Low-level naval and ground-based air defense systems.

Low-level Naval and Ground-based Air Defence Systems

Pity the Poor Aviator

To reduce the seriousness of the threat now posed by the latest generation of RPVs and missiles, widespread efforts are being made to improve the overall effectiveness of conventional active defences. In addition, there is increasing use of supporting systems, such as ground-based jammers, decoys and visual/IR smoke.

A comprehensive survey of air defence equipment would require a weighty tome, which would be out of date by the time it was published. This report concentrates on the actual weapons involved, with particular reference to recent developments. However, since any weapon is of limited value without the means to detect, identify and track incoming targets, the discussion is introduced with some examples of tactical sensors.

Radars and Sensors

Passive sensors include the IR-based Thorn EMI ADAD and Saab IRS-700, and the radar-based Marconi Sentry ESM. Visual identification of the target may be facilitated by the Tadiran Spot-It EO system, giving aircraft recognition at 8-10 km.

Early target acquisition demands that the sensor be mounted high.

French mast-mounted tactical radars include the Electronique Serge Dassault Romeo 2S and the Thomson-CSF Samantha. The latter company is also developing the intermediate-range RAC system, which has a hydraulic folding mast, giving a 15-meter antenna height and a range of up to 80 kilometres.

Contraves' SHORAR radar is used on the four-missile turret of the M113 vehicle in the Canadian version of the Oerlikon ADATS and on the M3 Bradley in the US Army FAAD-LOS-H system. The SHORAR/ACV is a command and control system, to be used on an Italian Army M113 to form the SIDAM mobile air defence gun system. In towed form it is known as Pagoda. Future possibilities for SHORAR include its use to cue MANPADS weapons.

During the 1980s the missile-armed helicopter has become a much more serious threat to armoured vehicles, due to improvements in ATGW and sighting equipment. Although a dedicated attack helicopter such as the Mi-28 Havoc may be virtually invulnerable to 7.62 mm fire, any helicopter can in principle be brought down by 12.7 mm. Several countries are therefore working on improved heavy machine-guns and ammunition. The objective is to upgrade and later replace the M2HB Browning, which weighs 38 kg, and fires the 12.7X99 mm cartridge at 500 rd/min, with a muzzle velocity of 880 m/sec.

Illustrating the revival of interest in heavy machine-guns, the British Army is buying 1 050 Browning AAADs (All Arms Air Defence Systems) from Fenlow Products, fitted with Hall and Watts sights and a new vehicle mounting. The gun itself comes from British Army stocks.

As for ammunition development, what is needed to kill an armoured helicopter is a projectile with some degree of armour penetration and with combined delayed-explosive and incendiary effects. Examples include the pyrotechnically-ignited Raufoss NM140 MP (Multi-Purpose) round, and Olin's WALAP (Winchester Anti-Light Armor Projectile), which has a tungsten penetrator and a zirconium baseplug to increase the incendiary effect. Olin is also responsible for the 12.7 mm SLAP (Saboted Light Armor Pentrator), housing a 7.62 mm tungsten alloy dart in a 12.7 mm Lexan sabot.

Although it currently exists only in prototype form, the full-calibre saboted Alpha cartridge appears to have a heavier penetrator than the SLAP round. The Alpha bullet has helical grooves, gripped by fingers extending forwards from its base sabot. The sabot is made of low-friction material, giving a high muzzle velocity. Boat-tailing of the projectile reduces inflight speed decay.

One possible future replacement for the Browning M2HB is the Stoner-designed TARG (Telescoped-Ammunition Revolver Gun) that is being developed by the American manufacturer ARES, and which fires plastic-cased cartridges. The 12.7 mm TARG weighs only 20.4 kg and has a muzzle velocity of 970 m/sec, although an even higher speed is possible with an increased cartridge diameter. The gun has already achieved a firing rate of 1 400 rd/min, but the long-term aim is 2 000 rd/min.

Since the early 1980s FN Herstal has been studying means of replacing the Browning, and has now produced a relatively conventional high-performance gun of slightly increased bore. The result might be regarded as a low-cost substitute for a 20 mm cannon. This BRG-15 weighs 60 kg and fires a new 15.5 x 106 mm round at a rate of 600 rd/min, with a muzzle velocity of 1 050 m/sec, giving an effective range of about 2 000 meters. It also features disintegrating-link belts and dual-feed.

The production BRG-15 will have a chrome-lined barrel, and the basic round has a non-jacketed steel projectile with a plastic driving band. The baseline AP round throws a 78 gramme projectile at 1 055 m/sec, but the ammunition range includes an APDS round with a 48 gramme projectile that departs at 1 340 m/sec. At Le Bourget FN announced work on a three-barrel Gatling-type gun derived from the BRG-15.

Before leaving the subject of machine-guns, it may be noted that the Marconi TAMS (Tank Anti-Missile System), though intended primarily to counter anti-tank missiles approaching at around 400 m/sec, is felt to have some potential against homing shells, sub-projectiles and their carriers. The TAMS is based on a small Lucas turret with mm-wave radar and two McDonnell Douglas 7.62 mm Chain Guns.

20 mm to 30 mm Guns

In general, cannon provide a much higher kill probability than machine-guns, but they are more expensive and their increased range demands more sophisticated fire-control systems. The smallest practical calibre for a cannon is 20 mm, as exemplified by the Oerlikon KAB, the General Electric M61 Gatling, the Rheinmetall Rh202 (as currently used by the West German Air Force in airfield defence) and France's GIAT M693(F2).

The 25 mm category is exemplified by the McDonnell Douglas M262 Chain Gun and the Oerlikon KBB Diana. Contraves has now developed the Gun-Star system, which can be fitted to manually-operated guns. In essence the target flight path is followed by means of automatic TV-tracking and laser-ranging, and a Contraves digital computer continuously generates lead-angles for up to six separate guns.

Since the 27 mm Mauser BK27 has not yet found application in the air defence role, the next step-up in calibre is 30 mm, as in the Mauser MK30 Model F. This 800 rd/min cannon is used in various twin-gun applications, including the Hellenic Arms Industry's Artemis 30, using the Philips Trackfire fire-control system, and the Mauser Arrow, which has been sold to Thailand with the Contraves Sky-guard. Another important application of the twin-Mauser is the Breda Sentinel, with Officine Galileo P.75 optronic fire-control and laser-ranging.

35 mm to 40 mm Guns

The 35 mm Oerlikon series (currently the KDC) is one of the most successful of anti-aircraft guns: over 1 700 twin-gun mounts are in service in more than 20 countries.

Oerlikon has recently embarked on the development of a family of subcalibre ammunition, which offers a decreased time of flight (and hence a higher hit probability against a moving target), combined with a high velocity at impact. To illustrate the improvement, if a desired hit probability requires a time of flight of no more than (say) 2.5 sec, then this subcalibre ammunition increases the corresponding firing range from around 2200 to 3000 meters, approximately 35 per cent.

For use against airborne targets, a saboted round normally has the disadvantage that it may pass straight through the structure, causing only minimal damage. Oerlikon has therefore developed a new type of penetrator, retaining the velocity and hit probability advantages, but closely reproducing the terminal effects of an HEI/SAPHEI round.

The Oerlikon philosophy is to combine the highest possible direct hit probability with a projectile that provides the best possible terminal effects in its calibre, hence a proximity fuze is not justified. In contrast, Bofors AB of Sweden advocates the longer range and greater weight of explosive associated with a larger calibre shell, though the extended time of flight reduces hit probability and thus calls for a proximity fuze. The current 40 mm Bofors L/70 is marketed with an integral tracking radar and semi-automatic optronic system, under the BOFI designation, but it is also sold in combination with the Signaal Flycatcher or Contraves Skyguard fire-control systems. Upgrades for the basic L/70 in terms of rate of fire, magazine capacity, optronic fire-control and improved ammunication, are marketed by both Bofors and FN Herstal.

Vehicle Mounts

Turning to self-propelled anti-aircraft guns (SPAAGs) with some armour protection for the crew, Bofors has recently demonstrated its 40 mm Trinity in this form, claiming a maximum range of 6 000 metres against aircraft and 3 000 against missiles. Another new SPAAG is the Soviet replacement for the ZSU-23-4, which is designated 2S6 and has a turret mounting two 30 mm guns and four SA-18/19 missiles. Egypt is modernising its 23 mm AAA with the Electronique Serge Dassault TA23E/RA20S system. This is based on M113 vehicles fitted with TA23E turrets, the "leader" vehicle carrying the RA20S fire-control radar, each of the "satellite" vehicles mounting paired ZU-23 guns (or six Sakr Eye SAMs) with Galileo optronic sights.

An Italian SPAAG development worthy of note is the Breda modernisation package for the US-built M42 twin 40 mm system. This includes the installation of the new Breda L/70 with a dual-feed ammunition system and a 450 rd/min rate of fire per barrel, combined with various fire-control options.

In the future, there may be a trend towards 35 mm and even larger calibres for dual-purpose (anti-aircraft and anti-armour) guns for IFVs. Sweden's CV90 will mount a 40 mm Bofors; Germany's Marder 2 will have a 50 mm Rheinmetall RH503, and the FMC Bradley Block 4 may have a 600 rd/min 45 mm ARES cannon firing cased-telescoped (CT) rounds developed by Honeywell.

In the grey area between guns and missiles, Bodenseewerk is developing a projectile to be fired from the main gun of a tank against helicopters up to 6 km distant, and using IR terminal homing. Designated EPHAG (Endphasengelenktes Hubschrauberabwehr-Geschoss), this system responds to a German Army requirement.

Naval Guns

Naval guns in many instances are comparatively slow-firing dual-purpose weapons, as evidenced by the 330 rd/min 40 mm Bofors Trinity, the 220 rd/min 75 mm Bofors SAK Mk. 2, the 120 rd/min 76 mm OTO-Melara 76/62, and the 90 rd/min 100 mm Creusot-Loire, which has a maximum range of 17.5 km.

However, lighter vessels need guns of smaller calibre. In 1988 Breda Meccanica unveiled its single 25 KBA gun (based on the well-known 600 rd/min Oerlikon 25 mm cannon). The company also showed at Le Bourget the twin 25 mm naval mounting, with a pair of Oerlikon KBBs giving a firing rate of 1 600 rd/min. For defence against sea-skimming missiles, the KBB can fire an AMDS (anti-missile discarding sabot) round with a 14.5 mm penetrator, giving a 0.84 sec flight time to 1 000 meters, where the residual velocity is 1 115 m/sec. In the past Breda's maritime success has been mainly in supplying single and twin 30 and 40 mm mountings. The Twin 40L70 Compact, for example, is now in service with 22 navies.

The 40 mm Bofors Trinity simultaneously introduces improvements to the gun, fire-control system and ammunition. Equipped with its own search and track radars and a new digital computer, the Trinity system can place around the target 10 individually-aimed 3P-HV pre-fragmented proximity-fuzed high velocity rounds, each with a six-mode fuze and 1 000 tungsten alloy pellets.

One advantage of larger guns is that at some future date they will be able to fire course-corrected shells. In the case of the OTO-Melara 76/62, there is a joint development effort with British Aerospace, and it is anticipated that production deliveries will begin in late-1991. There is likewise a 76 mm CORectable Ammunition System (CORAS) under development by Signaal and Diehl. It is claimed that CORAS will improve kill probability by a factor of four, or extend the range for a given kill probability from (for example) 600 to around 2 000 meters.

For last-ditch defence against anti-ship missiles, the CIWS (close-in weapon system) relies on a high rate of fire and accurate target tracking. Most such systems are based on Gatlingtype guns. General Electric's 4 200 rd/min 30 mm GAU-8/A, for example, forms the basis for the Signal/GE SGE-30 Goalkeeper, and for the Thomson-CSF Satan and Sagem Samos projects.

Missiles

Guided weapons can provide far more range than guns, delivering a larger warhead with a miss distance that is virtually independent of range. They can thus achieve a high kill probability, though missiles are more expensive than guns and are of limited use at short range, since their guidance systems need time to take effect.

At the lower end of the guided weapon range, the man-portable air defence system (MANPADS) provides the individual infantryman with a quite remarkable capability. A missile, launcher and sighting system together weigh less than half as much as a 12.7 mm machine-gun, yet can kill an aircraft at over twice the range.

The most significant of the first generation MANPADS was probably the Soviet SA-7 Grail, which entered service in 1966, and is now used in 56 countries, including 25 in Africa alone. It led to various imitations and derivatives, including China's HN-5 and Egypt's Sakr Eye: it is now being replaced in Soviet service by the SA-16.

Passive IR homing was also employed by the General Dynamics FIM-43 Redeye, which is still used by 16 nations, although production has now ceased. The Shorts Blowpipe entered service with the British Army in 1975, and employed optical tracking with radio command guidance, a TV camera automatically tracking the missile and generating corrective signals. Blowpipe performed reasonably well in the 1982 South Atlantic conflict, but was superseded in 1988 by the Shorts Javelin, which provided a new warhead and a more powerful rocket motor.

The latest FIM-92 variant of the General Dynamics Stinger is the Stinger-POST, which has a rosette scanpattern and both IR and UV sensors to discriminate against decoy flares. The Stinger is manufactured in the US by GD and Raytheon, and a four-nation (West Germany, Greece, the Netherlands and Turkey) programme led by Dornier is building up to start deliveries in 1992. Confirmation of Switzerland's selection of Stinger is expected later this year, presumably leading to in-country licence production.

One of the fundamental problems of the MANPADS concept is that the demand for portability tends to result in a very light warhead, which damages the target without killing it. There is thus a strong case for tripod-mounted systems that can accommodate a much more capable missile, like the Matra Mistral.

The Mistral can acquire an afterburning target at over 6 km and a light helicopter at more than 4 km.

The Sadral is a shipborne system based on the Mistral and has a six-round launcher, while the Simbad is a two-round system for small vessels. The French Army has ordered 2 300 Mistrals, and this weapon is also in production for seven countries, among which are France, Belgium, Abu Dhabi and Saudi Arabia.

The Bofors RBS70 Rayrider entered service in 1976, and employs laser beam riding. Over 10 000 rounds have been manufactured. The RBS90 Nightrider is scheduled to enter Swedish Army service in 1993 on Bv206 vehicles, equipped with an Ericsson thermal imager for night operation. Both the RBS70 and RBS90 are now available with the Mk.2 missile, which has a larger warhead and an improved motor, extending its range from the 5 km of the Mk. 1 to around 7 km.

For the future, Bofors has recently proposed the lightweight Batman missile, presumably to complement the RBS70/90 and a long-range derivative of the existing weapons, known as the RBS703 BAMSE. Used in conjuction with the Ericsson Eagle radar, the BAMSE would employ a larger boost motor and radar command-to-line-of-sight guidance, giving a range of 10-15 km.

Systems designed from the outset for use on vehicles make possible even more capable weapons than those fired from tripods. Examples include the Euromissile Roland, Thomson-CSF Crotale and Shahine, and the British Aerospace Rapier series. The latest Rapier to be tested is Laserfire, which employs automatic laser tracking of the target.

The Crotale NG has been ordered by Finland and has been selected by the Royal Netherlands Air Force.

The Crotale NG is reportedly derived from the Liberty system proposed for the US Army FAADS-LOS-H programme, which was won by the Oerlikon ADATS. The ADATS has also been selected by the Canadian Armed Forces. The ADATS employs Contraves search and track radars that can simultaneously follow up to six targets (with growth potential for ten), a Martin-Marietta EO module, and eight laser beam-riding missiles. The missile weights 51.4 kg and has a range of 10 km.

Turning finally to shipboard missile systems, naval versions exist of some of the land-based SAMs discussed above, such as the Matra Mistral and Thomson-CSF Crotale. Regarding the latter, reports indicate that the French Navy will upgrade its Crotales with the VT-1 missile of the NG system.

American naval SAM developments include the Raytheon RIM-7M Seasparrow, which now exists in vertical launch (VL) form, as does the Rafael/IAI Barak and BAe's Seawolf, which is still claimed to be the only anti-missile missile in full operational service. The General Dynamics RAM (Rolling Airframe Missile), based on Sidewinder, is intended to fill the range-gap between Seasparrow and the Phalanx close-in weapon system.

For the longer-term future, the emphasis is increasingly on international collaboration, with France and Italy working together on the Aerospatiale/Thomson-CSF/Selenia Eurosam series, the US, UK, Canada, West Germany, the Netherlands and Spain collaborating on NAAWS (NATO Anti-Air Warfare System), and France, Italy, Spain and the UK jointly studying FAMS (Family of Anti-air Missile Systems).

PHOTO : The Blowpipe was used briefly by the mudjaheddin in Afghanistan, but was judged to be

PHOTO : undesirably heavy and to require proper operator training to be effective. In contrast,

PHOTO : the General Dynamics FIM-92 Stinger seen here was lighter (16.1 kg with launcher, compared

PHOTO : to 21.9 kg for Blowpipe) and required only minimal training.

PHOTO : The Ericsson Giraffe 75, used with medium-range SAMs, has its antenna 13 meters above the

PHOTO : ground. The Giraffe 50AT (All-Terrain) has its antenna at 7 meters.

PHOTO : The Giraffe 50 AT (All-Terrain) has recently been ordered in combination with the Hughes

PHOTO : Low Altitude Surveillance radar (LASR) for the Norwegian Army Low-Level Air Defence

PHOTO : Systems (NALLADS).

PHOTO : The 20 mm GIAT is used by all the French services. For example, the French Air Force

PHOTO : employs it in the twin-gun Cerbere (76T2), with an Officine Galileo P.56 sight.

PHOTO : The Oerlikon KBB Diana is normally marketed with the Contraves Gun-King fire-control

PHOTO : system and laser-ranger.

PHOTO : The Breda Sentinel twin field mounting, with two Mauser MK30 Model F canon and a Galileo

PHOTO : P.75 computing sight with laser ranging.

PHOTO : Today's GDF-005 provides a combined rate of fire of 1 100 rd/min, and has a maximum

PHOTO : effective range of 4 000 meters. The basic defensive unit consists of two GDFs, generally

PHOTO : controlled by a Contraves Skyguard.

PHOTO : The Oerlikon TSD 055 APFDS (armour-piercing frangible discarding sabot) round employs a

PHOTO : sintered tungsten penetrator, which on passing through the target skin disintegrates

PHOTO : explosively in a cloud of incendiary particles. It is anticipated that the APFDS round

PHOTO : will be in production in the early 1990s.

PHOTO : The Flycatcher is employed with the Breda twin 40 L/70 field mounting (two barrels giving

PHOTO : a combined 600 rd/min) to form the Guardian system, the fire-control unit serving up to

PHOTO : three twin-mounts.

PHOTO : The M113 chassis is also used for the OTO-Melara SIDAM-25, of which 340 are being built

PHOTO : for the Italian Army. The system combines four 25 mm Oerlikon KBA cannon with the Galileo

PHOTO : MADIS fire-control system.

PHOTO : OTO-Melara has also private-ventured the Otomatic 76/62, which places the radar-directed

PHOTO : 76 mm Super Rapid gun turret on the Palmaria MBT chassis. Two prototypes are being tested,

PHOTO : and Krupp is reportedly to market the Otomatic turret in Germany, carrying out a trials

PHOTO : installation on a Leopard 1 chassis.

PHOTO : This year Breda promoted the improved 25 KBB version, either remotely-controlled or

PHOTO : manually operated with the Hawkeye fire-control system developed by a Breda subsidiary.

PHOTO : The Marconi Marksman turret, with two 35 mm Oerlikon KDA cannon and a Marconi 400 Series

PHOTO : surveillance and tracking radar on a T-55 chassis, as ordered by Finland.

PHOTO : The General Dynamics Phalanx employs the 20 mm General Electric M61, and now has a rate of

PHOTO : fire of 4 500 rd/min. It uses an APDS round with a 12.75 mm depleted uranium penetrator,

PHOTO : although there have been references to an Australian tungsten penetrator as a substitute.

PHOTO : Prior to 1989 the only apparent Oerlikon involvement in the CIWS field was the use of four

PHOTO : 25 mm KBBs to form the 3 400 rd/min Sea Zenith mounting of the Contraves Italiana

PHOTO : Seaguard.

PHOTO : Earlier this year Oerlikon announced the development of a seven-barrel 25 mm KBD 

PHOTO : Gatling-type gun, which fires at a rate of 5 000 rd/min. A twin-KBD mounting named Barrage

PHOTO : has been developed in conjuction with Breda. When associated with a fire-control system

PHOTO : developed by Contraves Italiana, Selenia and Elsag, this becomes the Myriad system.

PHOTO : The Shorts Javelin is an advanced derivative of the Blowpipe, which has been used

PHOTO : operationally in the South Atlantic and Afghanistan.

PHOTO : During the 1990s the Shorts Starstreak will enter service, combining hypersonic flight

PHOTO : with the shotgun effect of three explosive dart submunitions, which are guided

PHOTO : individually (by laser commands) to the target. Few details of this system have so far

PHOTO : been revealed.

PHOTO : The Matra Mistral illustrates the advantages of a tripod system: the missile weighs

PHOTO : approximately 18 kg and carries a 3 kg warhead, compared to around 1 kg for many

PHOTO : shoulder-launched rounds. Guidance is by IR homing (the sensor was developed in

PHOTO : collaboration with SAT), with a multi-element seeker in a pyramidal nose for minimum drag.

PHOTO : The Thomson-CSF Mygale vehicle-mounted air defence system being developed for the French

PHOTO : Army combines Mistral on Aspic firing units and the Samantha warning and control post.

PHOTO : Test firing of a Euromissile Roland from a modified Marder vehicle. The Roland 3 has a

PHOTO : range of 8 km and an improved warhead with 84 shaped charges.

PHOTO : The shelter versions of the Thomson-CSF Crotale NG, as proposed for the defence of targets

PHOTO : such as airfields.

PHOTO : The Thomson-CSF Shahine is an improved derivative of the Crotale, based on the AMX-30

PHOTO : chassis and the Matra SICA missile of 11 km range.

PHOTO : The 40 mm Trinity is said to have a maximum range of 6 000 meters against aircraft.

PHOTO : Development has meanwhile begun on the Rapier 2000, which will carry eight ready-to-fire

PHOTO : missiles on the launch vehicle, and will be able to engage two targets simultaneously. It

PHOTO : will also feature IR tracking for passive engagements, and will be hardened against

PHOTO : nuclear explosions.

PHOTO : The Swedish CV90 carries a Bofors L/70 gun. Its maximum effective AA range is 4 000 m.

PHOTO : At Le Bourget this year Thomson-CSF showed a mockup of the Crotale NG, which will combine

PHOTO : the acquisition, tracking, firing and computing units all in a single vehicle. It will

PHOTO : employ LTV's high-speed VT-1 missile, which is capable of 35G at a range of 8 km, and

PHOTO : command guidance, based on multi-sensor inputs.

PHOTO : The production of 170 ADATS fire units and 3 000 missiles is to be split between Oerlikon

PHOTO : and Martin-Marietta. The ADATS has also been selected by the Canadian Armed Forces.

PHOTO : One recent development combining active and passive measures is Breda's SCLAR (developed

PHOTO : jointly with Elsag), in which the company's 20-round 105 mm SNIA rocket launcher, which is

PHOTO : capable of delivering chaff and flares to 10 km, is combined with two three-round Mistral

PHOTO : launchers.

PHOTO : The Aerospatiale Aster 15 missile combines with the Thomson-CSF Arabel 3-D radar and fire

PHOTO : control to form the naval SAAM (Surface-Air Anti-Missile) system. This is part of the

PHOTO : French Syrinx programme, which could provide major elements for the tri-national FAMS.

PHOTO : Vertical launch, exemplified here by a British Aerospace Seawolf firing, makes possible

PHOTO : all-round air defence with a limited number of rounds.