Boeing 787 Dreamliner - Mark Wagner [38]
Although glass fiber-reinforced composites, mostly in the form of thin sheets sandwiching a honeycomb core, had found their way into secondary structures on commercial aircraft in 1960s in such areas as wing-to-body fairings and secondary control surfaces, it was not until the 1970s that things really began to take off as improved CFRP was developed. As with the push for more efficient engines, the first fuel crisis of the 1970s prompted NASA, among others, to begin a more serious look at structural composites for aerospace. Thanks to the sports industry, the commercial availability of carbon and aramid fibers also meant that the raw materials were more affordable.
Early civil uses included aramid/epoxy underwing fairings of the Lockheed L-1011 in the 1970s, and a carbon/epoxy aileron on late-production TriStars. McDonnell Douglas also introduced a carbon/epoxy upper rudder into the DC-10 as well as an aft engine pylon skin made from boron and aluminum.
Boeing initially used glass fiber/epoxy in the control surfaces, fairings, and trailing edge panels in the 747, and from the late 1970s, in the Kawasaki Heavy Industries (KHI)–made flap on the 747SP. Demonstrating considerable foresight, Boeing also developed and certificated a carbon/epoxy stabilizer for the 737-200 as part of the NASA Aircraft Energy Efficiency (ACEE) program, initiated in 1975.
Under this effort 5 1/2 shipsets were installed on the 737, and the modification received FAA type certification in August 1982. The composite design, which was 21.6 percent lighter than the equivalent aluminum structure, went into service in 1984 and was later analyzed by Wichita State University’s National Institute for Aviation Research (NIAR). Encouragingly, the analysis revealed few changes in strength and other characteristics after eighteen years and fifty-two thousand flight hours in service.
CFRP composites also were used for the elevator in later 727s and for spoilers on 737s from about 1973 onward. Composites featured more extensively on the 757/767 family of the late 1970s and early 1980s, particularly on the wing-to-body fairing, main landing gear doors, engine cowls, trailing edge panels, spoilers, ailerons, rudder, elevators, and stabilizer and fin tips. In most cases the materials used included CFRP, aramid/epoxy, and aramid-carbon/epoxy and glass-carbon/epoxy hybrid composites, similar to those being used by Airbus and by McDonnell Douglas on its MD-80 series. Almost all of these the parts were made up of sheets of composite co-cured or secondarily bonded to a composite honeycomb core.
Airbus had pioneered the use of large-scale composites for primary structure when it introduced a carbon-fiber-reinforced plastic fin and tailplane into the A310-300. The innovative design also ushered in the use of the tailplane trim fuel tanks for center-of-gravity control. Here an Air Transat A310-300 sweeps low over the beach seconds from touchdown at Sint Maarten in the Caribbean. Mark Wagner
COMPOSITE FUTURE
Boeing’s biggest move toward embracing composites on a more dramatic scale, however, came with the 7J7, which was a short-to-medium-range, low-operating-cost project aimed at replacing the 727. Begun in the 1980s against a background of steadily rising fuel prices, Boeing pumped every new technological innovation into the project, including GE36 propfan engines, new avionics, a fly-by-wire flight control system, and advanced structures. The 7J7 was therefore in some ways a bellwether for Project Yellowstone and the 7E7, particularly since the 7J7 had large-scale international involvement from Japanese aerospace (hence the “J”).
The 7J7 had an unprecedented 25 percent industrial workshare allotted to the Japanese group and was to have entered service in 1992. A key product of the 7J7 experience was the teaming