New European weapons on the horizon will change the Typhoon from air-superiority machine to multirole strike fighter

Shortly after it enters service, the Typhoon will be cleared to carry a range of advanced weaponry as the aircraft's full multirole capability begins to be exploited. At initial operational capability (IOC), the Eurofighter will be an air-defence aircraft, with AIM-120 Advanced Medium-Range Air-to-Air Missiles (AMRAAMs) and short-range AIM-9L Sidewinders as the basic armament for all four participating nations.

By full operational capability (FOC), however, systems will have been installed and software released that will allow the four customer air forces to begin expanding the aircraft's mission envelope, adding new weaponry to the list jointly and individually.

Reorientation of the programme in 1994 made air-to-air and air-to-ground roles of equal importance, but air-to-air will be certificated first. "We hope by FOC to have both roles certificated," says NETMA deputy general manager Christian Biener.

Development has been structured to clear air-to-air radar modes and basic weaponry in the lead up to IOC, scheduled for 2002. Before then, work will begin on clearing the systems and software required for FOC, which is planned for 2004.

Flight testing is being conducted in the basic air-defence configuration, with four AIM-120s semi-submerged under the fuselage and two AIM-9s on the outboard wing stations. The first AMRAAM release and Sidewinder launch were conducted in December 1997.

Fit checks have been completed with some of the advanced weaponry planned. With an empty weight of 11t and maximum take-off weight of 23t, production aircraft will be able to carry 6.5-8t of external stores on 13 fuselage and wing stations. Among the first weapons to be cleared on the Typhoon will be new short-range air-to-air missiles. German aircraft will be armed with the IRIS-T, being developed by a six-nation consortium led by Bodenseewerk Geratetech-nik (BGT), while UK aircraft will carry Matra BAe Dynamics' (MBD) ASRAAM.

Both weapons are designed to provide better close-range combat capability than the AIM-9. "Analyses of recent conflicts and manned air combat simulations have shown that more than 30% of all air-to-air encounters, no matter at what distance they start, end up in close-in combat," says BGT.

Air combat simulations conducted during design of the Eurofighter showed that Russia's AA-11 all-aspect short-range missile has dramatically changed close-in combat. In almost all engagements both aircraft and target will be flying towards each other, in stark contrast to traditional tail-chase dogfights. This means there is less time to acquire the target and launch a missile. In a significant number of fights, the target will be approaching from the side, requiring off-boresight engagement capability.

MBD says its ASRAAM (Advanced Short-Range Air-to-Air Missile) is an advance over today's AIM-9 in four areas: speed off the rail; short-range agility; off-boresight acquisition; and countermeasures resistance. These combine to give the weapon substantially greater capability against targets at all aspects.

The ASRAAM is a wingless missile with tail control fins. It is similar in length (2.9m/9.5ft) and weight (88kg/195lb) to the AIM-9, but has a wider (165mm/6.5in)-diameter airframe. This produces more body lift and houses more propellant, increasing agility and speed.

Supplied by Raytheon, the seeker is an infrared staring focal-plane array that is gimballed to provide full forward-hemisphere coverage. This allows the missile to acquire and engage targets up to 90º off boresight, when cued by the pilot's helmet-mounted display. The seeker's thermal imaging capability allows the ASRAAM to select an aimpoint on the target which increases lethality. MBD says modelling and testing indicates the missile will hit its target, but there is an active infrared-laser proximity fuze for use against smaller targets.

Inertial sensors allow the weapon to complete an intercept even if target tracking is intermittent. This also allows the seeker to lock on after launch, at long range or when the missile is fired 'over-the-shoulder' at a target behind the aircraft. The ASRAAM can pull 50g off the rail, the manufacturer says.

BGT says the new operational requirements emphasise "high airframe agility, large seeker look-angles and maximum counter-countermeasures". The IRIS-T (Infra-Red Imaging Seeker - Tail control) is a winged missile combining aerodynamic and thrust-vector control, and is similar in size and weight to the Side-winder. The infrared seeker has a ±90í look angle, and "intelligent" image processing provides a high resistance to countermeasures, the German company says.

The programme is led by Germany, with 46%, and prime contractor BGT also supplies the guidance section. Italy has 19%, Sweden 18%, Greece 9% and 4%. Development began in early 1998 and is to be completed by mid-2002. The ASRAAM, meanwhile, has been under development since 1992 and is planned to enter service with the Royal Air Force by year- end. Both weapons should be cleared on the Typhoon by IOC, Eurofighter says.

Later next decade, the partner nations plan to upgrade the Eurofighter with a new beyond-visual-range air-to-air missile (BVRAAM). The UK has drawn up the requirement for this missile, which is intended to overcome the perceived limitations of today's AMRAAM.

The threat the Eurofighter was designed to meet, and which remains on the horizon, is represented by an advanced Sukhoi Su-27 derivative armed with an advanced version of the AA-12 medium-range missile. The combination would be formidable in the BVR arena, outranging the Typhoon.

The UK's BVRAAM requirement calls for a "vastly improved" kinematic capability compared with that of the AMRAAM. It requires substantial increases in two key parameters: "F-pole", the distance between the aircraft and its target when the missile hits; and "no-escape zone", the range within which the missile can be fired and the target, no matter how it manoeuvres, cannot escape.

Shaped to fit in the Typhoon's semi-submerged fuselage stations, the BVRAAM has to be similar in size to the AMRAAM. Increased kinematic capability comes from the use of rocket/ramjet propulsion.

Whereas the AMRAAM's rocket motor burns for seconds, then the missile coasts, the BVRAAM is under ramjet thrust for its complete flight. As a result, the average velocity is higher and the missile arrives with the energy to out-manoeuvre its target. Both F-pole and no-escape zone are increased. There are two bidders for the UK contract: the European Meteor consortium and a team led by AMRAAM builder Raytheon. A decision is expected later this year. Germany, Italy and Spain have reviewed the UK requirement and agreements are in place which could make BVRAAM a multinational programme.

Led by MBD, the Meteor consortium brings together Alenia Marconi Systems, Casa, Marconi Electronic Systems, LFK and Saab. The weapon is all new, drawing on technology available in the partner companies. The missile uses a variable-flow ducted rocket/ramjet to be developed by Germany's Bayern Chemie. The conventional rocket boost motor, once burned out, becomes the combustion chamber for the solid-fuel ramjet.

The Meteor has an active radar seeker, inertial guidance and a two-way datalink for midcourse updates. The seeker is planned to be derived from that of the Aster surface-to-air missile, says MBD. Development of the missile will take "several years", the company admits.

Germany plans its own seeker for the missile, which it calls EURAAM. A Ka-band active radar with secondary X-band passive channel would replace the Meteor's Ku-band seeker, and provide higher resolution and countermeasures resistance, says developer Dasa.

Raytheon, meanwhile, is offering a phased approach to developing its Future Medium-Range Air-to-Air Missile (FMRAAM). This would begin by upgrading the AMRAAM to AIM-120B+ standard by fitting a new guidance section. Then the missile could be upgraded to extended-range ERAAM standard by fitting a larger, dual-pulse, rocket motor and shortened, low-drag, tail fins. Finally, the weapon could be brought up to FMRAAM standard by replacing the motor section with a rocket/ramjet.

The US company says the ERAAM offers 80% of the FMRAAM's range at 50% of its price. The extended-range missile could be available in 2005, while the ramjet-powered weapon could be ready by 2007.

Raytheon has assembled a European team to offer the FMRAAM to meet the UK BVRAAM requirement. Aerospatiale would derive the liquid-fuel ramjet from the engine powering French ASMP nuclear cruise missiles. Atlantic Research and Royal Ordnance would supply the booster rocket. European companies would provide the electronics, fuze, warhead, actuation system and datalink. Raytheon would supply the active radar seeker, and Shorts Missile Systems would assemble the weapon.

Among the first air-to-surface weapons to be cleared on the Typhoon will be the Matra BAe Dynamics Storm Shadow stand-off missile, under development for the UK and selected by Italy. The Storm Shadow is a conventionally armed cruise missile with a range of "several hundred kilometres", says MBD.

The weapon was selected by the UK in 1997 to meet its requirement for a day/night, adverse weather, stand-off missile for precision attacks on high-value static targets. The same weapon, dubbed Scalp EG, was later selected by France to arm the Mirage 2000 and Rafale.

Based on the Apache stand-off missile, the Storm Shadow uses the same stealthy airframe, flight controls and Microturbo TRI60 turbojet. The 1,300kg weapon features a new global positioning/terrain reference navigation system and autonomous terminal guidance combining an imaging infrared sensor with automatic target recognition software. A BROACH tandem-charge penetrator warhead developed by Team BROACH (BAe Royal Ordnance, Thomson Thorn Missile Electronics and the UK Defence Evaluation and Research Agency) is used.

After launch, the missile terrain follows at low altitude using BAe's Terprom terrain reference navigation system and an inertial measurement unit updated by GPS. In the terminal phase, the automatic target recognition software extracts edges from the infrared sensor image, which it compares with the stored target image modelled during mission planning. The system then realigns, recorrelates, tracks the target and refines the aimpoint. The BROACH warhead has a shaped precursor charge, which penetrates the target, allowing the main blast/fragmentation charge to enter and explode inside.

Fully guided flight tests of the Storm Shadow are scheduled to begin early in 2000. The weapon will enter service on RAF Tornado GR4s early in 2002 and is likely to become operational on UK Eurofighters around 2005.

Germany plans to arm its aircraft with the KEPD 350, a 350km (215 mile)-range stand-off missile under development by Taurus Systems, a joint venture between LFK (67%) and Sweden's Celsius/Bofors Missiles (33%), and scheduled to enter service in 2002 on German air force Tornados. Germany has not yet approved the purchase of KEPD 350s to arm its Eurofighters.

The KEPD (Kinetic Energy Penetrator Destroyer) 350 is an all-weather, low-observable missile powered by a Williams P8300 turbojet. Designed to terrain follow at low level and high subsonic speed, the weapon has combined global positioning/inertial navigation/-terrain reference guidance, an infrared terminal seeker and a tandem warhead, dubbed Mephisto, combining a pre-change and a kinetic energy penetrator.

Future versions of the Storm Shadow and KEPD are on the drawing board, and could eventually arm the Typhoon, including anti-ship derivatives.

Other weapons expected to be cleared on the aircraft include MBD's ALARM anti-radar missile, and Marconi Electronic Systems' Brimstone anti-armour missile. Laser-guided bombs will be cleared early in the Typhoon's life, and Eurofighter is drawing up the specification for a new targeting pod, to be carried on one of the fuselage missile stations.

Growth plans largely centre on exploiting its air-to-surface capability. Much of this is planned to be achieved through software changes, Eurofighter says, As a result, the aircraft's "character"' can be expected to evolve over time.

Source: Flight International