Composites may be the sexy story in aircraft structures - but overlook metallics at your peril, says GKN. Outlining the company's three-pronged development approach, GKN technology chief Rich Oldfield says that while carbonfibre composites are projected to grow to account for 50% of a typical airliner, that leaves half the aircraft to be made of metal.

And, says Oldfield, there are many aerospace applications for which the benefits of composite construction are proving inconclusive, while at the same time companies like GKN have enormous investment in capacity to fabricate components in metal. So it's crucial from both an engineering and a financial perspective to improve metal fabrication.

First, he says, to reduce weight and cut the amount of machining time needed - and reduce waste - structures need to be optimised. Ultimately, to move away from extensive component machining, techniques for achieving "closer net shape raw materials" must be industrialised. These range from increased use of welding to build up machining blanks that approximate final shapes to additive techniques.

And, says, Oldfield, new metallic materials - including nanometals - will also play a role.

There remains much to be done to move beyond first- and second-generation composites to take better advantage of their properties, he adds. To bring extensive use of composites to the next generation of single aisle airliners, manufacturing techniques must still be developed to reduce manufacturing cost, increase rate of production, and improve repairability.

Overall aircraft design also has to change to take full advantage of composites: "We're still designing effectively in a metallic world."

Composites, he stresses, also open a new world of opportunities to move beyond "dumb structures" to structure with embedded capabilities like anti-icing, structural health monitoring and low drag coatings.

GKN-made composite leading edges on the Boeing 787 are one example of a smart structure already flying, with built-in electric anti-icing.

Source: Flight Daily News

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