Tangle Free shock cord packing

[bill2654]

I like my shock cords on the long side but sometimes it's hard to get it all packed in a min diameter tube. Im using 750# 1/8" Kevlar but sometimes the cord will tangle on ejection. Anyone have a good way to pack a shock cord so it wont tangle? Remember Im talking
very little room in a 38mm min diam. rocket.

 

[dixontj93060]

I always dress my cords with the small "hairdresser" rubber bands or blue tape. Make z-folds of 4 to 6 loops. You can then stack four or five of these bundles and they should fit well in a 38mm dia.

 

[rharshberger]

This is how I do my Z-folds.

Edit: Evidently the pictures don't want to upload from my phone, will try from home later.

Edit to Edit: Ha! I got on my computer at home, here is some recovery harness love, a custom Onebadhawk 7/16" Kevlar Z-folded and taped.

 

[Ravenex]

Is fold them on a piece of blue tape them wrap the ends over. I the begin a tear with it cord at both ends.

 

[Onebadhawk]

I used to use masking tape to do my Z folds...
Now I use childrens braces small rubberbands.....
Works the same but you don't have to pick tape off of the harness after the flight...

Teddy

 

[Ravenex]

I used to use masking tape to do my Z folds...
Now I use childrens braces small rubberbands.....
Works the same but you don't have to pick tape off of the harness after the flight...

Teddy

I will have to experiment with that.

 

[kcobbva]

I used to use masking tape to do my Z folds...
Now I use childrens braces small rubberbands.....
Works the same but you don't have to pick tape off of the harness after the flight...

Teddy

I thought about that and bought some, but resorted to tape. I wasn't sure if it would separate cleanly. My drogue fouled in my I powered rocket this weekend. I'm assuming the tape may have come loose in the rocket, using yellow tape. I may have to try these after all.

 

[Banzai88]

I hand crochet with large loops. Once you get the technique, it works every time, and is as reliable as taped z folds.

 

[kcobbva]

I hand crochet with large loops. Once you get the technique, it works every time, and is as reliable as taped z folds.

Tom, Do you have any pictures of your technique? Sounds interesting, and always willing to learn, but having a hard time visualizing.

 

[Onebadhawk]

I hand crochet with large loops. Once you get the technique, it works every time, and is as reliable as taped z folds.

I saw pic's of that,,,
SEVERELY cool....
Looked complex to learn though...
Ya know,, I bet those pic's I saw were from you,, lol..

Teddy

 

[Onebadhawk]

Here,,

https://www.amazon.com/dp/B00MPZDFHS/?tag=skimlinks_replacement-20

These are the ones I use,, X heavy...
You still have to get the Z fold right
and the band or tape strap in the right place though...

Teddy

 

[Banzai88]

Tom, Do you have any pictures of your technique? Sounds interesting, and always willing to learn, but having a hard time visualizing.

I don't, but I will try to take some tonight.

I saw pic's of that,,,
SEVERELY cool....
Looked complex to learn though...
Ya know,, I bet those pic's I saw were from you,, lol..

Teddy

It's actually very simple, once you know how to start the first loop and the 'why' of forming it a certain way to prevent knots/tangles. After that, it's really simple, and as importantly, repeatable.

 

[vance2loud]

[video=youtube;ETiB_V-_SGs]https://www.youtube.com/watch?v=ETiB_V-_SGs[/video]
Apogee video of crocheting shock cords
Crocheting starts at 3:30
Once you get the hang of it you can do it reasonably quickly.
Keep it loose as you go for easier deployment.

 

[Banzai88]

[video=youtube;ETiB_V-_SGs]https://www.youtube.com/watch?v=ETiB_V-_SGs[/video]
Apogee video of crocheting shock cords
Crocheting starts at 3:30
Once you get the hang of it you can do it reasonably quickly.
Keep it loose as you go for easier deployment.

That's it. I do it WITHOUT the knot at 3:51-4:12, as I find that the knot rarely pulls free. By the time the rest of the cord pulls free, there's rarely enough energy left to do much more than pull the knot tighter, which is not something I want. I do the first loop and skip the 'double loop', then loop crochet from there. I keep that first loop very loose and open throughout the operation. The larger the cord, the easier it is by hand. I've used this technique in everything from the 100# Kevlar from Apogee to nearly 12 feet of 9/16" tubular nylon.

 

[bill2654]

Hey I like that crocheting idea. Im going to try that right now.

 

[o1d_dude]

I'm a big fan of the loose rubber band method and save the crochet method for 50' and 100' electrical extension cords and such.

 

[amell]

Crotchetry and rocketry? Whatever next!

 

[rharshberger]

I'm a big fan of the loose rubber band method and save the crochet method for 50' and 100' electrical extension cords and such.

+1, I have seen to many crocheted electric cords not easily stretch back out, so practice the technique lots until you get it right every time.

 

[bill2654]

Hmm....lets try Z folds. Crocheting hard.

 

[soopirV]

Speaking of crafts, my kids were really into the Rainbow loom fad, and now we have literally thousands of bands like these lying around. I'm going to test one tonight to see if it snaps easily, but this will be my go-to for shock cord management!

https://www.amazon.com/dp/B00DSX38O6/?tag=skimlinks_replacement-20

 

[Onebadhawk]

Hmm....lets try Z folds. Crocheting hard.

lol,,lol,,
I was waiting to see what you had to say about it Bill...
Nah,, I'll give a look at it when I have time to focus on it...
This isn't something you can fly till your confident with it..

Teddy

 

[Banzai88]

+1, I have seen to many crocheted electric cords not easily stretch back out, so practice the technique lots until you get it right every time.

There is no relation between the flex and bulk of an electric cord and that of the tubular nylon/kevlar cord used in rocketry. Worlds different.

 

[bill2654]

I thought about coiling the line inside the tube right before attaching the NC. Seems to take up very little room. I'll try some ground tests tomorrow.

 

[GlenP]

I think the key is repacking it just before each flight, like a parachute, you don't want it stored in the tube long term then expect to have a good deployment, you unpack it, unfurl it, then pack it up. The crochet technique sounds promising, but the video shows that you still may have a considerable length of crocheted cord to pack in carefully so that it doesn't tangle on itself, never tried it, but it might work fine.

While the diameter/length ratios are vastly different, the over-under winding technique used commonly for electrical and audio mic/instrument cables, and even garden hoses might be useful for long shock cord wrapping. You might need a dowel or pencil to wrap over/under and then slide that into the body tube, pull the pencil out. Never tried it, but I got to thinking about it thanks to this "thread" maybe could be used in combination with segments taped or rubber banded.

If you are not familiar with the over-under method it is not a matter of grasping how, but of how you grasp. (plenty of youtubes demos out there)

 

[Onebadhawk]

This is how I do my Z-folds.

Edit: Evidently the pictures don't want to upload from my phone, will try from home later.

Edit to Edit: Ha! I got on my computer at home, here is some recovery harness love, a custom Onebadhawk 7/16" Kevlar Z-folded and taped.

View attachment 287262

Wow,, I didn't see the pic before Rich..
Way too cool..
How do you like the way those came out,, really great right....
That's fantastic Rich,,
Thank you for posting the pic.....

Teddy

 

[rharshberger]

Wow,, I didn't see the pic before Rich..
Way too cool..
How do you like the way those came out,, really great right....
That's fantastic Rich,,
Thank you for posting the pic.....

Teddy

Teddy check your OneBadHawk email, there is two versions of that picture for you, a unmodified and a cropped and quality reduced version (they are the ones I post on TRF). As for the harness I love it, as does every one who gets their hands on it. This weekend will be its maiden flight.

 

[Onebadhawk]

Teddy check your OneBadHawk email, there is two versions of that picture for you, a unmodified and a cropped and quality reduced version (they are the ones I post on TRF). As for the harness I love it, as does every one who gets their hands on it. This weekend will be its maiden flight.

I am so glad to hear you love the harness...
Thank you for going to the trouble of sending me the pic's...

That flight's going to go perfectly Rich,,,
Just you wait and see...

Teddy

 

[cvanc]

Ted/all-

What's the loop (circled in red) for? An attachment point for the chute, perhaps? In any case, very nice harness...

 

[Onebadhawk]

Ted/all-

What's the loop (circled in red) for? An attachment point for the chute, perhaps? In any case, very nice harness...

View attachment 287347

Yes exactly Carl...
That's the 3rd loop for the drogue...
About 3 ft or so down from the av bay...
That loop should be far enough down from the av bay
so it, the drogue wrapped in the blanket can be forced freely down to the motor
so the action of that package being forced down by the e charge doesn't hinder separation...
Then the mass of the av bay / payload section / nosecone easily drags the drogue out of the booster...

Carl, thank you so much for the kind words,,
but if you think that's nice in that picture you should see the way it's constructed in person...

Teddy

Oh,,
And the "Y" on the right side of the pic is the bottom of the harness,,
This "Y" is also about 25" or 30" if I remember correctly...
Rich has an attachment point on either side of the top centering ring,, 180 degrees apart,,
to spread the load when the harness comes to it's end....

 

[bill2654]

My initial coiling test worked great. Think of the way the rope of a crab pot on Deadliest Catch gets coiled up, that's how I did my shock cord.
I only have 5 inches of space in a 38mm airframe and probably 3.5 inches of that is my chute and nomex protector and a pinch of dog barf. It's kinda tedious but easier than
crocheting. The first test I used 1/2 gram of BP. I think it was a tad on the "energetic" side. It stretched the shock cord just fine but should I back off a touch?
[video=youtube;kVchIbuNDzc]https://www.youtube.com/watch?v=kVchIbuNDzc[/video]