1000lb kevlar for shock cord

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for anything up to a couple pounds, with proper length and preparation, Absolutely!
 
How can one be sure that the shock cord of type/length can be used in a given rocket of a certain weight?

Example: 100lb kevlar is not usable in a 6lb rocket but is ok in a small 2 oz one.
 
Post says 1000lb kevlar whoooo... that 1/4" is tough Stuff...

2lbs times 100g is 200lbs.(i have had some 100g shock in my rockets during ejection and decent.)
10lbs times 100G is 1,000lbs....
Also, you need to de-rate the rating, 1000lb or 1000lb to fail, will fail at less of a value if it is a shock load.
so i would go up to a 6 lb rocket with a 40% safety factor.
this means the maximum shock load i would expect to fully load the shock cord is 600lbs.


Just watch it for wear. Kevlar doesnt particularly streatch so putting a tich of nylon webbing, a foot or so, will make your harness a little more absorbing to ejection shock. i have a 3 pound rocket I have flown dozens of times on elastic shock cord for MPR rockets from aerotech....the elasticity helps not zipper. tho i dont recommend elastic at all any more(hey it was before i flew hpr)
 
If that is 1/8" it is usually 750lb rated. I have seen a lot of stuff coming out of China on Ebay that claims 1000lb and is about 2mm thicker than the 750lb rated Kevlar but I would question the quality. Quality Kevlar should come with a MIL Spec rating specified so the quality is known. The stuff I sell is Mil Spec 87129 A (USAF), type 6. 750# Minimum breaking strength.

...Fudd
 
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Check these shockcords
They are made with USA military surplus webbing.
Teddy

https://www.ebay.com/sch/1badhawk/m.html?_nkw=&_armrs=1&_from=&_ipg=25&_trksid=p3692
To me the 5/16" Kevlar webbing for that eBay item looks identical to this:

$T2eC16R,!zEE9s3!((qnBQ9!SBDVcw~~60_57.jpg

This picture came from this eBay item: https://r.ebay.com/CSa1NN
This eBay item does not specify what the Kevlar webbing is rated for and does not include pre-sewn loops, but the webbing sure does look the same as the other eBay item.

What do you think? At $16.99 for 100 feet and free shipping I am thinking of purchasing it just to see what it is...

Cor
 
What you posted does not specifically say tubular nylon, it may be flat webbing which is not as strong.

To me the 5/16" Kevlar webbing for that eBay item looks identical to this:

View attachment 125318

This picture came from this eBay item: https://r.ebay.com/CSa1NN
This eBay item does not specify what the Kevlar webbing is rated for and does not include pre-sewn loops, but the webbing sure does look the same as the other eBay item.

What do you think? At $16.99 for 100 feet and free shipping I am thinking of purchasing it just to see what it is...

Cor
 
What you posted does not specifically say tubular nylon, it may be flat webbing which is not as strong.

I didn't mention anything about tubular nylon, I only mentioned 5/16" kevlar webbing.

I realize that it is probably flat webbing but according to my calculations it will be more than strong for my immediate needs for a rocket that I am scratch building that should be around 5 pounds in weight on the pad. I am basing my calculations based on the limited results of flat kevlar ribbon testing here: https://www.rocketmaterials.org/datastore/cord/Shock_Cords/index.php

In addition, this kevlar webbing looks exactly like the shock cord that I got with my K&S Rockets Flash kit.

Cor
 
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