Best knot for tying shroud lines to low power chutes?

[BABAR]

so Tom posted about bowlines for shock cords.

Is there a preferred knot for tying shroud lines to low power plastic chutes?

 

[Tom]

I just usually push them through the ring of a snap swivel, then pass the parachute through the loops. Easy and the swivel will help with the chute stability.

 

[kuririn]

I just usually push them through the ring of a snap swivel, then pass the parachute through the loops. Easy and the swivel will help with the chute stability.

I think Babar is asking about the knot that ties the shroud line to the parachute corner.

 

[Tom]

Oh, my bad. A bowline would be good there as you would have a loop at the attachment point?

 

[jqavins]

A bowline sounds like a good idea, but I haven't used them because they 1) take up a good deal of line which is in short supply with most LP kits' chutes and 2) are hard to keep even with regard to the line used, and to thus keep the shroud lines of even length. I just use square knots, but I'm sure there's something better.

Tom, with regard to the swivel, what you've got there is a lark's head knot.

 

[Tom]

Yes it would be very difficult to get the shrouds even doing bowlines I agree. I just like the fact that it would leave open loops at the point of attachment. A double overhand knot would scrunch down into the plastic.

So I don't know what other alternatives could be considered.

"Larks Head" huh, been using that knot on a hundred different things all these years and never knew it had a name

 

[jqavins]

Yeah, it does. The thing is, wven with a loop the thread will bite in to the edges of the holes. My way is worse, neither is great, I think.

Thise paper reinforcers ought to help, but they don't stay in place on the polyethylene sheet.

 

[mbeels]

I just make a loop in the end of the shroud line (no knot), and use a small square of packing tape to tape it to the parachute. The tape spreads out the load, and it seems to be plenty strong enough for LPR.

 

[mcderek]

I use a simplified figure 8 follow through knot.

The simplified version is to use a simple knot instead of the figure eight, over and through. Not, over, around and through. Clear as mud right?

 

[neil_w]

I just tie a loop with a simple square knot and have never had one come loose.

Of course, I'm knot-ignorant and use square knots for everything, but in this case it seems to work fine, at least with the carpet thread (?) that typically comes with LPR plastic chutes. I might put a drop of white or yellow glue on the knows to set them when finished.

 

[mcderek]

I just tie a loop with a simple square knot and have never had one come loose.

Of course, I'm knot-ignorant and use square knots for everything, but in this case it seems to work fine, at least with the carpet thread (?) that typically comes with LPR plastic chutes. I might put a drop of white or yellow glue on the knows to set them when finished.

The fact that if works fine is all that matters!

 

[brockrwood]

I just tie a loop with a simple square knot and have never had one come loose.

Of course, I'm knot-ignorant and use square knots for everything, but in this case it seems to work fine, at least with the carpet thread (?) that typically comes with LPR plastic chutes. I might put a drop of white or yellow glue on the knows to set them when finished.

I pass each shroud line through the hole in the parachute and then just tie a loop in the end of the string using an overhand knot. See pic. I attach six separate shroud lines and then get them all even by simply folding the parachute until the holes all line up and then knotting the ends of the shroud lines together. I cut off the excess shroud line. Yes, this method wastes shroud line but shroud line is cheap.

 

[caveduck]

I just make a 180˚ bend in the end of the shroud line and tape it down with a square of good 1 mil mylar tape. Strong enough for egglofters. Packing tape works too but is not as thin. I think you can also use Kapton tape if you have that.

 

[user 35280]

I swap out all my plastic chutes to nylon chutes.

 

[brockrwood]

Kapton tape

What is this "Kapton" tape you speak of?

 

[brockrwood]

Of course, I'm knot-ignorant and use square knots for everything, but in this case it seems to work fine, at least with the carpet thread (?) that typically comes with LPR plastic chutes.

I have been learning a lot about knots of late. Very handy to know how to tie several common knots that apply to model rocketry. The "101knots.com" website is a go-to resource.

The good old overhand knot that we all know how to tie, only works to put a loop on a model rocket parachute shroud line (the loop goes through the hole in the parachute) if you have access to both the "tag" end (short end) and the standing end (long end) of the string. So, to use this knot to tie a loop onto a parachute hole, you have to tie on six separate shroud lines. If you are doing the "three shroud line" approach, where one long shroud line connects together two holes in the parachute, the overhand knot will not work because, when you go to tie the second loop, you no longer have access to the standing part of the string. In that case, you can use the "figure 8 follow through knot", but it takes a lot of practice to get the hang of it. See this website: https://www.101knots.com/figure-8-follow-through.html

The bowline knot also works but it is designed to be untied easily, so I prefer the figure 8 follow through knot for model rocket parachutes.

And yes, because I am the worrying type, I always put a dot of wood glue on each knot, just to make sure it does not come undone.

 

[caveduck]

What is this "Kapton" tape you speak of?

It's used a lot in electronics because it has really good insulating properties and is heat resistant. It's much more available than it once was because it's also very useful as a bed adhesion layer in 3D printing. Here's an example: https://www.amazon.com/Mil-Kapton-Tape-Polyimide-yds/dp/B006ZFNB2I

 

[TheAviator]

It's used a lot in electronics because it has really good insulating properties and is heat resistant. It's much more available than it once was because it's also very useful as a bed adhesion layer in 3D printing. Here's an example: https://www.amazon.com/Mil-Kapton-Tape-Polyimide-yds/dp/B006ZFNB2I

I use Mylar (aluminized polyester) tape for my shroud lines. I imagine Kapton would work similarly, but it's pretty expensive, even compared to Mylar tape.

I also use a bowline to attach my lines to the canopy. I am less concerned with keeping them all the same length, because I pull all the corners together after I'm done and trim the lines to the same length. Braided fishing line works pretty well as shroud line if your kit doesn't come with enough.

 

[brockrwood]

I am less concerned with keeping them all the same length, because I pull all the corners together after I'm done and trim the lines to the same length.

Precisely. I could not tie each shroud line to the same length, or even close, if my life depended on it.

 

[brockrwood]

Braided fishing line works pretty well as shroud line if your kit doesn't come with enough.

I use this braided nylon cord from Home Depot: https://www.homedepot.com/p/Everbilt-18-x-250-ft-Nylon-Braided-Mason-Twine-Pink-73296/206094361

It is a little bigger in diameter than ordinary shroud line string, but I find that shroud lines that are a little thicker are less likely to tangle.

I like braided, as opposed to twisted, cord for shroud lines as it doesn't unravel the way twisted cord does.

Still, this stuff is a little thick and heavy. If I could find some strong, braided, nylon parachute cord that was a tad thinner, I think I would go for it. This stuff is about 3/32" in diameter (about 2mm). If I could find something that is about 1/16" in diameter, I think that would be perfect. The Big Orange Box does not carry anything thinner that is braided nylon.

 

[TheAviator]

Just looking at our local sporting goods store, I found this:
https://www.academy.com/shop/pdp/pr...-fishing-line?sku=hi-vis-green-50-lbs-150-ydsDon't know what size parachute you're looking for, but I use 6 lb strength monofilament Kevlar cord for my mylar parachutes. That's good for up to maybe a pound of rocket at 16 lines.

 

[brockrwood]

Don't know what size parachute you're looking for, but I use 6 lb strength monofilament Kevlar cord for my mylar parachutes.

I am making a simple polyethylene parachute, 13" (flat side to flat side). I am using a black, plastic garbage bag for cheapness and easy visibility in the sky. Putting a spill hole in it. About 2" in diameter.

Using Scotch clear plastic packaging tape for the reinforcements where the shroud lines connect to the parachute.

See pic:

 

[brockrwood]

I swap out all my plastic chutes to nylon chutes.

I did swap out several model rocket parachutes for nice, premade nylon ones. It is sort of pricey to swap out every parachute on every rocket in the fleet. So I am trying to make some high quality homemade poly parachutes.

I guess I could put a snap swivel on several nylon ‘chutes and then just transfer the chute to the rocket that needs it for immediate launching.

I do like the way the slippery nylon parachutes deploy easily and fully without becoming a “wad that doesn’t open up”, like some poly chutes.

 

[brockrwood]

I use a simplified figure 8 follow through knot.

The simplified version is to use a simple knot instead of the figure eight, over and through. Not, over, around and through. Clear as mud right?

I have been practicing the figure 8 follow through knot but I cannot get it right unless I make the loop that will go through the hole in the parachute HUGE.

 

[brockrwood]

I also use a bowline to attach my lines to the canopy

I considered a bowline to attach the shroud lines to the canopy but I feared the knot would come undone. Has that been a problem for you?

 

[TheAviator]

I considered a bowline to attach the shroud lines to the canopy but I feared the knot would come undone. Has that been a problem for you?

Never had one come undone. I do highly recommend using a finer line like the braided fishing line. Definitely helps with packing. I use Mylar tape because it resists tearing much better than scotch.

 

[prfesser]

Saw this on Imgur.com. Looks simple enough to work with a quick link or eyebolt. The accompanying text said that "it will maintain up to 95% of the line's breaking strength." Anyone use it? Pros and cons?

 

[BRS Hobbies]

I just use a double knot and then a dab of white glue on the knot to keep the knot from loosening or slipping on the string.

 

[Back_at_it]

I just create a circle in the line and tape it down with any quality brand "scotch" tape.

Never had a failure doing it this way. I have had a number of the prebuilt parachutes tear through the plastic due to that knot. The string acts just like a knife and cuts the chute. Started cutting off the prebuilt lines and doing it my way.

 

[brockrwood]

Saw this on Imgur.com. Looks simple enough to work with a quick link or eyebolt. The accompanying text said that "it will maintain up to 95% of the line's breaking strength." Anyone use it? Pros and cons?
View attachment 473726

I have been practicing with the Lefty Kreh knot as well. The knot is super strong and won't slip, but it is hard to tie with "springy" line such as elastic or polypropylene. It is also a big knot, and probably overkill for attaching shroud lines to a parachute canopy.

https://www.101knots.com/non-slip-kreh-loop-knot.html