ISUS-90 Powers Ahead

Submarine combat systems

1st Oct 2010


Given that submarines are more than ever being regarded as the Capital Ships of the 21st Century, those companies delivering appropriate weapons, sensors and combat systems seem well placed to survive during times of patchy defence expenditure. This seems especially so for the German defence technology company Atlas Elektronik - presently owned by Thyssen Krupp Marine Systems and EADS – which is able to adopt either a turnkey, or a mix-and-match approach to submarine contracts.

Located in pretty Bremen – the city’s symbol appears on the locally brewed world famous Beck’s beer bottles – the company presently employs 1,850 people and has a turnover just shy of US $480 million. Without detracting from the company’s many other activities such as mine-hunting, naval communications and surface ship command and control, it is the submarine technology part of the business for which Atlas is best known. These include various combat systems of the ISUS family (Integrated Sensor Underwater System); the full range of submarine sonars; and underwater weapons – principally a long line of heavweight torpedoes such as the latest DM2A4, developed for the Navies of Germany and Spain.

The absolute heart of an effective submarine is its combat system, which must make sense of vast amounts of data collected from sensors, then analyse this information so as to detect targets, classify them and if necessary engage them. Conventional submarines often use their masts when they are near the surface - which can collect ESM, radar and optronic data – but it is fair to say that in excess of 80% of the information will be provided by a number of passive sonar arrays. Typically a submarine will have a large cylindrical array at the bow, then a flank array made up of a number of elements, distributed arrays, a towed array, and various other bits and pieces.

The amount of data collected by these sensors is truly vast because the ocean is not only an inherently noisy place but also because sound travels long distances through water. Except in unusual circumstances, a submarine has to deal with the acoustic signatures of a lot of commercial shipping – varying from small fishing boats all the way through to super tankers – as well as trying to find telltale traces of military craft. This is truly a “needle in a haystack” exercise and a number of navies - including those of the US, Britain, France and Australia - have had periodic unhappy experiences in attempting to develop effective submarine combat systems.

In broad terms it can be judged that Atlas Elektronik with the ISUS 90 series has got it right. While the company has a history in electronics that indirectly can be traced back to the 1890s, during the modern era the contract that spawned ISUS 90 was the 1989 political deal for Germany to supply Israel with three state-of-the-art conventional submarines. After a complex start - boosted by the first Gulf War – the Israeli Defence Force specified an extremely advanced combat system able to control not only torpedoes but also submarine launched missiles such as Harpoon. It is even possible that Israel has developed land attack missiles that must also interface with the combat system. As well, the system needed to be highly reliable and ergonomically efficient.

This hugely demanding list of requirements led to Atlas developing a system which bears the same name as the preceding ISUS 83 product – but which in reality was completely new. The ISUS 90 was characterized by a scalable open-architecture approach, which made extensive use where possible of COTS technology. This sounds easy but is not so simple - as evidenced by spectacular failures such as the Royal Australian Navy’s selection in 1987 of a US product from Rockwell that promised many of the same things but completely failed to deliver. The US itself had not dissimilar problems around the same time with the BSY-1 combat system.

From these beginnings, variants of the ISUS 90 can now also be found on the submarines of 10 different countries, including Germany, Italy, Turkey, South Korea, South Africa, Greece, Portugal, India and Chile. The two largest customers – because of the size of their submarine fleets – are Turkey and South Korea. Because of ongoing pressure on the German defence budget, the present ratio of export to domestic sales of 80 / 20 is likely to increase in coming years.

These contracts mean that the ISUS 90 is the most prolific conventional submarine combat system in the Western world today and it looks likely to retain this distinction for some time to come.

Because it can be so effectively tailored for the differing requirements of customers the ISUS 90 is the default combat system for HDW submarines, including recent Type 209s, and – very importantly – all Type 214s. A partial exception are the German navy’s first six Type 212s which for political reasons are equipped with a Norwegian Kongsberg combat system, though with Atlas sonars and weapons.

The correct way to see ISUS 90 is not as a single product frozen in time but as an evolving system; hence various generations including 90/20, 90/40, 90/55, and 90/61. To use fashionable jargon, this might be called the “spiral development” of the original ISUS 90 system. The Head of Atlas Elektonik Marketing, Mr. Andreas Knychalla explained to DRA:

“The software kernel of the system remains fairly constant. However, there is a lot of variety in sensors, depending on customer requirements. Firstly with the sonars – for example, not every navy specifies a towed array and some customers have not asked for a flank array. In addition, there are important differences in the characteristics of hardware such as the submarine’s periscope, ESM system, and various items that could be considered to be on the periphery – but which are nevertheless important.

“Secondly – and very importantly – we can structure the number of operator consoles to exactly meet the needs of each customer. This means that variants of the ISUS 90 combat system can be comprised of four, five or six consoles – and theoretically more than that – depending on individual requirements.

“Finally, the system is also scalable depending on the weapons the submarine carries. In some cases this might only be torpedoes, but increasingly navies are looking for an anti-ship missile to be fired, or even a land attack capability - and this means that we must add on additional functionality”.

Because Atlas Elektonik also produces sensors and weapons, the company has a great deal of in-house expertise in the entire domain of undersea warfare. When this is combined with the use of Commercial-Off-The-Shelf software such as Microsoft XP for many functions and the additional use of flexible C++ software when required, it explains how the company has succeeded when others have failed.

Even in competitions it did not win, ISUS 90 has emerged with a great deal of credit. The best example is from a decade ago in Australia, where to the eternal shame of a small number of senior RAN officers and conservative politicians, an extremely thorough technical evaluation in favor of ISUS 90 was overturned because of a desire to purchase a US product for “strategic” reasons. The evaluation of ISUS 90 had been so detailed that a full system was run in Australia against several competitors – including the eventual winner – and was proven to be superior in every important respect. The selection of a US system was justified to the public on the basis that it would provide interoperability with the United States Navy.

This was a strange call given that submarines by their very nature are lonely beasts, frequently operating in isolation. However, the decision did guarantee an increasing level of co-operation with the USN in areas such as technology transfer and crew training and so had some justification, but these factors were completely external to the actual evaluation. There are many legacies of this flawed choice, including that the indiscretion rate of the troubled Collins Class has been negatively affected, because the replacement combat system – designed for a nuclear submarine with unlimited power – drains the batteries at a fearsome rate.

Unfailingly optimistic, Mr. Knychalla, believes that Australia might once again consider ISUS 90 as part of project SEA 1000, which aims to replace the six Collins Class boats with 12 new submarines. If the acquisition strategy goes down the Military-Off-The-Shelf path then an enlarged Type 214 with a baseline low cost low risk ISUS 90 will be in a strong position. However, the Australian current link with the USN looks difficult to break.

Irrespective of what might occur with individual procurements – no matter how large or small – Atlas Elektonik are specialists in an area of critical military technology. While their future submarine work is in a way guaranteed through their close association with platform manufacturer HDW, the company has the longer-term aim of being commercially independent – something they have already achieved with heavyweight torpedoes in particular.

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