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Comment: Added section on fabrics

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Hermes Disk-Band Gap Drogue

Materials

Porosity

There are two types of porosity related to parachutes: fabric and geometric porosity. Fabric porosity relates to the inherent permeability of the parachute material. Geometric porosity relates to what percent of the parachute's canopy is "cut out." The equivalent metric between fabric and geometric porosity measures is 27.4 ft3/ft2/min, at 1/2-inch water pressure ≈ 1% geometric porosity (Knacke, 5-71).

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Mathinline
bodyPorosity \uparrow: C_{D} \downarrow, F_{opening} \downarrow, Oscillation \downarrow

Fabrics

The following fabrics are used in parachute fabrication:

Natural Fibers
  • silk
  • cotton
Man-made fibers
  • Kevlar
  • Dacron
  • Nylon
  • Teflon
  • Rayon

Resources

T.W. Knacke, Parachute Recovery Systems: Design Manual

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