Stephen W. Miller – The concept of armoured vehicle use by infantry has evolved as has the size and purpose of its armament. Not only has calibre size grown but also the weapon’s purpose.
The first half-track carriers which appeared during World War II, such as the German Sd.Kfz.251 Hanomag had limited ballistic protection and typically mounted a medium machine gun. However, post war armoured combat vehicles have been fielded with progressively larger armament. In addition, the number of infantry carried has often been reduced to accommodate these weapon systems. These changes reflected a shift in focus from the infantry section to the vehicle itself and its firepower capability, especially in those designated as infantry fighting vehicles (IFV).
Modern infantry combat vehicles reflect a range of armament from medium to heavy machine guns, automatic grenade launchers (AGL) and up to medium calibre auto-cannon. Each reflects a different expectation in their tactical employment. Those with machine guns and AGLs are generally infantry carrier vehicles (ICVs) while those with auto-cannon are more often classified as IFVs.
The General Dynamics US Army M1126 Stryker with its .50 Protector Remote Weapon Station is an example of the former while the German Kraus-Maffei Wegmann/Rheinmetall Marder and US M2 Bradley with 20mm and 25mm auto-cannon respectively are the later. The primary role of the armament on the infantry carrier has been to support its dismounted infantry. This meant suppressive fires against enemy positions and in particular opposing machine guns, and this was met with guns like the M-2 .50 cal.
In the European Cold War period, the emphasis of combat shifted to attrition, i.e. killing more of the enemy. Here it seemed more efficient to target and destroy the vehicles that carried the enemy, which was reflected in the IFV’s role being defined as accompanying main battle tanks and complementing them against opposing light armoured vehicles.
For many western armies from the late 1970s, this led to adoption of the 20mm calibre followed by the 25mm auto-cannon. These emphasised the need for high velocity, flat trajectory and armour penetration. Examples include the Orbital ATK M242 25mm Bushmaster chain gun and Rheinmetall (Oerlikon) KBA which used the use of armoured piercing discarding Sabot particularly the fin stabilised round (APFSDS). However, as threats expanded to include increasing lethal ground anti-tank guided missiles, handheld anti-armour weapons, armed helicopters and unmanned aerial systems, optimising for penetration brought drawbacks. In addition, urban battle environments are more prevalent than ever before. It was recognised that effectively addressing this broader array of targets required new levels of gun and ammunition performance.
The Direction of IFV Armament
While most western armies went to 20mm and 25mm for their IFVs, the Swedish Army specified the 40mm cannon for its CV90 believing that it offered greater target engagement flexibility and superior lethality against a wider array of targets. Today there is a move by other armies towards larger calibre cannon on IFV’s reflecting a similar recognition. Anti-tank guided missiles can attack with precision at long ranges. Individual shoulder fired infantry weapons proliferate the battlefield. In addition, airborne platforms from armed helicopters to unmanned, yet armed, aerial vehicles (UAS) are being encountered. Addressing these requires an approach that optimises explosive force and target effect. Achieving this favours a larger round to accommodate advanced fusing, improved target effect and greater explosive power. Jarrod Krull, communications manager at Orbital ATK (now part of Northrop Grumman), explained that “additional volume offers more space in the projectile which translates to permitting integration of micro electronics. Ideally shell sizes of 30mm and above offer the most possibilities.”
Rheinmetall-Defence has responded to these demands through the development of its 30mm X 173 MK-30/ 2 ABM which are fitted in the Krauss-Maffei Wegmann (KMV) Puma being fielded by the German Army. In a statement the company shared, “we see more specialised munitions (which can be costly) but combined with greater more accuracy, stabilisation and fire computation to increase lethality and reduce rounds (and cost) per kill.”
A key to the enhanced lethality and effectiveness against multiple targets is Rheinmetall’s Air Burst Munition (ABM). It combines exchanging specific engagement parameters from the vehicle fire control system with a special programmable fuse in the projectile. Each round is automatically set to activate as required to achieve maximum effect. The projectile itself ejects a number of sub-projectiles to further multiply the damage to the target. This combination significantly enhances the capability of the IFV to engage and neutralise many of the non-armoured threats and to do so a much longer ranges.
A principle challenge for IFV armament and ammunition developers is that the solution to defeating these various targets must accommodate gun systems that in most designs have at most only two ammunition feeds. Typically one magazine will be loaded with armoured piercing rounds and the other with high explosive. This means ideally new ammunition solutions should offer one round to address all of these threats.
Orbital ATK’s PABM ammunition achieves this by using an inductive fuse setter on the gun to provide multi-mode function of the projectile. It enables the gunner to select the best setting to engage each target with optimum result. It uses a Semi-Armoured Piercing High Explosive Incendiary (SAPHEI) warhead that can be set for point, point delay, or air burst detonation.
Ready and Stowed Ammunition
On the face it would appear that simply mounting larger calibre cannon with bigger more powerful ammunition is the straightforward answer for IFVs. However, the complication is that the larger the calibre and longer the round the less rounds can be provided in the magazine ready to fire, as well as stowed onboard. This is illustrated by comparing the 40mm verses the 35mm and 30mm. In the space used for 24 40mm rounds, 70 rounds of 35mm or 160 30mm can be carried. This directly impacts on the number of targets that can be addressed. It is a trade-off that must be considered.
IFV gun and ammunition developers are offering various solutions to army decision makers. Dan Lindell, platform manager at BAE Hagglunds, explained that “our CV90 is offered with CV90 variants which fit different larger calibre main armament. Although the 40mm remains used by the Swedish Army other armies have fielded turrets mounting ATK’s Mk44 30mm/40 or Bushmaster III 35mm/50 guns. These offer users various solutions to meet their needs.”
A Rheinmetall spokesman explained that “both its Puma and Lynx IFVs and LANCE turrets use either the 30mm MK-30/2ABM, or 30mm, or more recently developed 35mm Wotan rounds. The later being its electrically powered auto-cannon. Each of these use of advanced APFSDS with high density penetrators for armoured targets and the multi-use programmable rounds for all other engagements.” The goal is to obtain greater target effect with minimal negative impact on the weight and other aspects of the IFV design balance. These gun and ammunition combinations, as effective as they are, however, have likely achieved as high a performance as is possible within their existing design.
Russia’s IFV Armament
The Soviet Union’s BMP-1 is viewed as one of the first IFVs. Its main armament reflected a different approach from the western IFVs. Its 2A28 Grom 73mm is a low velocity cannon using the ammunition of the SPG-9 recoilless gun. These include fin-stabilised High Explosive Anti-Tank (HEAT) and HE-Fragmentation with an effective battlefield range of 500-700 meters against point targets. As a result it is more a close support weapon with armoured targets relegated to anti-tank guided missiles.
The follow-on BMP 2 replaced the 73mm with the 2A42 30mm auto-cannon which has also used on naval, helicopter and air defence platforms since the 1980s. Its high explosive and APDS rounds reflected performance similar to western auto-cannon.
However, with the introduction of the BMP-3 in the late 1990s the Russian army returned, at least partly, to its original IFV concept. The 2A42 30mm was now matched with a 100mm 2A70 rifled gun/missile launcher. This gun can fire either 3UOF HE-Fragmentation or 3UBK10 (9M117) laser beam guided anti-tank missiles from a 40 round auto-loader.
This 30/100 mm gun combination has not, however, been carried forward to the newest Kurganets IFV with mounts only the 2A42 30mm with Kornet missiles. On the other hand the Russian Defence Company at the 2015 Russian Arms Expo displayed a version of the BMP with a new Baikal AU-220M 57mm auto-cannon in a remote operated turret. Some reports have suggested the Russian Defence Ministry may be considering standardising the 57 for all IFVs.
IFV Armament Development
CTA International, a venture by Nexter and BAE Systems, has developed a new auto-cannon utilising case telescoped ammunition. In it by using the projectile is encased by the round housing. Thus, it’s CTA 40 cannon provides the propellant and warhead payload capacity of the 40mm size in a much shorter the round length that then allows for a significantly shorter gun receiver, more compact feeder and larger magazine and on-board ammunition carry. In an interview when the CTA40 was entering production Colin Stephenson the CTA Integration Lead shared that “CTA40 is a complete system of a unique ammunition configuration, Ammunition Handling System and gun. Together they offer not only enhanced at target performance but also benefits in turret fitting and increased gun elevation and depression due to the smaller interior space claim.” The gun has APFSDS, General Purpose point detonating, General Purpose Air Burst, and A3B optimised for UAVs and low speed aircraft.
Orbital-ATK has taken another approach. Its Mk44 Chain Gun is also available modified in an enhanced Super 40mm X 180mm version. Originally developed under the US Army Advanced Light Armament for Combat Vehicle (ALACV) program, Super 40 offers even further improved lethality in both armoured piercing and PABM ammunition while being able to be fit into the same space as the 30mm Mk44. They have also applied this development to their 35mm. It can fire either the Oerlikon ammunition or a 50mm Supershot round that uses a straight wall cartridge and semi-telescoped projectile that was originally a 1980’s development. The objective of the Supershot is to achieve 40mm armour penetration performance without the drawback of its larger round size which significantly reduces the ready and stowed ammunition possible. A more recent application of the Supershot 50 reflects the concern over addressing the growing other threats mentioned previously. In this concept the “necked out” straight wall cartridge is combined with a new Extended Area Protection System technology. EAPS is to a course corrected projectile with command guidance and a programmable fragmentation warhead.
The promised improved target effect performance and growth potential of the 50mm calibre size has the US Army considering it as a possibility for its Next Generation combat Vehicle successor to the M2 Bradley. Orbital ATK indicted that it has delivered a XM319 50mm gun to the Army Armament Research and Development Center for concept evaluation while General Dynamic Ordnance and Tactical Systems has provided ammunition. This 50mm is, however, in an early stage of development with neither it nor its ammunition ready for production.
Bigger Guns New Tactics?
This movement toward larger cannon justified by new threats finds IFV’s are being developed with multi-target capability, sophisticated vision systems and fire controls, higher protection levels, survivability enhancements and greater situational awareness. These fighting systems reflect not simply a response to increasing threats but concurrently significantly improve their inherent combat capability. It will be interesting to see if this results in their consideration as a primary weapon system in its own right. Could this influence a move toward actually employing IFV’s independently, a shift from its traditional role? It is a movement to watch for.
