Tubular Nylon Replacements

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


Well-Known Member
Jan 9, 2004
Reaction score
Hey guys,

I have a couple questions about TN. I have been using 9/16 TN for connecting my parachute and my two sections. I really like TN, but it is bulky and weight a lot. I want to use drogue-less dual deploy with my L1 rocket-rebuild - and wondering what alternatives I have to TN for keeping the two sections together? Also - any other ropes/cords I can use for attaching the parachute to my e-bay u-bolts?


there are some climbing cords, but they are hard to tie and the knots become bulky and I dont think you save any weight. There is also tubular Kevlar but I think that is just as heavy. IN the end Tubular Nylon yeilds the best results because it is easy to knot, doesnt take up to much space, and is strong
as far as I know right now TN is about the best thing readily available.
It does seem to me I read about Spider Wire in larger than fishing line sizes but can't seem to find anything about it right now. I would imagine it would be costly if you can find it.
You can get tubular nylon in smaller sizes. It's used for lacing snowshoes.
Where do they sell it? I'm looking for 1/4ish sized...


You can get some nice Kevlar cord in that size from Pratt Hobbies.
I too need tubular nylon or Kevlar but can't figure out the "size" in relation to inches. I need something a tad smaller that 3/32". If anyone with such knowledge please help me. BTW if you are familiar with the Estes Blurrz Rocket Cars. I seek something that is exact or simliar to the tether line used with those kits.
you could use something of smaller diameter and you might save weight but I still would Use tubular. If you use a "line" then your chances of zipper are huge because there is mor pressur because the force is not spread out as much as with tubular nylon
It is not that difficult to make anti-zipper devices for your Kevlar twine or small braid (or for larger types for that matter). On modroc sized lines, this can be as easy as a piece of tape folded across the line at the point it touches the BT. On the Pratt mini kevlar braid, I have used a rubber ball and even bubble wrap covered in cloth tape.

One item that I've used for mid-power rockets is nylon cord from REI (https://www.rei.com). Their 4mm accessory cord has a breaking strength of about 700# and is much easier to pack into a confined space than 9/16" TN.

The only problem with the cord is that for maximum strength you need to "whip" loops into the ends of the cord instead of tying a knot. Whipping loops is easy to do, you basically use a light thread wrapped around the cord to "squeese" the tag end of the line to the running line. Get a copy of "Chapman Knots for Boaters" from your local library. It has a chapter on whipping with photographs and illustrations.

Ken Holloway
I am using it as a guide/tether line for a ground based rocket powered project. I plan on posting the results but in the mean time I need the cord first. I appreciate all of the comments though.