Oerlikon-Contraves Diana (two 25mm
KBB) ( Courtesy: Oerlikon-Contraves/Ian Hogg)
while the Stinger has a range of up to 5,000m. The HYDRA-70 missiles are intended for use against hovering helicopters which may be shielded against the heat-seeking Stinger; they have a range of up to 7,000m.
In the ever-increasing escalation of military equipment, the 25 X 137 has more recently been joined by a lengthened version, the 25 X 184 KBB. This fires a heavier projectile at a higher velocity, including an APDS shot which can penetrate 30mm of armour at a striking angle of 60° at 2,000m. The lightest mounting for the KBB is the unusual Oerlikon-Biihrle ILT1S, a single manual mounting weighing only 240kg in travelling trim. This is intended as an infantry weapon against low-flying aircraft and light AFVs, and features a low mounting with a prone operator's position. In contrast, the Oerlikon-Biihrle Diana twin powered mounting includes its own optical fire control system incorporating a laser rangefinder and digital computer and weighs around 3,000kg. Perhaps the most remarkable military acquisition of the KBB cannon is the reported purchase of a land-based version of the Oerlikon-Contraves Sea Zenith quadruple naval CIWS by the PLA, the Chinese Army!
Modern 30-76mm AA guns
Any weapon system represents a trade-off between conflicting requirements and AA gun calibre is no exception. Larger cannon need more substantial mountings and usually suffer a lower rate of fire. On the other hand, they gain in range and hitting power, so fewer strikes are necessary to destroy the target. Given effective sighting arrangements, the maximum effective AA range of a typical heavy machine gun is around 1,000-1,500m, of a 20mm cannon about 1,500-2,000m, a 25mm some 2,500m, and a 30mm about 3,000m.
The longer the range, the more difficult it is to score hits, regardless of the power of the cannon. It takes about three seconds for a modern 20mm projectile to reach 2,000m, during which time the target might easily have altered its course away from the predicted path; in that time, an aircraft travelling at 800 km/h will have covered nearly 700m. Larger-calibre weapons therefore need sophisticated fire control systems, usually with integral radar sets, to make effective use of their greater reach.
Such systems are equally compatible with many A A missiles, so towed (and some self-propelled) AA guns are often coupled with missile systems to deal with long-range targets.
Among the first of the post-war 30mm cannon was the big Hispano-Suiza HS 831 (later to be known as the Oerlikon KCB). This was used in the HS 661, a simple, manual single mount which weighed 1,540kg in travelling order and 1,150kg in action. Few other land AA mountings appear to have used this cannon, although two were fitted to the French AMX-13DCA and AMX-30 SPAAGs, based on the light and medium tank chassis respectively. Apparent similarities in equipment can conceal important differences in quality; the AMX-13 model used visual sighting and was therefore limited to clear-weather action while the AMX-30 version has an integrated acquisition and fire control radar.
The rival Oerlikon 30 X 173 round has been rather more successful, but in a German gun, the Mauser MK30 Model F, which has been incorporated into several towed and self-propelled mountings. In the former category are the Breda Sentinel Twin 30mm (a version of their naval A A weapon), with two barrels mounted close together, and the German Arrow and the Greek Artemis, both with two more widely separated guns. These equipments weigh between five and seven tonnes and are power-operated. While the Breda is autonomous, with its own fire control system and gunner, the others are usually linked to a central radar and fire-control system which operates the weapons remotely.
The MK30 has also featured in the Krauss Maffei Wildcat, a 6 X 6 armoured vehicle with one gun on each side of a turret which can also mount an integrated radar set. It is worth commenting on the modern tendency to mount AA cannon on the side of turrets, rather than close together. Apart from the fact that gun barrels too close together can disrupt accuracy (the muzzle blast from one barrel affecting the trajectory of a shell fired from the other), external mounting leaves the turret space free for crew and ammunition and also keeps it clear of fumes, as the fired cases are ejected outwards.
The largest of the army 30mm weapons were developed in Eastern Europe. The Romanian A436
Czech M53I70 (two 30mm M53) (Courtesy: Ian Hogg)
towed AA gun incorporates two of the Soviet naval NN-30 revolver cannon, firing the powerful 30 X 21 OB cartridge. The same cartridge is used in the Yugoslavian Zastava M86, although this is a gas-operated linear-action gun with a lower rate of lire. The M89 is a version adapted for dual belt feed. In both guns, gun recoil is used to drive the belt feed. Two of these guns are used in the BOV-30 wheeled SPAAG, externally mounted in a cradle at the front of the turret. This is a simple, manually aimed system suitable only for clear-weather use.
Most powerful of all is the Czech M53. This fires a huge cartridge, the 30 X 210, which is even bigger than the NN-30 round due to its larger diameter. The twin mounting, which weighs 1,750kg in action, is also fitted to two six-wheeled vehicles, the M53/59 and M53/70, in which applications it is hydraulically or electrically powered respectively. Ammunition supply, initially by a short belt, is achieved in these SPA AGs by huge fifty-round boxes on top of the guns. Because of their weight (84.5kg when full) they are able to be reloaded while in place, from the top. The mounting was one of the first applications of floating firing to an automatic cannon, but the fire control arrangements are primitive and the system is effectively obsolete. At the end of the 1990s it achieved international notoriety in Yugoslav hands, providing fire support for ground operations in Kosovo.
It appears surprising that the Soviet Union, so keen on equipment standardisation within the Warsaw Pact, permitted the Czechs to develop the M53 instead of using the 23mm ZU. The reason is that the weapon had already been developed at the Waffenwerke Brunn, the Czechoslovakia!! arms works at Brno, by the end of the Second World War. Known to the Germans as the Krieghoff MK 303, it was intended to provide the AA armament of the Kriegsmarine's revolutionary Type XXI U-boats, but never entered service.
More recently, the Russians have developed their own 30mm AA equipment, but only in SP form. Most impressive is the formidable 2S6M Tunguska (named after the place in Siberia which was devastated by a comet or meteorite in 1908). This combines two twin-barrel, water-cooled, 2A38M
ARMY W K A PONS
Russian Tunguska SPA AG (two twin-barrelled 30mm 2A38M, plus A A missiles) (Courtesy: Scorpion! KBP)
cannon together with eight A A missiles (SA-19 competition for the classic 40mm Bofors while most Treugolnik, or Triangle) and a multi-sensor target of the guns manage appreciably higher rates of fire.
The biggest of the Oerlikons, the KD appeared in the 1960s in two forms: the KDB in the GDF twin mounting, and the KDA in the Gepard each! The Tunguska has replaced the Shilka in SPAAG, with two guns fitted one on either side of Russian service and is undoubtedly the most effec- a turret mounted on a Leopard tank chassis. The tive short-range SPAA system in existence. A more Gepard has been in effect the German equivalent of modest effort is the Pantsyr-Sl, a truck-based the Shilka, trading rate of fire (550 rpm per gun) for SPAA system combining two slower-firing 2A72 effective range (up to 4,000m). The GDF is intend-
detection and fire control system on a tracked chassis. The cartridge is the current all-purpose 30 X 165 and the guns are capable of 2,500 rpm -
cannon (also 30 X 165) with twelve AA missiles.
Following in logical sequence, the next calibre of automatic cannon in service is the 35mm, this time represented by only one cartridge: the 35 X 228 Oerlikon. This is available in the widely sold all using the KD series cannon in a similar arrange-Oerlikon KD series (in several versions for different ment. Japan has developed the closely comparable purposes), and more recently the American ARES AW-X system. The Marconi Marksman is the ed for use with central fire control systems such as the Contraves Skyguard, which may also incorporate Sparrow AA missile launchers.
The Gepard has attracted various competitors,
Talon, the South African GA-35 and the Oerlikon-
British equivalent, a twin 35mm turret which can be
Contraves 35/1000 revolver cannon. The cartridge fitted to a range of tank chassis and has achieved is impressively powerful and provides effective some foreign sales successes. South Africa has
RAPID F 111Ii
Flakpanzer Gepard (two 35 mm Oer! ikon KD A) (Courtesy: Ian Hogg)
developed a twin 35mm system on a modified 8X8 armoured car chassis (the ZA-35, using the GA-35 cannon which has a similar performance to the KDA) and Oerlikon themselves have developed the GDF-D03 Escorter 35 system, which mounts twin KDF cannon on a large 4X4 chassis. One variation is the American Eagle system, which differs in using two ARES Talon automatic cannon of a similar performance to the Oerlikons. European production of this gun has been licensed to Mauser as the Model G.
The traditional ammunition for the 35 X 228 consists of a 550g projectile fired at a very high 1,175 m/s. However, APDS loadings have also been developed for dealing with light AFVs and these are capable of penetrating 40mm/1,000m/60°, compared with 15mm for the SAPHEI round. The 35/1000, intended for integration into the Skyshield 35 Air Defence System, has been designed to utilise the Oerlikon AHEAD ammunition, but earlier guns can also be adapted to use it.
The 37mm calibre, so common up to and during the Second World War, has now virtually disappeared. The sole survivors are the Chinese Type 55 (single barrel), Types 65 and 74 (twin) and P793
Damage inflicted by 35mm Oerlikon HEI shell
also used in air defence weapon systems, and specially developed weapons optimised for the ground-fighting role.
After the Second World War, there was some debate about the most appropriate armament for armoured cars (ACs) and other light armoured fighting vehicles (LAFVs). The British Saladin 6x6 AC epitomised the conflict. First designed with a modified manually loaded 40mm gun (called "Pipsqueak") firing APDS shot, it was eventually produced with a low-velocity (also manually loaded) 76mm gun which relied on HE shells for effect. Clearly, fire support had been given a higher priority than the anti-armour role.
Most other nations followed the same route. Low-velocity manually loaded guns of 76-90mm, firing HEAT (shaped charge) shells against armour, became the common armament of ACs. An early exception to this was the French range of high-velocity automatic cannon, commencing in 75mm calibre, which were fitted in oscillating turrets in light tanks and heavy ACs.
The starting point for this weapon was reputed to be the excellent gun from the German Panther tank, which was given an automatic-loading mechanism and modified ammunition. To solve the problem of how to reload the gun at different elevations, two six-round revolver magazines were mounted, one on each side of the gun breech, which moved with the gun. The whole mechanism was rigidly fixed into the upper half of the turret, which oscillated (elevated) in relation to the lower half of the turret. This was a clever idea which dispensed with the loader and permitted the rapid firing of twelve shots (at 12 rpm). The downside was the need to withdraw to a place of safety in order to reload the magazines, which could only be done from outside the vehicle.
A different approach to the same problem was taken by the Swedish Strv-103 S-Tank, which dispensed with a turret altogether. Instead, finely controlled hydraulic systems were used to achieve gun aiming by adjusting the bearing and tilt of the whole vehicle. This enabled the 105mm gun and fifty-round autoloader to be rigidly mounted into the hull, leading to a very low and compact AFV capable of rapid fire. The disadvantages were the impossibility of firing on the move, or without the engine running, which effectively limited it to a tank-destroyer role.
More recently, large-calibre (up to 125mm) self-loading cannon have become more popular in MBTs (main battle tanks), starting with Soviet designs. It is likely that all future MBTs will feature mechanisms to achieve this, despite the complexity they add to the design.
To return to fully automatic cannon in light AFVs, the German Army was unsurprisingly among the first to reintroduce the concept, with the adoption of the Schützenpanzer SPz 12-3 APC in the late 1950s. In modern parlance, this was really an AIFV or MICV, as it was intended for fighting as well as carrying troops. It was low, with well-sloped armour, and carried a 20mm HS 820 cannon in a turret. The SPz 12-3 was supplemented by the Spähpanzer Luchs 8X8 AC and eventually replaced from the late 1960s by the much heavier Marder MICV. Both of these feature an Rh202 cannon (firing the same 20 X 139 ammunition as the HS 820) in a turret mounting.
During the 1960s Hispano-Suiza offered a range of cannon in 20 X 139, 23 X 133, 30 X 138 and 30 X 170 calibres. These all used a short-recoil mechanism and were intended for AFV use. However, they might have been ahead of their time as they failed to achieve any sales.
Despite this failure, many other nations have since adopted high-velocity, small-calibre cannon for arming their light AFVs, a typical example being the South African Vektor Gl-2 in 20 X 139 which is fitted to light armoured cars. The initial exception was the Warsaw Pact, whose BMP-1 tracked MICV of the late 1960s featured a 73mm low-velocity smooth-bore cannon with an autoloader, in a turret which also featured an externally mounted rail for an anti-tank guided missile. Incidentally, the reason for the smooth-bore barrel in the 73mm gun is that it achieves better armour-piercing performance from HEAT shells, whose effect is lessened if the shell is spinning. There is a quite different reason for most modern MBTs having smooth-bored barrels, which is that rifling disturbs the stability of APFSDS shot.
The subsequent BMP-2 of the early 1980s switched to the 2A42 30mm cannon, which uses a percussion-primed version of the universal
ARMY W15 A PONS
Bulgarian BMP-23 AIFV with 23mm cannon (Courtesy: MoD Pattern Room)
30 x165 cartridge. The gun was specifically designed for the AFV role and features a variable rate of fire (either 200-300 or 600-800 rpm) although the higher rate is not used due to problems with excessive fumes in the turret. APDS (Kerner) ammunition is available with a claimed penetration of 25mm/l,500m/60°. In the recent BMP-3, the Russians have covered all the options, providing the turret with 7.62mm, 30mm (a 2A72, lighter than the 2A42 and with long-recoil instead of gas operation) and 100mm cannon; the latter is manually loaded but capable of firing a laser-beam-riding ATGW. One hopes that the vehicle won't be knocked out in combat while the crew is still trying to decide which weapon to shoot back with!
The Yugoslav Army went their own way with their locally designed 30mm M86 or M89 cannon (also used in the AA role) in the BVP M80AK M1CV. Armour penetration is claimed to be 60mm at 1,000m (striking angle not specified).
During the 1980s the Bulgarians introduced the BMP-23 AIFV armed with a new 23mm cannon, the 2A14. It is believed to use the same 23 X 152B
ammunition as the ZU A A gun; the 2A14 reportedly uses a different mechanism although no details had emerged at the time of writing. Armour penetration is a modest 25mm/500m/90°. The BMP-30 version uses the Russian BMP-2 s turret and 30mm 2A42 gun.
The British Army also moved to automatic cannon in the series of LAFVs introduced in the early 1970s, with the Fox 4 X 4 AC and the Scimitar tracked reconnaissance vehicle, which were both equipped with the ROF L21 Rarden cannon. This was a ground-breaking weapon in two ways: it introduced the 30mm calibre to AFVs, in a gun which was specifically designed for AFV use. The Rarden s cartridge was not new, being an adaptation of the HSS831 (Oerlikon KCB) 30 X 170 round, redesigned for a brass rather than steel case (as with the earlier HSS830) in order to improve the gas sealing on firing and thus reduce the amount of gun gas seeping into the turret. The low rate of fire means that the extra strength of steel cases is not required. The gun is very different from the KCB, being optimised for maximum single-shot accuracy
Scimitar LAFV with 30mm Rarden cannon (Courtesy: MoD Pattern Room)
rather than a high rate of fire, and despite the similar cartridge shapes, they cannot use each others ammunition. The main anti-armour APDS round has a sharply pointed tungsten-alloy projectile which will penetrate 40mm/l,500m/45°.
Interestingly, the British backed both horses with the 1970s LAFVs, as the original version of the Scimitar, the Scorpion, was introduced with a modified version of the Saladins 76mm manually loaded gun. This battle has evidently been won by the Rarden, since the 30mm gun has not only been fitted to the MCV-80 Warrior but is now being retrofitted to the Scorpion, using turrets from scrapped Fox ACs to create a new model called the Sabre. Incidentally, this change also indicates that the tracked reconnaissance vehicle has triumphed over the wheeled armoured car, at least in current British thinking.
The US Army was surprisingly slow to adopt the MICV concept. In fact their only modern light combat vehicle throughout the 1960s and 1970s was the M551 Sheridan, which featured a very
M2 Bradley MICV with 25mm Bushmaster cannon
(Courtesy MDHC/Ian Hogg)
low-velocity 155m gun, capable of firing the Shillelagh beam-riding ATGW. It was not regarded as successful. Some use was also made of the 20mm Ml39, which was the US Armys term for the HS 820, but this was not found to be satisfactory as it
35 mm Oerlikon KDE A FV gun with two 17-round magazines (Courtesy: Oerlikon!Ian Hogg)
needed to be kept clean and well-lubricated to function properly. The 1980s saw the introduction into US service of the M2 Bradley MICV, equipped with a turret-mounted 25mm McDonnell Douglas M242 Bushmaster, popularly known as the chain gun. This weapon has become a standard fitting in a wide range of light AFV turrets (including the USMC 8x8 LAV), with some competition from both the Oerlikon KBA and Mauser E, conventional fast-firing cannon using the same ammunition, and from the externally powered GIAT 25 M 811.
There is clear evidence of a classic gun-armour race taking place in MICVs. As their armour becomes tougher under the threat of attack from enemy MICVs, so the gun calibre goes up in order to defeat the thicker armour. The high-velocity 25mm Oerlikon KBB is attracting some attention as a LAFV weapon. Norway has recently selected the 30mm Bushmaster II for its new CV-90/30 AIFV. The Bushmaster II has reportedly also been selected for the US Marines' AAAV and the Swiss Army's SPZ2000 programmes, while Korea has selected the Mauser MK 30F for the KIFV (Korean infantry fighting vehicle), as have Austria for the ULAN AIFV and Spain for the almost identical Pizarro. Japan has chosen the 35mm Oerlikon KDE for its M80 MICV and other 35mm weapons are now offered, as described in Chapter 6. Sweden has already introduced a version of the classic Bofors 40mm L70 in its CV-90/40 - to date, the most powerful automatic cannon selected for service in a MICV.
The reasons for this increase in calibre can clearly be appreciated by looking at comparative armour
Postwar AFV cartridges (left to right): 20 X 139 APDS (HS820, Oerlikon KAD, Rh202); 25 X 137 AP (Oerlikon KBA); 30 X 165 APHE (2A38I42I72); 30 X 170 APDS (Rarden); 35 X 228 APDS (Oerlikon KD series); 40 X 364R with experimental APDS (Bofors)
penetration figures. Depending on the striking angle, a good 12.7mm API-HC will penetrate 12-15mm at 1,000m, a 20mm APCR shot about 25mm, a 25 X 137 APHE 20-27mm and APDS about 30^tt)mm, a 25 X 184 APDS 55mm, a 30mm APDS 40-60mm, 35 X 228 APDS 85mm and a 40mm APFSDS over 100mm at the same range.
A less expensive approach is to upgrade the ammunition rather than the gun. The 25 X 137 NATO cartridge is also available with an APFSDS projectile, which extends the APDS performance (30mm/1,000m/60°) to 1,400m. Attempts to produce similar ammunition for the 30mm Rarden have so far been unsuccessful.
Even larger calibres have been proposed, and in the 1980s both IMI of Israel and OTO Melara of Italy developed conventional 60mm high-velocity
Russian 30nun AGS-17 with cartridges (Courtesy: MoD Pattern Room)
automatic cannon (this was originally a co-operative effort). The Israeli gun is known as the hyper-velocity medium support weapon (HVMS 60) and is understood to have been sold to Chile to re-equip old light tanks. The gun weighs 700kg and fires at 100 rpm. The Italian version is heavier, at 1,000kg, and fires at 30 rpm. In both cases, the 870g APFS-DS penetrator, which has a diameter of 17mm, is fired at 1,620 m/s and is claimed to penetrate 120mm/2,000m/60°.
The conventional turret mounting of such weapons is also under threat in favour of external mounting. This in effect reduces the 'turret' to the gun mounting, leaving the crew sitting down inside the vehicle. The advantage is that only the gun need be exposed when firing from cover. This has only become feasible because of modern sighting arrangements, using low-light or thermal imaging electro-optical sights on the mounting, providing a day/night, all-weather image which can be viewed on screens inside the vehicle.
So far, all the weapons described have been for turret mounting. Some lighter weapons, however, have been developed for pintle and even tripod mountings, to replace the traditional .50" calibre HMGs. An entirely new class of automatic weapons has also been introduced for infantry use in recent years: the grenade launchers.
Among the light automatic cannon, which use older-generation, less powerful cartridges in order to minimise weight and recoil, are the South African 20mm GA-1 Cobra, which uses 20 X 82 MG 151 ammunition and weighs just 39kg, the Israeli G360, firing the 20 X 110 Hispano cartridge, which weighs 48kg, and most remarkably the 52kg McDonnell Douglas ASP-30, designed around the 30 X 113B Aden and DEFA aircraft cannon round. Despite the 450 rpm rate of fire, recoil reduction techniques applied to the gun and mounting are so good that the ASP-30 can be fitted to a standard .50" M2 tripod (admittedly at a significant price in terms of full-auto accuracy), while offering vastly
greater destructive power than any HMG.
Last but far from least are the grenade launchers. First introduced by the USA as single-shot shoulder-fired weapons, using a 40 X 46SR cartridge with a 76 m/s muzzle velocity, these have now developed into sophisticated tripod- or vehicle-mounted automatic weapons (known as AGLs: automatic grenade launchers) firing a slightly longer 'high-velocity' (240 m/s) 40 X 53SR round. This was developed for the American Mk 19 introduced in the Vietnam War, which can fire at 325-385 rpm and has a range of up to 2,000m. The gun weighs 33kg but with cradle and tripod added the overall weight is 62kg. Many similar weapons, using the same ammunition, have since been developed: Spain has produced the Santa Barbera SB40LAG, Singapore the CIS 40 AGL, Germany is developing the HK 40 GMG (grenade machine gun) and South Africa the Vektor AGL. The versatility of these weapons has been increased by the introduction of the Primex High Velocity Canister Cartridge, which fires a cluster of flechettes for use in short-range perimeter defence roles.
The Russians have produced various calibres of grenade launcher, but the one used in their automatic weapon is the 30mm VOG-17M (30 X 29B). The original AGS-17 weapon weighed 18kg (31kg with tripod) but the latest AGS-30 version weighs only 16kg on its tripod, and 30kg with a loaded ninety-round belt, contained in a magazine. It fires at up to 425 rpm and has a range of up to 1,700m.
The Chinese firm NORINCO has produced the 35mm W-87, which weighs only 12kg with a bipod and uses six- or nine-round top-mounted box magazines or a twelve-round drum. When mounted on a tripod, the effective range is increased from 600m to 1,500m. Romania has developed the 40mm RATMIL AGL, which rather curiously uses its own 40 X 74.5 ammunition, despite this having no significant ballistic advantage over the usual 40 X 53SR round.
It is interesting that this most recent type of military automatic weapon is, in its intended use of firing a stream of small explosive shells against enemy troops, identical in purpose to the original 37mm Hotchkiss revolver cannon of more than a century earlier. The principal difference is that the Hotchkiss was a massive piece of artillery while the grenade launchers, as well as benefiting from modern rangefinders which dramatically improve first-shot accuracy, are light enough to be carried and manned by a couple of soldiers, transforming their tactical potential.
Nordenfelt two-barrelled /" (25mm) gun on naval mounting (Courtesy: Royal Armouries)