Unmanned systems are at the centre of the next big step in military aviation and Europe is putting them at the heart of network centric warfare proposals

When Boeing's X-45 un-manned combat air vehicle (UCAV) flew for the first time this year, it looked as though the USA had again stolen a march on Europe in taking the next big step forward in military aviation. But across Europe a number of companies are developing network centric warfare initiatives with unmanned systems at their heart.

EADS in Germany and Saab in Sweden are developing core technologies and systems for UCAVs, unmanned reconnaissance air vehicles (URAVs) and unmanned air vehicles (UAVs). In France, Dassault flew the subscale Petit Duc UCAV demonstrator in 2000 as a precursor to larger systems, while in the UK BAE Systems is working on unmanned systems as part of Panavia Tornado GR4 replacement studies.

In Sweden the armed forces, defence materiel administration FMV, research organisations, Saab and other companies are working towards a national network centric warfare capability to enter service in 2010, with demonstrations planned from 2005. Sweden's Net Centric Defence (NCD) plans are not intended to merely link UCAVs and UAVs with the rest of the armed forces, but will initially connect every command and control (C2) centre, air force aircraft, naval vessel, army vehicle and ground-based surveillance system.

Later, as NCD develops, each platform's sensors will be resident on the network, as will be individual frontline soldiers. Lt Gen Johan Kihl, Sweden's head of NCD, says there will be local and large networks, and levels of information presentation from the big picture to microscopic detail - "political and diplomatic to very local tactical". As well as military and civil defence networks, Sweden plans to use the civilian internet.

During the Cold War, the issue was defeating a target with a particular weapon. With NCD, Kihl says the question concerns "how we use the system, how to be a good player: that's the challenge, and how to develop the system and the capability. We don't know the full capability of the system yet as we don't have the imagination."

Capability display

Demo 05, a large-scale exercise set for 2005, will be the first time that the "users will meet the technology, so we want to show how far we've got with the technology. The network users will find what the capability can give," says Kihl, adding that Demo 05 results will be "used to develop further requirements".

Kihl warns that, if development is too cautious, NCD will not be a revolutionary step forward. "I won't give [contracts] today for Demo 05," he says. The intention is to have the most capable system in 2005, not freeze the design now with 2002 technology. "I think we can be brave as we don't need the system in 2005, but 2010," says Kihl. Smaller-scale demonstrations earlier this year, in 2003 and 2004 are concentrated within industry and FMV to build understanding and confidence. Demo 05 will lead to a series of evolutionary exercises in 2006, 2007 and probably beyond.

NCD involves more than joining together platforms and presenting the information. "Data security and management is a major issue," says Kihl. Saab project director Carl-Johan Koivisto says the company's network centric warfare management is spread across the group. He says that previous military equipment, be it air, land or naval systems, was "platform centric with a rigid, slow decision process and poor interoperability. Today, we need short reaction times, and flexibility to manage the reduced, but more dynamic, threat." This drives network centric warfare, but "it is a long road map" to exploit fully the system's potential. "There are two types of system," says Koivisto. Legacy systems will have to be adapted for the network centric concept, while new systems will make use of common architectures. "The platform is a volume for transport of the C2, sensors and engagement systems. Each will be separate systems on the network," says Koivisto.

Saab is defining elements of Demo 05 and 06, says Peter Ohlander, Saab programme director network centric warfare, and is discussing related studies with the Swedish defence forces, including UAV operational analysis and integration of the air defence system into the wider picture. The company has developed a joint services operational-level software tool and a net defence simulator.

One of Saab's roles will be to produce network adapted products, including the JAS39 Gripen, UAVs and future C2, says Ohlander, adding: "Future Gripen, with its new capabilities, will be completely network centric warfare-adapted." The two-seat JAS39D, with a new rear cockpit providing enhanced situation awareness, will improve battle management and will be able to operate as a UCAV flight leader or a C2 node on the network.

The Gripen will take targets, air-to-air and air-to-surface, from other platforms, says Ohlander. The aircraft could also be used to aid civil powers during disaster relief, providing command and control while its sensors are used to locate and identify problems and transmit the information into the civil network.

The advantage of the two-seat Gripen as a C2 platform is its ability to move a decision-maker quickly from place to place while maintaining situation awareness, says Ohlander.

Within NCD, Saab has built a wide-area sensor picture as part of a network warfare systems simulator at Linköping. The company is also developing concepts for unmanned air systems and ensuring the Gripen is integrated into the network, says Lennart Sindahl, Saab Aerospace vice-president and general manager future projects. "Gripen is a net-centric warfare system. The first step was the Air Force 2000, linking the aircraft and C2 together. Gripen will be a key part of Demo 05."

Sindahl adds that Saab is working on a range of unmanned concepts, including a high-altitude, long-endurance (HALE) UAV equipped with an underfuselage-mounted Ericsson Erieye airborne early-warning radar. Other designs include URAVs, UCAVs, and vertical take-off and landing UAVs for the army and navy. Ohlander says the URAV could be used both pre- and post-strike. Initially the URAV would be launched to gather data for a precision engagement and then it would return to enable the battle-damage assessment to be conducted. Saab is also working on the Sharc (Swedish Highly Advanced Research Concept) as an unmanned technologies testbed.

Reliability problems

"UAVs have to be integrated into the C2 and moved away from remotely piloted vehicles to general sensor carriers," says Sindahl. This raises the issue of reliability. "It is time for a new generation of UAVs to overcome the problem of reliability," he says. An improvement of "maybe two orders of magnitude" is needed from today's rate of around one accident every 1,000h to one every 100,000h.

A Saab focus has been flight critical systems applicable to the range of unmanned systems from small tactical UAVs to large HALE vehicles, as well as UCAVs. The company's autonomous UAV technologies include automatic collision avoidance, navigation, and take-off and landing - while developing the Gripen has provided experience in flight-control systems, signature reduction and survivability, weapon and sensor integration, communications and datalinks. Sindahl says Saab is using "lean development labs...[and] will be demonstrating software development that's quick, but with quality, and be ready for certification."

Hans Berglund, Saab deputy programme director UAV systems, says it is clear unmanned platforms will be operational systems, which leaves two critical issues: "where can a UAV be best used; and how to do it so the system is safe and airworthy?" Saab is cleared under Sweden's military certification rules to operate UAVs in military ranges. To allow unmanned systems fly outside ranges, they "must be as safe as any other aircraft," he says. Civil requirements specify the probability of an accident as 10-6 to 10-7 per mission, while the Saab Viggen fighter achieves 3.2/100,000h, "which is acceptable, as the pilot survives because of the ejection seat". The flight-critical element of any unmanned system "should be as common as possible regardless of the UAV, be it tactical or HALE", says Berglund.

EADS in Germany is also working on UAV safety systems, working alongside German aerospace research organisation DLR. The German work is concentrating on operating UAVs in controlled airspace, which is a big issue in Europe's crowded skies. During a first phase, flight procedures for planned and unplanned flight were defined. Now, in the second phase, demonstrations will be flown using DLR's VFW614 testbed, and EADS Military Aircraft is developing a simulation linking a HALE UAV synthetic environment with an air traffic control simulator. EADS is discussing with German air traffic services provider LBA the use of experienced air traffic controllers in these trials.

Three flight-test campaigns are planned with the VFW 614, one this year and two for 2003. EADS says the simulation will allow scenarios that will not be possible to create with the manned aircraft, such as complete loss of engine power. The simulator will also allow the matching of a generic HALE UAV flight model with a more realistic flight envelope, "with regard to climb rates and turn rates".

Potential failures

Not all potential failures will lead to a crash, notes EADS, and procedures need to be in place to ensure the UAV can be landed safely without endangering other aircraft or people on the ground. If the datalink fails the aircraft could be out of contact with the ground station, and if the UAV is being used as a relay between the operator and air traffic controller these communications will also be lost. In such a failure, EADS says, the UAV could fly home, probably avoiding controlled airspace as much as possible, or it could divert to the nearest airfield or fly for another 30min so that the problem can be investigated.

Typical procedures that need to be defined include the handover between air traffic control centres and from one nation's air traffic service provider to another. "We will have to familiarise ATC controllers with the potential situation," says EADS. The first simulator-based test campaign will be in October followed by a second round of trials next year.

If UCAVs are to be successful, EADS says, they need to be flexible, with a basic airframe/engine combination able to perform a variety of roles with different weapons. Because it may not be possible or desirable to carry all the equipment to perform all the roles at once, the ability to swap avionics quickly would be advantageous. The level of autonomy is also important, says EADS, as it cannot be "automatic like a cruise missile". A UCAV will operate in high-threat environments. It is unlikely the datalink connection will be continuous because of jamming, tactical manoeuvring and other issues, so the "UCAV has to manage by itself. The UCAV must have the know-how to fulfil its mission," says the company. This drives a requirement for knowledge-based systems, which will also provide on-board monitoring and the ability to reconfigure the UCAV to manage battle damage or system failures.

A UCAV will also have to work with manned aircraft and other unmanned platforms such as URAVs, as well as with ground and naval forces. An operator will still have the ability to control an autonomous unmanned system, including the ability to terminate a mission, control the sensors, release the weapons and manage the communications links. The operator will also receive real-time sensor data and monitor the flight and onboard systems, communicate with ATC, view and change the preloaded flight-plan and co-ordinate fleets of unmanned platforms

Despite the lack of aircrew, which makes a higher attrition rate more acceptable, a UCAV must have an "acceptable level of survivability" to complete the mission, but survivability and autonomy are major cost drivers, says EADS. A minimum level of survivability can be provided through passive low-observability (LO) methods such as platform shaping and by using tactics such as low-level flight. To improve survivability would require an increased emphasis on LO, integration of defensive aids and towed decoys, and better manoeuvrability. Such methods will have to be evaluated against cost and mission effectiveness.

"To justify their acquisition, the overall system has to be cheaper than manned combat aircraft - with an acceptable fly-away price and substantially lower life-cycle costs," says EADS. From German studies, EADS believes a UCAV must be 25-30% of the cost of a fourth-generation combat aircraft. Operation and support costs must be less than one-quarter those of a modern fighter, reflecting the limited flying that UCAVs will perform and the lack of pilots to be trained and kept current.

EADS studies show the UCAV's empty weight would be 3,500-4,500kg (7,700-9,900lb), while maximum take-off weight would be more than 9,000kg. It would carry a payload of more than 1,000kg internally. Range would be more than 1,500km (800nm), speed Mach 0.8-0.9, and cruise altitude more than 25,000ft (7,625m), although low-level penetration would also be a requirement, says EADS. The air vehicle would be able to manoeuvre at ±6g, although there is some talk of manoeuvrability up to 30g to evade threats, the radar cross-section requirement is 0.01m2. Service life has been set at 1,000 flying hours (and 20 years storage), but this is too high for low-cost design, says EADS.

Sensors would include forward-looking infrared, synthetic aperture radar and emitter location systems. Datalinks are a crucial element of unmanned platforms and, although required during all phases of flight, they become critical in combat when they will need to be high bandwidth, allowing updates every 100ms, carry compressed and encrypted data, be capable of defeating enemy jamming attempts and operate beyond line-of-sight.

Long-term storage of an unmanned system also presents a challenge, says EADS. It envisages each vehicle stored in a humidity controlled container, with 50 to 100 vehicles stored at one site, clustered in groups linked to a single computer for automated monitoring of the vehicle and the conditions inside the container.

Exercises and checks

Every five years or so the vehicle would be removed from the container for exercises and checks. While moving to an all-electrical aircraft will eliminate the problems associated with hydraulic systems, storage and lack of use will still be an issue for the engine and fuel systems. Fuel tank sealing, engine bearings and landing gear components such as tyres will perish over time, while batteries will not remain charged for more than 180 days and electric connectors will corrode.

URAVs, EADS believes, will be launched by aircraft in a strike package. Studies suggest a 1,500km range is necessary, allowing a URAV launched by a strike package to fly ahead to the target, loiter, and then return to base. The sensor fit would be too expensive to make such vehicles expendable and, although URAVs could be ground launched, that shortens the range. EADS says that URAVs should be no bigger than larger stand-off missiles such as the MBDA Storm Shadow. "We hope, and think, we can use stand-off missile technology as the basis for a URAV. It's a question of the engines," says the company.

Use of URAVs in a strike package will require a two-seat fighter this allows the rear-seat crewman "to be freed from the air tactical task to concentrate on battle management", says EADS. The German air force is reviewing the numbers of two-seat Eurofighters it will acquire because of this, says a German source.

Source: Flight International