FLUG REVUE January 2003: Technology for the Airbus A380

THE TECHNOLOGY INSIDE THE A380

By Matthias Gründer

Ever since the project was first conceived in 1994, the A380, which at that time was still known as the A3XX, has been an aircraft of superlatives: it will be 73m long, weigh 560t, have a wingspan of nearly 80m and carry 555 passengers at a speed of Mach 0.85 over distances of 15,100km. It will have 35% more seats than the Boeing 747, but 49% more cabin space. Not all of this space can be used for more seats, for example around the points giving access to the upper deck, which is why the manufacturer is thinking of installing bars, fitness rooms or shops here.

Airbus A380

Never before in the history of civil aviation have engineers been tasked with a technological challenge on the same scale. But building a passenger aircraft of these dimensions would not have been possible at all before, at least not if it was to be operated at a profit. It is only thanks to a true revolution in the area of the materials used in aircraft construction that it has become conceivable to even think of such a project: some 40% of all the components used on the A380 are to be fabricated out of various synthetic materials (see also "Fortron film flies in Airbus” in FLUG REVUE 12/2002).

These materials, which in some cases are completely new developments, are not only more resistant to environmental influences than the metals used up to now, but they will also help to significantly reduce the enormous weight of the aircraft. Experience suggests that during the design phase an aircraft always becomes too heavy as the designers always aim for high strength. Only later does the weight reduction phase begin, when the results of computer modelling through to flight trials are used to identify areas in which savings can be made. The more successful this phase is, the lighter and hence the more economical the end product will be.

The use of such large amounts of composite materials implies a significant leap forward in quality. Whatever is needed in the way of glass- and carbon-fibre reinforced mats, profiles and moulded parts will require automated production rather than manual labour, as has been customary up to now – and the development of numerous new materials and machines, from autoclaves through to industrial sewing machines.

Airbus Deutschland has founded a Composite Technology Center in its Stade plant specifically to develop such technologies. Here, carbon-fibre mats are sewn, textile objects of all possible geometries are impregnated with industrial resins and are moulded under pressure and temperature into components that will fulfil a wide range of functions. This work is supported financially by the German government's aerospace research programme and by the state of Lower Saxony.

Working closely with the Bremen-based Fraunhofer Institute for Production Technology and Applied Materials Research, the carbon-fibre producer Hexcel, the textile manufacturer Saertex and the DLR Institute for Structural Mechanics in Braunschweig plus numerous other companies and institutions, Stade is thus developing into a major competence centre for composite technology in aircraft construction. From semi-finished products through to surface protection, the steadily increasing demand for components made out of carbon-fibre reinforced plastics (CFRPs) is to be satisfied here, and not just for the A380, but for all Airbus programmes through to the A400M military transporter. The biggest component to have been built so far is the rear pressure bulkhead for the A380, which measures 5.5m x 6.2m.

Calculations performed during an early phase of the work indicated that the new technologies would not only enormously reduce the mass of the ultra-large aircraft, but that, if the parts could be successfully series produced, then cost savings in the order of magnitude of up to 30% might be achieved. Plenty of reason, then, to step up the combined efforts in this area.

On the A380, all the control surfaces, the floors of the decks and the above-mentioned rear bulkhead are to be constructed out of CFRPs, plus, for the first time in international aircraft construction, the wing boxes. These, compared with conventional metal constructions, will alone bring weight savings of around 1,500kg.

LAMINATE OUT OF GLASS AND ALUMINIUM

Another new material is glass fibre reinforced aluminium (GLARE), a laminate that consists of several layers of thin aluminium film and resin-impregnated glass fibre mats. The whole thing is then baked in an oven rather like bread, and, being 10% less dense than aluminium, it is significantly lighter, while also being significantly more robust. Tests have shown that cracks artificially introduced into this material did not expand even after several thousand hours of simulated flying. The entire upper stressed-skin fuselage on the A380 is to be constructed out of GLARE. This wonder-material is manufactured at Stork Aerospace/Fokker in Papendrecht, the Netherlands, where production commenced in July 2002.

The lower stressed-skin fuselage will still be constructed out of aluminium, however it will no longer be riveted but welded. The laser welding procedure is a production method developed by Airbus Deutschland, in which eight metres of outer skin can be attached to metal sheets and stringers for longitudinal stiffening per minute. This technology has already been used for some time on the much smaller Airbus A318.

Weight savings are also being made in the design of the hydraulic control system, which, instead of the 3,000 psi that were customary before, now operates at a pressure of 5,000 psi, which otherwise is only found on military jets. Two hydraulic control circuits and two electrical control circuits will replace the three hydraulic circuits previously used, resulting in a lighter and more reliable dual architecture. Similar efforts are being taken by the other Airbus partners and systems suppliers, so that the A380 is becoming a true compilation of the latest technologies, something which leaves the competition looking way behind the times.

State-of-the-art technology is also being implemented, for example, in the cockpit: eight large, colour multi-function displays, sidestick control and two interactive computers for the flight management system with tracker ball control are only a fraction of what awaits the crew during flight.

COMPLETELY NEW TRANSPORT METHODS

But it is not only research and development that are breaking new ground. Airbus's logistics planners face their biggest challenge in co-ordinating activities that are spread all around Europe. The division of work on the construction of the A380 follows the tried and tested pattern: Airbus France is responsible for the cockpit, the centre section of the fuselage and final assembly, Airbus Deutschland for the front and rear sections of the fuselage, the vertical tail, internal finishing and paintwork, Airbus España for the horizontal tail and Airbus UK for the wings.

Numerous suppliers from all over the world are providing subsystems and components. However, due to the size of the subassemblies, a completely new transport system is having to be developed, as transportation by air with the Beluga super-transporter is no longer feasible. Work is now under way on a combination of sea, river and road transportation.

The transport process begins with loading of the approx. 44t German sections of the fuselage, on a roll-on roll-off ship that has yet to be procured. The wings will be brought in the British Mostyn (a complete set will weigh about 33t). The front section of the fuselage will be unloaded in St. Nazaire, France, attached to the cockpit that has been built there and then re-shipped again, along with the centre section of the fuselage. The next stop is then Bordeaux, where all the subassemblies will be loaded onto river boats together with the Spanish deliveries and transported some 80km inland. The final leg of the journey then entails transportation over roads that have still to be built to Toulouse. The entire process will have to be repeated once a week in order to achieve the planned production rate of four aircraft per month. This at any rate is the present state of planning and does not take into account the objections of French residents to road transportation in the affected areas.

When the first blueprints for the A380 were developed back in 1996, the question was considered of whether the subassemblies to be transported should be designed in smaller units, so as to enable transportation as previously using the Belugas. All the calculations have shown since then that, for example, if the fuselage sections were constructed as only half-shells this would result in irreparable distortion of the structure during transportation, so the system described was the only possible choice. The possibility of piggyback transportation of the wings on a modified A340 was similarly rejected as not feasible after thorough investigation.

If the A380 is to celebrate its maiden flight at the beginning of 2006, then deliveries of the first subassemblies will have to begin in the autumn of 2003 – a lot of work for the logistics people, who have another year to get to grips with the problem. For at that point a complete fuselage together with wings is to be shipped to Dresden for exhaustive fatigue testing over the next few years. IMA and IABG will be carrying out these tests as they have done in the past on other Airbuses. Even if all those involved on the A380 programme are still a little reticent, nevertheless the giant is slowly taking shape.

From page 78 of FLUG REVUE 1/2003

Last updated 5 December 2002

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