Airbus: 7E7 is rushed and ridiculous
From The Engineer, 11 June 2004
Rushed and ridiculous
By Richard Fisher
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 Jürgen Klenner, Airbus senior vice-president of structure
engineering, said today's carbon fibre is often no more than 'black
aluminium' - with the same attributes as traditional materials
-
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.