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Comment: Added information on nylon permability and specification. Also added details on treating fabrics.

...

The following fabrics are used in parachute fabrication (information gathered from Knake, Section 6 and Poynte, Section 4):

Natural Fibers
  • silk
  • cotton

...

A common type of nylon for parachutes is MIL-C-7020.

Fabrics are specified in

Mathinline
body\frac{oz}{yd^2}
and have permabilities between 80-120 cubic feet per minute (cfm).

  • Teflon
  • Rayon

This outdated material burns easily and has poor performance when wet.

Treated Fabrics

A note on treated fabrics from Poynter (4.021): coating/treating a fabric may decrease tear strength by preventing the fibers from adjusting around a tear.

Terminology

tenacity: a strength metric for yarn or fiber; 

Mathinline
body\frac{fiber \ breaking \ force}{denier}

...

Heinrich and Haak, Stability and Drag of Parachutes With Varying Effective Porosity

Dan Poynter, The Parachute Manual: A Technical Treatise on Aerodynamic Decelerators, Third Ed.