasks, such as driving and acquiring targets. This would free up cognitive capacity for the human crew to process intelligence gathered from the Terrex s5’s tethered UAV and monitor the operations of unmanned ground vehicle (UGV) or UAV ‘wingmen’, extending their situational awareness. With these concepts also beginning to seep into next-generation tracked IFV and MBT development, it is likely that 8×8 AFV development will also evolve to exploit AI in shortening the target engagement process.

The German Army opted to maintain the manned LANCE 2.0 turret on its Boxer Heavy Weapon Carrier. This turret will be heavier than an unmanned alternative, but may aid the situational awareness of the crew by allowing them to see out of the turret hatches.
Credit: Rheinmetall

Silent but deadly

Alone among the recent crop of 8×8 AFV developments, the Terrex s5 has also pushed the boundaries of conventional design practices by proposing a hybrid-electric drive, though it must be noted that the initial prototype uses a 711 hp diesel engine mated to an automatic transmission. As a notional capability, the exact nature of this hybrid-electric drive has not been disclosed, but it is possible that it will be based on ST Engineering’s Hybrid Electric Drive Kit that is being developed for its 4×4 Next Generation Protected Vehicle. Intended to be a modular kit that can be paired with any type of internal combustion engine, the Hybrid Electric Drive Kit is a series hybrid-electric system, meaning that the combustion engine powers a generator, which then supplies electrical power to motors for powering the wheels and batteries that store power for internal or external use.

In theory, such as system could provide a number of advantages. These include increased fuel efficiency from the internal combustion engine, the possibility of using the energy stored in the batteries to power external systems, or moving the vehicle silently for short distances, or powering the vehicle’s subsystems with the combustion engine turned off in ‘silent watch’ mode, reducing the chance that it will be detected. More radically, a hybrid-electric drive could open the door to weight savings because electric motors could be mounted inside the wheel hubs and the other components of the powertrain could be distributed around the vehicle and connected to each other via electrical rather than mechanical interfaces. This could negate the need for heavy transmissions, driveshafts, and axles, although this would depend on how the system was configured. The theoretical potential of this arrangement was demonstrated by QinetiQ’s 8×8 Mobile Test Rig (MTR), a scaled down technology demonstrator unveiled at DSEI in September 2021. By removing all of the aforementioned mechanical components, it gained the ability to individually vary the travel, steering, torque, and ride height of each wheel station.

However, the practical application of hybrid-electric drivetrains to 8×8s is unlikely to progress until solutions to two major problems have been devised. Firstly, the power density provided by the chemistries of existing lithium-ion battery packs is several orders of magnitude below that of diesel fuels, and they are similarly inefficient in terms of their volumetric requirements. This means that a battery pack capable of storing enough power to move an 8×8 IFV weighing 30 tonnes or more for any significant distance or length of time would incur a prohibitive weight and space penalty, negating any other weight savings.

The second major issue that would occur with scaling-up the technology demonstrated in the MTR for use in an 8×8 IFV concerns the use of in-hub electric motors. While fully-electric motors that transferred power to the hub without a mechanical transmission were trialled in the past, these are unable to deal with the varying torque and braking stresses demanded by a heavy 8×8 AFV. Consequently, an in-hub electric motor for an 8×8 would need to have the motor, brakes, and mechanical transmission elements integrated into a package small enough to fit within a standard rim. This would in turn require reinforcing the suspension so that it is strong enough to cope with the heavier rims and can mitigate the shock transferred to the components within the rim. Alternatively, the motors could be placed on the axles, but this would reduce the scope for weight savings and eliminate some of the flexibility provided by individual wheel station control. Technology demonstrators designed to prove out this technology have been created in the past, but there has been little tangible evidence of emerging solutions to these issues in the 8×8 sphere since FFG showcased the Genesis in September 2020.

Few hybrid-electric 8×8 AFV designs have been seen since FFG displayed its Genesis technology demonstrator in September 2020.
Credit: FFG

The road ahead

8×8 AFVs have the versatility to be employed in many roles, ranging from amphibious assault vehicles to a platform for self-propelled guns. Yet for all their versatility, new 8×8 AFV designs are almost invariably centred on the IFV role. While 8×8 AFVs can be armed and armoured to live up to this role, this undermines their perceived advantages over tracked vehicles in cost and mobility.

The first major implication of adapting 8×8 AFVs to the IFV role is that the vehicles have become larger and heavier in order to accommodate the armour and armament required. Confronted with an expanding matrix of threats, the temptation to integrate more on these vehicles is only growing. This is a problem for all AFVs – wheeled or tracked – but it is even more problematic for 8×8s, as more weight only exacerbates their intrinsic mobility shortcomings. Worse still, this also impinges on their survivability in another sense, as they lose the agility that drove their popularity in the immediate post-Cold War era.

In the short- and medium-term, there is little that can be done from a technological perspective to address these problems. While some users such as the Russian Ground Forces may be willing to accept a lighter, less-protected vehicle, other users that cannot afford to compromise on the survivability of their dismounts must accept the penalties to mobility or – as the British Army appears set to do – avoid using wheeled IFVs altogether in favour of tracked vehicles. Looking to the long-term, it is possible that advances in hybrid-electric drive technology and automation could restore the balance between the mobility, survivability, and lethality of an 8×8 AFV. Until that time however, militaries that have placed their faith in 8×8 IFVs must ensure that their troops are familiar with their limitations and trained to use their vehicles in a way that plays to their strengths.

Jim Backhouse