Lacroix: In the confidential world of decoys

They are often considered the final bastion against missiles. Since the appearance of this kind of weapon in naval combat nearly 50 years ago, decoys have evolved in keeping pace with the ever-increasing sophistication of missile technology by deploying new tactics to stay ahead of the threat. As in other areas of war at sea, it is an ongoing offensive vs defensive battle to gain the upper hand.

In the field of passive electronic war, France is considered to be at the forefront with its national champion, Etienne Lacroix, supplying its decoys throughout the world. This family-owned company is in its 168th year and began as a fireworks affair. The story began with its young founder, Etienne Lacroix, then a cook in Toulouse, France, deciding in 1848 to set up a fireworks workshop. It was the debut of a long history that would lead the company to put on some of the most memorable fireworks spectaculars of its time and to continue to pursue this activity even today. This internationally renowned savoir-faire was enhanced by that of Ruggieri — another French family specialised in fireworks — with an even longer history, dating back to 1739. From fireworks displayed before French kings and Russian tsars to today, with its impressive fireworks shows for events in Dubai, the football World Cup and in Carcassonne, France, Lacroix continues to dazzle audiences with new and increasingly sophisticated shows

Naval activity commenced in the 80s

Building on its historical basis and expertise, the group entered the military sector. After first applying pyrotechnics to land-based uses in the 50s, it was in the 70s that the Toulouse-based company dedicated itself to this field by specialising in naval decoys.

At the time, the French Navy was seeking to arm itself with a new countermeasures system capable of decoying the latest generation of homing missiles.

Furthermore the destruction of the British frigate, the HMS Sheffield, on May 10, 1982 by an Argentinian missile during the Falklands War left a mark. Navies then became aware of the vital need to be capable of defeating the new missiles.

It became clear at the time that the first generation of passive decoys were no longer sufficient: deploying a rudimentary cloud of chaff (metallic strips) to generate a larger echo than that of the ship had reached its limits. Missile companies had realised that their radar guidance systems were relatively easy to deceive. They in turn reduced the target zone — the telemetric window enabling the missile to select a given point on a given target.

Dagaie’s success

Lacroix provided a solution to this new threat by working in partnership with the CSEE (Compagnie de Signaux et d’Entreprises Électriques) and in collaboration with the Direction Générale de l’Armement (French defence procurement agency) and the Navy — the Dagaie. A munition was no longer deployed to generate a cloud of metallic strips, but rather mortars deploying over sixty sub-munitions in geometric order which took into account the missile’s telemetric window. The system utilises centroid seduction, which replaces the ship’s electromagnetic (EM) and infrared (IR) signature with a more attractive one to lure away the attacking missiles. Developed during the Cold War, the system was designed to quickly respond to saturation missile attacks. This unrivalled system is in service in 25 navies, which has given Etienne Lacroix access to a huge international market. The Dagaie is used with Sagaie decoys for an optimised system to protect large platforms such as France’s Foch, Clémenceau and, subsequently, Charles de Gaulle aircraft carriers, deploying rockets to carry EM and IR decoys to great distances.

Increasingly sophisticated homing devices

In the 90s, the miniaturisation of electronic components in conjunction with increased calculative capabilities underpinned unprecedented advances in missile homing systems that made them much more discriminate with respect to standard decoying techniques. Missile manufacturers, for example, succeeded in integrating sophisticated means of signal discrimination in order to compare ship and decoy radar echoes and infrared signatures. Radar homing systems no longer focused on the geometry of the cloud, but rather the radar image obtained through reflection of the decoy. Combining spectral analysis with spatial and temporal discrimination enabled homing systems to distinguish between radar echoes and radiation emitted by a ship and other sources.

In order to outsmart the decoys deployed by military vessels, homing devices were equipped with increasingly more discriminant systems over the years. Some missiles were given bimodal capabilities (EM and IR).

A broad range of parameters are taken into account to discriminate against decoys, such as the size and shape of the object, its stability while in operation, intrinsic characteristics and behaviour. A chaff cloud can be rapidly discriminated against due to its uniformity. Moreover, the strips move at in an agitated state and quickly go into the horizontal position: modern homing devices were developed to analyse these factors and to reject chaff (chaff discriminator).

The development of true stealth combat ships, beginning with frigates, such as the La Fayette in 1996, further advanced decoy effectiveness — at least for those navies employing surface vessels with the same reduced radar and infrared radiation.

New generation of decoys

These advances have resulted in the technological sophistication of missiles, making them increasingly effective. As the threats evolved, Etienne Lacroix developed, as early as the end of the 90s, new concepts which are in service today. The Sealem corner reflectors are employed against radar guidance systems and Sealir against infrared, providing a highly sophisticated system capable of reproducing exactly the same heat-emitting areas of a vessel and the contrast of its hull. “It is a complex technique that requires highly specialised savoir-faire. For example, the same effects of the funnel must be perfectly replicated and must remain stable over time and meet the requirements for infrared spectrum distribution. The area where the vessel is deployed must also be taken into account as exhaust generates much more contrast in the Nordic countries where it is cold, whereas in the warmer regions, humidity disrupts propagation”, explains the Naval Department Manager of Etienne Lacroix

Corner reflectors

Corner reflectors constitute a major advance. French engineers adapted the characteristics of a geometrically shaped reflector to project the image at any angle. “We developed optimised geometric shapes to reflect radar waves emitted by missiles. Geometry is very important and it must be perfect, otherwise it will not work in all bandwidths and therefore doesn’t ensure the best reflection possible”. Corner reflectors have to be quite large in order to confuse EM homing systems by replicating a vessel’s radar surface. One of the great difficulties of this concept was to come up with the technique enabling these structural decoys, that is to say solid structures, to be able to be ejected from the munition and to be deployed into the perfect geometrical form required. In the event of an attack, multiple corner reflectors are arranged to create a decoy. Both the shape and deployment system are carefully guarded secrets by Lacroix.

Thanks to recent technological developments, the French group has significantly enhanced its passive decoys’ credibility and effectiveness. This new generation is known as the Seaclad product range. Capable of defeating old, current and emerging missile threats, this latest generation includes structural electromagnetic decoys as well as infrared morphological and spectral decoys. “We match specific solutions to each type of threat. System effectiveness also depends on where decoy launchers are situated as they can only be mounted on certain areas of the ship”.

Deception techniques

Passive deception requires the decoy to be credible and suited to the stealth vessel to be protected. A number of deception techniques exist, which can be employed in addition to evasive manoeuvres and with a possible combination of active electronic or weapons warfare. The first principle in electromagnetic and infrared deception is distraction. To achieve this, EM and IR decoys are deployed as a preventive measure before the activation of the missile’s homing device which provides guidance during its last stage of flight on its initially designated trajectory. Jammers can be simultaneously employed with decoys on the part of the vessel as a means to confuse the attacking missile. However, a jammer may inadvertently aid in guiding the missile (home-on-jam), requiring that it be used with precaution. The second principle is centroid seduction which produces, as mentioned, a more attractive radar or thermal signature than that of the targeted vessel. Historically, electronic warfare has also employed means of confusion and dilution to create a large number of false radar echoes surrounding the ship, making target selection more difficult before firing. These two tactics are found to be lacking when modern radars come into play and therefore are used much less frequently. Lastly, electro-optic masking produces a cloud to dissimulate vessels and has proven to be effective against optically- and laser-guided missiles.

Diaporama

One of the great complexities of these systems in producing the required effects resides in the pyrotechnic compositions used, which require a highly specialised savoir-faire. “We develop special powders to meet precise burning times required by decoys that are deployed according to the desired effect, at a given speed and with a completely controlled acceleration. Reactions must also be stable and homogenous to ensure effective decoying”. The pyrotechnicians at Etienne Lacroix have made an art of developing their technology through years of research and numerous trials.

Diaporama

Layered self-defence

Significant increases in performance of jamming, artillery and, above all, surface-to-air missiles, such as MBDA’s Aster, designed to destroy on impact a supersonic anti-ship missile and including its own homing device, has led some navies to question the value of passive electronic warfare. “There are those who feel that jamming and missiles like the Aster are the future and that such missiles make passive decoys unnecessary. We believe that this view is mistaken and that decoys constitute the ultimate guarantee in a layered defence strategy, especially given that their cost is such a small portion of the value of the ship and its equipment. It is somewhat like suggesting doing away with safety belts in automobiles on the grounds that modern vehicles have ABS brakes and airbags”, points out the Naval Department Manager.

Blind detection systems

Nevertheless, notes Lacroix, the latest decoys must be compatible with active means for ship protection. This means that they must not mask missiles from detection systems. Compatibility is imperative for the simultaneous use of other protection systems, such as anti-air or artillery with a high rate of fire, like the Phalanx. Yet, certain decoying techniques simultaneously render EM, IR and optic detection systems blind, which must absolutely be avoided. “Decoys are designed to protect ships, not to deprive them of their means to counter missiles”. A number of large navies are dealing with this issue and see the French group’s products as a viable way of replacing the current decoy systems in service which may render other active self-defence systems blind.

Diaporama

Decoy-launching systems

Decoys initially produced by Lacroix had to be deployed by launchers manufactured by other companies, such as Dagaie and Safran’s NGDS which equipped numerous French ships, Horizon and FREMM frigates and numerous other frigates and corvettes for export. However, in recent years, the French group has developed its own systems to maintain its independence. The decoy launchers in the Sylena range were first designed to provide effective protection for small and medium-sized vessels (less than 2000t), such as light patrol boats and OPVs. These boats are equipped with sensors to detect incoming missiles, but do not have a complete array against missile attacks: jammers, anti-missile defence and artillery with a high rate of fire to protect them from threats. The fixed and compact Sylena LW (Light Weight) system was designed to adapt to low tonnage vessels. This 110kg launcher (only 150kg with munitions) deploys the latest generation of effects. It holds eight Sealem 08-01 mortars and two Sealir 08-01 mortars. The former measure 1.3m in length with a diameter of 62mm and weighing 4kg and the latter weigh 3.5kg and measure 60cm with a diameter of 80mm. “ The system is very easy to load and to operate”, explains the Naval Department Manager. With a reaction time under 2 seconds, the decoys are deployed within a short distance from the vessel. With an electromagnetic induction system igniting the pyrotechnic composition at the base of the munition, the decoys and their casing are, of course, perfectly suited to withstand marine conditions, be it watertightness or corrosion.

Etienne Lacroix provides a complete system for corvettes and frigates: le Sylena MK1 (300kg of munitions included), loaded with four Sealir 08-01 or 08-02 (1.6m, 80mm in diameter and 7kg).

Rockets

The Sealem and Sealir mortars produce, in the case of Sylena LW, centroid seduction while Sylena MK1 adds distraction. Both types of decoy are also available in a rocket model. A motor running on propellant generates propulsion of these devices, measuring between 1.65 to 1.8m, with a diameter of 150mm and weighing 36kg, enabling decoy effects to be deployed at required altitudes and distance to be programmed beyond a nautical mile. They can thus provide distraction with a reaction time of 7 seconds at only 1000m. These rockets are also effective within close proximity to the vessel by employing centroid seduction.

The bulkier rockets, however, require heavier launchers for deployment.

Diaporama

Bimodal anti-missile and anti-torpedo launchers

Etienne Lacroix, which is currently developing stealth launchers capable of being integrated into superstructures, has developed a system capable of deploying anti-missile countermeasures, as well as anti-torpedo decoys. The Sylena Mk2 (420kg with munitions), in addition to Sealem and Sealir, can deploy Sealat mortars (1.2m, 145mm, 25kg) loaded with the new Canto® decoys developed by DCNS. “It is a tremendous advantage to be capable of deploying both anti-missile and anti-torpedo decoys from a single, latest generation launcher. This low-cost, dual solution is easy to integrate and is attracting much interest”. The Egyptian Navy has opted for the Sylena MK2 to arm it Gowind 2500 corvettes.

It must be noted that Etienne Lacroix also offers masking solutions with its Seamosc, producing a sizeable cloud to hide vessels from electro-optic homing devices and laser-guided systems.

Intergraded with or without combat systems

When it comes to deployment, the systems developed by Etienne Lacroix can adapt to any configuration. “They can be easily integrated into the vessel’s combat system, such as the DCNS’S Setis or Thales Netherland’s Tacticos with simple and standard modern interfaces. If, however, the ship is not equipped with CMS, the system can directly interface with a radar detector (ESM), such as Thales’ Vigile, which can be configured to set off firing”. In addition to sensors setting off a warning of an incoming missile, as well as providing data on the threat, the decoy management system further takes into account weather conditions and navigational data (wind, speed, vessel’s route, etc.), which are critical for optimal effectiveness.

In 1999, Etienne Lacroix acquired the countermeasures unit of the state chemicals firm SNPE and is today the French industrial leader in the decoy segment, supplying not only navies, but land and air forces. The group equips numerous types of helicopters, the Rafale fighter jet and the A400M.

The company also utilises its pyrotechnic expertise to produce smoke and distress signals, notably for submarines, while it has diversified into numerous other civil applications: signalling systems for railroad track works, scaring birds from airports, plastic components of Airbus passenger seats, pyro-mechanisms embedded in satellites, an avalanche mitigation device enabling ski resort to be open, hail prevention rockets to protect vineyards, etc.