Military Land Vehicles - New threats and required protection technologies

It is now common knowledge that in Germany national and alliance defense and international crisis management operations are given equal priority. The Federal Government's White Paper and the subsequent documents describe the necessary paradigm shift, also due to the Russian aggression in Ukraine/Crimea.

Combat vehicles and tactical land mobility vehicles make a critical contribution to the success of military land operations, performing critical roles in all capability categories. The protection of crews and vehicles poses a particular challenge in view of the range of possible future threats to land forces.

The threat

The military activities of the Bundeswehr and the NATO allies are becoming more complex. The associated threats have also become larger and more dangerous, since the threats of symmetric warfare can be overlaid by threats of asymmetric warfare.

The Federal Government's 2016 White Paper already stated: "Overall, the spectrum of threats to our security is becoming broader, more diverse and more unpredictable."

Land vehicles are in the entire range of tasks essentially all around by means of action such. B. explosives (Improvised Explosive Devices, IED or Explosively Formed Penetrator, EFP), mines, shrapnel and direct firearms (including kinetic energy projectiles, KE) and hand-held anti-tank weapons.

In current operations as part of international crisis management, the threat posed by mines, IEDs and anti-tank handguns, e.g. B. the RPG-7 particularly acute. The danger of the RPG 7 results from the high penetration rate and also consists in the fact that it is inexpensive, was built in very large numbers worldwide and is available in all crisis areas.

New threats are also emerging. RPGs are also used from roofs in top attack mode and IEDs are used with the EFP effect and with high amounts of explosives, e.g. B. in culverts (Culvert Mines) used.

In the context of national and alliance defense missions, new Russian main battle tank developments (e.g. Armata T-14) and the modernization or ongoing increase in combat effectiveness of Russian main battle tanks and armored personnel carriers in recent years have led to a significant increase in the threat potential. Essentially, the firepower and protection characteristics of the main battle tanks have been significantly improved. The Russian 125 mm smoothbore gun also allows the use of KE shells with modern penetrators up to 695 mm long, with which high penetration rates (at least 600 mm Rolled Homogeneous Armour, RHA) can be achieved. Laser-guided missiles with a tandem HL warhead can also be fired from the weapon.

So the new threat is the use of large caliber KE penetrators, the high rate of smaller KE penetrators and laser-guided missiles with tandem HL warheads. Reactive and active protection technologies, improvements in the fire control system and powerful armament are the main features of these main battle tank variants. The new Armata T-14 main battle tank and the conversion of the T-72, T-80 and T-90 variants represent a developmental leap in terms of threat that will influence not only a possible new generation of western main battle tank developments, but also the development of new ones Anti-tank technologies of all kinds.

The military concept of protection

In the Bundeswehr, protection is described from a military point of view in the sub-concept "Protection of forces and facilities in action". Protection here means all measures and means against threats, in particular from enemy action. Protection serves to maintain one's own ability to act and deploy one's own forces and resources.

While "indirect protection" aims at measures, procedures and the organization to prevent the occurrence of a threat in advance, "direct protection" consists of active, reactive and passive protective measures.

The following article is essentially about "direct protection" and in particular about passive, reactive and distance-active protection solutions and their possible combination.

possible solutions

The protection requirements have increased significantly in recent years, also due to multiple threats. A stable basic structure is always required, which can safely absorb the residual amounts of energy or projectiles/projectile parts. However, military land vehicles are limited in terms of protection options due to their structural volume and weight.

passive protection

The basic protection of the pure steel construction is usually not sufficient to achieve protection against higher threats. Pure passive protection solutions and add-on solutions (new types of steel, ceramics, lining material, composite armor plates, bulkhead and dented plate armor) do not offer comprehensive protection and are not feasible due to the often required air transportability in available aircraft types and the always limited weight reserves. The weight and construction volume of this possible solution even exceed the weight and construction volume limits of current German battle tanks.

Great success has been achieved in some cases with the use of materials that have the same or better performance than steel (e.g. titanium) or that offer more resistance to hydrodynamic penetration (glass, ceramics, composite armouring). However, such advantages have always come at the expense of a larger construction volume and/or a high price, with the weight savings usually being a maximum of 50 percent. Whether armored steel, innovative composite materials or ceramic composite systems are used, significant weight savings should be achieved in addition to a high protection factor.

Even with the most advanced materials available today (e.g. nano-materials) the tactical weight ceilings of the platforms would be exceeded. However, since significant improvements in material properties are not foreseeable, alternative approaches must be found to increase crew protection without significantly impairing the mobility of land vehicles.

For land vehicles with integrated protection, the vehicle shells are made from materials with high protective properties by specialist companies (e.g. Rheinmetall, Krauss-Maffei Wegmann, IBD Deisenroth Engineering GmbH, GEKE Schutztechnik GmbH) using the largest possible components and therefore fewer weld seams or connecting elements. The production requires special know-how in handling the special materials, especially when bending and welding.

In recent years, IBD Deisenroth Engineering (Rheinmetall Protection Systems since June 1, 2019) has developed concepts and solutions that have been used in several vehicles. IBD/RPS has developed a range of high-strength nano-materials based on metals, ceramics and fiber composites that have significantly increased energy absorption capabilities. By combining these materials in hybrid solutions, new protection solutions can be developed to cover the complete threat spectrum and all relevant threat levels. Embedded in 3D fiber composite molded parts as a hybrid solution, metals and ceramics can also protect complex vehicle areas and close ballistic gaps. The new protection technologies are used for the entire range of STANAG 4569 Level 2 to 6 as well as against large-caliber threats. In addition, they offer protection against all known types of blast and splinter IEDs.

If these measures are not sufficient to fulfill the protective capabilities, further protective solutions or combinations of protective systems must be found, which can also be used in a modular manner.

Reactive protection

In reactive protection, a basic distinction is made between explosive, reactive, non-explosive and electrical armor. Explosive reactive protection solutions in particular are characterized by significant success in the protective effect and have been in use on vehicles in many nations for a long time.

The explosive reactive protection (Explosive Reactive Armour, ERA) not only counteracts the shaped charge jet with armor material, it does not disturb the projectile itself, but works with a defense principle that disturbs the shaped charge jet itself. Of course, this reaction has to be very fast, since after the grenade hits, the processes take place at a very high speed. Explosives can therefore be used as an active agent here. One or more layers of explosives are placed between two plates (metal or composite). An impacting shaped charge jet triggers the explosive, which then accelerates the plates at an angle against the jet and maintains a high blast effect in the gap. This mechanism leads to a drastic reduction in the penetration depth of the shaped charge jet.

Of course, the overall size of the structure and the amount of explosives depend on the performance of the threat to be combated. In practice, reactive protection elements are used in boxes. As a result, in the event of a hit, the effect is usually limited to one box. The weight of the boxes is such that they can be installed or replaced by the vehicle crew without great effort.

Of course, the weight and the structural volume of such a protective arrangement compared to steel armor are of interest for practical use in vehicles. By using reactive protection, a weight reduction of up to 90 percent can be achieved compared to a pure steel solution. If reactive protection is used on a vehicle, only extremely insensitive explosives are used. They only detonate upon hitting a shaped-charge beam and remain passive to autocannon fire, high-powered KE rounds, or the effects of IEDs. Neighboring boxes also do not react, since only the active elements directly hit by the shaped charge jet detonate.

The protection not only has to be tested with regard to its ballistic effectiveness, but also the so-called system compatibility and compliance with special security requirements must be taken into account. Just like the vehicle, the reactive protection must withstand different environmental conditions without losing its effectiveness and its insensitivity or changing its properties. This includes standard test methods for temperature changes, rain, sand, lightning, vibration and fire from different weapons and ammunition types.

Mainly because of the feared collateral damage, people in Germany were initially skeptical about reactive protection. Only the consistent use of non-fragmentable material and the use of a special, very insensitive explosive led to acceptance here. Composite plates and plastic screws are used, which disintegrate after the explosives have been deployed in the immediate vicinity of the vehicle being fired on and do not produce any dangerous splinters. In the course of the qualification, existing safety concerns were cleared up so that an effective and harmless product for protecting military vehicles (e.g. on the Puma infantry fighting vehicle) is now available. The manufacturer of this reactive protection is Dynamit Nobel Defense GmbH.

With the development of SMART PROTech, Reinmetall Protection System has succeeded in providing effective protection, particularly against shaped charges. The basic element is a module that contains a sensor and one or two countermeasures, depending on the module size and its position on the vehicle. When the threat hits the module interface, the associated countermeasure is triggered.

The energy beam it produces is designed to destroy the main warhead before the shaped-charge spike develops. The modules cannot be triggered by small and medium caliber weapons.

Distance active protection solutions (Hard-Kill)

Der Schutz der Gefechts- und Transportfahrzeuge gegen Hohlladungsgefechtsköpfe ist eine besondere Herausforderung. Die Verwendung herkömmlicher Schutzmaterialien (Stahl, Keramik, Verbundwerkstoffe), aber auch aktiver, mit Sprengstoff wirkender Schutzelemente ist hinsichtlich des Volumens und der Gewichte bei Fahrzeugen nur schwer realisierbar, ohne die Mobilitätseigenschaften wesentlich zu beeinflussen. Dieser Art der Bedrohungen kann mit abstandsaktiven Schutzsystemen begegnet werden, die nach dem Hard-Kill-System arbeiten.

In the 1980s, the first hard-kill protection systems were introduced on Russian main battle tanks. Other armies have been far more reluctant to use these automatic defense systems.

Since guided and unguided missiles of anti-tank weapons usually have a comparatively low speed (150 m/s to 400 m/s), the time available between firing and impact of the active agent on the vehicle allows the projectiles to be actively combated and destroy it by taking countermeasures.

Distance-active protection systems are offered by a number of companies worldwide and some are already in use on combat vehicles. Systems for use on combat vehicles and lighter systems for use on wheeled vehicles are offered by some companies.

In Rafael's Trophy, threats are detected using radar, tracked, and eliminated with a series of small shaped charges using a fire control computer. Trophy is successfully used in Israel on combat vehicles (Merkava). The US Army procures a Trophy interim solution for its M1 Abrams main battle tanks and an Iron Fist interim solution from Elbit (formerly IMI-Systems) for the Bradley vehicles. Investigations by the US Army into equipping the Stryker fleet with a distance-active protection system have not yet been satisfactorily completed and are still ongoing. Demands on the vehicle structure in connection with weight and space challenges are probably decisive here.

How it works Trophy (Video: Rafael)

The lack of distance-active protection systems is also a weakness for German battle tanks that has been known for years, and which most recently became apparent in January 2017 when Turkish Leopard 2 A4 battle tanks were destroyed by IS forces due to this lack of protection.As part of the Very High Readiness Joint Task Force Land 2023, 17 Leopard 2 main battle tanks are to be equipped with Trophy.

Artis' Iron Curtain uses radar and optical sensors to detect targets and, after calculating the threat, engages them with counter-munitions. Attacks can be repelled a few centimeters before impact. Proof of functionality within the framework of the US Army test program for active hard-kill protection systems could not be provided for Iron Curtain. As a result, the US Army decided to include the German ADS system from Rheinmetall in the test program and to test it extensively.

Elbit's Iron Fist is a standoff protection system that uses a defensive projectile to neutralize a detected threat. Approaching threats (including anti-tank grenades and missiles) are detected using radar and infrared sensors. The defense body is launched at an optimal distance from the missile, which detonates near the target and disrupts the approaching threat with its pressure wave or triggers the shaped charge at some distance from the platform to be protected.

How Iron Fist Works (Video: Elbit Systems)

Diehl's AVePS (Active Vehicle Protection System) is a launcher-based protection system that fires effectors against incoming threats. Combined radar and IR sensors are used to detect and track the threat from a distance of several hundred meters as well as at close range.

Rheinmetall's Active Defense System (ADS) has radar-based and redundant electro-optical sensors that activate a protection sector when a threat is detected. Threats are destroyed by the directional (pyrotechnically generated) blast effect. The system is particularly effective in multi-hit scenarios and can be adapted to any vehicle size.

Missiles are detected as they approach and are destroyed directly in front of the target with a directed blast effect. The active charges are fixed around the vehicle and do not use rotating launchers. The sensor tracks the trajectory and the defense logic determines if the weapon will hit. If there is a flyby, the other components are not activated.

The ADS-Gen3 system was designed with a tiered number of redundant sensors and killer charges capable of withstanding at least three attacks in any given area, simultaneously and from different directions. It is therefore possible to destroy the threat from ten meters in front of the carrier vehicle.

The extremely short reaction time - the reaction times of the ADS-Gen3 are in the range of less than milliseconds - coupled with the ability to ward off threats at the shortest distance result in further advantages:

The sensors of the ADS-Gen3 only monitor a radius of around 30 meters around the vehicle to be protected. In comparison to launcher systems, which have a longer reaction time and therefore have to reliably detect a target much earlier, only little electromagnetic energy is emitted. The short monitoring distance of the ADS-Gen3 radar favors a high resolution, with which both weapons with a low radar profile can be reliably detected and attacks staggered over time can be recognized. The low radiated energy also reduces mutual interference with vehicles in the immediate vicinity, and the precise engagement in the absolute closest range destroys the attacking missile without the actual ignition of the warhead taking place.

The required response times ADS-Gen3 require autonomous functions. The focus is on functional safety and system safety, which has been consistently implemented using DIN ISO 61508. In this context, system security means that an unintentional triggering can be ruled out with a very high probability. The triad of proof of function, reduced collateral effects and proven system security must be fulfilled in order to be able to guarantee a controllable and reliable introduction on vehicles of armed forces and to create trust in this technology.

How ADS works (video: Rheinmetall)

In principle, distance-active hard-kill systems offer potential for improving the protection of forces in action, especially when protecting against projectiles from anti-tank weapons and guided missiles. Defense against fast-flying large KE projectiles, high rate KE projectiles and IED/EFP effects require additional protective measures.

Active distance protection solutions (soft kill)

The distance-active multifunctional self-protection system (MUST) from HENSOLDT is integrated in the Puma infantry fighting vehicle. The IFV Puma is currently the best-protected infantry fighting vehicle in its class. The system works according to the soft-kill principle. Incoming missiles are thrown off course by interference with the guidance systems, or the target is obscured from the detection systems to avoid hits. MUSS protects against both laser- and wire-guided missiles and is suitable for use against fire-and-forget weapons. However, the system does not protect against unguided anti-tank handguns that are aimed with purely optical sights.

The future

The large number of possible threats, from incendiary devices to IED effects to the large-calibre KE shell of a modern enemy battle tank, requires the individual protection components to be optimally coordinated. The design of the protection systems of military vehicles depends crucially on the threat situation and can only be implemented in an overall system approach. Land vehicles must be designed in such a way that various protective measures can be combined to achieve a maximum level of protection, depending on the threat. The solution lies in hybrid measures and the intelligent combination of protection technologies.

In addition, the individual systems - especially with regard to newly emerging threats, e.g. B. by KE projectiles - to improve the protective effect. Active protection systems can be supported by both passive and reactive solutions, e.g. B. by designing the reactive armor in response to KE threat (higher sensitivity to explosives) or by combining passive and reactive solutions. Since distance-active protection systems against KE threats (symmetrical warfare) and top attack attacks are not very suitable and purely passive solutions are generally ruled out due to weight and construction volume, there is a need for an effective combination of passive and reactive protection technologies. The significant reduction in the effect of modern KE bullets is z. B. already worked through the combination of passive and explosive reactive protection armor.

Passive, reactive and active protection solutions should therefore be implemented in the interaction of different protection technologies, because this is the only way to achieve the best possible protection for land vehicles. As a German manufacturer, Rheinmetall has reacted to this need - most recently with the integration of IBD Deisenroth Engineering and all of the protection technologies available in the group (hard-kill protection, soft-kill protection and passive protection production) into Rheinmetall Protection Systems GmbH - and is the first able to offer comprehensive and holistic protection solutions.

There is no such thing as 100% protection. However, the residual risk must be kept as low as possible, and protection has a high priority, not least in view of the employer's duty of care. It is now also important to implement the military protection requirements in the subsequent documents of the Bundeswehr concept in such a way that a differentiated, realistically achievable level of protection that is coordinated with the financial resources is required and achieved in a timely manner.

Michael Horst