Airbus has attacked the high proportion of composites used in Boeing’s 7E7 Dreamliner, branding the aircraft’s development ‘rushed’ and ‘ridiculous’.
The 7E7 will contain double the amount of composites used in the Airbus A380 – including most of the fuselage and wings. But Airbus claims Boeing has rushed through the technology before it is sufficiently matured.
Colin Stuart, Airbus vice-president of marketing, said composites should be introduced with caution in aircraft design. ‘If you start to look at the various loads on composites [in an all-composite fuselage], it is absolutely the wrong thing to do.’
Current composite material is unsuitable for many areas of the fuselage claimed Alain Garcia, executive vice-president of engineering. ‘It’s perfect for tension and fatigue, but poor for compression.’
Airbus has stepped up the war of words with Boeing after the US company criticised weight increases in the A380. Airbus claims the 7E7 will be heavier than Boeing has admitted. ‘The 7E7 carries the weight penalty of a compromised and rushed design,’ the company said.
Dr JÃ¼rgen Klenner, Airbus senior vice-president of structure engineering, said today’s carbon fibre is often no more than ‘black aluminium’ â€” with the same attributes as traditional materials â€” offering few benefits for the extra cost. Carbon fibre does have weight advantages, but according to Klenner the cost of the raw material is up to 500 per cent higher. ‘We do not apply a material because it is trendy, we do it when we are convinced it is mature enough. There are crucial questions that have not yet been answered,’ he said.
There are concerns that composites present a higher fire risk, delaminate in humid conditions, and are more expensive to repair. Prof Phil Irving, civil aviation authority expert in damage tolerance at Cranfield University, said engineers should dripfeed composites into aircraft design to avoid ‘unexpected failures. ‘There is always a risk when introducing something new on to an aircraft, no matter how many tests. There’s always something we haven’t realised.’
Bird strike, stones or taxiing accidents would greatly reduce the compressive strength of composites such as carbon fibre. ‘You can avoid the problem by making it thicker, but that has economic implications. It’s rather difficult to see how you can have a whole fuselage made of composites.’
Airbus chief executive Noel Forgeard claimed the 7E7 would have identical technology to the A380. ‘This is why Boeing has strongly discounted it to sell it,’ he said. Airbus accused Boeing of tinkering with the 7E7’s supposedly advanced technology during its development, saying the final product will be more conventional and heavier than originally claimed.
Stuart said: ‘They have rushed this aircraft through in a ridiculous way.’But Boeing denies this, pointing out that the aircraft was developed in parallel to, rather than after, the company’s now-cancelled project, the Sonic Cruiser.
A Boeing spokesman said: ‘We’ve put a great amount of work into composites, drawing on the work we’ve already done on the 777 and a whole variety of military aircraft. The 7E7 is a bold move, but if you look at the efficiency and environmental advantages it’s a move in the right direction.’
The 7E7 will contain 50 per cent of its weight in composites, making it lighter and more fuel-efficient, Boeing claims. The A380 structure contains under 25 per cent composites, while Airbus chose not to use the carbon fibre wing planned for its future military aircraft.
Boeing announced this week it expects up to 200 orders for the 7E7 in 2004. Only Japan’s All Nippon Airways and Air New Zealand have placed orders, compared with 129 orders to date for the A380.
Airbus’s approach for the A380 is in sharp contrast to Boeing’s claims for the smaller Dreamliner. Airbus is focused on shipping up to 550 people between megahub airports, while Boeing believes flying faster and lighter point-to-point is the future of air travel.