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1000lb kevlar for shock cord


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  1. #1
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    23rd January 2009
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    Question 1000lb kevlar for shock cord

    Would you trust it in your rockets?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  2. #2
    Join Date
    13th February 2012
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    Yes.
    Temporarily potential impulse transformed into no-longer-potential-anymore impulse since 2013-01-01: A lot.

  3. #3
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    27th September 2010
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    for anything up to a couple pounds, with proper length and preparation, Absolutely!
    Unstable by design
    www.wooshrocketry.org NAR Sec. 558
    WOOSH Rocketry (mostly) on YouTube - http://www.youtube.com/user/guytogo75?feature=mhee

  4. #4
    Join Date
    23rd January 2009
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    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.

  5. #5
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    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)

    "Dad, I am going to put a big motor in this skinny rocket... its going to disapear like a ghost!!!.....

  6. #6
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    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
    Last edited by Fuddrucker; 5th April 2013 at 09:31 PM.
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  7. #7
    Join Date
    11th January 2013
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    Old Bridge,,,,,,,,,,,,, New Jersey
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    Check these shockcords
    They are made with USA military surplus webbing.
    Teddy

    http://www.ebay.com/sch/1badhawk/m.h...&_trksid=p3692

  8. #8
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    7th November 2012
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    Quote Originally Posted by onebadhawk View Post
    Check these shockcords
    They are made with USA military surplus webbing.
    Teddy

    http://www.ebay.com/sch/1badhawk/m.h...&_trksid=p3692
    To me the 5/16" Kevlar webbing for that eBay item looks identical to this:

    Click image for larger version. 

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    This picture came from this eBay item: http://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

  9. #9
    Join Date
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    What you posted does not specifically say tubular nylon, it may be flat webbing which is not as strong.

    Quote Originally Posted by cruiten View Post
    To me the 5/16" Kevlar webbing for that eBay item looks identical to this:

    Click image for larger version. 

Name:	$T2eC16R,!zEE9s3!((qnBQ9!SBDVcw~~60_57.jpg 
Views:	48 
Size:	115.4 KB 
ID:	125318

    This picture came from this eBay item: http://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
    L3, TRA #11847
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  10. #10
    Join Date
    7th November 2012
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    Quote Originally Posted by dixontj93060 View Post
    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: http://www.rocketmaterials.org/datas...ords/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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