Boys and girls who decades ago assembled scale-model aeroplanes in plastic are today doing the same for real aircraft at full scale. With composites reaching proportions of up to 50% by weight in the latest aircraft, the signs are that the age of metallic preponderance in airframes could be coming to an end. Nowhere is this more true than in commercial air transport. Here we review progress on some of the flag bearers leading the charge for composites in this sector.
At the forefront are Boeing, with its B787 Dreamliner, now well established in service, and the Airbus A350XWB, which recently entered airline service also. Both are approximately half metal, half plastic.
Dreamliner
After suffering a fraught development phase, followed by troublesome issues in early service, Boeing's revolutionary new passenger jet has been settling down on customer route networks. One of the lightest aircraft for its size and capacity (nearly 300 passengers on the −9 variant), the 787 has carbonfiber content that includes the fuselage, center wing box, wing skins with integral stringers, raked wing tips, tail cone, horizontal and vertical stabilizers, control surfaces, internal pressure bulkheads, floor structure, certain engine parts and various fairings. The fuselage, made up of tape-wound barrel sections, is the most revolutionary aspect and the first for a commercial airliner. A maiden flight in December 2009 was followed by entry into service with launch customer All Nippon Airways (ANA) in 2011.
With 270-plus Dreamliners now delivered, the type is earning revenue for dozens of operators worldwide. Customers reporting creditable performance and fuel economy have helped boost the orders total to 1184 (at time of writing). To meet high demand, Boeing managed to ship 114 units last year and is targeting build rates of 12 per month by late 2016 and 14 per month by 2018. By late this year it intends to have rationalized manufacture to two main production lines, one at Everett, Seattle and the other at Charleston, South Carolina. By then it will have closed a third, temporary ‘surge’ line at Everett, thereby reducing unit production cost.
With such large orders and each aircraft having, on average, some 23 tons of CFRP, it is small wonder that Toray, as one major player in the extensive supply chain, has felt it worthwhile to open a new carbonfiber factory at Charleston. Other suppliers are cashing in, but only if they can keep up with the rates Boeing demands. Spirit AeroSystems, for one, is investing over $100m on automated manufacturing so that it can deliver major structures at appropriate speed, not just for the B787 but also for other platforms, notably including Dreamliner's European competitor, the Airbus A350.
One fly in the ointment for Boeing is that the battery problem which grounded for three months most of the world delivered B787 fleet early in the type's service, has never been satisfactorily explained. Lithium-ion batteries used to start the auxiliary power unit suffered over-heating, thermal runaway and even combustion but modifications carried out since have ensured that any recurrence is at least contained and cannot spread to adjacent structure. The extended supply chain within which this happened was part of Boeing's intended business model for the 787, and the misadventure prompted the airframer to bring several previously outsourced functions back in house so that it could maintain effective oversight.
Other issues included fuel leaks, electrical problems and software glitches. Unfortunately for Boeing, B787 development coincided with the rise of social media so that every setback quickly became widely aired. Most have now been overcome and dispatch reliability has risen to 98%, against a target of something over 99%, preferably the 99.5% yardstick set by Boeing's B777 fleet. Meanwhile, one of the flight test fleet has already become a museum piece, being displayed at the Museum of Flight in Seattle.
This article appeared in the July/Aug issue of Reinforced Plastics.
