Richard Nakka's Experimental Rocketry Web Site

Fabric for canopy

Suggested material is lightweight ripstop nylon. For the prototype parachute that I constructed, I simply used a nylon shower curtain, which was nearly ideal, the only drawbacks being it was not ripstop and that it was somewhat heavier fabric than was necessary. It had a nice tight weave, not surprisingly, since it's intended purpose dictates that it be water-resistant! The following table lists the specifications for commercial parachute fabrics, as well as for the fabric that I used for the prototype parachute:

Parachute Fabric Properties

			WARP	FILL	THICKNESS	TEARING	BREAK	AIR
MIL		WEIGHT	COUNT	COUNT		STRENGTH	STRENGTH	PERMEABILITY
CODE	TYPE	(oz/sq.yd.)	(per in.)	(per in.)	(in)	(lbs)	(lbs/in)	(CFM/sq.ft)
498E	D	0.88	90	90	N.A.	2.5	40	300-500
498E	G	0.88	90	90	N.A.	2.5	40	100-325
7020H	I	1.10	120	120	0.003	5.0	42	80-120
7020H	II	1.60	120	120	0.004	5.0	50	100-160
44378	I	1.17	126	132	0.003	5.0	45	0-5
*	*	1.81	80	100	0.004	N.A.	47	N.A.

*  IKEA^tm, Billingen shower curtain (white) or Rosanna (off-white), 180x200 cm.; p/n 17763 (Billigen), 14331 (Rosanna), $14.50 CAD (sufficient fabric to make two 1-metre diameter canopies). Fabric for both is identical (100% nylon). The latter has a water-repellant coating, but this can be eliminated (before dyeing) by washing the fabric in hot water with laundry detergent. Properties listed for this fabric were determined by measurement and/or testing.

Fabric Dye

One half of the quantity of fabric that was used to make the canopy was dyed red. The dye used was:

• RIT ^tm, tint & dye, #5 scarlet, one 32 gram package, $1.77 CAD.

Cord for shroud lines

The type that I used was braided nylon cord, the kind that is sold in the camping department of stores. The specific type that I used was:

• World Famous^tm, p/n 3150, 15 m. package, $2.47 CAD.

The approximate width and thickness of the cord, measured under light tension loading, are :

• width = 0.175 in. (4.5 mm)
• thickness = 0.050 in. (1.27 mm)

and the cord tested breaking strength is:

• Breaking strength = 185 lbs (822 N.) average

Sewing thread

The thread that was used for machine stitching the canopy together and for sewing the shroud lines to the canopy was the following:

• Coats ^tm, 100% nylon upholstery thread, 137 m. spool, $2.79 CAD

The measured diameter, and tested breaking strength of the thread are:

• Diameter = 0.013 in. (0.33 mm)
• Breaking strength = 9 lb. (40 N.) average

Seam Binding

The seam binding that was used to join the canopy panels was as follows:

• Wrights ^tm, Iron On Hem Tape, 100% polyester, PC22, 2.75 m. package, $1.97 CAD

which is identical to the
• Wrights ^tm, "Soft and Easy" Seam binding, 100% polyester, PC16, 2.75 m. package, $1.97 CAD

except that the hem tape has heat activated adhesive to facilitate the joining process.

The measured dimensions and tested breaking strength are:

• width = 0.525 in. (13 mm)
• thickness = 0.005 in. (0.13 mm)
• Breaking strength (longitudinal) = 61 lbs (271 N.) average
• Breaking strength (transverse) = 46 lbs/in (81 N/cm.) minimum