In all seriousness, a long shock cord saved my rocket, because the parachute was high in a tree, but the rocket touched the ground. No such thing as too long a shock cord!Use enough Kevlar that the rocket reaches the ground before the chute deploys.
Seriously, Kevlar is awesome. However, I must have two left thumbs because half the time with LPR, the Kevlar turns into a rat's nest. Elastic doesn't ball up on me like Kevlar. That said, I only use Kevlar with MPR because I've snapped the elastic on a Star Orbiter.
shock cord- kevlar plus rubber?
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I have that problem sometimes. I experimented and designed a spool that I wrap the kevlar around then it unrolls during deploy. This has proven to be relatively reliable. I've also tried the crochet trick and it works sometimes but not other times. Once you have turned 10' of thin kevlar into a crochet it is halfway to a rat's nest then you have to get it into the body tube. What I usually do is fold it up in the parachute. Sometimes I get lazy and just stuff the kevlar into the body tube, this hasn't been that much less reliable than the crochet. My spool works with my BT60 and larger rockets but not my BT55 rockets so I have to use the stuff method for those.
I used to get tangled up Kevlar on smaller rockets until I started using Kevlar that was much larger diameter than what is really necessary. The 150# sometimes tangled, the 350# never has for me.Use enough Kevlar that the rocket reaches the ground before the chute deploys.
Seriously, Kevlar is awesome. However, I must have two left thumbs because half the time with LPR, the Kevlar turns into a rat's nest. Elastic doesn't ball up on me like Kevlar. That said, I only use Kevlar with MPR because I've snapped the elastic on a Star Orbiter.
Hans.
That’s a good idea. I use the trick of running it in a figure 8 around two fingers and this has worked surprisingly well, even on very long cords.
I'm using the 500#. Here's another opportunity to watch Xyla installing and wrapping the shock cord.
I'm looking for a good source of braided or tubular Kevlar. It's been working great in my LOC Patriot 4in. Rocketman looks great.
https://the-rocketman.com/braided-kevlar-shock-cord/
Thus the two left thumbs...
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I'm using the 500#. Here's another opportunity to watch Xyla installing and wrapping the shock cord.
I'm looking for a good source of braided or tubular Kevlar. It's been working great in my LOC Patriot 4in. Rocketman looks great.
https://the-rocketman.com/braided-kevlar-shock-cord/
Thus the two left thumbs...
Here’s a pic of mine, not as much fun as her’s, but still….
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jahall4
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... then simply put your harness (shock cord) is not long enough and/or you ejection charge is too energetic. Don't complicate your rigging by adding more "stuff". As others have mentioned, use Kevlar, keeping in mind that Kevlar does have a little bit of stretch. As I often say... "A long harness is the great redeemer."
@Ronz Rocketz --
Are you using twisted or braided Kevlar ?
I've never had a problem with braided Kevlar but twisted twine, no matter the material, always becomes a mess eventually ...
HTH.
-- kjh
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My LPR launches yesterday were with 100-lb braided Kevlar, figure-8 wrapped around my fingers and folded inside the parachute. Parachutes are set up with a quality ball bearing snap swivel to the harness loop. No tangles, no twists. Got my Deco-Puff wrap down to two sheets working great even in BT-60.
When I google Deco-Puff wrap I get mesh puffs for parade floats??? What are what your using?
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That's it. I have tested them with a BBQ lighter over concrete and they are more flame-retardant than Estes TP wadding. Both will appear to burn while the lighter flame is against them. When the lighter is removed, the Estes TP will burn for awhile before going out. When the lighter is removed, the Deco-Puff extinguishes immediately.
Many posters have said that Deco-Puffs are what is included with Quest motors as wadding; I can't tell the difference, except that I prefer starting with a flat piece, rather than the crisply-folded pieces from the Quest packages.
Rather than wadding it up to make a plug, I wrap the chute. I bunch one square up to form a cup that more or less plugs the body tube and insert the folded chute in that. I then wrap another square around the outside of the cup, kind of like a burrito, roughly folded over the bottom of the cup and the top of the chute, and then insert the whole bundle in the tube. It's kind of in between wadding and a Nomex burrito wrap. A nice thing is, it doesn't require the 1.5-2 diameters of wadding or dog barf taking up length in the body tube. It's basically the same size, only slightly bulkier, than the folded chute by itself. And it's less material than would be required to form a TP wadding plug.
The problem I've had using the Quest squares this way is with the whole thing being kinda loose, the creases seem to want to make gaps. At least, I've had burn holes show up with Quest squares used as I describe and not with flat ones. Might keep working on the Quest materials, since the chute is burned anyway, to figure out a method that works.
I understand that. The time I had a problem I was using 8' or kevlar in an Estes ESAM with B6-4 motor. I think going beyond 10' of kevlar in a rocket that size is starting to become impractical. Most of the time I use 10', I could go 12' or a little bit more but not much more.
How thick is that stuff compared to the normal Estes stuff?
I have experimented with using crepe paper streamer material. It is treated to be fireproof and it seems that the decopuff is also. I but 3 or 4 pieces of crepe paper about 12" long, lay them on top of each other and tie a string around them right at the middle, then rough them up a little bit to form a pompom. My old crepe paper was strong enough that one of these would last 6 or maybe 8 launches. I bought a new roll of crepe paper from Hobby Lobby and it was not very durable, the pompoms became one time use only so for now I'm back to dogbarf.
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Deco-Puffs are the thickness of tissue paper. No texturizing to give them body like crepe paper. They are much stiffer than the Estes TP wadding. My gut worries that if used in the same way as Estes TP, you'd be even more likely to have gaps around the edges. I like them as wraps.
I have bought a few rolls of crepe paper at Dollar Tree to try as streamers. Will at least try them without wadding to see how that goes. I'm interested in getting as much weight as possible out of tiny rockets.
I have bought a few rolls of crepe paper at Dollar Tree to try as streamers. Will at least try them without wadding to see how that goes. I'm interested in getting as much weight as possible out of tiny rockets.
It's Kevlar kite string. I've been looking into getting braided or ribbon Kevlar from Rocketman. Let me know if there's a better source.
Here's the best wadding. It's 99c per roll and extremely flame resistant. They don't want the birthday candles catching the streamers on fire.
https://www.walmart.com/ip/Way-to-Celebrate-Party-Crepe-Paper-Roll-150ft-Orange-1-Ct/37748877
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@Ronz Rocketz --
I thought I posted this the other day ???
Anyhow, I can't recommend it because I've not pulled the trigger on my small Amazon order yet but this 'line' of braided Kevlar looks promising:
Amazon > 9KM DWLIFE Kevlar Kite String
But I was thinking ...
I like first-hand shopping and in your case, there might be a local big-game fishing supply shop on Oahu that carries hollow, 12-strand braided Kevlar fishing line and accessories ?
-- kjh
EDIT: p.s. avoid the twisted line and go with braided !
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You can get that brand cheaper/ft and in smaller quantities on AliExpress. It's what I've used so far.
Wow !
The prices for the 9KM stuff at AliExpress are PDG !
AliExpress > Search > 9KM Braided Kevlar Line
Thanks, @SolarYellow !
-- kjh
