L2 Kevlar Cord Replacement

[dragonsp]

I did some deployment testing for my L2 bird earlier, and to my surprise, one of the charges blew the shock cord apart. It was even glowing and smoldering when I came to it, which made me question how much heat this Aerocon kevlar can take. Now in retrospect, I should have protected the cord per CJ's stickied build thread, but now I'm questioning whether I should replace the cord entirely.

To mitigate this problem I will protect the cord from the charges with a nomex blanket and by wrapping the top of the cord in tape. But I'm wondering if I should replace the cord with something with a tighter weave, since I suspect the loose weave is why it blew apart after just 2 charge tests. It's attached at the motor mount, so I would have to mount the cord to a coupler, which would be kind of a pain.

What do you guys think, should I replace the entire cord? Or should I be fine with sufficient protection going forward?



Thanks,

dragonsp

 

[David Schwantz]

Did you wrap the cord around the charge? I use, what looks like, the same cord. Never had that happen. Replace it.

 

[rfjustin]

Link to product in question please?

Are we sure that is not a fiberglass pull tape?

IMO, replace the entire cord if possible.

 

[dragonsp]

I didn’t wrap the cord around the charge, I think the cord must have just happened to nestle next to it.

I believe that this was the stuff. I bought it a while back, so it’s also possible it hasn’t aged well.

https://aeroconsystems.com/cart/launch-recovery/kevlar-tape-for-recovery-bridles/

 

[Rocketclar]

That looks like braided nylon line that is used (minus the wire) to pull wires long distances. A buddy gave me many, many feet of that and I removed the small wire. It's strong, but has to be protected from the ejection gases. I've successfully used it but with a Nomex shock cord protector around the first 3 to 6' ft and plenty of dog barf. I now only use it when doing ground testing and have gone to either tubular nylon climbing stuff I get from REI or Kevlar. Sometimes I use the Nomex cord protectors on the nylon. After every flight, my Nomex blankets, shock cord protectors, shock cords all get a soaky bath to wash off the acidic residue from the BP charges.