Emerald Group Publishing Limited
Copyright © 2004, Emerald Group Publishing Limited
A380 - a new century, a new aircraft
A380 - a new century, a new aircraft
Keywords: Aircraft, Design, Aerospace engineering, Airbus
The A380 programme, launched in December 2000, represents one of the outstanding aerospace engineering effort of recent times.
Airbus believes that as a spacious, advanced and efficient aircraft, the A380 will provide a technology platform for future aircraft programmes. While offering all the advantages of a completely new design, it will also extend the benefits of Airbus family commonality to the very large aircraft sector.
Airbus has a long and successful record of pioneering new technology in an evolutionary and responsible manner, to ensure better aircraft performance, lower operating costs, easier handling and greater comfort. This, Airbus believes is the cornerstone of its success in the marketplace.
The A380 takes this philosophy into the 21st century, and an array of new technologies for materials, processes, systems, and engines have been developed, tested and adopted. Airbus explains that all technology considered for the A380 is carefully studied to determine its effects over the lifetime of the aircraft, and is selected for its proven maturity and long-term benefits. Each selection therefore contributes to attaining or bettering the programme targets, in keeping with the basic design tenets of reliability, low seat-mile cost, passenger comfort and environmental friendliness.
Moreover, while offering all the advantages of a completely new design, the A380 will extend the benefits of Airbus family commonality to the very large aircraft sector. Owing to the same cockpit layout, procedures and handling characteristics, pilots will be able to make the transition to the A380 from other Airbus fly-by-wire aircraft with minimal additional training.
A number of innovations introduced on the A380 will reportedly ensure considerable weight savings despite the aircraft's spaciousness, and tests are said to show that aerodynamic performance of the aircraft will also be significantly enhanced. Better aerodynamics and lower airframe weight reduce the demands placed on engines and translate into lower fuel burn, reduced emissions into the atmosphere and lower operating costs.
For instance, based on the excellent in-service experience gained on its existing products, Airbus is extending the use of carbon fibre reinforced plastics (CFRP) to the A380. The A380 will be the first Airbus aircraft ever to boast a carbon fibre central wingbox – representing a weight-saving of up to 1 1/2 tonnes compared to most advanced aluminium alloys. A monolithic CFRP design has also been adopted for the fin box and rudder, as well as the horizontal stabiliser and elevators. Furthermore, the upper deck floor beams and rear pressure bulkhead will be made of CFRP, while the wing covers will be constructed from advanced aluminium alloys. The fixed wing leading edge will be manufactured from thermoplastics, and secondary bracketry in the fuselage (serving, for example, to hold the interior trim) is also likely to be made of thermoplastics. Further applications of thermoplastics are under investigation, such as for the ribs in the fixed leading edges of the vertical and horizontal stabilisers.
An estimated 40 per cent of the aircraft's structure and components will thus be manufactured from the latest generation of carbon composites and advanced metallic materials, which, besides being lighter than traditional materials, offer significant advantages in terms of operational reliability, maintainability and ease of repair.
A new lighter and even more resistant material will also be used for the first time on a civil airliner after intensive trials. The upper fuselage shell of the A380 will be fashioned from GLARE, a laminate alternating layers of aluminium and glass-fibre reinforced adhesive. According to Airbus, in addition to being some 10 per cent less dense than aluminium – for a weight-saving of around 800 kg – GLARE has proven superior in terms of fatigue as well as fire and damage resistance. Testing has reportedly demonstrated that an artificial crack subjected to thousands of flight cycles barely increases in size. The new material also resists exceptionally well to corrosion with the first glass-fibre layer preventing any penetration beyond the superficial aluminium coating. GLARE uses a hot bonded manufacturing process but is repaired in the same way as standard aluminium.
Following an in-depth study, two test flight campaigns and numerous laboratory and simulator tests, A380 engineers have also succeeded in moving the aircraft's centre of gravity aft by around 6 per cent. This change in centre of gravity, coupled with an enhanced fly-by-wire system, has led to a reduction of approximately 40 m2 in the area of the vertical stabiliser and a consequent saving in weight, while preserving the stability of the aircraft in-flight.
The net weight-savings resulting from these and other innovations discussed below, allow the A380 to weigh in at around 240 tonnes – a full ten to 15 tonnes lighter than a similar sized aircraft using 747 technology.
Another weight-saving feature is the use of an increased pressure for the A380's hydraulic systems. Thought to be for the first time ever in civil aviation, the A380's hydraulic systems will have an increased pressure of 5,000 pounds per square in. (psi), as opposed to the traditional 3,000 psi. This increase in pressure allows the necessary power to be transmitted with smaller piping and hydraulic components. The reduction in the size of components, unions and piping not only lowers the weight of the aircraft by around 1tonne but also improves its maintainability. Military aircraft have already been using these high pressure systems for many years and the change is an evolutionary move which reportedly has stood up well to qualification testing. Trials with existing hydraulic fluids and components are said to have shown that the fluid does not degrade under the higher pressures and no evidence of erosion has been found.
In addition to the increased hydraulic pressure, a dual architecture for the flight control system has been implemented, featuring four independent primary flight control systems with two different configurations. Two of these systems use a conventional hydraulic actuation system, whereas the other two feature local electro-hydraulic actuators for the control surfaces. The aircraft can be controlled using any one of these four systems. This brings system separation and redundancy in flight controls to a level never achieved before on an aircraft, whether civil or military.
The A380 will moreover benefit from a completely re-designed double spool air generation system, which is more efficient in terms of thermodynamic cycles, provides more flexibility between different air generation requirements on the ground and, at cruise, takes up less space and offers more redundancy and damage-resistance. Airliners are generally equipped with two air-conditioning packs, each of which converts high temperature, high pressure bleed air (from the compressor stage of the engines) into pressured cabin air at room temperature. Instead of using four such packs to generate the necessary air, the A380 will be equipped with two innovative double-packs, in which each unit performs separate functions of the overall cycle. This more robust approach provides valuable systems redundancy as well as greater overall efficiency.
Several innovative manufacturing techniques have been selected for use on the A380 programme, some of which have proved so advantageous they have gone into series production on other existing Airbus aircraft programmes.
One example is laser beam welding which is used to attach the “stringers” (longitudinal reinforcements) of the lower fuselage shell instead of traditional riveting. This technique not only engenders a potential weight reduction, it is also much faster than conventional riveting – 8 m of stringers can be laser beam welded per min. The method includes a built-in automated inspection unit and tests run on the resulting structures to determine damage and fatigue tolerance have demonstrated that they behave as well or better than conventional alloy construction. A further major advantage of this technique is that it eliminates fasteners, and thereby the major source of corrosion and fatigue cracks.
Laser beam welding went into series production in 2001, for the manufacture of the rear fuselage lower skin on the single-aisle A318.
According to Airbus the A380 will help cope with growing passengers numbers without negatively impacting the environment, due to significantly reduced noise and emissions levels. The company states that in spite of its higher weight and thrust requirements, the A380 will make less noise while carrying 30 to 50 per cent more people. Current noise certification rules (ICAO “Chapter 3”) will reportedly be met by significant margins and the A380 will be compliant with the strictest local noise regulations, classified QC2 for departure from London's busy airports and QC1 for arrival.
For ground operations, the A380 can taxi with only two engines if required, will use only two thrust reversers and will employ a low-noise auxiliary power unit to help eliminate any noise concern.
The A380's new generation engines are said to surpass the requirements of the latest regulations for the landing and take-off cycle. Because of its larger capacity, the A380 will make a better use of the available take-off and landing slots, thus reducing fuel wasted in airborne delays and holding patterns.
The economic fuel consumption of the A380 – stated by Airbus to be around 13 per cent lower fuel burn than its closest competitor – will also help reduce the impact of exhaust gases on the atmosphere. The A380 will reportedly be the first long-haul aircraft to consume less than 3l of fuel per passenger over 100 km – a fuel burn comparable with that of a mid-sized automobile.
What will be the impact on existing airports by the introduction of an aircraft of this size? In answer to this question, Airbus explains that the A380 has been designed in close collaboration with major airlines, airports and airworthiness authorities. For the past 6 years, the company has been working with representatives of more than 60 international airports to ensure the most cost-effective integration of the aircraft commercial operations. Airbus reports that as a result, all the A380's major destinations are working to a master plan enabling them to accept the aircraft when it enters into service.
The company believes that the A380 is in many ways compatible with the facilities used today by existing large aircraft. According to Airbus the A380's large wings and new engines will provide a better take-off and landing field performance than that of current large aircraft and therefore require a shorter runway. In addition, due to the 20-wheel main landing gear, the A380's pavement loading will remain within the parameters of in-service aircraft. The footprint of the A380 landing gear is comparable with that of existing aircraft and does not require new runways.
The A380 cockpit is midway between the two decks, which means the pilot sits near the aircraft centre-line providing an enhanced view. This, alongside cameras located in the tail fin and on the belly, allow accurate placement of the aircraft.
At the gate, the A380's two decks and wide forward stairs will, it is stated, allow turnaround times comparable to those of today's largest airliner, even only if single deck access is possible.
According to Airbus, with traffic and airport congestion increasing annually, the A380 represents a positive investment for key international hubs as it will contribute to the resolution of the congestion problem at major gateways. Airbus believes that its analysis of this issue has been irrefutably confirmed, both implicitly, through industry – wide participation in the programme from its outset, and explicitly, through the already immense success of the A380 on the market.
The definition phase of the first aircraft was essentially complete by the end of 2002. Sub-assembly of parts for the A380 is now underway at Airbus manufacturing units across the world and delivery to the final assembly line, in Toulouse, France, took place in early 2004. The aircraft's first flight is scheduled for the beginning of 2005 with entry into commercial service planned for 2006.
To ensure the aircraft meets the needs of all stakeholders Airbus continues to hold open dialogue with customers, airports and industry authorities. Work is ongoing with the planning teams from major airports to ensure full airport compatibility and a smooth entry into service.
The fully integrated A380 programme, implemented company-wide, currently involves more than 6,000 people, co-located at the various Airbus sites across the world. One of the key elements of the programme is the use of Airbus Concurrent Engineering (ACE) methods and processes worldwide. First implemented at Airbus on selected new or heavily modified sections of the A340-500/-600, ACE provides an online collaborative working environment for aircraft development, extending from the customer to the supply chain. Sharing data online continues to provide more effective working practices, shorter development times and allows verification to take place from a very early stage. This ensures the full integration of all tasks linked to product design, manufacturing and support.
Since the start of production, a number of industrial milestones have been achieved at Airbus sites around the world. In January 2002, the first metal cut took place at Airbus in Nantes, France, which began manufacturing the cruciform fittings from aluminium as well as the wing box, from carbon fibre reinforced plastic. Following this, in March 2002, at the Bremen site in Germany production began with two formed sheet aluminium parts for integration into the fuselage section aft of the wings. During April 2002, in Varel, Germany, manufacture of the first aluminium frame assembly for the rear fuselage section began and production was launched at Nordenham and Stade, also in Germany. In the UK, in August 2002, the first metal cut of components for the A380 wing took place at Airbus in Filton. In Spain, production of the first carbon fibre rear fuselage section took place in February 2003 in Illescas. This section is first produced using fibre placement technology. During April 2003, the first part of the A380 belly fairing central area was assembled at the Airbus in Puerto Real, Spain.
The programme continued to move forward rapidly with the manufacture and assembly of major parts. In August 2003, the centre wing box was the first key component of the aircraft to be completed. Known as the “heart” of the aircraft, it is located at the junction of the wings and the fuselage and therefore submitted to considerable loads. The wing box is being constructed in Nantes, France, using the ground breaking applications of carbon fibre technology mentioned earlier.
Completion of the A380's central fuselage was on target. The lower part of the central fuselage was completed and delivered to Saint Nazaire in France during October 2003. Parts include the central section of the wing, forward lower shell, landing gear boxes, central lower shell and floor grid, which are being manufactured at various sites across the world. Assembly of the upper central fuselage was completed during October 2003 ahead of schedule. The forward, central and rear upper shells arrived in Saint Nazaire from Airbus in Hamburg and from supplier Alenia Aeronautics in Italy.
At Airbus in Puerto Real, Spain, the first A380 central belly fairing was completed in the middle of October 2003. It is one of the main structures being produced at Airbus in Spain and, at 32 m long, 10 m wide and 4m high, is the largest ever belly-fairing produced for a civil aircraft. This important part has now been transferred to St Nazaire's assembly stations where it is being integrated with the lower and upper central fuselage sections. The first ever fully equipped central fuselage was delivered to Airbus in Toulouse, France, during the middle of 2004, where it joined other major sections of the aircraft on the final assembly line.
The first nose section and forward fuselage sections were delivered from Airbus in Meaulte, France, and assembled together at Saint Nazaire. Production of these sections uses an innovative concept that employs spatial positioning techniques assisted by laser beam measuring. In addition, during November 2003, the first set of wings for the twin-deck aircraft were completed in Broughton in the UK. Equipping work, including the wiring and fining of components such as hydraulic, pneumatic and fuel systems, has now begun. The wings each measure more than 36m in length and 11m in width and are built to tolerances of just fractions of millimetres. Assembly of the first complete rear fuselage started in November 2003 at Airbus in Hamburg and will be followed by assembly of the first horizontal tail plane in Spain.
Construction work to house the production facilities and employees working on the A380 programme in Toulouse, location of the final assembly line, have been completed. The facilities are over 50 hectares (123 acres) in size and comprise mainly the static test building and the final assembly hall, 490 m long, 250 m wide and 46 m high (1,600 × 820 × 150 ft) The hall accommodates 34,000 m2 (365,900 ft2) of office space on six levels.
In addition, at the nearby Toulouse St Martin site, a new 19,000 m2 (204,516 ft2) building has been constructed to accommodate the A380 cockpit simulator and “iron bird”, the test rig which will be used for systems integration simulation and verification. This building was officially opened in November 2003.
In Hamburg, the A380 Major Component Assembly hall was officially inaugurated in May 2003. The hall is 228 m long, 120 m wide and 23 m high (748 × 393 × 75 ft) It houses the structural assembly of the forward and aft fuselage sections of the new A380, as well as the equipping of their essential flight systems. Other facilities on the site include the interior finishing hall, a delivery centre, two paintshops, a pre-flight hangar and an engine run-up facility. The whole site covers 140 hectares (346 acres).
In Broughton, Wales, UK, a 83,500 m2 (over 900,000 ft2) facility, was officially opened in July 2003. Known as the “West Factory”, it houses wing assembly for the new aircraft, as well as other aircraft manufacturing activities. Three other new buildings have also been constructed for A380 wing production. A 21,000 m2 (226,044 ft2) building to manufacture stringers for bottom wing skin panels and extensions to the existing skin mill and creep forming buildings. In Filton, the building to house the largest ever landing gear test rig for a commercial aircraft was completed in 2002.
In Spain at Getafe and Puerto Real, new assembly halls for the A380 horizontal tail plane and belly fairing cover some 16,000 m2 and 15,000 m2, respectively (204,516 and 161,460 ft2). In Illescas, an extension houses new fibre placement machines that will help to deliver some of the first large all carbon fibre fuselage sections to be used on a commercial aircraft.
At Airbus in France, Nantes, a 10,000 m2 (107,640 ft2) workshop houses the manufacture and assembly of the A380 centre wing box. In Saint Nazaire, the fuselage assembly hall has been increased by some 5,000 m2 to assemble, equip and test the forward and centre section of the A380 fuselage, while in Meaulte, the flexible fuselage assembly facilities have been increased by four times their original size.
Transport of the aircraft sections to the final assembly line in Toulouse includes a mix of sea, river, road and air transport. An itinerary for the oversized loads has been developed to move sections from Airbus sites across the world. A huge roll-on, roll- off sea vessel will be used to take components on the first stage of the journey, by sea, from Airbus sites in the UK, Germany, France and Spain to the French city port of Bordeaux. Specially designed barges will then carry the components on the penultimate part of the voyage, along the Garonne River, from Bordeaux to the river harbour of Langon. Here the aircraft components will be transferred to road trailer to continue the final part of the journey to the final assembly line.