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The following fabrics are used in parachute fabrication (information gathered from Knake, Section 6.6.1):
Natural Fibers
- silk
- cotton
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This is the most-commonly used fabric for parachute gores. All of the MIT Rocket Team's Parachutes to date (January, 2018) have been fabricated out of the ripstop variety. It is important to note that nylon retains most of its strength up to 250 degrees Fahrenheit. Nylon has the following, other general property ranges:
- elongation
Mathinline body 29 \rightarrow 40\% - tenacity:
, usually 6.6 for parachuteMathinline body 2.5 \rightarrow 9.5 \frac{g}{denier}
- elongation
A common type of nylon for parachutes is MIL-C-7020.
- Teflon
- Rayon
This outdated material burns easily and has poor performance when wet.
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denier: fiber mass per 9000 meters
Procedures
Shroud Lines
From Knacke (6-84), "all lines and tapes are [traditionally] measured under a preload. A preload of about 1% of the ultimate material strength is required to align all fibers in the woven or braided material before the individual fibers are stretched." Furthermore, "[it] is practical to let all fabrics relax for a short period after rewinding from the storage spool before measuring the material."
Terminology
take-up: the shortening of two pieces of fabric around the seam. Ideal parachute design takes this into account.
Resources
T.W. Knacke, Parachute Recovery Systems: Design Manual
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