Looking for Spectra shroud line material

[Neutronium95]

After Bama recovery closed up shop, I got interested in sewing my own parachutes. After having a parachute come out at Mach 1, and snap the kevlar leader, I was very impressed with the material choice in the canopy and shroud lines. I've managed to procrastinate long enough for Ben Graybeal to get back into making parachutes, but I'm still interested in making my own.

I've found similar ripstop nylon, but I haven't been able to find a source for the 200 lb Spectra that was used for the shroud lines. The closest I've been able to find is a 200lb Spectra line, but it's a braided cord, instead of a cord with a core and sheathe like was used on the Bama parachutes.

I found an article on the Fruity Chutes website, which seems to mention the lines they use, but when I search for the specific term, all I find is that article again.

 

[K'Tesh]

I would certainly doublecheck your sources... Back when I worked for Catch The Wind Kites (Florence, Oregon 1987) I used spectra line for my stunt kite(s) (500 lb test for 8-9x 6' Flexifoil Stackers). It's slick enough for stunt kites, but it has a low melting point (especially when it comes across Kevlar). It was annoying how many times another flier would cross lines with me (or vice versa) and cut my line(s).

And I'll add a little kite story:

After being hospitalized with a concussion (#1 of 3, and the first of the two that happened on the same date, one year apart) when my kite dragged me off Brill Hill (Buckinghamshire, UK (10/8/1989)), then slammed me into the ground when I twisted my ankle trying to jump clear, I coined a phrase in a Kitelines Magazine article on kite flying injuries...

If your kite can't kill you...

IT'S TOO SMALL!!!

 

[Neutronium95]

I would certainly doublecheck your sources... Back when I worked for Catch The Wind Kites (Florence, Oregon 1987) I used spectra line for my stunt kite(s) (500 lb test for 8-9x 6' Flexifoil Stackers). It's slick enough for stunt kites, but it has a low melting point (especially when it comes across Kevlar). It was annoying how many times another flier would cross lines with me (or vice versa) and cut my line(s).

It's good enough for two well regarded parachute manufacturers. I haven't run into any issues with the melting point on the parachutes I've gotten from Bama. Parachute shroud lines shouldn't be exposed to high temp gasses from ejection charges anyways.

 

[Andrew Brown]

Following as I'm very interested in what you find. I've been using 200 lbs test Dacron line and interested in better options.

 

[mtnmanak]

All the spectra lines on my Fruity Chutes are braided lines, which are pretty easy to get. Basically, it is just spectra braided fishing line:

200# example: https://www.amazon.com/PowerPro-Spectra-Hollow-ACE-200-White/dp/B004U6NDCC

400#: https://www.amazon.com/Braided-Spectra-Bowfishing-Select-Length/dp/B01N6QD0H

500#+: https://bluetunaspearfishing.com/products/spectra-reel-line-500-725-1000-lb-strength-per-foot

It sounds like the product you are looking for is sheathed cordage (like this: https://speargun.com/products/spectra-wishbone-line-1000-lb-per-foot), but I prefer braided lines for parachutes. They are lighter and pack smaller.

 

[sriegel]

I use 200# 8-strand braided Spectra as my standard. As others have said, fishing line is great. I am looking to play with some 12-strand hollow line to allow splices for a particular application down the road.

Regarding melting, I've had only one report of a popped line and that was on a previously damaged line (singed in a ground test) when the airframe went sideways in a gnarly wind. The deployment happened well above what any of us would consider a prudent velocity...

 

[AlexBruccoleri]

How does Spectra compare to nylon in regards to melting and longevity? It is certainly stronger but curious on robustness over the long term.

 

[OzHybrid]

I believe the type of line you are looking for is UHMWPE. Either as braided fishing line, speargun line or rope. Use the term you want to find the diameter you're after.

 

[justforfun]

I use Spectra / Dyneema Ultra-High Molecular Weight Polyethylene line.

https://www.amazon.com/Dorisea-Extreme-109Yards-2187Yards-Incredible-Superline/dp/B07TSN7VRQ?th=1
Roy

 

[mtnmanak]

How does Spectra compare to nylon in regards to melting and longevity? It is certainly stronger but curious on robustness over the long term.

https://www.christinedemerchant.com/rope_material_comparison.html
https://southernropes.com/ropeinfo

 

[AlexBruccoleri]

https://www.christinedemerchant.com/rope_material_comparison.html
https://southernropes.com/ropeinfo

Thanks! On a practical level it is hard to tell how the lines hold up to real world conditions. How has your experience been? Have you had any lines get scorched and fail, do they tend to hold up for one mishap?

 

[mtnmanak]

Thanks! On a practical level it is hard to tell how the lines hold up to real world conditions. How has your experience been? Have you had any lines get scorched and fail, do they tend to hold up for one mishap?

I have had some spectra lines get "scorched" due to exposure to an deployment charge, but not fail. The only lines I have had fail, thus far, were nylon lines. In both instances, the failures were on Fruity Chutes and neither failure was due to heat - they were snapped due to either a manufacturing defect or the line was cut when it hit a sharp piece of metal (design flaw on my part) in the rocket.

My anecdotal experience of only hundreds/thousands of flights (which, in the grand scheme of things, is a pretty low amount of data) is that spectra lines are stronger, smaller, lighter and pack better.

Caveat - I try to take pride in packing my chutes well and protecting them with an abundance of nomex - my preferred method is to use deployment bags, but do use pouches and blankets for smaller rockets. Therefore, I have little data about how well spectra lines stand up to repeated exposure to extreme heat.

 

[AlexBruccoleri]

My anecdotal experience of only hundreds/thousands of flights (which, in the grand scheme of things, is a pretty low amount of data) is that spectra lines are stronger, smaller, lighter and pack better.

Thank you for the detailed reply. It’s worth noting you are one of the most experienced and thoughtful fliers I know. Your data set is not that small, at least I find it useful to guide some of my decisions.