Questions about Chute Lines

[LaunchPad]

I decided to untangle them all and will have to re-string a few of them.

1) Any suggestions for what string to get? It was suggested to look for it at a fabric store.
Will kite string work?

2) And is there a way to keep the strings untangled or is that just the nature of the beast?

I'll admit that when I first attached the chute to the nose cone almost 30 years ago, I put the string through the eye hook and tied it on that way to itself instead of putting the chute through the string.
I don't know if Estes changed the instructions from 30 years ago or if I did it differently.
Just wondering if it matters how I attach the chute to the cone if that makes a difference in lines getting tangled.

[JStarStar]

I usually use "medium carpet thread" from a crafts or fabric store.

I usually cut adhesive paper stick-on labels (from address labels, etc etc) into tape strips to attach the shroud lines to the chute.

The best way I have found to keep chute lines from tangling is to buy a package of fishing snap swivels at the sporting goods store, like this:



and tie the chute lines through the loop end.

This reduces chute tangling because rather than the chute and rocket torquing against each other as they come down, the chute is pretty much free to rotate however it wants.

Plus, it allows you to swap out different chutes for different rockets whenever you feel like it. Just unsnap the snap end of the swivel and snap on another chute.

[Micromeister]

One of the best things I've discovered over the late 10-12 years has been the 2 strand 13lb Kevlar thread sold on 600yd spools by Edmund Scientifics http://scientificsonline.com for about 20bucks.

This stuff makes Fantastic Chute and Streamer Heat Resistant shrould lines. I haven't burned off a shrould or stripped a canopy since switching to this very light weight thread. I've used it on chutes as large as 48" dia. 1/4mil metalized mylar competition chutes with 16 shrouds. or as small as 4" dia with 6 shrouds for micro models. Great thread for making other parts or twisting into heavier lines for shockcords, Theathers and anchors.

Snap swivels will help greatly but the simplest thing you can do to stop much of the Shroud line twisting is to switch from the line attachment method shown in most assembly instructions to attaching lines accross the canopy (see illistrations below)

[Huge Blues]

I tend to scratch-build my parasheets. Too much less-than-stellar performance converted me.

1. Absolutely use a snap swivel. My chutes get detached when not in use and hang open from the ceiling.

2. I have used kite string for sport models and been quiet happy. Heavy carpet thread works great as well.
Next on the list to try is Kevlar thread from Edmund Scientifics per Micromeister.

3. I have a 3/8" hole punch I use to cut out tape discs from Monokote trim sheets. The kite string or carpet
thread can be tied on through these. I have also cut discs from Band-aids. (Pick up a box at a .99 cent store.)
These will attach the carpet thread lines just fine old-school style. Just remember to burnish them down good.

[evil ed]

Go to e-bay and type in "kevlar thread" for a search. There is a guy there that sells TEX-90 black kevlar thread for $10.00 plus shipping for a 1 lb. spool

Works great !

Evil Ed

[MarkII]

Peripheral issue: I don't like to use the "safety pin"-style fishing swivels. A strong tug can pull them open. I feel that the "coastlock" style has a greater safety margin. Under great stress the loop will be pulled tighter like a noose, but it won't open up.

Click here for The Ultimate Swivel Thread.

[MarkII]

What drives me nuts is unfinished cotton thread or twine; it develops "fuzzies" that make the shroud lines cling to each other. Good quality carpet thread is better. I haven't tried using thin Kevlar, but it seems like it would work out pretty well too. For large parachutes, woven or tubular nylon is the best choice.

[luke strawwalker]

I usually use "medium carpet thread" from a crafts or fabric store.

I usually cut adhesive paper stick-on labels (from address labels, etc etc) into tape strips to attach the shroud lines to the chute.

The best way I have found to keep chute lines from tangling is to buy a package of fishing snap swivels at the sporting goods store, like this:



and tie the chute lines through the loop end.

This reduces chute tangling because rather than the chute and rocket torquing against each other as they come down, the chute is pretty much free to rotate however it wants.

Plus, it allows you to swap out different chutes for different rockets whenever you feel like it. Just unsnap the snap end of the swivel and snap on another chute.

I wouldn't recommend these types of snap swivels... these "brass" looking ones are non-locking, and susceptible to straightening out under a hard deployment (the eye will pop open and release the chute from the rocket, dropping your rocket like a brick from altitude, which of course isn't good for your rocket!) Yes, it can and does happen, even with surprisingly light rockets, on an especially early or late deployment...

The black finish "locking" snap swivels are FAR superior... They're still not absolutely 100% foolproof, but better than 99% of the time they will work well. The small locking tang on the end of the loop wire "hooks" over the clip part to ensure that it won't come open except under the very most absolutely extreme conditions...

They can be had almost as cheaply as the cheapy brass ones at Walmart... Later! OL JR

[LaunchPad]

I wouldn't recommend these types of snap swivels... these "brass" looking ones are non-locking, and susceptible to straightening out under a hard deployment (the eye will pop open and release the chute from the rocket, dropping your rocket like a brick from altitude, which of course isn't good for your rocket!) Yes, it can and does happen, even with surprisingly light rockets, on an especially early or late deployment...

The black finish "locking" snap swivels are FAR superior... They're still not absolutely 100% foolproof, but better than 99% of the time they will work well. The small locking tang on the end of the loop wire "hooks" over the clip part to ensure that it won't come open except under the very most absolutely extreme conditions...

They can be had almost as cheaply as the cheapy brass ones at Walmart... Later! OL JR

I'm curious to know two things:
1) From my parachute experience today, they unfurled but the lines got so twisted that it couldn't fully open up. If I use snap swivels will that keep the lines from twisting?
2) In regards to the brass looking snap swivels, is the suggestion that they may fail based on speculation or experience? Because I have a similar set up with my kite and in high winds, it has never failed me.

[LaunchPad]

Snap swivels will help greatly but the simplest thing you can do to stop much of the Shroud line twisting is to switch from the line attachment method shown in most assembly instructions to attaching lines accross the canopy (see illistrations below)

From your illustration/photos:
Some readers object to those types of swivels pictured insisting that they will fail and open at some point. True?
If I string the parachute as shown, would the string that goes over need to be longer or the same length as the other two?

[Micromeister]

First the shroudline length all remain equal. a bit longer length for all doesn't hurt (actually helps get a fuller open canopy but all lines regardless of the number remain equal.

I've been using snapswivels with my Parasheets, Parachutes & Streamers for more the 40 years. Most were the original non-safety locking bend brass type. I've had lots and lots of high speed deployment that have resulted in chutes being ripped from the shrould lines or bursting into 6, 8 or 10 streamers but to date have yet to straighenout a single brass snap swivel.
Is it possible to straighten one...Sure I've lost a few very big Bass to straightened hooks and snap swivels but To date not a single rockt LOL
Perhaps it's the choosing the best Size over more then style that make the difference. I now purchase the new safety bend locking type because they seem to be made a tiny bit lighter, any lose of mass is a good thing, Still I have no fear of using the straight clip type if that's what I have available.

I try to use #14's for 8,10 & sometimes 12", #10's for 12" to 24" and #2 for anything bigger then 24" and most 24 to 48" nylon chutes.

Use Whichever suits your flying. Any Terminal tackle Can Fail if inproperly sized or exceeding it's specs. Just depends on how and what your flying.

[luke strawwalker]

I'm curious to know two things:
1) From my parachute experience today, they unfurled but the lines got so twisted that it couldn't fully open up. If I use snap swivels will that keep the lines from twisting?.

Again, YES a swivel will HELP but not totally ELIMINATE twisting... swivels have a certain amount of friction or resistance to turning that prevents them from TOTALLY eliminating winding, unless you go with fancy (and rather expensive) ball bearing swivels which have MUCH less resistance...

2) In regards to the brass looking snap swivels, is the suggestion that they may fail based on speculation or experience? Because I have a similar set up with my kite and in high winds, it has never failed me.

Again, as I posted before, YES, from EXPERIENCE. I've had a couple different rockets on a couple different occassions suffer from a popped swivel, and in both cases they were the simple brass nonlocking type. On a hard deployment, such as with too long a delay, too heavy of a rocket (didn't coast long enough and fell picking up speed before deployment) or severe weathercocking leading to a horizontal deployment at high speed going into the wind, the parachute CAN open with SUCH a jerk that it simply yanks the swivel hook hard enough that the end slips out of the "latch" holding it closed... if the tug is severe enough it can yank the eyelet or screw eye right out of the wire hook... and drops your rocket sans parachute! I have from personal experience had this happen twice... once it was hard to determine, because even though the jerk was hard enough to uncouple the latch and yank the swivel off the screw eye, it didn't damage the loop... it sprang back into position after the rocket tore free of the swivel... the only way I knew what happened was because the swivel was "open" when I found the parachute afterwards, and I KNEW it was closed securely before launch, and the deployment was hard. In another case, the wire hook was bent out wide open and didn't spring back. I've seen pictures of swivels which suffered SUCH a strong yank at deployment that the wire was straighted out COMPLETELY, just like a straightened out paper clip! It's rare, but it DOES happen! The "locking" type black swivels have the end of the wire hook bent 90 degrees into a "lock" that pulls against the latch when the swivel suffers a sharp yank... this prevents them from springing open 98% of the time... but of course, NOTHING is 100% foolproof... in a bad enough hard deployment, the wire hook CAN be straightened out and yanked through the latch, usually straightening the swivel out like a straightened out paper clip... BUT this mode of failure is probably 98% preventable by using the locking type swivels, which are readily available at Walmart pretty cheap. That's why I don't chance it... I toss the brass looking nonlocking swivels and use black locking type ones I buy myself-- it's cheap insurance.

Kites don't pop fully open from a fully folded position in a 50+ MPH slipstream (or more) and produce such a massive JERKING force like a parachute in a hard deployment does... the 'steady pull" of a kite is MUCH more manageable for the swivels to handle-- thus the lower failure rate in that application...

later! OL JR

[luke strawwalker]

From your illustration/photos:
Some readers object to those types of swivels pictured insisting that they will fail and open at some point. True?

It's POSSIBLE... not particularly PROBABLE, but it IS POSSIBLE. That said, this type of failure is virtually TOTALLY preventable by using the locking type swivels, so IMHO it's rather silly NOT to use locking ones...

Later! OL JR

[JStarStar]

All else being equal I'd use the black swivels, but a few years ago I was in a hardware store and happened to remember I needed swivels, and all they had were the brass ones, so I grabbed a bag of 72 for 3.99 or whatever it was, and I still haven't run through that stockpile yet.

[luke strawwalker]

All else being equal I'd use the black swivels, but a few years ago I was in a hardware store and happened to remember I needed swivels, and all they had were the brass ones, so I grabbed a bag of 72 for 3.99 or whatever it was, and I still haven't run through that stockpile yet.

Well, they'll work... no doubt they'll work... Until you have that one odd flight where things go wrong and the thing pops open and drops your rocket... course, who knows... maybe you'll have excellent luck and that will never happen... if you're flying only smallish LPR rockets, then it's probably a 1 in a million chance... both rockets of mine that suffered swivel failures were large-ish midpower (D's) that went somewhat awry... so mass plays a big part in it.

BUT, IF you're shopping for a pack of swivels, the black ones are far superior to the brass ones...

Good luck! OL JR

PS... even the black ones aren't foolproof... I've seen pics of them straighted out like an old paperclip from a rough enough deployment... again, mass X velocity... so the odds are even less of this happening... BUT, it DOES happen once in a blue moon so to speak... Simple fact is, in a rough enough deployment, even if the swivel DOESN'T fail, odds are something else will... "weakest link in the chain" and all that ya know...

[Micromeister]

My point is. Any Swivel is better then no swivel as it relates to preventing or lessening Chute Line twisting.

There are small #14 black locking wire Ball Bearing swivels at are designed for heavier loads then the lighter crimped bead types shown earlier. These Ball bearing swivels run about .50 each rather then the usual price of about half that. I've switched to these ball bearing type as they seem a bit safer to me then the standard bend lock wire which always looked wimpier to me becaused of the thinner guage wire used in their construction, this newer bearing barrel swivel doesn't seem to be subject to seperate as easily at the swivel ball.

At the extream for swivels are the Deep Sea Ball Bearing extreme shock load swivels. Some small enough to be used on MPR and LPR models. The problem is they are pretty darn expensive for use on LPR models...I believe the last 5 pack I picked up was around $7.50 or $1.50 each. 3 times as expensive as the Black locking wire ball bearing swivels we just discussed. One don't have to worry about these swivel parts failing. The smallest size i've found (Size 3) is about the same fisical size and our everything #14 fishing swivel aobut 7/8" long. These Swivels are used with closed Kevlar loops or custom closure snaps rated for expected break strengths so there is no thought about lock wires being pulled from anything. The last Size 3 pack I found was rated at 150lb break strength.

All that to say pick a chute swivel that suits your flying need. if your flying estes LPR kits does it really make sense to use a buck fifty swivel? some of your higher dollar MPR's or custom Scale models perhaps warrent the investment. but again even on the cheapest little lpr model a plain old #14 brass swivel beats no swivel at all when it comes to helping line twist go away.

[nukemmcssret]

Here is a thread manufacturer, this is the web-site http://www.thethreadexchange.com, you can get any kind of kevlar thread you want. Any pound test they make. They also have carpet string for other shroud lines. Way cheaper than E-Bay. I bought some and it lasted a year.

[MountainRocketeer]

I have straightened out a snap swivel like those. It was the first time I flew my first midpower rocket. It had a really long body tube, so I split it in two and put a coupler and bulkhead at he breakpoint, so tha tthe "nosecone" was about 24" long. Upon ejection, the heavy nosecone aassembly reached the end of the 8 foot kevlar cord with such force that it straightened the bail/arm of the snap swivel straight as a needle and turned the round eyelet into an oval. The chute was attached a third of the way down the shockcord, so it stayed attached, but my nosecone/bodytube/bulkhead assembly came in ballistic from 1000 feet and planted itself like a javelin in the sod while the fincan drifted all the way across the field. Very embarrassing, but thankfully nobody was downrange or put in danger. Since then, I use locking snap swivels on all midpower birds and quicklinks on anything that needs more than a 30" chute.

I have since learned that the best thing you can do to prevent shocks like that, though, is to z-fold and tape your shockcord.

[AfterBurners]

I remember I made some parachutes from a Hefty trash bag. It was one of those heavy duty bags. I used the thin Kevlar thread for the shroud lines. I made a 24" eight sided parachute with a 5" spill hole. It worked fantastic. Then again if you get that Kevlar thread tangled it is very hard to untangle it.

[luke strawwalker]

I personally don't really see the purpose for using kevlar for shroud lines... shock cords I can see... after all, there's a lot of heat coming out of that tube and during ejection whatever of the shock cord is attached below the lip of the tube is going to get pretty roasted from the heat after the wadding passes it on the way out of the tube...

From what I've seen kevlar isn't very smooth, doesn't like to stay "twisted" in twine (unless it's woven like a braid) and is pretty stiff, abrasive, and VERY hard to get a knot to stay put in, and is rather brittle. There's little reason to need that kind of heat protection for shroud lines, because if you get enough heat to burn through a cotton shroud line your canopy is going to be toast LONG beforehand, whether it's plastic or nylon... simply due to the thinness if nothing else...

I guess if it works for you and floats your boat, that's cool and all... personally I prefer a lighter, easier to work with (not to mention cheaper) heavy carpet thread or twine type material for shroud lines that is less brittle and takes and holds knots better, isn't as stiff, and isn't as brittle or abrasive...

Whatever you choose to use, good luck! OL JR

[Micromeister]

I personally don't really see the purpose for using kevlar for shroud lines... shock cords I can see... after all, there's a lot of heat coming out of that tube and during ejection whatever of the shock cord is attached below the lip of the tube is going to get pretty roasted from the heat after the wadding passes it on the way out of the tube...

From what I've seen kevlar isn't very smooth, doesn't like to stay "twisted" in twine (unless it's woven like a braid) and is pretty stiff, abrasive, and VERY hard to get a knot to stay put in, and is rather brittle. There's little reason to need that kind of heat protection for shroud lines, because if you get enough heat to burn through a cotton shroud line your canopy is going to be toast LONG beforehand, whether it's plastic or nylon... simply due to the thinness if nothing else...

I guess if it works for you and floats your boat, that's cool and all... personally I prefer a lighter, easier to work with (not to mention cheaper) heavy carpet thread or twine type material for shroud lines that is less brittle and takes and holds knots better, isn't as stiff, and isn't as brittle or abrasive...

Whatever you choose to use, good luck! OL JR :)

A lot of HEAT,Gas & burning particles that blow past or through the wadding at ejection as well.
It is this heat and burning particles that are responsible for most of the burned & melted chute Wads, Holes in chutes & burned off shroud lines I'm sure you see as often as I. Many of the above observation/objections do not really pertain to the 13lb twisted kevlar thread I've been using from edmund scientific. I don't really know what kevlar you've been used to but all the twisted and braided stuff I use from Edmund, The Thread exchange and Kevlar Store on-line have been pretty smooth, while smaller in diameter for a given break strength than cotton, or nylon carpet threads.

This two stranded twisted kevlar is lighter then any carpet thread I've been able to find.

As for holding knots, this thread holds the usual overhand, 2 half hitches and improved clinch knot I use in assembling Chutes and Streamers. If terminal tackle is used (snap swivel or barrel swivel) I tend to use the improved clinch knot with this theard.
Canopy attachments particularly for competition 1/4mil mylar chutes are with 1/2" square Chrome Monokote adhesive backed discs. Once brunished down hold the simple over hand knot in the Kevlar shroud half loop under a chrome monokote adhesive backed mylar "tape disc" permanently. To date (more then 25years in competitions) I've yet to loose a single shroudline to heat or stray ejection hot particle. As mentioned earlier I have had a few of these mylar chute burst into 6 or 8 streamers under hard deploy with a dual egg capsule. but the kevlar and tape discs attachments did not fail. Not at all the case or record for Carpet thread or cotton thread shroud lines which are burned off on a regular basis as seen at our large club launches all the time. Even with very careful wadding placement some heat pass as these seals leak.

While this kevlar thread may be somewhat more abrasive if used in a sawing action, that feature has yet too present itself in any way I've seen or documented. If a simple doubled over piece of 1/2" masking tape can be an effective "anti-zipper" device, I don't know where the abrasion mode comes in?

Brittle? Kevlar? Where in the world did you get such a strange idea? Kevlars degrade at temps above 900°F, If exposed to temps at or above this repeatedly eventually the line will snap but this is not because it's become brittle.. it's because the line has decomposed to the point of failure.

Again the twisted 2 strand 13lb Kevlar suggested generally outlasts the canopy on most size chutes retardless of canopy material Plastic, Mylar or Nylon.

To be sure it is slightly stiffer then cotton carpet thread but the advantages outweight that slight shortcoming if you'd really call it that. Kevlar does not Fuzz as carpet and cotton thread does and doesn't seem to hold a memory even after being left in the model or chute bags for months.

With an added swivel these super light weight shroudline make packing a 30" 1/4mil mylar chute in a BT-5 almost easy, You'd never be able to do so with carpet thread.

Too be sure Kevlar thread is a bit more expensive 20bucks for 600yard roll. I believe it more than pays for itself in NOT burning off causing landing damage on models flying with it's superior tuffness and small diameter.
May not be the shroud material for everone but its one of those little things that eliminate one more potential flight problem for those who want or need to concentrate on other phases of the flight.

Hope this explains why Kevlar over Carpert thread for shroudlines.