By Peter La Franchi in Berlin
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Fresh from its public roll-out at last month’s ILA 2006 air show in Berlin, EADS Military Aircraft’s Barracuda low-observable unmanned air vehicle demonstrator will resume flight tests from late this month and continue into early July.
The new programme of trials will continue to explore aircraft flight dynamics, extending air vehicle endurance up to 2h at a stretch during this year. More intensive flying is planned beyond this, in parallel with plans to expand Barracuda’s access to a wider range of airspace categories, aimed ultimately to include non-segregated civil airspace.
At the same time, EADS is exploring derivative versions of the demonstrator, which it plans to bring to the market in the near term.
Concepts and technologies from the demonstrator programme may also flow into a future common European unmanned combat air vehicle, according to Johann Heitzmann, head of EADS Military Aircraft. But he stresses that Barracuda itself represents a generational shift in UAVs as a whole, rather than being a UCAV demonstrator.
“We believe the first missions will be reconnaissance and surveillance. If the customer comes with a need for weaponised UAVs we will have to discuss if we could fulfil this. But at the moment for this, the application is reconnaissance and surveillance.”
Airspace issues
A key priority is the early resolution of airspace issues. Heitzmann says he expects the demonstrator to undertake “pioneering work towards the certification of UAVs in controlled airspace”. According to Dr Peter Hunkel, Barracuda programme director at EADS Military Aircraft, the company’s airspace integration strategy approaches the challenge by increments. The most immediate target is securing approvals for relatively unrestricted flight operations in designated military airspace in Germany.
The UAV incorporates features designed to aid the pursuit of certification standards for flights in non-segregated airspace as they evolve. The Barracuda’s all-electric flight control and navigation systems support triple redundancy, Hunkel says, while all hydraulically actuated systems – used only for ground manoeuvring – have dual redundancy. A similar approach has been adopted in development of the Barracuda ground architecture, although future certification is likely to require further development of that part of the system.
Sense and avoid
The UAV’s visibility to other airspace users will initially be provided by a Mode S transponder, but there are plans to incorporate an off-the-shelf traffic collision avoidance system as the initial basis of an organic sense-and-avoid capability.
The sense-and-avoid architecture is likely to draw on work by EADS in co-operation with Germany’s DLR national aerospace research organisation using its VFW 614 Advanced Technologies Testing Aircraft System (ATTAS). However, Hunkel says that there are no plans to directly port systems already flown aboard the ATTAS aircraft on to Barracuda, though there may be some conceptual overlaps.
One anticipated continuing challenge, Hunkel says, will be how Barracuda handles operations in non-segregated airspace shared with light aircraft without co-operative systems, although he notes this is a problem shared among the wider UAV community. As it stands, the air vehicle already has air navigation lights and a forward-facing pilot video camera.
The evolution of the air traffic integration technical architecture will take place in parallel to development of the UAV’s sensor suite. The immediate focus will be the fitting of an initial electro-optic/infrared (EO/IR) suite and secure datalink, followed by synthetic-aperture radar (SAR).
The UAV’s voluminous payload bay is almost 2m (6.5ft) long, 600mm (23.6in) deep and 600mm wide. Payload weight is given as 300kg (660lb), with the aircraft having a maximum take-off weight of 3,250kg. Fuel weight is given as 650kg, while the aircraft’s empty weight is 2,300kg.
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Hunkel says the SAR array will be mostly conformal with the Barracuda’s flat underfuselage, although the demonstrator could have a minor belly bulge. It remains unclear whether the EO/IR system will be turret- or aperture-mounted.
The datalink architecture is intended to progressively incorporate broadband line-of-sight and beyond-line-of-sight radio links, MIDS Link 16, and a satellite link.
The large payload bay has been achieved by constructing the all-composite fuselage in box sections to provide internal rigidity. The bay’s two side walls extend through the airframe as its primary internal longitudinal stiffeners. The top and bottom sections of the 8.25m-long fuselage have been moulded as single structures using EADS vacuum-assisted manufacturing techniques, with access panels cut after manufacture. While the all-composite approach is clearly intended to help reduce observability as well as weight, EADS has not at this stage filled fastener heads used to hold down fuselage and wing access panels.
The only significant metal airframe component is the centrally mounted wing spar, which passes through the fuselage to extend out on both sides by almost 1m, almost one third of the way along the wing structure and ending directly in line with the trailing-edge “crank”. Within the fuselage the spar passes to the immediate rear of the payload bay and well ahead of the engine mount.
Hunkel says the spar is derived from glider designs, intended to take the bulk of lift forces and at the same time provide a simplified mechanism for exploring alternate wing forms, including the proposed medium-altitude, long-endurance version being considered by the German air force alongside vehicles such as the General Atomics Aeronautical Predator B and EADS’s own EuroMALE system. The current configuration has a span of 7.22m with the wings produced in Spain by EADS Casa.
Easy removal
Hunkel says the spar also makes wing removal easy for transport purposes, with dismounting and re-mating each taking around an hour.
The bulk of aircraft ancillary systems, including generators and undercarriage hydraulics, are located directly above the spar in the fuselage space beneath the air intake. The forward upper fuselage supports avionics and mission systems.
Subsystem suppliers on the demonstrator include Meggitt Dunlop Aerospace, MTU Aero Engines, Messier Dowty, Honeywell, L-3 Communications, Smiths, Goodrich and Ruag.
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| EADS plans as much commonality as possible between Barracuda variants |
Options for the development of derivative versions was factored into the Barracuda programme from an early stage. “In the past we segmented into tactical UAV, MALE, HALE [high altitude, long endurance], and we tried to bring in the requirements in this segmentation,” says Heitzmann.
“But the customer’s requirement changes due to the experience they have gained, and in the same time you have an overlap of the requirements, between HALE, MALE and tactical application...We should forget this segmentation because there is too much overlap.”
Tailored solution
The derivative already proposed to the German air force “is not a pure MALE solution; it is solution which is tailored, laid down to the customer needs”, and capitalises on the basic modular nature of the overall air vehicle design.
While Barracuda itself is likely to remain a technology demonstrator, ongoing development will aim to ensure that the overall family of systems that evolve from it “have as much as possible common elements”, Heitzmann says. That same approach should also assist in helping reduce the overall system cost: “You see that UAVs are always [produced] in small quantities, so to have economy of scales you need a lot of common modules.”
Derivatives would have a number of significant changes to the basic demonstrator he says, regardless of type: “There will be a change of engine; you can think of a twin engine concept for example, because you need power for the payloads.”
The supporting ground architecture would also need to undergo further development as the air vehicles evolve into a fully integrated system. “At the end you need the flying vehicle so that you can gather information, but you have to have all the mission systems as well; it is just paramount.” In that context, Heitzmann says, one of Barracuda’s near-term benefits is expected to be to help EADS explore in greater depth the potential of new generation UAVs as elements within a network centric warfare environment.
“We will go on with our test flights”, he says. “And I am absolutely sure that we are on the right track; that we can offer very soon a first product on the market.”
Source: Flight International
