Inexperience with Chute Release ??

[Glasspack]

John, & Anyone who uses a Chute Release:

I have two of the JL Chute release devices you make. I don't have much experience with them but let me tell you they are one of the coolest
developments in Rocketry in many years....

My son used one to attempt his LVL 1 Cert this past weekend at BONG in Wisconsin. It already had a tether on it & was attached to the same swivel the chute is on. The landing was not very good, as the chute never billowed out and filled with air. Upon recovery after a three day search, we found it undamaged, (Thanks to the 7 foot grass bed) with the shroud lines twisted bad around the tether. The release opened at 600 feet like it was set.


I assume the lines came out of the fold BEFORE it reached the 600' release, but can't be certain. Watching it, I actually thought the Nomex "burrito" never unfolded.

I am pretty sure this is my fault for making the tether too long. Can you confirm? There MUST be a reason the tethers that are included are so short?
Is this why the instructions say to hook it to one of the shroud lines ? I used the swivel because its way more secure than a shroud line.

Thank you Paul

 

[Glasspack]

Here are two more pics.............

 

[rharshberger]

I never attach anything to the parachute swivel for the very reason things tend to tangle in the shrouds. I attach the JLCR to its own loop in the shock cord away from the parachute attachment point.

 

[afadeev]

[...] It already had a tether on it & was attached to the same swivel the chute is on. The landing was not very good, as the chute never billowed out and filled with air. Upon recovery after a three day search, we found it undamaged, (Thanks to the 7 foot grass bed) with the shroud lines twisted bad around the tether. The release opened at 600 feet like it was set.

I assume the lines came out of the fold BEFORE it reached the 600' release, but can't be certain. Watching it, I actually thought the Nomex "burrito" never unfolded.

I am pretty sure this is my fault for making the tether too long. Can you confirm? There MUST be a reason the tethers that are included are so short?
Is this why the instructions say to hook it to one of the shroud lines ? I used the swivel because its way more secure than a shroud line.

Paul,
Can you clarify what do you mean by "I used swivel [...] instead of shroud line"?
Initially, I assumed you had a ball-swivel attachment between chute and [SIZE=-1]the shock/tether cord, but your last sentence suggests you were NOT using the JL CR's rubber tether to hold chute in folded position?[/SIZE]

I actually had something similar happen to me once: the chute came out, and spun around as a streamer tangling up the chute [SIZE=-1]shroud [/SIZE]lines. When CR released, the chute did not inflate, but the rocket landed with minimal damage (1" of crack on one fin fillet).
I also had a swivel on the connection between chute and shock cord, CR is always tethered to a shock cord. I suspect it either did not spin freely enough or fast enough to keep with spinning CR-folded chute/streamer. On that flight, I had purposely folded the chute to act like a long streamer. Which it did, but evidently, this had also allowed the parachute shroud lines to be pulled out of the fold by the drag created from using folded chute as a streamer.

My current working solution is to pack the chute into CR more tightly, folding it at least 3 times over shroud lines, similar to the instructions in the PML pamphlet (link below). This will trade off the streamer area for increased circumference of the folded chute that CR will be squeezing, making it less likely that the chute shroud lines will pull out again.

PML chute packing instructions here:
https://publicmissiles.com/secure/parachutepacking.asp
https://publicmissiles.com/images/pmlchutepacking.pdf

HTH,
a

 

[Otimebomb]

I agree, looks the lines came out ahead of time. I pack mine super tight, I really stretch the band to get it to lock in place. Who knows you could have had it perfect and just had bad luck. Lots of things floating around while it's dropping before deployment. Nose, rocket itself, chute, chute release, altimeter, shock cord.. Bound to be a tangle up now and then no matter careful the stuff gets packed/put together.

 

[John Beans]

There are a number of threads on this site with regards to tips and techniques for using Chute Release, and we have a folding tips video on the Jolly Logic site as well. If you haven't already, check these out.

I think one very natural tendency (since deployment is the hardest thing about rocketry) is to stick to how you've always done it, but then just add Chute Release as an extra step. Chute Release parachute folding is its own special skill, and should change how you fold your chutes. As a test, it should be true that you'd never fold your chute like you do with Chute Release if you were NOT using Chute Release (because it would just fall apart and not bundle up well). Not saying that's what happened here, but just as general advice to everyone.

There are things to keep in mind:

1. Never tether Chute Release in a way that could put tension on the tether, or get tangled up. In other words, you should be able to pull the nosecone in one direction and the fuselage in another until something breaks, yet the Chute Release is not tugged at all. I attach it somewhere close to the bundle, in a way that it can't get tugged or twisted up; you want the minimum tether needed that will work (not sure this was a factor here, but a very long tether may have contributed)

2. Do a shake test. You shouldn't be able to grab the shock cord and shake the bundle loose. (this might be the start of what happened here)

3. If you use a blanket, make sure there IS tension on it when you pull the nosecone one way and the fuselage the other, so that it gets whisked away when the shock cord goes tight on ejection and on the way down. Several folks (me included) have witnessed flights where Chute Release worked as planned, but the blanket stayed wrapped around, blocking the wind from opening the bundle on the way down. (this may be a factor here, too)

What you're going for is a bundle that stays neat in the slipstream without letting anything twist up but "pops open" upon release. With practice you can slow your rocket within 100 feet of planned release, 50 feet or better if you're really good.
Some rockets and chutes make this pretty easy, especially if there is lots of space. For instance—not to put too fine a point on it—I'm not sure why anyone would set an Estes Pro Series II rocket to anything but 200 feet, even if (maybe especially if) you're sticking H's and I's in it.

 

[crossfire]

John, & Anyone who uses a Chute Release:

I have two of the JL Chute release devices you make. I don't have much experience with them but let me tell you they are one of the coolest
developments in Rocketry in many years....

My son used one to attempt his LVL 1 Cert this past weekend at BONG in Wisconsin. It already had a tether on it & was attached to the same swivel the chute is on. The landing was not very good, as the chute never billowed out and filled with air. Upon recovery after a three day search, we found it undamaged, (Thanks to the 7 foot grass bed) with the shroud lines twisted bad around the tether. The release opened at 600 feet like it was set.

View attachment 329353
I assume the lines came out of the fold BEFORE it reached the 600' release, but can't be certain. Watching it, I actually thought the Nomex "burrito" never unfolded.

I am pretty sure this is my fault for making the tether too long. Can you confirm? There MUST be a reason the tethers that are included are so short?
Is this why the instructions say to hook it to one of the shroud lines ? I used the swivel because its way more secure than a shroud line.

Thank you Paul

Paul
The next time we are at Bong I will show you how I pack the chute for the JLCR. I have used mine all summer and only had 1 flight were chute deployed at apogee and it was my fault. I always attach the JLCR tether lines to the quick link where chute is attached but not to the chute swivel. It seem to work best if you fold shroud lines with in the chute. Make sure you use the right size rubber band. I have about 12 HP flights using the JLCR so far this year. Largest chute was a 60".

Gary

 

[Glasspack]

Afadeev,

If you zoom in on the end of the tether, where the altimeter is also attached......you will see the hint of metal swivel. The tether of the chute release is about 8" long and was all wraped up inside the shroud lines.
I normally wrap the lines inside the chute folds to be held by the chute release rubber band. I think i learned a good lesson that John already has in the instructions. Use a short tether......
There would not be any tension on the tether as John stated; since the recovery harness was not bundled with it. The chute on my SA-14 Archer is 58".... and it worked great the next day. The tether on that one was a stock tether. I really believe the tangle on this V2 had a lot to do with the length of tether i used
I am 100% certain this tangle is all user error. Wich makes me even feel worse....knowing my son may have failed his cert attempt because he used my release with my own kevlar tether.

Thank you all for the feedback.....

Paul

 

[crossfire]

Afadeev,

If you zoom in on the end of the tether, where the altimeter is also attached......you will see the hint of metal swivel. The tether of the chute release is about 8" long and was all wraped up inside the shroud lines.
I normally wrap the lines inside the chute folds to be held by the chute release rubber band. I think i learned a good lesson that John already has in the instructions. Use a short tether......
There would not be any tension on the tether as John stated; since the recovery harness was not bundled with it. The chute on my SA-14 Archer is 58".... and it worked great the next day. The tether on that one was a stock tether. I really believe the tangle on this V2 had a lot to do with the length of tether i used
I am 100% certain this tangle is all user error. Wich makes me even feel worse....knowing my son may have failed his cert attempt because he used my release with my own kevlar tether.

Thank you all for the feedback.....

Paul

Paul
What are you calling a tether? Most of my rockets I put a quick link some where on the shock cord than the chute is hooked to the quick link with a swivel.

 

[afadeev]

If you zoom in on the end of the tether, where the altimeter is also attached......you will see the hint of metal swivel.

I can't really see it, but I trust your description, and take it that the chute shroud lines were attached to the shock cord via a metal swivel.
And, based on your initial email, the JL CR itself was tethered to the very same metal swivel as the chute? Same end? Opposite end? Some place on the shock cord?

I can't really tell much from the pics, other than that you must have had a tone of fun untangling those shroud lines!

The tether of the chute release is about 8" long and was all wraped up inside the shroud lines.
I normally wrap the lines inside the chute folds to be held by the chute release rubber band. I think i learned a good lesson that John already has in the instructions. Use a short tether......
There would not be any tension on the tether as John stated;

I'm not sure how tether length has much to do with your troubles.
But if you think you need a shorter tether than the one JL CR came with, then go for it.

I really believe the tangle on this V2 had a lot to do with the length of tether i used I am 100% certain this tangle is all user error.

Regardless of the length of the CR's tether, if the chute shroud lines had stayed inside the properly packed chute, they would not have been tangled up upon CR release. I bet that's your culprit.
I do agree that the root cause is, likely, user error. Probably in chute packing.

YMMV,
a

 

[Glasspack]

I didn't mean for it to sound like I think the tether should be shorter than stock. At first recovery, I thought the one I made, must have been too long !! Look at these pictures Crossfire, here I pointed out the Chute Release Tether and swivel. The swivel attaches to the Shock Cord and the Shroud lines. I attached the Release tether to the same point on the swivel as the shroud lines.

here is what the swivel looks like...

It might look like the 1/2" wide, white shock cord is all tangled but its not......The shroud lines are. Like John pointed out: folding a chute for use with the Chute Release is different from conventional chute folding. The video on Jolly Logics page is NOT how this one was folded. I am certain I even told my son not to roll it or wrap the lines around the chute.... (I believe wrapping shroud lines around the chute is a horrible idea when folding a chute)

I am sure now that ...(like you guys said)... the problem was that the shroud lines came out of the fold BEFORE the programed 600 feet.

Thank you all for your feedback