Boeing 787 Dreamliner - Mark Wagner [40]
Following the game-changing moves during the buildup to Y-2 and the intervention of the Phantom Works (see chapter 1), the stage was set for the use of composites on the 7E7. The questions were how much, and what they would be used for. The answers, when they first emerged at the Paris Air Show in June 2003, shocked the outside world. Not just the empennage but also the whole primary fuselage and wing structure was to be made of composites, representing a staggering 50 percent of the new jet by weight. Depending on the 7E7 version, Boeing said this would make it twenty thousand to forty thousand pounds lighter than its nearest rival, the A330-200. Yet the 7E7 would still be able to fly 1,700 nautical miles farther with the same load of about 250 passengers.
Originally Boeing intended assembling the structure in a conventional way, but using composite panels in place of metal sheets—the “black aluminum” approach. Gillette said that instead Boeing “took the challenge of understanding the properties of composites and decided to make the fuselage in one piece. It’s what composites really want.” The ovoid cross section of the new airliner was well suited to the use of the new material, he said. Unlike former Boeing 7-series designs, in which the intersections between the ellipses were contoured out with aluminum, composites allowed the entire one-piece section to be completed without any additional strengthening or filleting. “It’s fifteen to twenty percent lighter than aluminum, doesn’t fatigue and doesn’t corrode, and will require a lot less maintenance over the life of the program,” said Gillette. Stringers would be co-cured into the structure in the autoclave, and mechanically fastened composite circumferencial frames, floor beams, and panels would run the length of the fuselage.
Mitsubishi’s composite wing know-how was perfected on the Japan Air Self-Defense Force F-2 attack fighter, a growth derivative of the Lockheed Martin F-16. The Mitsubishi-designed, graphite-epoxy composite lower-wing box structure included lower skin, spars, ribs, and cap, and was co-cured together in an autoclave. The wing, which had a Fuji-made upper skin, was the first use of co-cured technology in a production tactical fighter, and paved the way for the 787.
The 777 was the first production Boeing jetliner to use large-scale composite materials in the primary structure. The main torque box of the vertical stabilizer was a graphite-reinforced unit made up of front and rear spars, while the whole box was covered with composite skins. For reinsurance the conservative design included a conventional aluminum auxiliary spar. The rudder also was made up of carbon fiber-epoxy sandwich panels attached to carbon fiber spars and ribs. Mark Wagner
The company made the gutsy commitment to go to a single-piece barrel in late 2003, thanks to the “instrumental” influence of Frank Statkus, the former Joint Strike Fighter program vice president, who had recently been appointed vice president of advanced technology, tools, and processes. “We knew we would one day figure it out: the question was could we make it in time to meet the delivery schedule,” said Gillette. “The challenge was to understand a manufacturing plan that allows you to build them at a commercial rate,” he added.
By May 2004 Boeing announced that Tokyo-based Toray Industries, one of its main suppliers for composite materials on the 777, had been selected to provide its 3900-series toughened carbon fiber–reinforced epoxy prepreg material for the 7E7. Based on Boeing’s BMS8-276 specifications—regarded industrywide as one of the most exacting material standards—Toray planned to produce an array of toughened polyacrylonitrile-based fibers for the job. T800S was selected because of its applicability