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Major Advantages to Composites
On a weight-for-weight comparison, composites have proved stronger than many metals. Performance characteristics directly related to an aircraft's weight are: |
Composites
are strong and stiff, like conventional airplane materials (i.e.
metals), yet, lighter in weight and offer great savings in airplane
fuel. The “Voyager” aircraft, made almost exclusively
from composites, circumnavigated the world in 1986 without refueling.
Pilots Gina Jaggard and Dick Rotten completed this historic journey
in nine days due to lightweight composites.| • Payload | |
| • Flight-range | |
| • Fuel consumption |
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Advances of strong yet light in weight composites have produced other unique aircraft designs, such as “The Daedalus.” Developed by scientists at MIT, “The Daedalus” is an ultra modern vehicle weighing less than seventy pounds (70 lbs.) and powered solely by the bicycle-like pedaling of its human pilot.
Composites were first used in military aircraft. Today's advanced
military planes, including the “F-16 fighters,” used
by the Air Force as thunderbirds for their exciting show maneuvers,
make extensive use of composite materials. The “AV-8B Harrier
II,” a vertical take-off and landing craft (STOVL), has
many component parts made of composites. Even the newest and
most advanced airplanes use composites, such as the forward swept
wings of the experimental “Drummond X-29”. The truly
space-age plane, the proposed “New Orient Express”
(X-30 NASP, National Aerospace Plane), will be able to fly commercial
passengers from Los Angeles to the Asian continent in less than
two hours. Even the “NASA Space Shuttle” utilizes composites
in its interior structure. The remote-manipulated arm, so crucial
to many shuttle missions, is made almost entirely of composites.
Special high-strength fibers, such as aramid or graphite, are used in the formation of composites. Made of highly near-polymers, they combine strength with low-weight properties. When heated, they become formable, facilitating easy shaping and diversity in designs involving complex shapes. Formed by the reaction of resin and a hardener, two different matrixes are used in composites: |
Dramatic savings
in fuel costs are due to the use of weight-reducing composites.
The stiffness, as compared with the low weight of composites,
can be illustrated by this simple test of (A) aluminum metal
against a (B) honeycomb composite with a nome core and graphite/epoxy
skin. When a two-kilogram (2-kg) weight is placed on supportive
(A) aluminum, there is slight sag. The (B) honeycomb composite,
subjected to the same load, appears unaffected, without sag or
apparent deformation.
| • Thermoplastic | Produced in diversity of designs because of its heat sensitivity |
| Uncured resin forms a variety of shapes easily | |
| Can be re-formed/recycled for use | |
| • Thermoset | Cured to give a three-dimensional, cross-linked polymer structure |
| Cured hardens into a rigid solid | |
| Cannot be melted/re-formed |