Picture wire as a shock cord mount

I went to micheals today and bought some light picture hanging wire ( used for lighetr pictures & frames), i intend on using this as a shock cord mount in a model rocket...this rocket would at HIGHEST eject the parachute at around 30 fps....I can, with a good amount of effort, break this wire using a pair of pliers to pull at either end....Is this strong enough to be a viable shock cord mount...or should i go back and get the Heavy picture wire...



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I'd suggest that you use Kevlar thread instead... Stronger and much more flexible..

Available on line at places like Pratt hobbies

(use the braided stuff, and not the twisted)

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AZ Woody

I imagine you want the wire for heat resistance as well as strength.

As Bob Kaplow points out, and I am here to verify, an ejection charge CAN melt a small diameter steel cable. I've used braided steel fishing leaders for mounts and two of them which are directly exposed to the ejection charge have individual wires melted through.

Kevlar seems to do better insofar as being "heatproof".

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I've used it in a couple of models, D through F power, with no problems. I used it more as an anchor for a longer length of kevlar. What I've found that is a much better substitute (in addition to Kevlar), is fine stainless steel braided wire. McMaster Carr sells this stuff. It's much less "coarse" than picture hanging wire, and is not nearly as ductile. Neither assembly of both materials has broken even under some fairly spectacular ejection conditions.


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Suggestion: try braided Kevlar. For one thing, it's a lot easier to work with. I like to tease the fibers out of one end for an inch or so, soak it in epoxy, and laminate it to the inside of the tube. It makes a very smooth mount, and if you use epoxy that will soak into the paper, it ain't going anywhere.

If you have a bulkhead or plywood centering ring around your motor mount, try a trick that was suggested to me by Sonny Thompson. Drill a hole roughly the diameter of the Tubular Kevlar and poke one end through. Feather out the fibers, and epoxy them down in a circle around the hole. This spreads the load very effectively; I suspect it's stronger than an eye bolt, although smarter people than me are going to have to prove it.

Doug Pratt

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Doug Pratt

Having a flared countersink shape would be better so you do not get cutting forces on the edge.

Who is the manufacturer of the braided tubular Kevlar?

I see a rocketmaterials.org test coming :)

Reply to
Jerry Irvine

Twisted picture wire sounds like a good idea but it isn't. I tried it and it failed the first time out using Estes motors. Go for kevlar or elastic. Even nylon cord works better.

Layne Rossi CAR S767 L2

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L & K

This stuff will break if exposed to ejection flame or bent and kinked in any way. And if it's thin enough, it can cur right through elastic.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

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Bob Kaplow


I've done tons of shock cords. Never picture hanging wire. Could be interesting data.

-- Drake "Doc" Damerau

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NEPRA President NAR Section 614 NAR 79986 L3
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