An ode to the A380
In mid-February, Airbus announced it will make the final delivery of the A380, the world’s largest commercial aircraft, sometime in 2021. This followed the cancellation of orders from Emirates Airlines, the largest customer of the plane since it was first delivered in late 2007 to Singapore Airlines. Once the remaining orders are filled, Airbus will have produced 251 aircraft, but will fail to break even on the development costs. A common argument for the lack of demand for the plane is a fundamental change in the aviation industry, moving from a large international airport hub-and-spoke model to a point-to-point model, which involves smaller twin-aisle jets efficiently moving people across oceans without having to make connections to reach their destinations. The high cost of the A380, and its large size limiting the airports that had infrastructure to handle it, may have doomed it from the beginning.
Standing more than seven stories tall with capacity for more than 500 passengers in a three-class configuration, the A380 was touted as much more fuel-efficient than Boeing’s largest offering, the 747. Although I have yet to climb aboard an A380, many friends have commented to me how comfortable and quiet the aircraft is in flight. Though the cancellation of orders from Emirates was obviously a setback for Airbus, Emirates converted its canceled orders to other Airbus planes, notably the composites-intensive A350 XWB.
In 2002, three years before the first A380 aircraft took flight, I had the opportunity to write the feature story about the materials and processes on the A380 for the September issue of High-Performance Composites, the predecessor to CompositesWorld. We had been granted extensive access to Airbus management and to the supply chain, which provided us with lots of information — so much that I requested (and was granted) a double-length feature of 10 magazine pages, a length which had not been done prior, and I don’t believe since. There was just so much to tell, and I believe it was the most comprehensive story ever written about composites on the A380. Even then, we followed with four additional in-depth articles over the next couple of years on some of the more novel processes and applications used on the A380.
The A380 was composed of more composites content than any passenger plane that came before it, with 16 percent of the structural weight from advanced polymer composites. I contend it is more multimaterial and more multiprocess than any commercial aircraft ever built, and when one considers the massive size of the components (the carbon fiber center wing box, the first ever for a commercial plane, alone weighed more than 9 tons), it stands as a groundbreaking achievement in aviation. An additional four percent of the structural weight came from the use of GLARE (glass laminate aluminum-reinforced epoxy) in the upper fuselage panels and leading edges of the vertical and horizontal stabilizers.
What were some of the other innovations? To start, the use of automated tape laying (ATL) on large airfoil skins in the horizontal and vertical stabilizers. The A380 horizontal rear stabilizer is approximately the dimension of the main wing of the A310 twin-aisle, 220-passenger aircraft, so this was a big step up from previous aircraft. Success here, I believe, led to the confidence to produce the main wing skins of the Boeing 787 and the A350 XWB. The rear pressure bulkhead of the A380, measuring 6.2 by 5.5 meters, was produced using resin film infusion and non-crimp carbon fiber fabrics — breakthroughs in materials and processing for a part this size.
The upper cabin floor beams, spanning the full width of the aircraft (5.92 meters) without stanchions, were produced using a novel prepreg pultrusion process developed by JAMCO in Japan. The same process provided stringers and stiffeners for the vertical tailplane, which were much smaller and already proven across multiple Airbus aircraft. The leading edge of the main wings, also called the D-nose, was produced from glass fiber-reinforced PPS thermoplastic. Although this technology had been initially used on the A340-600, the size of the A380 provided plenty of challenges. The parts married autoclaved PPS skins to compression-molded ribs and stiffeners via thermoplastic welding, rather than adhesives or mechanical fasteners. Resin transfer molding (RTM) and vacuum-assisted RTM (VARTM) featured extensively in the aft fuselage and vertical tail plane, in spars, frames and other structures. Automated fiber placement (AFP) simplified fabrication of the aft fuselage skin panels.
I could go on, but the point is clear: While many will consider the A380 a commercial failure, the success of the A350 XWB and Boeing 787, both groundbreaking in their own ways, owe a great deal to the materials and processes advanced by the A380.
Compared to legacy materials like steel, aluminum, iron and titanium, composites are still coming of age, and only just now are being better understood by design and manufacturing engineers. However, composites’ physical properties — combined with unbeatable light weight — make them undeniably attractive.
The structural properties of composite materials are derived primarily from the fiber reinforcement. Fiber types, their manufacture, their uses and the end-market applications in which they find most use are described.
Applications aren't as demanding as airframe composites, but requirements are still exacting — passenger safety is key.