Parachute Question

[Dane Ronnow]

Any specific tips on how to attach the shroud lines to the nylon? Or pictures of what you've done would be helpful.

I haven't got that far yet on my own parachute. But the best picture of shroud line attachment I've seen is one from Apogee's product page for a 36" flat parachute. Open the images. It's the fourth one (says 'Top Side and Bottom Side').

36" Printed Nylon Parachute

This 36" diameter parachute will fit in 41.6mm (BT-60 size) tubes and provides a nice slow and stable descent for small and mid-size rockets. Made from thin rip-stop nylon cloth, but feels like silk. Comes with heavy-duty suspension lines for extra durability.

www.apogeerockets.com

Look at the bottom side to see how the line lays. I'm going with two inches up, two inches back down. On the top side, you can see the stitch. It runs right through the center of the line, up and down (expect some pucker in the fabric alongside the line. It can't be helped when sewing shroud lines). I'm going with stitch length that gives me 10 stitches in an inch.

Regarding the link posted above (post #56) to Nakka-Rocketry, Richard's design and explanation of the semi elliptical canopy is great. I'm using his 80cm gore pattern (with the top of the gore chopped to allow for a 6" spill hole) for my parachute. But there are a few points I would do differently as far as sewing seams.

Halfway down the page you'll see 'Construction'. Right below that is 'Parts List'. In the list he uses a Coats 100 percent nylon upholstery thread. That's a heavy thread, which will require a heavy needle. You're far better off with a Gutermann Tera 80 thread. It's polyester, and just as strong as the Coats nylon, but much lighter in weight. It's also abrasion resistant. With the Tera 80 you can use a 70/10 needle, which, like the thread is very lightweight. Look for Singer or Schmetz Microtex (which is sharper than the standard 'universal' needle), in a 70/10 weight. Links to thread and needle at the bottom of this post.

Back on the main page of Nakka's parachute page, scroll down a bit from 'Construction' and you'll see an illustration of the hem (the red line with the a black dotted line through it). That's a rolled hem, and that's what you want to do with the top and bottom of the gore, but not the sides where the gores will join.

In the next seam illustration, Nakka uses the rolled hem on the sides, then butts the two gores together and joins them with seam binding tape (sometimes called ribbon). A flat-felled seam (link to youtube video below) is stronger, and doesn't require seam tape, which eliminates unnecessary weight.

Further down he describes the apex cap. I don't use this since I'm using a spill hole.

Then he illustrates shroud line attachment. Note that he's using flat shroud lines, so the zigzag stitch works. If you're using round cord, refer to the illustration from the Apogee product page.

My basic construction technique is a rolled hem on the top and bottom, then join the gores with a flat-felled seam. Use a Microtex needle, 70/10, and Tera 80. The job for me has been a breeze now that I got the right thread and needle. (Disclaimer: I know how to use a sewing machine. Others may find the job not as much a breeze as a windstorm.)

Links:

Shopping

www.rockywoods.com

This is an 875-yard spool, larger than a standard spool. I made it work on my machine with an insert that made the center opening small diameter. Rockywoods Fabrics is in Loveland, CO. They've got several shipping choices, reasonable costs.

Schmetz Microtex Home Machine Needles - 5/Pack

Schmetz microtex home machine needles use systems 15 X 1, 130R, HAx1, PF130, HAx1GT, HAx1SP, SY2020, HAx1ST and SY2031. Available in a variety of sizes. 5 per package.

www.wawak.com

Wawak is headquartered in New York, but my order shipped from Sparks, NV. I received my needles in Las Vegas four days after I ordered them.

Hope all this helps.

 

[Sluggo]

I don't, other than to say look for screen printer in your area. I've worked with them before and if you can give them a design, they screen it on your ripstop. I'd ask them how heavy the ink will be when it's dry. Also, how flexible.

Good questions to ask but neither should be an issue. How many colors are you wanting.??

 

[Sluggo]

OP here reporting back...... I flew 6 rockets today and I took my time folding the chute and kept the lines organized. I had no tangles.!! Another thing I did was rather than stuff the chute into the tube with the attached lines pointing out, I put the chute in the tubes with the attached shroud lines pointing aft. Or the top of the chute pointing up/forward. I hope you understand that. lol.

How do you all pack the direction of the chute.??

Being the OP here I'm amazed by the replies here. You guys are into it.!!! Pretty cool.

 

[teepot]

I z fold the chute, z fold the shroud lines and put them between a fold in the chute. The nomex blanket is attached about 6 inches above the chute attachment point. I roll the chute up, add the JLCR if I'm using it, roll the chute in the blanket and insert. At ejection the nose cone comes off, then some shock cord then the blanket then the shroud lines then the canopy. Since I started doing it this way I've had 1 tangled chute in 10 launches. And I learned this technique here on the forum from someone who packed chutes for paratroopers.

 

[Sluggo]

Thanks Teepot. I need to incorporate the Nomex blanket. I'm not sure if this helped me or not but yesterday I moved the swivel on the chute back about 2 feet back from the nose cone attachment. In other words, I attached the chute to the shock cord. I was thrilled not to have any tangles. We'll see how it goes next time.

 

[AfterBurners]

Right. This is the reason I'm checking in here. I get a lot of tangles too. Braided lines. I also move chutes from/to different rocket. And I have swivels on them but don't understand how the lines get so messed up. No love for that issue. Any suggestions to help avoid this issue.??

Chutes like your typical flat chute the lines are sewn to where they cross. They are sewn corner to corner and not across from each other. If someone would figure this out then there wouldn't be a problem. PML chutes are sewn the same way. Grab the chute at the APEX and pull the lines. They cross. The only chutes that don't have this problem are X chutes and Fruity chutes. This is why when I buy kits I get rid of the chutes that come with them. They tangle, twist and they don't trap any air underneath. On top of that your rocket will swing back and forth while its coming down. Now this is fine if you fly somewhere where your landing field is soft like sod, but the desert playa forget about it... you are asking for some broken fins.

 

[Blast it Tom!]

So (sew?) since we're on the subject:

I z fold the chute, z fold the shroud lines and put them between a fold in the chute. The nomex blanket is attached about 6 inches above the chute attachment point. I roll the chute up, add the JLCR if I'm using it, roll the chute in the blanket and insert. At ejection the nose cone comes off, then some shock cord then the blanket then the shroud lines then the canopy. Since I started doing it this way I've had 1 tangled chute in 10 launches. And I learned this technique here on the forum from someone who packed chutes for paratroopers.

Just a little question, I can't quite visualize the nomex vs. canopy positioning. The nomex blanket is supposed to protect the chute (I see you wrapped the chute in it), yet it exits first. I'd kind of figure (hope?) that canopy and shrouds were still with it. Or are you speaking of of order up the shock cord? Sorry for my parachute illiteracy here...

 

[Sluggo]

Chutes like your typical flat chute the lines are sewn to where they cross. They are sewn corner to corner and not across from each other. If someone would figure this out then there wouldn't be a problem. PML chutes are sewn the same way. Grab the chute at the APEX and pull the lines. They cross. The only chutes that don't have this problem are X chutes and Fruity chutes. This is why when I buy kits I get rid of the chutes that come with them. They tangle, twist and they don't trap any air underneath. On top of that your rocket will swing back and forth while its coming down. Now this is fine if you fly somewhere where your landing field is soft like sod, but the desert playa forget about it... you are asking for some broken fins.

Thanks for your reply. I've always understood the cross-over lines. f the chute has 8 attachment points you can't avoid it. Now, if the chute has 6 attachment points, they SHOULD stitch one of the lines across, rather than going corner to corner. Such a simple fix and don't know why LOC doesn't do this. Drives me nuts.

I did learn from your comment about the the main airframe swinging wide on the way down. I see that a lot and as I mentioned here in a previous post, I broke a fin yesterday. Now I know why. Thanks for that.

Another thing I did yesterday in regards to improving the tangles, I reefed the lines with tape about 4 inches up from the swivel. I want to say this again..... On 6 flights II had NO tangles. That makes a great day even better.!!

 

[AfterBurners]

Thanks for your reply. I've always understood the cross-over lines. f the chute has 8 attachment points you can't avoid it. Now, if the chute has 6 attachment points, they SHOULD stitch one of the lines across, rather than going corner to corner. Such a simple fix and don't know why LOC doesn't do this. Drives me nuts.

I did learn from your comment about the the main airframe swinging wide on the way down. I see that a lot and as I mentioned here in a previous post, I broke a fin yesterday. Now I know why. Thanks for that.

Another thing I did yesterday in regards to improving the tangles, I reefed the lines with tape about 4 inches up from the swivel. I want to say this again..... On 6 flights II had NO tangles. That makes a great day even better.!!

Glad the changes are helping you.

 

[teepot]

So (sew?) since we're on the subject:


Just a little question, I can't quite visualize the nomex vs. canopy positioning. The nomex blanket is supposed to protect the chute (I see you wrapped the chute in it), yet it exits first. I'd kind of figure (hope?) that canopy and shrouds were still with it. Or are you speaking of of order up the shock cord? Sorry for my parachute illiteracy here...

Order up the shock cord. Nose cone, 2' to 3' of shock cord, blanket, 1' of shock cord, parachute. I haven't had any singed chutes. I use a hand full or two of dog barf then a hand full of wadding. The dog barf and wadding are usually still in the tube when it lands. I think the idea is to not have anything above the canopy and to have the chute deploy in an orderly fashion. I used to wrap the shroud lines around the chute and had all kinds of trouble. The way everything comes out now just about guarantees an immediate inflation. And no questions are bad questions.

 

[Sluggo]

I never bought into the wrapping the lines around the chute. Now that I've read what teepot has said, I'll go with that. I have been tempted..... Never again.

 

[Blast it Tom!]

Thanks to @teepot for the help. Sir, I think I saw the thread where the fellow who folded 'chutes for real people noted how to fold them. I'll try to find it again and link it here. To be honest, I've been wrapping my lines around the Estes plastic jobs, no problems in the summer, but that cold day launch was bad. I'm not sure how I'd get a chute into a BT-50 body tube without somehow getting the bundle pretty tight.

As long as I'm here, perhaps I can sort out my next item of confusion:

Chutes like your typical flat chute the lines are sewn to where they cross. They are sewn corner to corner and not across from each other. If someone would figure this out then there wouldn't be a problem. PML chutes are sewn the same way. Grab the chute at the APEX and pull the lines. They cross. The only chutes that don't have this problem are X chutes and Fruity chutes. This is why when I buy kits I get rid of the chutes that come with them. They tangle, twist and they don't trap any air underneath. On top of that your rocket will swing back and forth while its coming down. Now this is fine if you fly somewhere where your landing field is soft like sod, but the desert playa forget about it... you are asking for some broken fins.

My beloved is going to attempt to sew some elliptical chutes for me. I figure there are several basic ways to attach shroud cords. Let's assume a 6 sided hexagon flat chute for ease of visualization.

1. 6 equal length lines, one at each corner
2. Same as the above, but the line is continuous over the top of the canopy, for strength
3. Estes method - three loops, with ends to adjacent corrners, or vertices of the hexagon

Well, at the bottom of it, those are only two. For more shroud lines, you could come up with more ways to twist/tangle them. But is one superior to the other as far as twist/tangle goes? Or is it best to take specific steps down at the knot, as Nakka does (see Figure 12)?

 

[Sluggo]

Thanks to @teepot for the help. Sir, I think I saw the thread where the fellow who folded 'chutes for real people noted how to fold them. I'll try to find it again and link it here. To be honest, I've been wrapping my lines around the Estes plastic jobs, no problems in the summer, but that cold day launch was bad. I'm not sure how I'd get a chute into a BT-50 body tube without somehow getting the bundle pretty tight.

As long as I'm here, perhaps I can sort out my next item of confusion:


My beloved is going to attempt to sew some elliptical chutes for me. I figure there are several basic ways to attach shroud cords. Let's assume a 6 sided hexagon flat chute for ease of visualization.

1. 6 equal length lines, one at each corner
2. Same as the above, but the line is continuous over the top of the canopy, for strength
3. Estes method - three loops, with ends to adjacent corrners, or vertices of the hexagon

Well, at the bottom of it, those are only two. For more shroud lines, you could come up with more ways to twist/tangle them. But is one superior to the other as far as twist/tangle goes? Or is it best to take specific steps down at the knot, as Nakka does (see Figure 12)?

I am having a hard time understanding your post but I'll say this...... On the 6 sided chute go corner to corner with 2 lines. The 3rd line crosses over the chute. In this case, the lines won't be crossed when you attach the swivel. Hope this helps.

 

[Blast it Tom!]

So you say attach the shrouds this way: (Dashed line goes 'under" the canopy):

(Blasted drawing looks way too much like these masks we've been wearing...)

 

[teepot]

A mask is what I thought when I saw it

 

[Blast it Tom!]

Well, I'm wondering if and why attaching the shrouds this way is superior to the Estes method of all three loops going between adjacent corners... if it works, I'd be tickled pink. Assuming proper folding, of course.

 

[Dane Ronnow]

Maybe I'm missing something here, but I don't see how the arrangement of shroud lines—to adjacent corners, or across to the opposite side—makes any difference once the lines are gathered at the bottom in a knot, or with heat-shrink tubing. Can somebody clue me in?

 

[Dane Ronnow]

My beloved is going to attempt to sew some elliptical chutes for me.

I don't know how close you are to starting your project, but I'm getting ready to post a thread on my parachute build, with step-by-step description and pictures, but most importantly, the problems I ran into and how I solved them. I'm hoping to have it finished today.

 

[Blast it Tom!]

I'm still waiting for the fabric, but yes any help is good help!

 

[Sluggo]

So you say attach the shrouds this way: (Dashed line goes 'under" the canopy):
View attachment 449292

(Blasted drawing looks way too much like these masks we've been wearing...)

Yes.!! That's the ticket right there.

 

[Sluggo]

Well, I'm wondering if and why attaching the shrouds this way is superior to the Estes method of all three loops going between adjacent corners... if it works, I'd be tickled pink. Assuming proper folding, of course.

It's superior because the lines don't cross one another. You can clearly see that in his sketch. There is no knot. See picture attached.....

 

[Blast it Tom!]

This is how Estes 'chutes come out of the box (and don't get me started on the fact that we can't even assemble a parachute these days....):

So this would be acceptable also?

As a side note, when I was a kid, I had those 12" GI Joes (and the Mercury Capsule as well). I'd make parachutes for them out of dry cleaning bags. I was like, 10 -12? I think they were 36" canopy diameter, and I ran the shrouds all the way across the top and down the other side.

I was a strange kid, I guess...

 

[Kelly]

I'd make parachutes for them out of dry cleaning bags.

I was a strange kid, I guess...

I guess so! You should have been saving the dry cleaner bags for sky lanterns.

 

[Dane Ronnow]

I'll ask the question again: Does it matter how the shroud lines attach—opposite corners, or adjacent corners—when the lines are gathered at the bottom? Sorry to sound dense, but I really don't get this. It seems like once they're all pulled together, it doesn't matter where they come from on the canopy.

 

[teepot]

where they come from on the canopy.
[/QUOTE
I believe that the concern is that it is easier to get a tangled chute if the shroud lines are already tangled.

 

[Sluggo]

I've been wanting to say this about parachutes........ Most parachutes are made with crossed lines, in my experience. Its not the end of the world. The 6 flights the other day all flew with crossed lines and all 6 flights landed relatively softly. Neatly put the lines together and take care when you fold it up. I'm learning that I like a delay in the 6 to 7 second range on a nice still day. Hopefully I can tame the ejection. That protects the chute.

 

[Blast it Tom!]

Well, to both of you, my experience with the Estes 3-loop (my second sketch) has been not tangle, but twist. And that no doubt comes from wrapping the canopy in the shrouds and then possibly the chute behavior itself - I recall my son's partially open chute twisting a lot on it's way down. That was a cold day launch with the stock Estes plastic which I now know is a no-no. So I want to go the nylon route; they look prettier and are more efficient anyway and It gives my wife a stake in the game. So thanks to all on this; @Dane Ronnow, I look forward to your thread and my delivery from Rip Stop By the Roll, and I look forward to some pretty parachutes!

 

[Dane Ronnow]

I guess the problem I'm having with understanding the difference between shroud lines attaching at adjacent corners or opposite corners, is that I'm looking at an elliptical parachute—which is what I'm making—rather than a flat parachute. In the attachment (borrowed from Fruity Chutes) you can see how all the lines are gathered at the bottom in a harness. At the harness point, you'd be hard-pressed to say whether these lines were attached to opposite sides (which is the way Fruity Chutes does it) or adjacent corners (more accurately, gore seams).

 

[Handeman]

When it comes to chutes made with flat hexagonal, octagonal, or other gonal shapes, I think having the shrouds looped like Estes or like the "mask" are really an aesthetics thing more than any practical difference in performance. When all the lines meet at the juncture and they are all arranged to match the attachment points of the canopy, it looks neat. Neat and orderly is generally assumed to work better, but in this case, I don't think it makes any kind of measurable difference.

IMHO, having all shroud lines the same length is much more important than how they are exit the juncture.

 

[Dane Ronnow]

I'm still waiting for the fabric, but yes any help is good help!

It's ready when you are: https://www.rocketryforum.com/threads/31-5-semi-ellipsoidal-parachute-build-part-i.164478/
@Nytrunner , @mo2872