rigger, has more good than poor qualities.
First, we will review the good characteristics of
nylon:
1. Strength. Nylon is one of the strongest
synthetics made.
2. Elongation. Nylon stretches from 18 to 40
percent, which is well above military specifications
of 20 to 25 percent.
3. Elasticity. Nylon returns to 100 percent of
its original length.
4. Weight. Nylon fibers are very strong for
their weight; therefore, the fabrics manufactured
of nylon fibers are lightweight fabrics.
5. Resistance to abrasion. Nylon doesn’t have
enough resistance to last forever under all the
rugged use parachutes get, but it is better than
any other material tested for parachute use.
6. Resistance to mildew and insects. Nylon
has no food value. This makes it unappetizing to
moths and other insects. It cannot support the
growth of mildew. This isn’t true, however, when
a cup of coffee is accidentally spilled on a
parachute assembly, or other edible foreign matter
comes in contact with it. What we really mean
is clean nylon has no food value.
We warned you that nylon is not the perfect
fabric. Where possible, improvements have been
made in manufacturing nylon. The limitations you
must keep in mind when handling nylon are as
follows:
1. Moisture regain. Remember, we said that
if the percentage of moisture a fiber absorbs from
the air is less than 5 percent, the fiber is difficult
to dye and builds up static electricity when rubbed.
The moisture regain of nylon is only 4.2 percent,
so you can expect static electricity to develop as
you service the assembly.
2. Resistance to sunlight. We mentioned
earlier that yellow dye improves resistance to
ultraviolet light damage. That is why yellow dye
is added to deceleration canopy material. In
addition, a chemical known as Chemstrand “R”
has been developed, which, when added to nylon
fiber as the yarns are manufactured, makes nylon
more resistant to ultraviolet light.
3. Heat resistance. Nylon has a relatively low
melting point, 482 °F, which makes it very
susceptible to damage from heat. This is why it
is so important that suspension lines be stowed
properly. In the rapid deployment sequence, lines
crossing each other will break from the friction
heat generated.
In short, there are several natural enemies to
be aware of when you handle parachute textiles
of any type. These are the hazards of sunlight,
abrasion, heat, chemicals, insects, and fungi on
parachute components.
Keep in mind the natural enemies of textiles
you have learned. Then it is easy to see which
elements are to be avoided when you store
parachute fabrics.
SPECIAL HAND TOOLS
When working in the fabric shop, you will find
that you have a need for tools that are not
commonly stocked in the average tool room.
Therefore, we must discuss some of the specific
tools used in the fabric shop. The tools used for
fabric and rubber maintenance are not highly
complicated, but they are designed for a specific
purpose. In your hands these tools can help
produce a finished product of which you can be
proud.
SHEARS
A scissor-type tool that you often use for
fabric work is known as shears, as shown in figure
10-5. A pair of shears consists of two cutting edges
so hinged that, when closed, the cutting edges
cross each other in close contact. This shearing
action is used for cutting fabrics. The large loop
in the handle is for two or three fingers and the
small loop is for the thumb. The blades are not
straight, but are slightly curved toward each other
so that, inclosing, the two cutting edges are held
firmly together by the spring action of the blades.
Always keep the shears sharp. If the shears
are not sharp enough to effectively cut the
material, they must be sharpened. A more
239.370
Figure 10-5.—Shears.
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