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Senior Space Cadet

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Got to launch rockets today for the first time in months.
No pictures yet, I need to download them and run them through Paint Shop Pro.
I launched five rockets, four of which I'd never launched before.
The good news is all five flew nearly flawlessly. Flew straight, no motors came loose.
The bad news is not a single parachute opened all the way.
I just don't get chutes. I watch videos on packing chutes and I don't see anyplace I'm making any kind of major error, yet the don't open.
One of the rockets was the one with the parachute packed into the nosecone. Some of you were skeptical it would work.
I'm an honest man. It didn't work. The chute was still tucked up in the nosecone when I picked it up off the ground.
That rocket also had long, skinny fins. Two of them broke on landing. The joint didn't fail, so they were glued on good and strong, but the balsa broke.
No more long skinny fins on my rockets.
I used nothing bigger than a C motor. They went plenty high for the small field I was launching from. In fact, the one BT-50 rocket I launched went too high. Even with the chute not opening all the way, and very little wind, I had to chase it about a quarter mile and it landed in a parking lot. I'm going to stick with BT-55 and BT-60 for my builds.
 

Funkworks

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Is it that the parachutes eject and don't open, or that they stay stuck in the tube?
 

crossfire

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Why was chute in nose cone?
 

aerostadt

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If the air temperature is as cold as it is here, the plastic might not open.
 

Senior Space Cadet

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If the air temperature is as cold as it is here, the plastic might not open.
No, temp. wasn't bad. Probably at least 45. And the guy I was launching with had no problems.
I think the problem must be the way I'm packing the shock chord. It's getting tangled up, even though I'm using a swivel.
One mistake I might have made is I was in a hurry to get them ready (short notice) and used a swivel on the chute but none on the nosecone.
 

hcmbanjo

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On the few models where I've had to put the chute into the nose cone -
Push some of the shock cord into the nose cone first, followed by the chute.
When the shock cord extends at ejection it can pull the chute out.

With the weather getting colder, open the chutes right before launch and dust them with
some talcum powder before re-packing.
 

samb

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What was the other guy doing differently to get his parachutes out ? Did you try his method ?
 

ThirstyBarbarian

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Are you wrapping your chute shroud lines around the chute, or are you laying them inside and folding the chute up? I think it’s better to fold them in, not wrap around.
 

Tobor

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I have several rockets with the parachute parked in the NC with a sleeved bulkhead that projects the chute from ejection charge pressure,. Although to be fair, none of them fly on BP and they all have nose weight added for stability.

Here is an example from my modded Estes Big Daddy on an AT E23-5T.
Big Daddy Landing.jpg

Build pics (Here).
 

Senior Space Cadet

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On the few models where I've had to put the chute into the nose cone -
Push some of the shock cord into the nose cone first, followed by the chute.
When the shock cord extends at ejection it can pull the chute out.

With the weather getting colder, open the chutes right before launch and dust them with
some talcum powder before re-packing.
My launch day partner also suggested dusting with talc. I'll try that. Can't hurt.
 

Senior Space Cadet

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What was the other guy doing differently to get his parachutes out ? Did you try his method ?
We went over his set-up. A little unusual. He used some narrow nylon webbing instead of Kevlar chord (larger rocket). It may be less prone to tangling. I'm compromising and ordered some thicker Kevlar, thinking it might be less likely to tangle up than the really thin stuff. Otherwise, what he was doing wasn't much different.
 

Senior Space Cadet

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Are you wrapping your chute shroud lines around the chute, or are you laying them inside and folding the chute up? I think it’s better to fold them in, not wrap around.
I'm folding the chute's lines inside the chute, inserting the chute in the rocket, then stuffing the shock chord in after. Sometimes I try and put the shock chord in first, then put the chute in. Not sure if I'm having any better luck with one over the other. I think I need to take a more scientific approach. Pack the chute differently with each of three rockets and see if any of them open.
 

Senior Space Cadet

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I have several rockets with the parachute parked in the NC with a sleeved bulkhead that projects the chute from ejection charge pressure,. Although to be fair, none of them fly on BP and they all have nose weight added for stability.

Here is an example from my modded Estes Big Daddy on an AT E23-5T.
View attachment 441360

Build pics (Here).
Interesting idea.
 

Senior Space Cadet

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I'm attaching my nosecone very close to where the parachute is attached.
Good idea or bad?
 

BABAR

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I'm attaching my nosecone very close to where the parachute is attached.
Good idea or bad?
With chute in cone, probably a bad idea. Your mechanism requires the ejection charge energy to pressurize the body tube and force out the nose cone, hopefully transmitting much to kinetic energy of the cone. The cone moves away and unravels the shock cord. I would say you need to attach the chute to the SHOCK cord AT LEAST the length of the chute shroud lines plus the radius of the chute to make sure the chute is fully OUT of the nose cone before the shock cord goes taught.

I am curious, how is your shock cord attached to the nose cone? If it isn’t glued into the tip, it could be your attachment point is blocking a smooth chute exit from the cone (nose cone internal tip attachment is hard but not impossible to do—— drill a hole from side to side across the cone a bit back from the tip, insert dowel, cut off external dowel piece as close to outer cone surface as possible, and sand smooth. Somehow get a loop of Kevlar around it from inside, and fix with a couple drops of polyurethane glue ((original Gorilla Glue). Do NOT use CA with Kevlar, it makes it brittle.
 

Tobor

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Hey Cadet,
I should have mentioned HOW my technique works. The setup uses two pieces of shock cord. Shock cord #1, attaches the bulkplate to the airframe. Shock cord #2 attaches to the other side of the bulkplate (along with the parachute) and the other end attahes to the nosecone.

The total length of both shock cords equals the length of a single shock cord that would be used in a standard recovery setup (3x ~ 5x total airframe length).
So....
Cord #1 length = 30~45% single cord length
Cord #2 length = single cord length - Cord #1 length
 

mooffle

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I'm folding the chute's lines inside the chute, inserting the chute in the rocket, then stuffing the shock chord in after. Sometimes I try and put the shock chord in first, then put the chute in. Not sure if I'm having any better luck with one over the other. I think I need to take a more scientific approach. Pack the chute differently with each of three rockets and see if any of them open.
This sounds fine, but are you able to post a video or series of pictures of your process? Depending on tube diameter you'll also have to vary your process quite a bit.
 

Antares JS

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Are you packing your parachutes immediately before launch or some time beforehand? Plastic parachutes have a tendency to not open if they've been packed in a body tube for too long. Talcum powder can help with this but you're better off unpacking and repacking immediately before launch, especially if it's cold.

Are you using enough wadding such that the parachute doesn't get damaged? If it melts together it's going to have trouble opening as well.

Are the shroud lines getting tangled with the shock cord? Despite some people saying it's a bad idea, I've had more success wrapping the shroud lines around the folded-up canopy. It prevents the lines from tangling with the shock cord.

Those are the only things I can think of if they're ejecting but not opening.
 

Blast it Tom!

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Well, here in frigid PA, I had 4 bad chutes yesterday - all Estes plastic, word over on the other thread was that cold (32°F, 0°C) can certainly affect plastic chutes opening. But that sure doesn't affect @rklapp! Guess it can happen to the best of us, and I sure ain't one of those!
 

Mike Haberer

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My launch day partner also suggested dusting with talc. I'll try that. Can't hurt.
I always dust plastic parachutes with talc, regardless of temperature. That said, I avoid them as much as possible. I used one as a drogue on a recent launch in advance of the JLCR opening - it shredded. I only used in because I left my rip stop nylon drogue at home...
 

Tobor

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Top Flight makes some really nice Thin Mill chutes and can handle a fair amount of abuse, like early chute ejections.
 

lakeroadster

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That rocket also had long, skinny fins. Two of them broke on landing. The joint didn't fail, so they were glued on good and strong, but the balsa broke.

No more long skinny fins on my rockets.
No need to eliminate long skinny fins, just use a material that'll survive.

Have you tried basswood, or lite-ply, or making your own plywood with balsa?
 

crossfire

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Well, here in frigid PA, I had 4 bad chutes yesterday - all Estes plastic, word over on the other thread was that cold (32°F, 0°C) can certainly affect plastic chutes opening. But that sure doesn't affect @rklapp! Guess it can happen to the best of us, and I sure ain't one of those!
Get rid of the plastic chutes.
 
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