MEADS: Experiences and Possible Contributions by German Industry

MEADS: Experiences and Possible Contributions by German Industry

by Wolfgang Erlewein, DASA engineer, and Wolf Krueger, Siemens engineer
Bonn WEHRTECHNIK
Jun 95 pp 19-21

[FBIS Translated Excerpt]
In January 1995 five leading European firms Aerospatiale, Alenia, DASA [Daimler-Benz Aerospace AG], Siemens, and Thomson-CSF jointly established the Joint European Industrial Entity (JEIE) for the MEADS [Medium Extended Range Air Defense System] project, aimed at providing an effective counterbalance to the major American corporations. This collaboration will reach its climax in the establishment of a European MEADSCO. In line with the American conception, the system will be defined by two competing consortia, only one of which will be entrusted as winner with the definition phase. In the United States, three firms have now emerged as potential lead contractors for both the national CORPS SAM program and its international component, MEADS: Hughes & Raytheon, Lockheed Martin, and Loral. Two of these will be selected in the current down selection (a purely American phenomenon) for the definition phase. This means that two American competitors will face a single European rival. The official declaration of intent specifies two separate, equal teams in the running for JEIE; they will form two Transatlantic Industrial Entities (TAIE) with the two American firms selected. To avoid any suspicion of anticompetitive action in the United States, the allocation of European teams to American partners will be by the drawing of lots.

Worksharing between American and European firms is intended to be entirely equal and in line with each company's particular specialisms. The same principle applies to the worksharing within Europe. The JEIE parent firms are the lead partners for other firms in their own countries.

Contributions by German Industry

German firms have been involved in systems design and development of technologically advanced components for over 25 years, as witness their experience derived from Roland, Hawk, and Patriot missiles. This provides an excellent basis for future negotiations on MEADS worksharing. German industry can make major inputs in all specialist fields involved in developing and producing air defense systems. The same goes for system development, testing, and integration, and for the development and production of components. Examples will now follow of areas where German industry is able to make major contributions.

System Development

Before discussing technology, the system will be briefly described. The major system components are the monitoring and fire-directing radar, the fire-directing command center, and the launcher with a number of "containerized" guided missiles. These three components form the smallest autonomous firing unit. A complete echelon includes four launchers, each with at least eight vertically-launched guided missiles; a second battlefield command vehicle, for operational command, in addition to the command center; and several support vehicles, which will not be detailed here.

The German concept of the echelon involves linking the battlefield command with radar by optical waveguide, owing to its high data rate, and with the launchers by optical waveguide or UHF radio. Radio link enables the launchers to be erected in relation to the object being defended, at a maximum distance from the command center of approximately 10 km.

After launching, the guided missile is navigated inertially, with the radio transmitting course correction commands. Contact with the group command center and neighboring echelons is by radio link, with each echelon having its own radio link crew.

Standard architecture in Europe will involve the launchers being site-centered under the command center, with scope for networked operation of multiple distributed/netted command centers, radars, and launchers; this may become the preferred architecture in the United States.

All system components are mounted on all-terrain all- wheel drive two-or three-axle vehicles, and need to be relocatable using the transport vehicles available the C- 160 Transall in Germany. In the United States, all components are required to have roll-on/roll-off capability for the C-130 and C-141.

Radar

The major design drivers for the radar are high- velocity cruise missiles, ARM's, TASM's, TBM's, saturation attacks, and the entire stealth and ECM area. Potential combat scenarios require very high mobility and air relocatability.

These requirements can be met by the technology now fully developed in the form of multifunction radar with active phased array antennas. In the TLVS concept phase, Siemens was responsible for the multifunction radar. Siemens has been active in this area for many years, putting it in an excellent position to apply the lead the company thus enjoys to this international collaboration.

Active Phased Array Antennas

In an active phased array antenna, the radar transmitting power is produced in a number of purely semiconductor-assembled transmitter/receiver modules (T/R modules). The outputs of the individual modules accumulate in the antenna's radiated field pattern, without incurring expense and losses from complex waveguide junctions. Electronic beam steering and beam forming using phase advancers and amplitude control elements involve no increase in system losses, as signal distortions are compensated by the active elements (amplifiers) of the T/R module.

T/R Module: A Key Component

In its technology programs, the German radar industry is continuing to give development priority to T/R modules, which are ultimately the key components for an active array. The development of T/R modules is the result of progress in gallium arsenide monolithic microwave integrated circuits (GaAs MMIC) technology. In future, a T/R module will comprise only two or three GaAs MMIC's. This high degree of integration enables costs to be kept under control. Other major module parameters include high output and high efficiency. This latter factor determines the size of the generator and refrigerating set required, and thus the mobility of the radar system as a whole.

Siemens and DASA in Ulm are collaborating on a Cx-band T/R module as part of the Radar 2000 technology program, partially funded under the Defense Ministry's research and technology program. They have demonstrated great progress in integration, miniaturization, and performance.

Digital Beam Forming

A major step in increasing the efficiency of an active array radar is the use of adaptive digital beam forming to combat jamming. This is another major advance in performance, the operational efficiency of which justifies the greater cost. The introduction of digital beam forming represents a technological breakthrough. The considerable demands made on digital signal processing are met by very rapid parallel processor structures.

Programmable Signal Processing

Rapid analog/digital converters and rapid digital processors have facilitated the introduction of programmable hardware. Hardware solutions can therefore now be replaced by software solutions, whose flexibility enables the use of automated systems.

COTS Multicomputer Parallel Processor Systems Commercial off-the-shelf multicomputer parallel processor systems are increasingly being used for signal processing.

These provide clear cost advantages over hardware development tailored to the needs of radar signal processing. Developments in signal processing software, exploiting the high standards in software development achieved by German industry, have therefore assumed major importance recently.

Radar Management

Phased array antenna technology makes it possible to find the antenna lobe position with virtually no delay and in any order, and to illuminate it with a wide variety of signal forms.

Radar management is concerned with the efficient use of the available radar power in area scanning. Conflicts inevitably arise in terms of the aims of the various functions. These are resolved according to specific criteria.

The high levels of flexibility and dynamic optimization of power distribution achieved by Siemens as part of a TLVS design study have demonstrated a newly- developed extension to all major radar functions. The system optimizes itself autonomously, using criteria of scenarios, environment, and reference guidelines. In future, the radar manager, in conjunction with the man-machine interface, will enable the multifunction radar to be adapted to different tasks and operational conditions, without the need for costly adjustments, such as extensive software changes.

Fire-Directing Command Center

With its Heros, AWHQ, and Samoc systems, Siemens has acquired extensive experience in mobile command centers. This has included the development of tried and tested commercial products, extending to commercial off-the-shelf (COTS) military applications.

These include both data processing hardware and the basic software required. Examples of the latter include the operating system, the database management system, and the basic display software. A particular feature of this modern software is that it typically extends to over 1,000 kilolines of code (1,000 kLoC), with the related development software adding many times more than this. This is in contrast to only around 300 kLoC for the user software to be developed.

The user software for the specific command functions can be further subdivided into general support software of approximately 200 kLoC, a typical example being military data links; and the remaining command-specific software of approximately 100 kLoC, a typical example of which is threat appraisal.

In developing Gehoc for the Improved Hawk, DASA in Ulm has acquired extensive experience in programing fire- directing command centers for FlaRak systems experience which it also uses with Samoc. With its expert systems software technology, Siemens has broken new ground in the development of military user software. Examples include the Aidex operational test system for indirect identification and the Battleman test system for optimal weapon selection. Despite the predominant use of commercial equipment, the scaffolded cabins meet as a unit all military requirements in terms of resistance to vibration, radiation, etc.

Missiles

The participating countries have not yet reached total agreement on missile design; agreement has, however, been reached on the following characteristics: Active radar seeker head, preferably in the Ka band, possibly with integrated IR seeker head to enhance measuring accuracy against small targets such as TBM's; Aerodynamic tail steering with lateral thrust guidance in final phase, to enhance direct hit probability; Warhead, preferably directable; Ignition sensors for precision timing of ignition, and if required precision targeting of (directable) warhead; Solid fuel propulsion, if possible with double pulse, to adapt velocity profile to impact situation; Small internal dead zone; Low pad weight (for air relocatability). Diagram 5 [not reproduced] shows a cross section of the TLVS missile of the German design study; it is wingless, weighs 300 kg at launch and 150 kg after burn cutoff, and measures 4.60 m in length, with a diameter of 25 cm.

Seeker Head

The all-weather capability required at all altitudes, including use against targets with very small radar signatures (e.g., ballistic missiles), can only be achieved by means of an active radar seeker head, preferably in the Ka band. The low antenna size specified enables a sufficiently low beam width to be achieved, a prerequisite for defense against ECM and for good lock-on range. DASA-Ulm has been working on the Ka band seeker head for a number of years. The heart of the transmitter is a traveling-wave tube (TWT), giving medium-range output of several hundred Watts. Rapid frequency change and scope for adapting pulse shape and modulation to the given situation provide high resistance to ECM and clutter and excellent remote resolution, enabling parts of a target (e.g., the tip of a ballistic missile) to be tracked. This enables considerable reduction in glint of the radar cross section over the target, and improvement in measuring accuracy; the distance gained from the target can be used as input for optimal ignition of the warhead.

Signal evaluation is digital to the maximum extent possible, in line with state-of-the-art technology. DASA-Ulm is undoubtedly a leader in Ka band TWT technology. The tube is used in the Erint seeker head, selected as the ATBM missile for the Patriot system, and in Erint's previous competitor, the Patriot missile with multimode seeker.

An IR seeker head would be ideal against ballistic missiles at high altitudes. The target's temperature is greatly raised by its re-entry at high velocity from a cold background in space without atmospheric interference. There is therefore good reason to examine the scope for an additional IR seeker head. The Bodensee- Geraetetechnik company has wide-ranging experience in IR seeker heads on Sidewinder, Stinger, and Ram.

Lateral Thrust

To prevent minor impact errors in the case of small, rapid, and agile targets, an air defense missile requires two specific features: High lateral acceleration capability during its entire flight and also low reaction times at medium acceleration values during the final phase.

One solution involves a combination of aerodynamic tail steering and lateral thrust. Tail steering provides a high g number with build-up times in the range 200-300 ms; lateral steering with the available weight and volumes gives low g, with considerably reduced reaction times. DASA has analyzed various lateral thrust concepts: Solid-fuel engines with hot gas on-off valves, as on Aster; Solid-fuel cartridges, as on Erint; Reignitable liquid-fuel engines (without hot gas valves), as widely used in space flight. From the operational point of view, the third solution is the best one. It does, however, have the drawback that the fuels used are poisonous and can auto-ignite when flowing or being mixed (hypergol).

DASA has in recent years developed a concept for a fluid lateral model, with a view to design to safety; tests have shown that this meets safety requirements.

Guidance and Steering

With a missile system using command guidance in the cruise phase and seeker head guidance in the final phase, optimized adaptation of the missile's trajectory in terms of type of target and velocity, terrain, natural and artificial interference (ELoKA) is possible at medium and remote interception distances. Computer simulations have shown that correct selection of a trajectory against ballistic missiles reduces flight times and can greatly increase the zone protected. Adaptive filtering of seeker head signals, by means of optimal combination of aerodynamic steering and lateral thrust, can achieve the required hit probability, even against TBM's.

DASA has been working intensively in these areas for some years; the experience it has acquired will be valuable in international collaborative projects.

Warhead

Effective defense against ballistic missiles can only be achieved by destroying the warhead. If this is not possible with a direct hit, then large rapid splinters are required, which can penetrate the hard hull in this small, vulnerable area. A large number of splinters, which may also be lighter, are more effective against smaller, less hard but more maneuverable targets. Given the low weight and volume of a relatively small air defense guided missile, the desired effect can only be achieved if the splinters seeking the target are particularly numerous and/or rapid. With the directed, asymmetric initiation of the explosive, the splinters achieve enhanced velocity in the preferred direction. In the second process, the warhead is faced in the preferred direction by a first charge; this serves to pack the splinters in this direction when the main charge is ignited, a fraction of a millisecond later. DASA subsidiary TDW has acquired extensive experience in both processes in recent years. The enhanced velocity process is the preferred one.

Propulsion

High acceleration is normally needed during the launch phase of a guided missile; the velocity attained then needs to be maintained for a certain time. Appropriate composition and shaping of the propellant enables this velocity to be attained, even with single- chamber propulsion. The thrust profile can only be set during construction, however, and cannot be maintained at the same optimal level for both short and long flights.

However, with twin-chamber propulsion, the second engine can be ignited at will, there are also disadvantages to be considered, in terms of weight and bulk factor. DASA subsidiary Bayernchemie has designed a single-chamber propulsion unit, with the second engine separated from the main engine by an explodable ceramic shell. Early ignition of the second impulse enables the flight time to be minimized, given short interception distance; delayed ignition with longer trajectories enables the velocity during the final phase to be increased, thus enhancing maneuverability and hit probability. [passage omitted]