Zipper prevention...best methods ?

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Silverleaf

Silverleaf

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What are the best methods to curtail or to prevent zippering ?.

I ask because I'm nearing the point of worrying about a proper method to lower the odds of a zipper effect, but also know that no method is 100 % flawless. Any help would be appreciated. 8)

Cheers and happy New Year,
 
there are lots of things, zipperless coupler (can still cause zippers though), fiberglass will toughen your airframe, a longer shock cord, and o yeah deployment at apogee always helps :D
 
I saw an add for a soft kevlar covered ball that attaches to the shock cord at the point where it would press against the BT end. It would probably be very hard to zipper that setup.
 
The kevlar covered ball that rbeckey describes is the Fireball from Giant Leap.

A method I like to use is adding a 1" strip of carbon fiber around the opening of the tube. typical glassing hten covers that. Gives amazing rigidity to the tube. I have never zippered a tube thus far.
 
Originally posted by rocwizard
A method I like to use is adding a 1" strip of carbon fiber around the opening of the tube. typical glassing hten covers that. Gives amazing rigidity to the tube. I have never zippered a tube thus far.
Click to expand...

Eric, do you put the carbon fiber on the inside or outside of the body tube? Or on the actual edge?
 
This question is really kind of open ended - the solutions you've seen posted are mostly for the high power end of things. If you're talking about low power models with a kevlar leader out the top of the tube, wrap it loosely with a thick layer of masking tape where the cord hits the top of the tube. You don't want it really tight - let it give a little. This should help on the low power end of things.

Loopy
 
Rocketmaniac, the carbon fiber strip is placed on the exterior of the tube up on the end. Fiberglassing then takes place as usual which sells down the carbon, not to mention that since carbon can't be sanded it must be covered in 'glass.

It might be a tad overkill for most rockets, but the rockets I ahve used this on are high performance. I will start a thread on one inparticular soon.


HTH;)
 
Silverleaf,

Go to Rocketry Online's InfoCentral and look at the zipperless design article by Stu Barrett. I'm currently using the design to build my first zipperless rocket. This design allows the rocket to seperate somewhere along the midsection of the bodytube allowing for the parachute to be pulled out the back of the forward bodytube section. This design will work for LPR-MPR and HPR.
 
Many thanbks for the comments and suggestions. I found the zipperless article, that should do the trick. 8)

Happy New Year
 
Anyone know a manufacturer of a carbon fiber or other suitable material that will fit over a LOC VII, 7.5 inch paper body tube? If it is necessary to cut the ring, are there any special techniques used for the putty in the gaps? Thanks for your help.


While frightening the confronting of the likes of the Ripper, much more is the terror of an "O" engine zipper. o_O
 
Super said:
Anyone know a manufacturer of a carbon fiber or other suitable material that will fit over a LOC VII, 7.5 inch paper body tube? If it is necessary to cut the ring, are there any special techniques used for the putty in the gaps? Thanks for your help.


While frightening the confronting of the likes of the Ripper, much more is the terror of an "O" engine zipper. o_O
Click to expand...
Soller Composites sells glass or carbon sleeving to epoxy on as a skin.
 
Want to avoid a zipper - don't deploy at speed.
Snarky reply, yes.........but accurate.

Your first efforts should be placed to make sure you nail the deployments which is the "root cause" of zippers.
 
Super said:
Anyone know a manufacturer of a carbon fiber or other suitable material that will fit over a LOC VII, 7.5 inch paper body tube? If it is necessary to cut the ring, are there any special techniques used for the putty in the gaps? Thanks for your help.


While frightening the confronting of the likes of the Ripper, much more is the terror of an "O" engine zipper. o_O
Click to expand...

Super,
Many people over the years have taken a strip of Kevlar and made a zipper reinforcement ring at the mouth of the body tube.

Your question about “putty” makes me wonder: What exactly is your level of experience with composite construction and rocketry in general?
 
As mentioned, the first order of business is proper deployment timing. There is no substitute for proper planning. But since nothing is perfect (with the possible exception of some forms of human stupidity) it can be good to take precautions...

Cross-form chutes tend to have softer opening characteristics than conventional chutes so they can give everything a tad more time to get properly oriented before the big yank (Texans don't like big yanks...:p). Plus they look cool... I use that type anytime there is a question about deployment, like when using motor ejection and your rocket sims out right between two available delay times. In fact, I use them most of the time because, well, they look cool.

Top Flite has them down to 10" diameter, I think, and in thin-mil. They make fantastic drogues for DD.
 
FWIW, I’ve used as much pool noodle as will fit on the ends of the tubular nylon for large rockets. Nerf darts for smaller ones, and masking tape applied face to face for even smaller ones.
 
Steve Shannon said:
Super,
Many people over the years have taken a strip of Kevlar and made a zipper reinforcement ring at the mouth of the body tube.

Your question about “putty” makes me wonder: What exactly is your level of experience with composite construction and rocketry in general?
Click to expand...

Dear President Shannon: I am uncertain what you mean by my "Level of Experience." Thank you for your input though. It was truly helpful. To explain, I assume that all Kevlar rings do not fit all body tubes appropriately. Some may need to be cut and tightened to fit? I use the term "putty" generically to mean a filler-type substance. I hope I did not promulgate any confusion. I simply wanted some help because i don't even know half of what is in NASA's library. I will be more cautious the next time I write the forum.

Sincerely,
Tom Long, PhD.
 
Super said:
Dear President Shannon: I am uncertain what you mean by my "Level of Experience." Thank you for your input though. It was truly helpful. To explain, I assume that all Kevlar rings do not fit all body tubes appropriately. Some may need to be cut and tightened to fit? I use the term "putty" generically to mean a filler-type substance. I hope I did not promulgate any confusion. I simply wanted some help because i don't even know half of what is in NASA's library. I will be more cautious the next time I write the forum.

Sincerely,
Tom Long, PhD.
Click to expand...

Tom,
The Kevlar ring I mentioned is made by wrapping a strip of fabric around the mouth of the tube in an epoxy matrix, which is typical of composite construction. Because the ring is made from fabric it fits any size tube and there’s no gap which needs filling. That’s why I asked for your level of experience with composites, so you would receive answers that don’t talk above or below your knowledge level. Apparently you feel offended by my question; my intent was not to insult you. Your question didn’t seem to indicate prior experience with composites, so I asked.
In the same way as Kevlar, fiberglass or carbon fiber reinforcement rings can be added to the mouth of a body tube: Fabric embedded in an epoxy matrix.
When you do need fairing compound (putty), having experience mixing laminating epoxy with various amendments, such as fumed silica, carbon or glass pulp, or microballoons can be helpful.
 
Haaaaa, i like that reply. Hey, a Snarky? Is that a ballistic missle of the US? Many were painted red with a huge hawk on the side? I think the hawk's mouth surrounds the forward intake? Anyway, funny response. Thanks


QUOTE="FredA, post: 1869900, member: 279"]Want to avoid a zipper - don't deploy at speed.
Snarky reply, yes.........but accurate.

Your first efforts should be placed to make sure you nail the deployments which is the "root cause" of zippers.[/QUOTE]
 
steve
Steve Shannon said:
Tom,
The Kevlar ring I mentioned is made by wrapping a strip of fabric around the mouth of the tube in an epoxy matrix, which is typical of composite construction. Because the ring is made from fabric it fits any size tube and there’s no gap which needs filling. That’s why I asked for your level of experience with composites, so you would receive answers that don’t talk above or below your knowledge level. Apparently you feel offended by my question; my intent was not to insult you. Your question didn’t seem to indicate prior experience with composites, so I asked.
In the same way as Kevlar, fiberglass or carbon fiber reinforcement rings can be added to the mouth of a body tube: Fabric embedded in an epoxy matrix.
When you do need fairing compound (putty), having experience mixing laminating epoxy with various amendments, such as fumed silica, carbon or glass pulp, or microballoons can be helpful.
Click to expand...


Steve, Thank you very much. Your information is extremely helpful. Your high level of expertise is evident and certainly stands you in great stead. I bet you are a great resource for many people similar to me.
 
Super said:
steve



Steve, Thank you very much. Your information is extremely helpful. Your high level of expertise is evident and certainly stands you in great stead. I bet you are a great resource for many people similar to me.
Click to expand...

Thanks. This is a link to the West Systems Handbook, which is chock full of helpful information on composite construction:
https://www.westsystem.com/instruction-manuals/user-manual-product-guide/

There are also a lot of very interesting looking books available from Aircraft Spruce and Spar that get into more advanced techniques.
https://www.aircraftspruce.com/menus/cm/books.html
 
Hi dhbarr,

Thank you for your response. So I have these followup questions for you, or for anyone, please:
  • Are people suggesting that fiberglass then be laid over the carbon sleeve? I don't understand the point of that, but perhaps I am misunderstanding.
  • Epoxying the carbon around the outside the air frame would add some thickness to the air frame, which could make the fit of the nosecone too tight, right? So why not epoxy the carbon sleeve to the inside of the air frame? Wouldn't that contribute the same amount of anti-zippering protection as epoxying the carbon sleeve to the exterior of the air frame?
Stanley
 
MetricRocketeer said:
Hi dhbarr,

Thank you for your response. So I have these followup questions for you, or for anyone, please:
  • Are people suggesting that fiberglass then be laid over the carbon sleeve? I don't understand the point of that, but perhaps I am misunderstanding.
  • Epoxying the carbon around the outside the air frame would add some thickness to the air frame, which could make the fit of the nosecone too tight, right? So why not epoxy the carbon sleeve to the inside of the air frame? Wouldn't that contribute the same amount of anti-zippering protection as epoxying the carbon sleeve to the exterior of the air frame?
Stanley
Click to expand...

Stanley,
1. If you use a carbon sleeve there’s no need to add fiberglass to the outside.
2. Nosecones typically fit inside the body tube so composite reinforcement on the outside doesn’t affect the fit.
 
Hi Steve,
  • Good on issue #1. So I would measure the correct length of the carbon sleeve to fit around the exterior circumference of the air frame and cut the sleeve to that length. Then I would put epoxy on the back of the carbon sleeve and stick it onto the air frame. Perhaps I would do a little sanding to help with the epoxy attaching.
  • On issue #2. Of course. How silly on my part. I need to attach the sleeve to the exterior of the air frame precisely so as to not cause a misfit.
Thank you.

I will definitely consider this technique. It couldn't hurt except for the added weight of the carbon sleeve and the epoxy, and that might not make a difference.

Stanley
 
Hi everyone,

But then here's a problem. I went to the Soller Composites website, and I tried to do a rough calculation of the price of 3K (Light) Carbon Sleeves. If I am reading the information correctly, you have to buy so much material at a minimum that the project would cost several hundred dollars.

I would plan to do this on my Minie-Magg, whose diameter is 5.5 inches (slightly less than 14 cm). This yields a circumference of a bit more than 60 inches (slightly more than 153 cm). That's all I need. But customers have to buy a minimum amount of fabric that far exceeds this.

Stanley
 

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