Wire Rope Part of Shock Cord

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RPMyers

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I recently read an article about attaching a length or wire rope between the motor mount and point of rocket separation and then attach regular shock cord to that. This was done to prevent heat damage to the shock cord. I had a shock cord sever on my Zepher rocket because a was burnt. Has anyone tried this? Any comments? Thanks
 
I had one in a Cluster-R kit I acquired years ago. The shock cord/burrito tangled with the end of the cable resulting in a failure to deploy. Probably something I did wrong, but I rebuilt the rocket without it and no longer have failures.
YMMV
 
I did something similar, pictures here. I'm pretty sure my leader was small enough that it sits well below the chute so it can't snag anything. If I was going to have it come out near the top, I would add extra swage fittings and probably some heat shrink tube to make sure that the ends of the wire rope gets contained and can't snag the chute.
 
As mentioned by others, it works. I've used it in larger projects where like you point out, one doesn't have "easy access" to replace a harness that's buried in a rocket.
I used like 1700lbs. test stranded cable and bought a crimping tool to crimp on the cable retainers so I can form a loop in the cable at both ends. Made the cable length long enough so it's close to and reachable at the end of the rocket tube. If the harness I connect to the cable gets worn, it is easily replaceable. Thing is, a lot of rockets get lost, have CATOs with research motors or have deployment failures long before the harness wears out. I haven't had to replace a harness yet using a wire cable "leader" in the airframe yet.
Fishing wire leaders are good for smaller rockets as mentioned by one of the other respondents. It's one less thing to worry about with that portion of the harness that's not easily inspected. Though.........There are some relatively cheap, stiff but bendable endscopes out there that can be used for internal inspection of rocket internals. I bought a couple many years ago when they were pretty economical.
I had a forward motor casing burn through that left a hole in a rocket as depicted. I used a scope and saw it burned through the opposite side of the internal harness and was intact. Did a coupler repair and rocket still flies. Kurt
 

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This is how I make a loop in the end of a wire rope. Used in my Motoreater that has lasted for 75 HPR flights.
The rope goes through the front CR around the motor tube 1-1/2 times and back out through the front CR. Both ends are looped and I quick link both loops.

ww1.jpg ww2.jpg ww3.jpg ww4.jpg ww5.jpgww6.jpg ww7.jpg
 
I used to fish for sharks (surf fishing and offshore out of a kayak) and I have a big roll of steel cable left over I used to make shark leaders out of. I use double barrel crimping sleeves. I've used this method on for several rockets. It's good for rockets with very little room for conventional shock cords, like this 2.6 inch body tube with a 54mm motor mount. The rubber bands are holding the steal cable flat while the epoxy sets,
 

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I every previous thread I can remember that discussed this, lots of people commented that the steel corrodes due to the black powder residue and in the long run isn't any better than a similar weight of Kevlar. No experience with it myself, but I'm surprised that point hasn't been mentioned yet in this thread.
 
I used to fish for sharks (surf fishing and offshore out of a kayak) and I have a big roll of steel cable left over I used to make shark leaders out of. I use double barrel crimping sleeves. I've used this method on for several rockets. It's good for rockets with very little room for conventional shock cords, like this 2.6 inch body tube with a 54mm motor mount. The rubber bands are holding the steal cable flat while the epoxy sets,
Plenty of room in a 2.6" with 54mm for kevlar.
 

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Just make sure those ferrules are crimped down real tight. I've had one slip the cable, and now routinely use a little bit of epoxy to seal it down as extra insurance it'll stay put.

And if the cable is nylon covered, remove that nylon covering wherever crimp connectors are used.
 
Are these stainless?
Product labeling doesn't specify.


PRODUCT SPECS​
More Information​
FINISH/PLATING​
Bright​
PACKAGE PACK​
Leaders​
PACKAGE QTY​
8,3​
LENGTH​
Assorted,9",12",18",6"​
WATER TYPE​
Freshwater & Saltwater​
 
Thanks. That's my only concern - if I'm using a system like this where it's designed to be permanent, I'd want it to be as robust as possible.
 
Thanks. That's my only concern - if I'm using a system like this where it's designed to be permanent, I'd want it to be as robust as possible.

IMO: It still makes sense to make the cable removable. I'm sure there are a few exceptions, but I fail to see the logic in making a shock chord a permanent part of the rocket, unless we're talking a rocket that is only designed for just a couple flights.
 
I every previous thread I can remember that discussed this, lots of people commented that the steel corrodes due to the black powder residue and in the long run isn't any better than a similar weight of Kevlar. No experience with it myself, but I'm surprised that point hasn't been mentioned yet in this thread.
Kevlar or steel, both wear over time and exposure to ejection charges. I believe this is a case of “6 of one a half dozen of the other”, “pick your poison”, and “different strokes for different folks”.
 
How do you make it removable with this system? Feels like I'm missing something obvious.

Depends on the rocket body diameter and motor diameter.

Here's a couple options:​
  • Drill a hole in each centering ring and run the cable through the holes, then loop the cable over the motor extension at the base of the rocket.
  • Secure an eyebolt to the upper centering ring and attach the cable to that.
 
Product labeling doesn't specify.


PRODUCT SPECS​
More Information​
FINISH/PLATING​
Bright​
PACKAGE PACK​
Leaders​
PACKAGE QTY​
8,3​
LENGTH​
Assorted,9",12",18",6"​
WATER TYPE​
Freshwater & Saltwater​
While it’s not definitive, you could see if a magnet sticks. If it doesn’t, it’s almost certainly 316 stainless. If it does, it could be plated steel or 304 stainless.
 
Kevlar or steel, both wear over time and exposure to ejection charges. I believe this is a case of “6 of one a half dozen of the other”, “pick your poison”, and “different strokes for different folks”
I only fly 100% fiberglass rockets. I wash them inside and out (very little liquid detergent), I pull brubrushes through and spend time on the kevlar cloth and shock cords. I have 25 flights on one and it looks almost new....
 
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