To engineers, the Boeing Co (BA.N) 787 is made from reinforced carbon composites. To everyone else, the Dreamliner is the world's first plastic jet.
Boeing's departure from traditionally reliable aluminum construction was driven by airlines demanding a big plane that requires less fuel to operate and is less costly to maintain.
Common in military aircraft for some time and in a range of everyday products from soup ladles to golf clubs, composites are showing up more frequently on commercial planes.
Some Boeing 777s have composite tails and its European rival, Airbus EAD.PA, has used composites for years on its planes, including the superjumbo A380 that first flew in 2007. Its rival to the 787, the A350, is due to be mostly composite.
But Boeing has made the substantial business and scientific bet first. Composite materials comprise 50 percent of the Dreamliner, including the huge, single-piece fuselage barrel that will seat about 250 passengers and wings holding thousands of gallons of jet fuel.
"It's gutsy," said David Roylance, a materials engineering expert at Massachusetts Institute of Technology who said designers are comfortable with composites although the scale of use on the 787 has yet to be seen on a large commercial plane.
The Dreamliner design advanced after Boeing scrapped plans for a faster plane called the Sonic Cruiser. In the throes of a financial slide accelerated by the September 11 attacks, airlines in 2002 expressed a preference for greater efficiency and lower costs in a new design.
Boeing had experience with smaller-scale carbon fiber and blending it with light metals, like titanium, which comprises 15 percent of the Dreamliner.
It knew about the less-dense, high strength-to-weight properties of composites and considered using carbon-reinforced paneling before settling on a seamless technique for wrapping a gooey mix of super-strong carbon fibers bathed in epoxy around a mold and then stuffing it in a giant oven.
With lighter materials, Boeing expects the Dreamliner to use 20 percent less fuel. A contoured exterior and fewer rivets and metal fasteners enhance aerodynamics also lowering weight.
Mark Tuttle, who led a team at the University of Washington partly funded by Boeing that analyzed composites for the 787, said the new design should enhance passenger comfort as well.
For instance, Tuttle said the nonmetal fuselage will allow the crew to maintain higher humidity in the cabin. An allowance for higher air pressure may help lower incidence of jet lag. Finally, the 787's windows are 30 percent larger than conventional windows on a passenger jet.
"This is a big step for Boeing," Tuttle said. "I would say composites are here to stay."
Beyond expected fuel savings, airlines expect maintenance costs should fall by about 30 percent because composites -- unlike aluminum -- do not corrode and will not require a similar frequency of inspection and repair.
Safety advocates generally approve of the 787 design, but they have raised some questions over the years about crashworthiness of rigid composites, epoxy resin and toxicity in fires and detecting imperfections in the fiber laminates.
Jim Hall, a former chairman of the National Transportation Safety Board, said "what we don't know" about how composites will perform at the 787 scale is a disadvantage.
There have been some problems on a smaller scale. For instance, the Federal Aviation Administration proposed a $2.4 million fine last week against Cessna Aircraft Co, a unit of Textron (TXT.N), for alleged quality control problems at a plant in Mexico where composites used for making wings on a high-performance plane did not cure properly. Cessna says it has made changes to the plant and is working with the FAA.
Boeing made fuselage design changes to improve crash protection, and the FAA said composites performed well in tests in preventing fire and toxic fumes from penetrating the cabin. The FAA certified the plane for carrying passengers in August.
John Goglia, a former mechanic and NTSB member, called the 787 safe but said there would be startup challenges.
One concern, Goglia said, is the potential for damage from normal rigors of airline and airport operations.
"I think initially the airlines and the manufacturer will be sensitive to everything that happens to that aircraft," Goglia said. "They will pay special attention to the jetway and ground workers and baggage handling around the plane."
(Reporting by John Crawley in Washington DC, editing by Matthew Lewis)