Julian Moxon/TOULOUSE
Airbus will know only after a six-month commercial marketing campaign that begins in January whether it has predicted correctly the demand for its A3XX.
If enough airlines, with enough geographical and commercial diversity, are prepared to put their confidence in the 550-seater and order a minimum of 50 aircraft between them, the programme will be launched and Europe will be on the way to fielding its long-awaited competitor to the Boeing 747. Before this can happen, however, an all-important milestone must be met (Flight International 21-27 July). In November, Airbus will decide whether technical solutions it has prepared for the A3XX over the past few years can provide the 15% lower direct operating costs (DOCs) compared to the Boeing 747-400 that airlines are demanding.
November will also bring a critical decision on where the A3XX will be built. The original choice between six potential sites has been narrowed to two, and perhaps not surprisingly they are in Toulouse and Hamburg where other Airbuses are built. This decision carries with it huge implications for the future of the Airbus final assembly process. It could continue more or less as it does now, with production of single-aisle aircraft divided between the two sites and Toulouse assembling all twin-aisle output. Or there will be a rationalisation that could leave Germany in charge of all single-aisle production, Toulouse building the widebodies and Spain - if the A400M transport is launched - being responsible for the military line.
Given the deadline, now only four months away, a surprising number of key technology decisions still need to be taken. According to Pierre Froment, Aerospatiale's research and projects programme director, these include the use of Glare aluminium/metallic composite for the upper fuselage, a possible shift to a 5,000lb/in2 (345bar) hydraulic system, which would reduce the size of actuators needed for the huge A3XX control surfaces, reducing weight by around 500kg (1,100lb), and use of the new IM7 carbonfibre for composite components such as the empennage.
A further question mark hangs over the use of A340-style floor beams for the two-deck A3XX. These differ from the previous design in being integral with the fuselage cross-beams which support them, resulting in an overall structure which is thinner by around 50mm. This reduces the height of the ovoid fuselage by 100mm, saving 300kg and reducing profile drag.
"We have a hundred or so issues to decide on before November," says Froment. "We have no doubt that we can reach the 15% DOC target, but we have to do so in a way that provides the right performance with achievable, cost-effective technologies."
Half of the DOC cut is simply the result of carrying more passengers, increasing revenue per kilometre. Of the rest, half comes from the best use of technologies taken from the existing A330/A340 generation of transports. The rest comes from the use of new technologies.
Part of the saving is inherent in the final assembly decision. The very size of the A3XX means that the traditional Airbus production system, in which sections of the aircraft are delivered by the Satic Beluga transport from the partners to either Toulouse or Hamburg, must be reviewed. The converted A300-600, with its characteristic enormous egg-shaped cargo deck added to the original lower fuselage, is too small to carry complete wings or A3XX fuselage sections. This has driven studies of some interesting solutions to the transport problem.
Piggy-back deliveries
One is the idea of delivering single wings piggy-back on an Airbus A340 from British Aerospace's manufacturing plant at Chester to the final assembly site. Windtunnel tests have shown that the only major aerodynamic modification that would be required is the use of the taller A330-200 fin to maintain directional stability - and that the combination would fly at Mach 0.6. "At a production rate of four aircraft a month that would mean just two rotations a week," says Froment. He says the alternative is to ship the wings by sea, which would take at least a week. "That is not cost effective," he says. "We're very sensitive to just-in-time manufacturing to minimise the inventory of high value components." He adds that air carriage also "minimises the possibility of strike action by road hauliers or dockers preventing delivery".
The A3XX wing will weigh around 35t if it is built as a monolithic item and would be mounted on a structure designed to minimise changes to the A340 fuselage. This would be based around a single frame attached at the fuselage sides, to support the wing centre section, and a smaller support at the front. The main centre frame would be supported by a simple triangulated structure within the fuselage.
A second possibility would result from building the wing in two halves, the section outboard of the engines being built of composites and transported separately. The Beluga could then be used for both sections, but for the inboard element would need a small extension to the upper fuselage to accommodate the wing root.
Another key decision rests on how the fuselage will be assembled. This, perhaps, more than any other, illustrates the difficulty faced by Airbus in choosing the final assembly site.
The Toulouse option, being land-based, requires sections to be air or road-transportable. Hamburg, on the other hand, could take entire fuselage sections delivered by sea directly to its site for subsequent assembly.
One of Aerospatiale's arguments for Toulouse is that while joining circular sections of the current range is relatively straightforward, the double-deck arrangement of the A3XX means that matching the twin decks to within a few millimetres accuracy is considerably more difficult. "You can't play with rotation to match up the decks," says Froment. "So we are proposing building the top and bottom fuselage sections separately. This would enable the upper and lower sections to be matched first, so that only a single deck at a time would have to be aligned. Then the upper and lower sections would be joined to create the fuselage."
Froment adds that such a method also has the advantage of "keeping the partner specialities which have made the Airbus system so successful", since the sections, being smaller, could be manufactured and transported, fully equipped as they are today, by the Beluga.
Toulouse promotes its final assembly expertise, but Hamburg counters by offering major incentives to build an entirely new plant on the other side of the River Polder - a decision made easier by the lack of capacity at the current site.
The two contenders insist that the final choice can have nothing to do with politics. Only the solution that contributes the most to reducing costs can win, they say. The prestige value of the A3XX site, however, and the knock-on economic benefits that will accrue will ensure that some extremely hard bargaining takes place before the final decision is made.
Source: Flight International
