Characteristics, Properties, and Types of Fabrics Used in Aeroplanes Flashcards
Define the term “weft” or “fill” in fabric construction.
“Weft” or “fill” refers to the threads that run perpendicular (90°) to the warp fibres. These threads interweave with the warp threads to create the reinforcing cloth.
Define the term “warp” in fabric construction.
“Warp” refers to the threads that run the length of the fabric as it comes off the roll or bolt. Warp direction is designated as 0° and has more threads woven into it, making it stronger than the fill direction. The warp must be applied parallel to the direction of flight in aircraft construction.
What are the primary types of fabrics used in aircraft construction today?
The primary types of fabrics used today are polyester-fibre materials and glass-fibre materials. These materials are less sensitive to the elements than traditional fabrics like cotton and linen and offer longer service lives.
Describe the historical significance of fabric-covered aircraft.
Fabric-covered aircraft played an important role in aviation history, such as the Wright Flyer, which used fabric to cover its wooden frame. Though rarely used today due to advancements in materials like aluminum and composites, fabric coverings remain important for the restoration of older aircraft and some modern light aircraft.
Define the term “bias” in fabric construction.
“Bias” is the fibre orientation that runs at a 45° angle to the warp threads. The bias allows manipulation of the fabric to form contoured shapes and can be stretched along the bias, but rarely along the warp or fill
What is a “selvage edge” in fabric construction?
“Selvage edge” (or “selvedge”) is the tightly woven edge parallel to the warp direction that prevents the threads from unraveling. This edge must be removed before the fabric is used since it does not have the same characteristics as the rest of the fabric.
Describe the properties and characteristics of cotton and linen materials used in aircraft.
Cotton and linen are older materials for covering aircraft but have a relatively short service life due to biological effects like mildew and UV sensitivity. These materials require significant labor for proper application and maintenance, making them less cost-effective compared to modern alternatives.
Describe the properties and characteristics of polyester-fibre materials used in aircraft.
Polyester-fibre materials are fitted using pre-sewn covering envelopes or an approved adhesive. A good fit is achieved by ironing, and they are less sensitive to the elements than natural fabrics. Polyester deteriorates mainly due to UV light exposure, but applying approved coatings can protect the fabric and extend its service life.
Describe the properties and characteristics of glass-fibre materials used in aircraft.
Glass-fibre fabric is typically fitted to the mainplane and tailplane in a spanwise direction. Like polyester fibre, it is less sensitive to environmental elements than natural fabrics.
What are aircraft dopes, and why are they used?
Aircraft dopes are coatings, originally based on cellulose dissolved in nitric or butyric acid, applied to fabrics to tighten, stiffen, and make them airtight and weatherproof. They provide a smooth, durable finish and protect the fabric from elements like moisture, dirt, and UV radiation.
Explain the advantages and disadvantages of nitrate dope.
Nitrate dope provides excellent adhesion and protection for fabrics, making them airtight and weatherproof. However, it is highly flammable, which is a significant safety concern.
How does butyrate dope differ from nitrate dope, and why are they used together?
Butyrate dope is less flammable than nitrate dope and protects the fabric from dirt and moisture but does not adhere well to fabrics on its own. A combination of nitrate dope for adhesion and butyrate dope for reduced flammability is often used.
What are the ideal storage conditions for aircraft fabrics?
Aircraft fabrics should be stored at a temperature of about 20°C (68°F) in dry, clean conditions, away from direct sunlight.
What safety precautions should be followed when applying aircraft dopes?
Safety precautions when applying aircraft dopes include reading the manufacturer’s safety data sheets, wearing appropriate Personal Protective Equipment (PPE), and only applying dope in a well-ventilated environment to avoid intoxication and injuries.
Why are aluminium solids added to butyrate dope?
Aluminium solids are added to butyrate dope to reflect UV rays, protecting both the fabric and the underlying aircraft structure from UV damage.
