Smart Non-Nuclear Submarines in Changing Times – a HDW Group Industrial View
NATO/PFP UNCLASSIFIED
Smart Non-Nuclear Submarines in Changing Times – A HDW Group Industrial View
Pär Dahlander Hendrik Goesmann Kockums AB Howaldtswerke-Deutsche Werft AG Stora Varvsgatan 11 Werftstraße 112-114 S-205 55 Malmö D-24143 Kiel Tel.: +46 40 34 8253, Fax: +46 40 97 8558 Tel.: +49 431 700 2491, Fax: +49 431 700 2425 http://www.kockums.se http://www.hdw.de
Email: [email protected] Email: [email protected]
Joachim Reuter Prof. Dr. Jürgen Ritterhoff Howaldtswerke-Deutsche Werft AG Howaldtswerke-Deutsche Werft AG Werftstraße 112-114 Werftstraße 112-114 D-24143 Kiel D-24143 Kiel Tel.: +49 431 700 4711, Fax: +49 431 700 2425 Tel.: +49 431 700 4440, Fax: +49 431 700 2425 http://www.hdw.de http://www.hdw.de
Email: [email protected] Email: [email protected]
ABSTRACT Due to the changed geostrategic situation and with a particular view towards combating international terrorism, the mission profile of conventional submarines has undergone a subtle change.
In the view of North European navies with non-nuclear submarine flotillas, such as GE and SE, the submarine operating in littoral waters will increasingly be tasked with employment in such roles as forward sensor, scout, relay station, as the operating base for unmanned underwater (UUV) or aerial (UAV) vehicles, and as a platform for the insertion and recuperation of special forces (Revolution of Military Affairs – RMA).
The real “revolution” is taking place in the field of communications between the submarine on the one hand and the major naval assets and Marine HQ on the other. New procedures are necessary to provide real-time transmission of very large quantities of data to and from the submerged submarine (Network Centric Warfare – NCW).
The submarine’s armament will be adapted to meet this mission profile. Greater emphasis will be given to defensive weapons and to the development of weapon systems suitable for coping with an escalating situation (different levels of impact), such as guided missiles.
This presentation aims to provide some technical answers to the changed demands being placed on non-nuclear submarines. Changing times make more demands on the flexibility and interoperability of existing submarines and will add specific tasks with respect to RMA and NCW: A shift is discernible from large, fast nuclear-powered submarines with blue-water capabilities towards the smaller, smart non-nuclear submarines designed to excel in green and brown water areas.
Paper presented at the RTO SCI Symposium on “Multi-Platform Integration of Sensors and Weapons Systems for Maritime Applications”, held in Norfolk, USA, 21-23 October 2002, and published in RTO-MP-097(I).
RTO-MP-097(I) 3 - 1
NATO/PFP UNCLASSIFIED NATO/PFP UNCLASSIFIED Smart Non-Nuclear Submarines in Changing Times – A HDW Group Industrial View
Figure 1: The Royal Swedish Navy GOTLAND Class Submarine.
THE CONVENTIONAL SUBMARINE IN THE EMERGING GLOBAL SECURITY ENVIRONMENT After the end of the Cold War with East-West polarisation and in the post-September 11 world, interstate wars are becoming increasingly unlikely due to economic and political integration, international treaties and disarmament. However, as the events of September 11 and others more recently have shown, the emerging global security environment is still far from benign. Rather than a military clash between super-powers, the threat now comes from low intensity conflicts which are spawned by and in turn create terrorism, epidemics, refugee flows, explosive population growth and the smuggling of drugs and persons, all on a national and international scale. We speak of the Revolution in Military Affairs. This emerging global security environment puts new demands on the armed forces. Not only must they maintain their ability to fight wars in spite of reduced military budgets in the majority of technologically advanced nations, the new environment also calls for a wide range of military operations other than war to be carried out around the world. As the world becomes increasingly urban and its population centres are concentrated in coastal areas, it is clear that future conflicts are also likely to be concentrated here. This amplifies the role of the relatively small conventional submarines already in operation around the world, with more units being built, all fully capable of operating in littoral waters.
3 - 2 RTO-MP-097(I)
NATO/PFP UNCLASSIFIED NATO/PFP UNCLASSIFIED Smart Non-Nuclear Submarines in Changing Times – A HDW Group Industrial View
Figure 2: The German Navy Class 212 A Submarine ‘U31’.
While the traditional role of the conventional submarine was to gather intelligence and to attack surfaced and submerged targets with torpedoes, the newest generation of non-nuclear submarines is already in various stages of design and construction (and on its way to being commissioned as U31, Class 212A for the German Navy or even already in service as GOTLAND and her sisters, Class A19 for the Swedish Navy) and will lend itself to a wide new range of tasks and missions. Previously, the traditional strengths associated with a quiet, conventional submarine were its independence and its suitability for covert operations. It was less associated with the kind of operations defined as Network Centric Warfare. The network centric concept seeks to maximise the combined capabilities of the participating units by using modern information technology to harness and link the capabilities of all available platforms within a battle group into one entirety. For the submarine to be an active participant, an entirely new concept in command, communications and information technology was necessary. Having achieved this, the ultra-quiet non-nuclear submarine is the ideal forward observer in littoral waters to support rapid deployment of naval and airborne forces to critical areas.
RTO-MP-097(I) 3 - 3
NATO/PFP UNCLASSIFIED NATO/PFP UNCLASSIFIED Smart Non-Nuclear Submarines in Changing Times – A HDW Group Industrial View
Figure 3: Mission Spectrum of Modern Submarines.
The modern, non-nuclear submarine is equipped with air-independent propulsion (AIP), extending mission endurance and enabling it to remain fully submerged for long periods of time. Fully integrated into the overall communications and information network, it serves as a hub for surrounding strike and intelligence assets, a platform for reconnaissance and forward observation, an insertion and extraction vehicle for special forces, while fully retaining its own enhanced strike potential with torpedoes and missiles against sea and land targets. The combination of air-independent and modern but non-nuclear provides for lowest signatures (quiet, no IR trace) and minimum target strength (small, amagnetic), a totally new concept in stealth reflecting submarine design and construction capabilities that were not achievable in the last century.
Even relatively small coastal nations and organisations can control large bodies of water bordering their shores through the use of cheap Unmanned Aerial Vehicles (UAVs) and anti-ship missiles with an increasingly long range. This means that naval operations must remain far back over the horizon, or when operating in littoral waters they are forced below the surface to avoid detection for as long as possible. The smart AIP submarines already being built by the HDW Group are capable of covert operations in genuinely shallow waters at depths of 50 m or less. Equipped with a modern, fully integrated Command and Weapon Control System incorporating sensors, weapons, communications and data processing and with the help of subordinate Unmanned Underwater Vehicles (UUVs), the submarine provides the network centric input needed to support sea, air and land operations. This presentation aims to illustrate some key features of new smart submarines. Due to their relatively small size of less than 2000 tons, some of them indeed around 500 tons, some are hardly larger than a number of autonomous underwater vehicles or baby submarines.
3 - 4 RTO-MP-097(I)
NATO/PFP UNCLASSIFIED NATO/PFP UNCLASSIFIED Smart Non-Nuclear Submarines in Changing Times – A HDW Group Industrial View
MOBILITY When the AIP submarine is called on, as part of an international coalition, to respond to and manage smouldering or emerging conflicts in geographically remote areas, speed is of the essence. Increased transit speed is also important at the tactical level for the exploitation of time-sensitive targets. This increased speed is achieved by improved hull design with less hydrodynamic drag and an improved snorkel mast with higher structural endurance. Once the operations area has been reached, the smart AIP submarine can remain submerged at low speeds for considerable periods of time, undetected in deep or in shallow waters.
Figure 4: Network Centric Warfare.
COMMUNICATIONS For the submarine to actively participate in NCW and crisis management operations it must be able to maintain almost continuous contact with other units in the network, even when deep submerged. The submarine’s ability to covertly gather intelligence is an established fact, but in network centric operations it must also be possible to transmit and receive large amounts of data in real-time, in such a way that it is difficult for the opponent to intercept or disrupt the information flow, and without revealing the submarine’s position. This is not possible with conventional VHF/UHF submarine communication means, but enabling the submarine to use satellite communication facilities provides global reach and rapid data transmission times.
One such practical satellite link solution is the CALLISTO project currently being developed in Germany. This system is a combination of hoistable mast and communication buoy. The buoy incorporates SATCOM, GPS and ESM/EW facilities. It is attached to a conventional hoistable mast and can be
RTO-MP-097(I) 3 - 5
NATO/PFP UNCLASSIFIED NATO/PFP UNCLASSIFIED Smart Non-Nuclear Submarines in Changing Times – A HDW Group Industrial View operated as a conventional antenna or released from the top of the mast to float to the surface. It is connected to the boat by cable, which provides the communications link and also enables recovery of the buoy, which can be wound back down to the mast. In an emergency, the buoy also serves as a rescue transmitter.
Figure 5: ‘CALLISTO’ Communication System.
Other options for modern submarine communication facilities for the submarine and for UUVs include information exchange via modular lasers or underwater modems, which use fibre-optic technology for fast data exchange with C4SI centres. Another interesting option is the use of an aerostat, which provides communication via microwave link, laser link or retro-reflectors.
SENSORS Because of the interaction between the platforms forming the NCW concept, the data received by the submarine’s advanced sensors is made available to its naval HQ. Smart AIP submarines have a comprehensive array of own and remote sensors (using UUVs) for intelligence gathering, mine reconnaissance, evasion tactics and target acquisition and attack purposes. By deploying UUVs as forward sensors, the submarine can extend its range of observation even further inshore into extremely shallow water without additionally endangering the boat or risking detection.
The submarine’s sensors alone would provide for several hours’ worth of presentation and discussion, and here it may suffice to say that the sonar system remains the principal source of information for the submarine. For many years, pride of place was given to passive sonar due to its minimal detection risk, but new specific applications are making active sonar systems interesting once more. Hoistable masts enable the submarine to raise a wide variety of mast-mounted sensors above the surface from snorkel depth, which permit detection and identification of surface, land-based or airborne targets using radar, ESM, visual and optronic systems. Modern data processing ensures that all sensor input is fed into and analysed by the submarine’s Combat System.
3 - 6 RTO-MP-097(I)
NATO/PFP UNCLASSIFIED NATO/PFP UNCLASSIFIED Smart Non-Nuclear Submarines in Changing Times – A HDW Group Industrial View
FLEXIBLE PAYLOAD For the smart modern conventional submarine, a flexible payload consists of much more than weapons. Precisely its ability to function as a forward observer in littoral waters means that the intelligence its sensors provide to an over-the-horizon HQ Commander may be far more valuable than its own attack possibilities. Nevertheless, a wide range of weapons is equally essential for the submarine to exercise self-defence and to play a flexible role. A modular approach means that the smart modern submarine can be fitted with a wide variety of weapons, mines and equipment, depending on the likely mission profile.
The torpedo has been the standard submarine weapon for over half a century. Modern torpedoes are quiet and locate their targets by passive sonar, making not only the torpedo itself but also the submarine difficult to locate. Most modern torpedoes are connected to the submarine by wire or fibre-optic cable, enabling them to be controlled right to the last second and additionally feeding back more information from their own sonar to the submarine.
In the last 30 years, increasing importance has been attached to missiles as a submarine weapon for use against surface ships or land-based targets. The submerged submarine can fire missiles from its torpedo tubes or from dedicated missile launching tubes. However, once they break the surface of the water, missiles can be detected by optical, radar or IR sensors. The disturbance on the sea surface also gives away the position of the carrier submarine. To avoid severe risk to the submarine, it must therefore be in an operations area where own forces have sea and air superiority before firing missiles.
A new generation of lightweight fibre-optic guided missiles for submarines is currently being developed in Germany (project name IDAS: Interactive Defence system for Air-attacked Submarines). IDAS is connected to the submarine by fibre-optic link during its entire mission duration. The missile transmits a constant stream of images from its IR camera to the consoles of the submarine Combat System. The missile is intended for use against the modern submarine’s deadliest enemy: the ASW helicopter. However, the degree of precision with which the missile can be controlled makes it suitable for operations against surface ships and coastal targets as well. The IDAS missile is launched from a launching container that can be loaded in a torpedo tube like any heavyweight torpedo. The system can therefore be retrofitted into an existing submarine with relatively little difficulty.
Figure 6: IDAS Operational Scenario.
RTO-MP-097(I) 3 - 7
NATO/PFP UNCLASSIFIED NATO/PFP UNCLASSIFIED Smart Non-Nuclear Submarines in Changing Times – A HDW Group Industrial View
The use of UUVs not only as forward sensors but also as remotely operated weapons carriers is fast becoming a reality. They can be launched, controlled and recovered by the submarine and reduce the risks to the boat and crew. On the other hand, operating unmanned aerial vehicles from the submarine will require more comprehensive alterations in design philosophy to enable the vehicles to be recovered. The trend towards modular submarine design concepts where entire sections can be configured to meet specific requirements is opening new possibilities in this kind of field. The submarine can be equipped with a cargo bay, provided with a mission-specific payload of weapons, mines, electronic countermeasures and decoys, or other special-purpose materials.
SIGNATURE MANAGEMENT One of the most important features of the submarine is its ability to operate concealed. In order to succeed in this, the submarine must have low signatures. Today’s conventional submarines have a very low signature footprint and are extremely difficult to locate and classify, particularly in a littoral environment. The development in submarine signature management is an ongoing struggle, pushed by the development in sensor and signal processing technologies. New generations of submarines have lower signatures in most aspects, compared to earlier generations. This includes radiated noise, acoustic target strength, hydrodynamic, magnetic and electric signatures.
Active, and more advanced, signature reduction and control systems are introduced in the areas of acoustics and electromagnetics. Owing to the development in mathematics and computer sciences, there are increased possibilities for modelling and predicting the submarine signatures at an early stage of the development process. This, combined with experience, model and full-scale tests, makes it possible to reduce the signatures even further.
The development in AIP technology has increased the conventional submarine’s ability to stay submerged for considerably longer periods and, thus, the probability of disclosure has decreased significantly.
CONCLUSION This paper has only briefly touched on a few new and emerging submarine technologies that are at various stages of construction, design and development in Europe within the HDW Group. It should, however, have become clear that the advantages of stealthy operation and the flexible mission profile and payload of smart AIP submarines make them predestined to play an importance role as a forward node in the network centric concept. They can operate close into shore and remain undetected or indeed show themselves intentionally to assert their presence as the situation requires.
3 - 8 RTO-MP-097(I)
NATO/PFP UNCLASSIFIED