Structure is key to performance

For an aircraft of the A380's size, it has been more vital than ever to focus on weight reduction. The A380-800's 569t maximum take-off weight means that even a 1% saving equates to over 5,000kg. It is therefore no surprise that, at 22% of the total weight, the aircraft has the greatest use of composites yet seen in airliner construction.

The A380's structure also incorporates major use of other new construction technologies and materials.

The major innovations are:

* Carbonfibre-reinforced plastic (CFRP) composites are used for the construction of the centre wingbox, rear pressure bulkhead, unpressurised fuselage and wing ribs, in combination with advanced technologies. Intermediate-modulus carbonfibre material is also used in some areas.

* Glare - a metal/fibre laminate - is used in the construction of the upper fuselage panels on the forward and aft sections. This equates to 3% of the A380's weight, exclusive of the 22% that is composite.

* Airbus has also introduced two categories of advanced alloys - aluminium alloys (for the wing box) and aluminium-lithium.

* Laser beam welding technology, first introduced on the A318, is used in combination with 6000-series aluminium alloys on lower fuselage panels.

Speaking to Flight International late last year, executive vice-president, A380 programme Charles Champion said that in early 2001 the A380's manufacturer's weight empty (MWE) was "several tonnes above target" because of changes to the specification to meet customer range, payload and noise requirements.

"Two weight-recovery programmes were instigated, and a series of 'Tiger Teams' were established, which incorporated multidisciplinary experts to reach the target," says Champion. One key area where Airbus hopes to drive weight down is the interior furnishings, with suppliers tasked with finding reductions of up to 30%.

Airbus says that the fourth A380 (MSN007) will be the first built to production standard and incorporate weight savings. Airbus declines to be specific on the weight issue, saying that is about "four to five tonnes" over the target - ie 1-2% of the last published operating empty weight which was 276t (608,000lb). Airbus confirms the operating empty weight has been increased to meet customer requirements, but has not yet released what that weight is.

It is clear the weight-saving effort will continue for the life of the programme, with new gains to be incorporated in later A380 versions. "A competitive new aircraft programme with a lifespan of 40 to 50 years requires the introduction of new materials and technologies that allow for further optimisation as the aircraft family evolves," says Robert Lafontan, senior vice-president engineering for the A380 programme. "Thus, the launch versions of the A380 family establish a technology platform for future developments."

Source: Flight International