Challenger 3: Keeping the Tracks on the Road

A demonstrator for the Challenger 3 turret pictured during trials in Germany. Courtesy of Defence Imagery / MOD News Licence

Ensuring that Challenger 3 avoids the impediments that have bedevilled Ajax requires that the Army makes clear decisions early and avoids rushing the programme.

The recent report into noise and vibration issues with the Ajax armoured vehicle raises serious concerns as to how large programmes are managed by the British Army. Alongside defects in design and quality control by the manufacturer, General Dynamics Land Systems UK (GDLSUK), the report highlighted cultural issues within the Army including optimism bias. The Army has recently committed to upgrading 148 of its Main Battle Tanks to Challenger 3. Ensuring that similar problems do not afflict this programme is essential to the Army’s future vision.

On the face of it, the Challenger 3 programme appears to be on firm foundations. The prime contractor overseeing the programme – Rheinmetall BAE Systems Land (RBSL) – owns the intellectual property for Challenger 2, the base platform, and the gun around which the new turret is built is owned by Rheinmetall Waffe Munition. Many of the engineers on the project were integral to the delivery of Challenger 2. In contrast to GDLSUK, BAE Systems Land UK and Rheinmetall – the two companies that formed RBSL – have a strong track record designing and building tracked armoured vehicles.

Despite these strong foundations, two outstanding questions could pose serious challenges to delivering the programme on time and on budget, and it is the Army that must ensure that these are resolved. The first question is the preferred ammunition for the main armament. The second is the integration of an active protection system on the vehicle, which is contracted to Rafael, but has significant implications for the base design.

The Hard Road or the Blind Corner?

Central to the decision to upgrade the Challenger 2 was the need to increase its lethality against modern armour. This is to be achieved by changing the rifled 120mm gun on the Challenger 2 to a smoothbore L55A1 120mm gun able to fire munitions at a much greater velocity. Futureproofing the weapon’s effectiveness is to be achieved by integrating a new ammunition nature, either the multipurpose M829A4 or the German KE2020Neo.

The significance of the multipurpose round is that as well as providing improved performance against enemy armour, the round can be programmed prior to firing to achieve effects against structures, vehicles or dismounted personnel, overcoming the need for multiple ammunition natures to be carried and therefore increasing the number of ‘ready rounds’ available for targeting whatever the vehicle may encounter.

Whereas previous single-purpose rounds would usually be loaded into any gun that met the requisite NATO standards for the common calibre, the transition to smart ammunition imposes some constraints on whether the gun is configured for the ammunition. Firstly, there is the software interface between the ballistic computer and the munition. Secondly, to transmit data, there must be a mechanism for passing the data to the round in the breach. There is no NATO standard for these points.

The integration of an Active Protection System (APS) onto Challenger 3 is a major component of ensuring the platform’s survivability against modern anti-tank guided weapons

The M829A4 is a known quantity as it is already in use. However, the software and design are US classified, and the round is manufactured by a direct competitor to Rheinmetall Waffe Munition, the maker of the not-yet-fully-mature KE2020Neo and of the gun for the Challenger 3. Given the proprietary software and hardpoint between breach and gun for the M829A4, firing it through the L55A1 would require modifications to the gun, necessitating the provision of a technical package from one company to its competitor. It would also require US classified material to be passed to a German company. Hence, while it is technologically possible for the Challenger 3 to use US ammunition, it would be programmatically challenging. It would require the British Army to go firm on this decision early, as it has design implications for the weapon around which the new Challenger 3 turret is built.

Designing Challenger 3 to fire the German KE2020Neo poses very few integration issues but does create a potential difficulty as regards the timeline for delivery. The German round is still in development, with testing expected to commence in 2024 and full certification in 2026. The exact performance of the round, therefore, is currently not fully known. Since the munition uses its own interface for accepting data, choosing it would not allow the British Army to revert to the M829A4 should the KE2020Neo prove unsatisfactory. The decision on ammunition must therefore be made early.

Active Protection

The integration of an Active Protection System (APS) onto Challenger 3 is a major component of ensuring the platform’s survivability against modern anti-tank guided weapons. Challenger 3 is to have the Trophy APS made by the Israeli defence company Rafael. This is probably the most capable APS in the world, with a highly credible track record. The challenge that the British Army has is that there is no such thing as an ‘off-the-shelf’ APS.

Trophy utilises radar to detect incoming threats and then intercept them with a shotgun-like system to cause the munition to detonate away from the hull. This requires highly accurate tracking of small objects moving at considerable speed, their appropriate classification, and highly precise cuing of the interception system. The location of the radar, however, significantly alters what it sees. Aerials, crew sights and remote weapons stations can all create blind spots. Even the interaction between the radar and the turret or hull shape can change how the radar perceives its environment.

Although there are a range of APS products on the market, these are best understood as APS methodologies, rather than modular components. Integrating an APS onto a specific new vehicle type is always a unique challenge. The location of the sensors changes the distance and angle between detection and the effector, which in turn changes the equation for when the effector must fire to engage targets at different angles. Some positions just won’t work, or under certain conditions will cause the effectors to frag the radar or other equipment on the vehicle it is supposed to be protecting. The process of calibrating the APS to find the ideal location for optimal performance takes up to three years based on the testing and adjustment process needed on other platforms fielding Trophy.

The difficulty for Challenger 3 is that adjustments to the location of the APS have far from trivial consequences for the design of the rest of the vehicle. An APS adds between 1–3 tonnes of weight to the vehicle, and most importantly, it adds that weight to the highest point of the vehicle and at the edge of the turret, where it has the greatest effect on the vehicle’s performance. Moreover, radars require cooling. In aircraft this is achieved through airflow. For ground vehicles it requires a cooling system. Adjusting the location of the radar during testing therefore means reconfiguring the plumbing beneath it in the turret.

With Ajax raising grave concerns as to the Army’s ability to manage the procurement of its platforms, it must focus on ensuring that Challenger 3 delivers and remain clear-sighted as to the complexities of the project

The shifting of 1–3 tonnes and complex electronics on the periphery of the turret is precisely the kind of issue that could throw up vibration and performance problems, disturbing the carefully calculated balance of forces across the rest of the platform. Changing the position of the APS during trials may therefore require further refinement to other aspects of the design to keep the system as a whole within tolerance. This means that testing of the APS needs to happen early in the process of designing and refining the turret, and not late in the process after large numbers of turrets have been fabricated.

The risk to the Challenger 3 programme here is that the APS procurement has been run separately from the main programme. This means that in many respects the Ministry of Defence’s Defence Equipment and Support (DE&S) is the integrator for the APS system, not RBSL. It is therefore vital that DE&S actively engages with Rafael and RBSL to ensure that there is sufficient data passed between them to conduct accurate modelling and testing. If these things are left too late then there is considerable risk that the APS cannot be effectively integrated within the timeframe envisaged by the Army.

Design and Testing is Paramount

The Challenger 3 programme is set to deliver the majority of vehicles into service towards the end of the decade. With the retirement of Warrior and the difficulties with Ajax, there is widespread discussion in the Army of accelerating its delivery. Increasing the tempo of manufacture, however, is not particularly viable given both the supply chain and facilities, and the implications of keeping the production line open for long enough to secure exports in line with the Defence Industrial Strategy. Acceleration in practical terms therefore means eating away at the time for design and testing.

Rushing the design and testing phases could expose the Challenger 3 programme to considerable risk. The timeline for the development of the German munition will not change, even if the Challenger 3 programme accelerates, while integrating the US munition would add considerable friction to the programme. Cutting the time available to fabricate and test turrets for calibrating the APS could similarly expose the platform to unforeseen vibration and performance issues.

Delivering Challenger 3 therefore requires the Army to make some critical decisions and hold a steady course. The Army must avoid the temptation to seek shortcuts or shift the goalposts. With Ajax raising grave concerns across Whitehall as to the Army’s ability to manage the procurement of its platforms, it must focus on ensuring that Challenger 3 delivers and remain clear-sighted as to the complexities of the project.

The views expressed in this Commentary are the author’s, and do not represent those of RUSI or any other institution.

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Dr Jack Watling

Senior Research Fellow, Land Warfare

Military Sciences

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