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Best Kevlar for LPR shock cord attachment?

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neil_w

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I'm almost out of my kevlar, need to buy some more. The first time around I bought 130 lb thread, seems to be working fine. I just looked at Emmakites (didn't know about them the first time around) and all their stuff is braided... I don't know if that's better or not. I've also been wondering if I should get something slightly heaver (like maybe, 200 lb)for the 24mm stuff I've been doing... but then I don't know if that'll be overly bulky for the smaller rockets.

I'm typically attaching the kevlar to the motor mount, and then connecting a sewing elastic shock cord to the kevlar just below the end of the BT.

What weight and style do other folks use?
 

Cabernut

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I've used 220# kevlar on my BT-5 Optima, and a couple BT-20 rockets. Works great so far after several launches. Packs in the BT-5 nicely.
 

MCriscione

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Unless your 24mm stuff is up around the 2lb mark, you can probably keep using 120-130ish. Braided is better. I've been eyeing the emmakites stuff myself, for the next time I run short. I have a hundred feet or so left to use up first though.
 

kyle

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I use the 100# and 300# Kevlar from Apogee for most stuff, both weights are nice and soft/flexible.
 

Forever_Metal

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Unless your 24mm stuff is up around the 2lb mark, you can probably keep using 120-130ish. Braided is better. I've been eyeing the emmakites stuff myself, for the next time I run short. I have a hundred feet or so left to use up first though.
been using it for most of our lpr stuff, works great!

fm
 

Micromeister

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For most of my LPR models up to about 2.5lbs I'm using 90 or 100lb braided kevlar from thekevlarstore.com They sell spools of natural yellow and UV resistant Green in several line strengths up to 1000lb. Great stuff at reasonable prices.

Kevlar Line-d2_Yellow 70lb Braided (Tubular) Kevlar_11-16-15.JPG


Kevlar Line-e_Green 100lb UV Resistant line_11-16-15.JPG


Kevlar Line-f_Blue 200lb twisted Kevlar Line_11-16-15.jpg
 

Onebadhawk

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Teddy from OneBadHawk just got some new 3/16th, likely much heavier for some of your builds but it is a good option if you have some bigger 29 and 38mm rockets.

http://www.rocketryforum.com/showthread.php?137055-Onebadhawk-Recovery-Harnesses
Thank you very much Michael..
I think this person wants much smaller then the 3/16" Tubular Kevlar..
I have "Very light" kevlar and I have 1/8" Tubular Kevlar..
Both are in 50 ft hanks at a great price...
Take a look on my site..

Teddy
 

TopRamen

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Emmakites stuff is great! Onebadhawk is the "Go To", but the thread from Emmakites is really nice and worth sampling.
If you think you are going to have any problems at al, go with Onebadhawk, as they post here and are renown for quality of service to the customer.
If you just want some convenient and nice supple braided Kevlar of the lightweights, the Emmakites I got in two different weights off of Amazon is great stuff, and I even used it in knife handles, as it is affordable and supple. It's great for rockets too, but I don't think there is any customer support, so to me, Kevlar is Kevlar, and the only Kevlar I will never buy again is that rigid stuff that for some reason is springy and stiff, and not supple at all. I'm not going to drop any names, as the seller of that Kevlar is a good person otherwise, but really? For rockets? Cheapo crappy Kevlar that is not supple?
You will be pleasantly surprised with the quality of Emmakites if you try it.
 

Woody's Workshop

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I bought some Kevlar a few years back and started retro fitting old rockets, and using on new builds.
I bought some from Sunward I think, and Rocketarium. Not sure what the #'s were, but probably 100 or less.
I follow quite a few kevlar thead sellers on ebay. Kevlar makes great stitching threat on knife sheaths. Especially the waxed threads.
For leather crafting I prefer the black, but for rockets the yellow, or UV resistant green.
Go with MCriscione's advice and you can't go wrong.
 

mikemech

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+1 on thekevlarstore.com. I bought a 1000 foot spool of 100# yellow 3-4 years ago. I use it on all my rockets. On my single (so far) HPR I just doubled it. Still have at least half the spool left.
 

BEC

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+2 on thekevlarstore.com. When he first set up shop he gave folks here killer deals (buy one get one free or something along those lines). I probably have a lifetime supply of kevlar suitable for LPR models from my one buy from there
 

OverTheTop

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I have always used the braided stuff (300lb from Apogee) for anything D motor and above, even though it is overkill from a breaking force point of view. I think the skinny stuff is likely to floss the body tube easier during a sub-optimal deployment, so I go with the 1/8" or thereabouts braided. YMMV.
 

ksaves2

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I have always used the braided stuff (300lb from Apogee) for anything D motor and above, even though it is overkill from a breaking force point of view. I think the skinny stuff is likely to floss the body tube easier during a sub-optimal deployment, so I go with the 1/8" or thereabouts braided. YMMV.
Ever so true about zippering. I flew a Fliskits Starlord last weekend for the first time since it was built over 7 years ago. http://www.fliskits.com/products/01prod_fs.htm Back then I did a flawless paint job to look like the rocket on the insert.
I used some small diameter kevlar for a shockcord that could zipper the tube like heck if less than nominal deployment. I was going to get some RDF experience with a Beeline RDF tracker even though the flight was simmed to 1900 to 2000 feet and
I expected it to come down in sight using three E9-8's. Simmed the daylights out of it and 8 seconds is what it said was reasonable. I then had a flash idea to use a Jolly Logic Chute release with the logic that if the apogee deployment was a bit more early or late than I expected, the restrained parachute pack with the JLCR would be less likely to zipper the tube.

Well, my battery went bad in the tracker. I should have cycled/tested it as it was very old. Left it in the rocket as it was simmed with its mass. Launched it and it looked like it really got up there on the three lit motors. Apogee deployment
looked good and with the 8 second delay it seemed to have a very nice, slow ascent. Could barely see the rocket in the early stage of the descent but I did a very shiny clear coat over the color coat and could follow the flashes till it got lower.
I had the chute release set for 800' so I could get some hang time for using the (defunct) RDF tracker and the release did its thing right on schedule. Took a fairly long walk out to get it and when I picked up the rocket, there wasn't a single ding
in the cardboard from the kevlar cord. I did use a relatively long cord but it had tangled and didn't extend its full length. Nonetheless, the rocket had a nice first flight.

Bottom line is, if one has the room in a cardboard rocket with motor ejection for a Jolly Logic Chute Release, it will likely allow more protection against zippering with a too early or late ejection. RS after several runs had suggested a 14ft/sec rate after
apogee when the chute deployed. It was so far up, I couldn't tell if that was the case. It just seemed to hang in the sky for a moment.

Kurt
 

pythonrock

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I've used many sizes from Emmakites, it's all good stuff. It's a tighter braid than most of the tubular kevlar from our vendors, so it's a little narrower for a given strength but harder to make "DeHate loops" and a little less stretch.
 
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