Content area
Full Text
The development of the Boeing 777 was made possible by the development of breakthrough materials that allowed reductions in structural weight while maintaining affordability.
Nestled between the 767 and the 747 in terms of size, the Boeing 777 is the world's largest twin-engine airplane. It was initially conceived as an enlarged version of the 767, but it grew to 85% of the 747 in actual size, and sports a wingspan of nearly 200 feet and a fuselage approximately 11 feet in diameter. Its passenger seating and range combination put it in a unique niche that has allowed development of a generation of stretch and range variants.
To enable such a large twin-engine airplane, Boeing had to achieve significant reductions in structural weight while maintaining overall affordability. This was made possible by the development of breakthrough materials.
The 777 Program enabled the maturation of a large number of materials that were under development in the mid- to late-1980s. Materials that were transitioned into production included new advanced 7000 and 2000 series aluminum alloys, damage-tolerant composites, and advanced titanium alloys. These materials as well as non-structural materials advances enabled a reduction in weight of over 5800 pounds.
The aluminum airplane
From a structural-weight standpoint, the 777 is primarily an aluminum airplane. Seventy percent of the overall structure is aluminum, including the wing box and fuselage. Of course, the aluminum alloys are not the garden-variety aerospace materials of the past. These are engineered alloys offering improved strength, toughness, and corrosion resistance.
Despite the predominance of aluminum, the 777 does contain significantly more composite materials by weight than earlier Boeing aircraft. The vertical fin, horizontal stabilizers, and passenger-floor beams utilize a Boeing/supplier developed toughened, damage-resistant carbon fiber epoxy resin system.
Titanium alloy improvements are critical in combating the galvanic potential difference between aluminum and Carbon Fiber Reinforced Plastic (CFRP), and titanium alloys are used extensively in interface areas. In addition, titanium replaced many steel components in the landing gear and engine strut area in an effort to reduce weight and improve corrosion resistance.
Although structural materials receive the most attention, it is important to note that the 777 also paved the way for a wide variety of non-structural advanced materials. Significant material applications included the introduction of...