Chute placement & Z-folds

[AP aroma]

Hello all,

I am wondering about a couple of things:

How far along the shock cord do you attach the parachute? This is the main parachute in a dual deploy rocket. The upper body tube is secured to the AV-bay and the nose cone pops off at deployment, hopefully pulling the parachute out.. Have I heard that the chute should be attached 1/3 of the length of the shock cord away from the AV-bay?

Also I want to use taped Z-folds to lessen the impact of the parachute when it inflates. Is there any reason to Z-fold and tape the entire shock cord, or do you just need to do the portion that is between the AV-bay attachment and the parachute?

Thanks as always,

Jim

 

[Wayco]

I usually put an "alpine" loop about 1/3 way down from the nosecone, and attach the chute and a nomex pad at the loop. You can Z fold your shock cord in next to the chute. That way the "burrito" comes out sooner, everything is protected from your ejection charge and the pad acts as a "sabot" holding everything in place until it leaves the payload tube. The best way to limit the impact of the parachute opening is to lengthen the shock cord.

 

[David Schwantz]

I z fold everything I can. Neater that way. I put a third loop in shock cord, depending on rocket size, any where from 1 to 3 feet down from NC. Just make sure it is not long enough down for NC to hit main tube. Also, the best way to lessen shock at deployment is to have your BP charge correct. Always ground test. And do so in flight config.

 

[Jmhepworth]

I agree with Wayne. He’s the one who taught me how to pack a chute, and since I started doing what he taught me, I’ve not had a deployment failure. (I almost didn’t say that so as not to jinx myself.) One of the most important things Wayne taught me was to pack everything so the chute is the first thing to come out.

 

[Viper3]

I would attach the main chute to the nose cone. Many fliers attach it about one third down the shock cord from the nose cone.
It's ok to tape or rubber band (small) the shock cord. I do it to minimize tangles in the shock cord. As to lessening the shock of the chute opening (never had a problem ) you can use a plastic ring and slide it over the parachute shroud lines up to where the lines met the fabric of the chute and as the chute opens the ring slides down the shroud lines and increases the time it takes to open. You can buy these from some chute manufacturers or use a napkin ring.
Jim

 

[rocketcharlie]

OP here. I'm trying to do all this in a 38 mm airframe. Do you feel there is room to "burrito" the 18' shock cord as well as the 24" parachute in the nomex blanket?

 

[rocketcharlie]

I just did some ground testing without any tape on the shock cord and I was very happy with the results.
Thanks everyone-

Jim

 

[Wayco]

I pulled down my Star Orbiter, which is 1.64 inches in diameter with an 18" Top Flite thin mill chute and a 6" nomex pad of my own mfg. The shock cord is pretty small, but it all fits easily.
I start by flaking out the chute and folding the skirt back:


S fold the chute

Roll it up and tuck it into a corner of the pad

S fold the lines and roll them in


S fold the shock cord as you roll it up


Fold the corners of the pad over


Plenty of room, I even use a JL chute release on this rocket.


Then Sharon came in and asked if I could do that with a 24" chute.
Same type of TF thin mill chute, and a heavy duty Wildman 9" nomex pad.




Not a problem, I can make another post and show this all over again, but you get the idea.
Thanks to Joe H. for the endorsement, He is one of the many people I show this to at almost every launch I go to.
I could talk about the thousands of man rated chutes I have packed for skydiving students, or the thousands of chutes I have packed for my rockets, but then someone would think I'm bragging....

 

[rocketcharlie]

Wayne, thanks for that post. With all the photos it helps a great deal. I will try that system next time I ground test.

Jim

 

[Hardline]

Good post, honey. I hope people appreciate the amount of time it takes to setup the photo shoot, compose the pictures, make the content pertinent, upload the photos and get them into a post with clarity. You taught me as well as many other folks in the field and on the forum and it is much appreciated. (I'm the Sharon in Wayco's post so I get to call him "honey" )

 

[JoePfeiffer]

You want the nose cone shock cord to be substantially shorter than the airframe shock cord. It's got a lot less weight on it, and typically it's much more robust. For a 38mm rocket you can probably take some of the advice above and connect the chute swivel pretty much directly to the nose cone.

The one hard and fast rule is you don't make the nose cone shock cord the same length as the body tube shock cord. That's a prescription for having the nose cone hit the body tube as the main chute opens.

 

[neil_w]

I could talk about the thousands of man rated chutes I have packed for skydiving students, or the thousands of chutes I have packed for my rockets, but then someone would think I'm bragging....

Thanks for the extremely useful photos. Although I haven't had any problems up until now, I still feel like I need to up my chute-packing game. Also will be starting with a Chute release this year, and I gather Z-folding is ideal for that as well.

If not using a nomex blanket (yeah, I should probably start), what changes? It seems like the nomex is what keeps everything together in the airframe, whereas the classic Estes technique of wrapping the shroud lines around the parachute serves that purpose without the burrito.

 

[Jmhepworth]

(I'm the Sharon in Wayco's post so I get to call him "honey" )

I’d call him “honey,” too, but I’m pretty sure I can’t say that to a Marine.

 

[dhbarr]

I’d call him “honey,” too, but I’m pretty sure I can’t say that to a Marine.

You can do anything you want on your last day

 

[Wayco]

Thanks for the extremely useful photos. Although I haven't had any problems up until now, I still feel like I need to up my chute-packing game. Also will be starting with a Chute release this year, and I gather Z-folding is ideal for that as well.

If not using a nomex blanket (yeah, I should probably start), what changes? It seems like the nomex is what keeps everything together in the airframe, whereas the classic Estes technique of wrapping the shroud lines around the parachute serves that purpose without the burrito.

Sharon has had some luck using the Chute Release without a pad, but I just can't bring myself to trying it. I also cringe when I see someone coil the lines around the chute, although I know that a lot of people do it this way.
My background with man rated 35 ft. parachutes (T-10) is reflected in the way I pack everything, even the ram air "square" chutes I jumped with for many years in the sport. I watch closely when I'm hanging under a deploying chute to determine the sequence of it's opening, and have done the same with my rocket chutes, usually with binoculars. The sequence looks much more organized when it comes out of the payload tube and catches air as it leaves the burrito.
I have watched thousands of students exit the jump plane and deploy the parachutes I packed. All of them worked, because the sequence was to pull all the lines out straight before the chute inflated, that's what my pack job does.
When you're doing this:

You don't want the lines wrapped around all that nylon.

One of the things I love about this hobby is that everyone develops a method that works for them, and if it doesn't, they usually figure it out by either trying it again or by asking someone who has figured it out already. Those that ask me get my lesson with the precautionary statement that this is just MY way, there are lots of other ways that can work too.

I’d call him “honey,” too, but I’m pretty sure I can’t say that to a Marine.

You can do anything you want on your last day

You're likely to get more grief from Sharon than you would ever get from me.

 

[JoePfeiffer]

You can do anything you want on your last day

Even if it wasn't your last day before you did it!

 

[Angel_of_the_Skies]

I pulled down my Star Orbiter, which is 1.64 inches in diameter with an 18" Top Flite thin mill chute and a 6" nomex pad of my own mfg. The shock cord is pretty small, but it all fits easily.
I start by flaking out the chute and folding the skirt back:
View attachment 456491

S fold the chute
View attachment 456492
Roll it up and tuck it into a corner of the pad
View attachment 456493
S fold the lines and roll them in
View attachment 456494

S fold the shock cord as you roll it up
View attachment 456495

Fold the corners of the pad over
View attachment 456498

Plenty of room, I even use a JL chute release on this rocket.
View attachment 456501

Then Sharon came in and asked if I could do that with a 24" chute.
Same type of TF thin mill chute, and a heavy duty Wildman 9" nomex pad.
View attachment 456502

View attachment 456504

Not a problem, I can make another post and show this all over again, but you get the idea.
Thanks to Joe H. for the endorsement, He is one of the many people I show this to at almost every launch I go to.
I could talk about the thousands of man rated chutes I have packed for skydiving students, or the thousands of chutes I have packed for my rockets, but then someone would think I'm bragging....

I launched my Zephyr Jr a couple weeks ago and had two flights. First flight, lines extended but plastic chute was packed tightly, second flight the shroud line caught with the shock chord somehow and prevented an opening. Luckily that day was windy so the wind added a lot more drag on the chute.

Planning on launching this weekend and trying this out as I los have a nomex on my rocket. Pictures help a lot !

Just to confirm, shock chord in the nomex are from the chute to nose cone portion correct?

 

[ep29030]

If you want to avoid the snap when kevlar reaches its end, consider Z-folding your shock cord and wrapping it with a rubber band (or several of them). They break during deployment and bleed off some of that kinetic energy at ejection. I do this on MPR/HPR kits. It also keeps your bridles more organized as you pack the rocket.

 

[Handeman]

I launched my Zephyr Jr a couple weeks ago and had two flights. First flight, lines extended but plastic chute was packed tightly, second flight the shroud line caught with the shock chord somehow and prevented an opening. Luckily that day was windy so the wind added a lot more drag on the chute.

Actually, the "wind" doesn't affect the chute, only the vertical speed. Wind is caused by an air mass moving relative to the ground or stationary object. When a rocket falls, it is moving with the air mass at the same ground speed as the air. The rocket/chute only has a vertical speed relative to the air mass. Both the rocket and the air mass are moving relative to the ground, not each other.

 

[Wayco]

I launched my Zephyr Jr a couple weeks ago and had two flights. First flight, lines extended but plastic chute was packed tightly, second flight the shroud line caught with the shock chord somehow and prevented an opening. Luckily that day was windy so the wind added a lot more drag on the chute.

Planning on launching this weekend and trying this out as I los have a nomex on my rocket. Pictures help a lot !

Just to confirm, shock chord in the nomex are from the chute to nose cone portion correct?

I put both ends of the shock cord in the Nomex pad. Chute goes first, roll it up in the pad, then the shroud lines, roll them in, then the long end of the shock cord to the payload anchor, then the upper shock cord to the nosecone. If you roll them in just a little for each part, hold the roll and pull the top of the pad to tighten it, there should be room.
When the burrito comes out of the payload tube, the nosecone pulls the first part of the shock cord out, then the lower part of the shock cord extends, and last comes the chute. It happens pretty fast, but that is the correct order for deployment.
I have been using the Wildman Nomex for a few years now, prefer it to my homemade pads, but I still make some of the smaller ones for the little rockets. I also sew a pouch for my drogue/streamer.

 

[Angel_of_the_Skies]

I put both ends of the shock cord in the Nomex pad. Chute goes first, roll it up in the pad, then the shroud lines, roll them in, then the long end of the shock cord to the payload anchor, then the upper shock cord to the nosecone. If you roll them in just a little for each part, hold the roll and pull the top of the pad to tighten it, there should be room.
When the burrito comes out of the payload tube, the nosecone pulls the first part of the shock cord out, then the lower part of the shock cord extends, and last comes the chute. It happens pretty fast, but that is the correct order for deployment.
I have been using the Wildman Nomex for a few years now, prefer it to my homemade pads, but I still make some of the smaller ones for the little rockets. I also sew a pouch for my drogue/streamer.

I plan on launching my zephyr jr very soon again. Currently looking to get my recovery to properly deploy

I will hope to add on to this thread very soon with my results. Thank you for the guide, will test it out

 

[Angel_of_the_Skies]

If you want to avoid the snap when kevlar reaches its end, consider Z-folding your shock cord and wrapping it with a rubber band (or several of them). They break during deployment and bleed off some of that kinetic energy at ejection. I do this on MPR/HPR kits. It also keeps your bridles more organized as you pack the rocket.

I plan to follow Wayco's method for my launch tomorrow (hopefully). I plan on mask taping the shock chord in a Z-fold fashion to keep the lines cleaner and make it easier to burrito wrap with the chute protector

 

[Angel_of_the_Skies]

I put both ends of the shock cord in the Nomex pad. Chute goes first, roll it up in the pad, then the shroud lines, roll them in, then the long end of the shock cord to the payload anchor, then the upper shock cord to the nosecone. If you roll them in just a little for each part, hold the roll and pull the top of the pad to tighten it, there should be room.
When the burrito comes out of the payload tube, the nosecone pulls the first part of the shock cord out, then the lower part of the shock cord extends, and last comes the chute. It happens pretty fast, but that is the correct order for deployment.
I have been using the Wildman Nomex for a few years now, prefer it to my homemade pads, but I still make some of the smaller ones for the little rockets. I also sew a pouch for my drogue/streamer.

awesome info. As per my testing by hand, the process occurs as you described : parachute to nose cone cord comes out first, followed by the chute to motor mount (where my shock chord is attached) connection, then the last part of the burrito unravels leaving the Z-folded chute to open up. I am using an Apogee cut to size plastic chute so instead of rolling up the chute, I simply fold my chute. I will be launching I hope soon (Maybe tomorrow), and I will document my results.

 

[SolarYellow]

I put both ends of the shock cord in the Nomex pad. Chute goes first, roll it up in the pad, then the shroud lines, roll them in, then the long end of the shock cord to the payload anchor, then the upper shock cord to the nosecone. If you roll them in just a little for each part, hold the roll and pull the top of the pad to tighten it, there should be room.
When the burrito comes out of the payload tube, the nosecone pulls the first part of the shock cord out, then the lower part of the shock cord extends, and last comes the chute. It happens pretty fast, but that is the correct order for deployment.
I have been using the Wildman Nomex for a few years now, prefer it to my homemade pads, but I still make some of the smaller ones for the little rockets. I also sew a pouch for my drogue/streamer.

How would your system interact with a chute release system, such as the JLCR? If it's bundled around the whole thing, then the shock cords may be prevented from extending, and the nose cone and airframe may not separate as much as you'd like. At release, the cords would still need to extend without the inertia of ejection and separation helping.

 

[Angel_of_the_Skies]

How would your system interact with a chute release system, such as the JLCR? If it's bundled around the whole thing, then the shock cords may be prevented from extending, and the nose cone and airframe may not separate as much as you'd like. At release, the cords would still need to extend without the inertia of ejection and separation helping.

I launched my rocket this past weekend, using this technique. I took binoculars to the launch site to be able to see when the rock unravels the recovery.

I z folded the parachute, along with Rocket to parachute / parachute to nose cone shock chord.

I taped the rocket to parachute shock chord after z folding the chute with masking tape. At apogee, the ejection had no problem ripping the tape and separating the chord.

If I were to do this with a JLCR, I would try to crochet braid the shock chords. I’ve yet to test it at apogee but in ground test, I have been able to extend the shock chord lines without any tangle. I would crochet both shock chord lines from the rocket to parachute and parachute to nose cone. I would leave them out of the Nomex blanket if crochet.

 

[Angel_of_the_Skies]

I taped the rocket to parachute shock chord after z folding the shock chord (rocket to chute) with masking tape.

CORRECTION

 

[Angel_of_the_Skies]

With an MPR, I’m able to crochet with just my fingers without a sweat.

 

[Wayco]

How would your system interact with a chute release system, such as the JLCR? If it's bundled around the whole thing, then the shock cords may be prevented from extending, and the nose cone and airframe may not separate as much as you'd like. At release, the cords would still need to extend without the inertia of ejection and separation helping.

It depends on the rocket. Most of my high power rockets are fiberglass, with redundant dual deploy systems. With the smaller paper rockets that we fly, I get mixed results, depending on the mass involved. If they are light enough, and the bundle stays intact, the JLCR works. Larger rockets can pull the chute out at apogee. When I pack for a JLCR, I leave about a foot of shock cord outside the burrito at both ends, and have used elastic instead of the rubber bands that come with the kit.
Honestly, I have little faith in the JLCR for reliable dual deploy. I only use it for small paper rockets.

I launched my rocket this past weekend, using this technique. I took binoculars to the launch site to be able to see when the rock unravels the recovery.

How did your recovery work?

 

[SolarYellow]

It depends on the rocket. Most of my high power rockets are fiberglass, with redundant dual deploy systems. With the smaller paper rockets that we fly, I get mixed results, depending on the mass involved. If they are light enough, and the bundle stays intact, the JLCR works. Larger rockets can pull the chute out at apogee. When I pack for a JLCR, I leave about a foot of shock cord outside the burrito at both ends, and have used elastic instead of the rubber bands that come with the kit.
Honestly, I have little faith in the JLCR for reliable dual deploy. I only use it for small paper rockets.

That makes sense. I'm still in the "small paper rockets" world. Actually, too small for a JLCR. Putting together a Quark running a hot wire setup instead. I'm pretty sure I can make it work down to BT-50 with the size of my hotwire "sled." It will be tethered to the nose cone where the Quark lives.

 

[Angel_of_the_Skies]

How did your recovery work?

The chute deployed right after apogee, I could see the lines come out from the burrito with the chute unraveling after the shock chord.

Chute opened up at around 1k feet on an Estes E12-6.

I would like to mention that this rocket is no longer with us and resides on top of a tree