horribly twisted kevlar

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Buckeye

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I am using Wildman's 1/4" tubular kevlar for my drogue harness. I have flown it drogueless and with a small drogue chute. Every time the cord comes back to earth horribly twisted like Jamaican dreadlocks. I have a swivel at the fin can and a swivel at the drogue chute which seem to do very little in preventing twist.

I am skeptical of this cord, because it is stiff, more "flat" than "tubular", and there is no way in hell it measures 1/4". Calling it 3/16" would still be generous. When I received this cord in my order, I questioned Wildman about it, and he insisted it was correct. However, I have what I consider true 1/4" tubular kevlar (from Fuddrucker, I think. On far right of first picture, attached to other half of swivel). It is soft and supple and does not twist as a drogue cord on my other rockets. Likewise with soft, 1/8" tubular kevlar, even with no swivels!

So is it the cord, the swivels, or something else at play here?

20180304_183956.jpgCapture.PNG
 
If you are using the type swivels seen in the left picture, they may not be turning as freely as they need to, the Wildman 1/4" kevlar (which I love by the way) has a soft feel and twists easily, if the swivel may take more effort to turn and the kevlar offers little resistance so the kevlar twists. I would recommend finding a ballbearing swivel if possible and see if that helps with the issue.
 
+1

Find a ball bearing swivel for the fin can (you can probably delete the swivel on the drogue chute). As Rich said, the Kevlar is easily twisted so you have to overcome the resistance of the swivel. A true ball bearing swivel will have the least resistance and prevent twisting of the kevlar better than other types.
 
Thanks. Yeah, I am not thrilled with my swivels. I tend to go cheap on my recovery gear. I will look for better ball-bearing swivels.

I still think the Wildman kevlar is more twist-prone than others. The weave is very tight, and it wants to twist just in handling. The other Kevlar I have measures 1/4 in, and the weave is more supple and compressible. It doesn't twist very much for me.

Maybe somebody knowledgeable in the physics/material properties can chime in.

Capture1.PNG
 
Thanks. Yeah, I am not thrilled with my swivels. I tend to go cheap on my recovery gear. I will look for better ball-bearing swivels.

I still think the Wildman kevlar is more twist-prone than others. The weave is very tight, and it wants to twist just in handling. The other Kevlar I have measures 1/4 in, and the weave is more supple and compressible. It doesn't twist very much for me.

Maybe somebody knowledgeable in the physics/material properties can chime in.

View attachment 340178



There are a few different grades of Kevlar. I guess the suppleness depends on the grade used in the product. A friend of mine uses Kevlar mule tape exclusively in his rockets. It is just flat not tubular and is very supple.
 
Buckeye if you would like to send that Kevlar back I would happy to send you some 1/4 that you will like.
It is soft and supple .
I don’t like it myself ,it unravels easily and feels like it will cut easy but looks identical to what you are showing as what you like in Kevlar shock cord.
 
Buckeye if you would like to send that Kevlar back I would happy to send you some 1/4 that you will like.
It is soft and supple .
I don’t like it myself ,it unravels easily and feels like it will cut easy but looks identical to what you are showing as what you like in Kevlar shock cord.

Thanks, Wildman! However, I already used your cord in a different project.

I did try some different kevlar in this rocket with no better luck. I carefully watched the rocket (MAC Firestick XL) fall under drogue, and the fin can spins like a whirling dervish! It is cranking at such a high RPM, it probably could generate electricity! I am wondering if the 4 smallish fins may be the culprit. My 3 fin rockets just tumble, no spin.

I need to try some high-quality ball bearing swivels.
 
There are a few different grades of Kevlar. I guess the suppleness depends on the grade used in the product. A friend of mine uses Kevlar mule tape exclusively in his rockets. It is just flat not tubular and is very supple.

This is weird I just posted a thread about 10 minutes ago about Kevlar. I also have the mule tape that I bought from Aerocon was wondering if it would be suitable for a recovery harness.
 
I use onebadhawks 11/32 "I think" tubular on my Firestick XL and don't have any problems with twisting. but Im done buying flat kevlar cause no matter what swivel I use I get same think you have posted I don't know what it is but it knots up like crazy.
 
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