Plastics, composites, and carbon fibers are used extensively in aircraft construction in addition to metals. Plastics are used for both structural components, like reinforced plastic in wingtips, and decorative trim. Transparent plastic is used for canopies and windshields. Reinforced plastic is a sandwich material made of fiberglass facings bonded around a honeycomb core, providing high strength to weight. Composite materials using layers of graphite epoxy or boron epoxy bonded to aluminum honeycomb cores provide extra high strength to weight for high performance aircraft.

1. AIRCRAFT MATERIAL
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2.  In addition to metals, various types of plastic materials are found in aircraft
construction. Some of these plastics include transparent plastic, reinforced
plastic, composite, and carbon-fiber materials.
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3.  Plastics are used in many applications throughout modern aircraft. These
applications range from structural components of the thermosetting plastics
reinforced with fiber glass to decorative trim of thermoplastic material.
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4.  Transparent plastic is used in canopies, windshields, and other
transparent enclosures. You need to handle transparent plastic surfaces
carefully because they are relatively soft and scratch easily. At
approximately 225°F, transparent plastic becomes soft and pliable.
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5.  Reinforced plastic is used in the construction of radomes, wingtips,
stabilizer tips, antenna covers, and flight controls. Reinforced plastic has a
high strength to weight ratio and is resistant to mildew and rot. Because it is
easy to fabricate, it is equally suitable for other parts of the aircraft.
Reinforced plastic is a sandwich type material (fig. 4-4). It is made up of
two outer facings and a center layer. The facings are made up of several
layers of glass cloth, bonded together with a liquid resin. The core material
(center layer) consists of a honeycomb structure made of glass cloth.
Reinforced plastic is fabricated into a variety of cell sizes.
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7.  Rubber is used to prevent the entrance of dirt, water or air, and to prevent the loss of
fluids, gases, or air. It is also used to absorb vibration, reduce noise and cushion impact
loads. The term “Rubber” is as all inclusive as the term “metal”. It is used to include not
only natural rubber, but all synthetic and silicone rubbers.
 Natural rubber has better processing and physical properties than synthetic or silicon
rubber. These properties include :
1. Flexibility
2. Elasticity
3. Tensile strenght
4. Tear strenght
5. Low heat build up due to flexing (hysteresis)
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8.  Synthetic Rubber
 Synthetic rubber is a available in several types, each of which is compounded of
different materials to give the desired properties. The most widely used are :
1. Butyl
2. Buna-S
3. Buna-N
4. Neoprene
5. Thiokol
6. Silicon
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9.  High performance aircraft require an extra high strength to weight ratio material.
Fabrication of composite materials satisfies this special requirement. Composite
materials are constructed by using several layers of bonding materials (graphite
epoxy or boron epoxy). These materials are mechanically fastened to conventional
substructures. Another type of composite construction consists of thin graphite
epoxy skins bonded to an aluminum honeycomb core. Carbon fiber is extremely
strong, thin fiber made by heating synthetic fibers, such as rayon, until charred, and
then layering in cross sections.
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10. 1. Q4-6. Materials currently used in aircraft construction are classified as
what type of materials?
2. Q4-7. What are the most common metallic materials used in aircraft
construction?
3. Q4-8. What are the non metallic materials used in aircraft construction?
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