First homemade fiberglass rocket tube

CarVac said:

If you hold back on resin, there will be tons of micro-voids.

The best way to avoid this is to lay it up with additional resin and squeeze it out through peel ply.

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SinfulDarkLord said:

I really do not see how one can hold back on resin. It is called control you know. Fiberglass turns transparent, which allows you to realize that you have applied enough resin.

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Car vac is right if you are using a net resin fiber volume with no squeeze out you will end up with a resin rich part or lots of voids.

I would recommend some sort of compression. There are a few ways to get it. I have had decent luck using electrical tape stretched out and overlapped about 50% A better option would be https://www.shrinktape.com/ use a latent resin that can take some heat before gel.

There is a reason most tubes you buy are ground on the outside....

Performance nut said:

The sleeves look to be the easiest route, just wasn't sure how the method differed between rolling it and stacking it with sleeves. How did you set up your barrier between the mandrel and the product? I see you used parchment paper, what I'm wondering is how you taped it down. Soller recommends a single piece of tape down the middle. I emailed him about it and he said that with careful application and the assistance of the lubricant you put between the mandrel and barrier, everything stays smooth.

I also like the shrink wrap, was what I intended to use. Any issues with it?



Sweet, thank you Jim! I have read several and I have to say, my head is swimming.



I'm starting to get that feeling Tony. It seems this process differs depending on who you talk to. I'm sure there are more ways not to do this but there seems to be several ways to do it, which in a way is a bit of a relief. BTW, I really liked the videos you did, those helped out quite a bit.

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I really liked the shrink tubing. Got a cheap shrink ray from Harbor Freight to do the job. I had ONE end of all the composite layers taped down to the mandrel where they would not slip and slid the shrink tube on from that end once I felt everything was properly saturated. I think I may have started in the middle and shrunk to each end but in subsequent shrink work, I have started at the taped down end and worked toward the other end. Be careful not to overheat one area as it will make your epoxy bubble. Once all is nicely cured, cut off the tube and sand until your heart's content, or not. As for the tape, clear tape will not stick to the parchment but you can wrap it around each end over itself to make a nice tight joint. For the seam running lengthwise, the tape will stick "good enough" to hold the paper down.
-Ken

I've become rather fond of wrapping tubes under tension. The pic shows an example, but this can be done starting with 10-foot-plus pieces of cloth. You have to build a jig, but it's not that hard.

I'm showing a motor tube as the weight in the picture, but once you get a wrap or so on the tube, it's possible to add more weight to the motor tube until it gets quite hard to turn (motor tubes are good for this because they're hollow). This process forces most of the excess epoxy up through the cloth to the surface, where it can be removed. I know that when I do this (with carbon), I can reduce the amount of epoxy in the layup from a typical 55% by weight to less than 45% by weight for a tube made with a single piece of carbon.

That may not sound like that much, but let's do a bit of math. If we have a 3'-long, 3" tube with 5 wraps of carbon, that's 1.3 yd^2 of carbon. If it's 6-oz carbon, that's 7.85 oz of cloth. If we use 55% to 45% as an example, the amount of epoxy this represents is about 90 grams.

I've tried shrink tape in many configurations and I've never been successful in removing anywhere near that much epoxy, and tubes where a significant amount of epoxy was removed were generally not usable. It's possible that the shrink tape approach may be easier to use on fiberglass layups (my gut feeling is that this is the case, but I've never rolled a 5-wrap fiberglass tube, so I don't really know). For carbon, however, I have no doubt as to which of these techniques is superior.

It may be something of a coincidence, and there are other factors, but when I started to roll tubes this way, I stopped having airframe and coupler failures on my two-stage flights.

Jim

flynfrog said:

Car vac is right if you are using a net resin fiber volume with no squeeze out you will end up with a resin rich part or lots of voids.

I would recommend some sort of compression. There are a few ways to get it. I have had decent luck using electrical tape stretched out and overlapped about 50% A better option would be https://www.shrinktape.com/ use a latent resin that can take some heat before gel.

There is a reason most tubes you buy are ground on the outside....

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I really dont like saying it to you too flynfrog, but I must. Like I said before to CarVac it is called control. The fiberglass turns transparent giving you the signal that you have enough resin.

In the area of thinking one needs to compress the lay up. That window is open to you when rolling the tube by applying tension as you role the airframe. Using the brush or roller one applies tension to compress the layers together. Thus squeezing out any excess resin. Jim used the idea of weights so he doesn't have to do the hard part.

No need for vac bagging, shrink tape, or shrink tubing. Just to get an advanced part.

I believe I'm done here.

Good luck Performance Nut


Alexander Solis

Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet

:rant on:

Some people are unwilling to accept someone's experience or knowledge when it conflicts with their own personal ideas of how something works.
I find this one of the most alarming things about aspiring engineers. The inability to learn from people more knowledgeable then themselves is extremely arrogant and counter-productive from an engineering standpoint.
If you have an incorrect notion of how something works, proven by people with more credibility then you, learn from that and move on. Arguing is pointless when you're wrong.

:rant off:

Alex

Here's my take.

Performance nut said:

Method: Using the fiberglass sleeves seems like a good start for a beginner; however, the results have been varied (some good, some bad). I really like the setup tfish has with the mandrel on top and the feed on the bottom, not sure if he just made it look easy due to experience or if it is really that easy. Recommendations?

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None of this stuff is hard, but results are very dependent on how prepared you are and the care you take. If you plan things out, work clean, do and are careful, you can get very nice results.

Performance nut said:

Fiberglass sleeve: For the fiberglass sleeve, the 2" diameter light fiberglass sleeve at the bottom seems to be my choice. Do I need more than one, stacked on top of each other or just one sleeve will work?

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If you use a sleeve that's heavy-weight enough to provide the strength in one layer, then you will most likely want a second layer as a "veil".

Performance nut said:

Fiberglass roll: For cloth, the FHX88-50 looks like it will offer a smoother finish but the FG3743-38 is lighter. How many layers do you need? Is there a recommendation other than what I listed? I'm trying to keep cost down since I'm likely going to mess up.

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If you use 6oz fiberglass cloth, you will need at least four layers.

Performance nut said:

Finish: shrink wrap or porous Teflon coated release film? Both look like they have their pros and cons.

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I'm a fan of the Teflon release film. It's easy to use and does not wrinkle unless you really treat it badly. Since you're not bagging the parts, that would be my recommendation.

Performance nut said:

Protecting the mandrel: I was rather confused on step V on this write up as I have read that you don't put tape in the middle, you tape the ends. So what is the best way to protect the mandrel?

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I wrap the mandrel with a layer of non-porous Teflon or Mylar.

Performance nut said:

Adding discussions on which epoxy to use...

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Well, we all have our favorite products. Make sure you choose something with a long pot life (1 hour) so you don't have it curing while you work.

I did a hand layup recently of 3 layers of 6 oz CF over a 4 inch LOC tube. I decided I wanted more stiffness, so a couple days later I went back and added a 4th layer under vacuum. There were some wrinkles in the veil layer of fiberglass, but after sanding the FG away, the underlying CF Layer was perfect. I think the next tube I wrap, I am going to try 2 layers of CF under vacuum and see how that goes. CF seems more stable (moves around less) and easier to work with than FG unless the tube diameter is really small, like less than 3 inches. In the picture below, I left the vacuum connection in the middle of the tube (brain fart). After about an hour under vacuum it hit me and I just decided to leave it there. It only left a small mark in the layup which sanded out easily.

Vacuum is doable if you pull the cloth extremely tight, since it will already be mostly compacted.

In smaller diameters, you can use vacuum for a layer of longitudinal unidirectional ply that doesn't care one bit if it gets sanded off...

CarVac said:

Vacuum is doable if you pull the cloth extremely tight, since it will already be mostly compacted.

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I think the next time I roll a tube, I'm going to try this. For the sake of my mandrel, I hope this isn't a "crushing" experience. Using tension, the extra cloth is mostly removed. Another thing that helps is that most of the excess epoxy is removed too. I think this will allow using less breather, which should give a smoother surface. For bagging fins, I use breather directly over the peel ply. I guess I would try it that way for a tube too.

Jim

JimJarvis50 said:

I think the next time I roll a tube, I'm going to try this.

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In my experience, larger tubes are easier to do. Also, I would suggest no more than 2 layers at a time. All the custom tubes I've done have used cores, so I apply fiberglass, carbon fiber and core, bag and let partially cure, then apply carbon fiber and fiberglass.



We're veering off-topic now, but here's how I made the tube above: jcrocket.com/nike-asp.shtml#tubes. Removing them from the mandrel was a pain, so later I used non-porous Teflon and didn't vacuum bag the tubes for my Wac-Corporal: jcrocket.com/waccorporal.shtml#tubing.

I will be making a custom airframe for my RS-2U, and I will make a video.

FWIW, I wouldn't bother hand-rolling a tube in a standard size. You won't get better results than a commercial fiberglass tube (and I doubt you'll save money at least until you perfect the process).

Wow. Liquid nitrogen to remove the mandrel. That's pretty cool, and kind of funny at the same time.

JohnCoker said:

In my experience, larger tubes are easier to do. Also, I would suggest no more than 2 layers at a time. All the custom tubes I've done have used cores, so I apply fiberglass, carbon fiber and core, bag and let partially cure, then apply carbon fiber and fiberglass.

View attachment 166211

We're veering off-topic now, but here's how I made the tube above: jcrocket.com/nike-asp.shtml#tubes. Removing them from the mandrel was a pain, so later I used non-porous Teflon and didn't vacuum bag the tubes for my Wac-Corporal: jcrocket.com/waccorporal.shtml#tubing.

I will be making a custom airframe for my RS-2U, and I will make a video.

FWIW, I wouldn't bother hand-rolling a tube in a standard size. You won't get better results than a commercial fiberglass tube (and I doubt you'll save money at least until you perfect the process).

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Fyrwrxz Dave and I have been discussing doing a wrap on our Frys booty, the Mega Der Red Max and taking it up to 38mm . The wrap is to help make it less Frangible for transport and a hard landing .. not for vMax or Warp 9.

So after watching your informative video have a few questions :

JohnCoker said:

Here's my take.


... I'm a fan of the Teflon release film. It's easy to use and does not wrinkle unless you really treat it badly. Since you're not bagging the parts, that would be my recommendation...

I wrap the mandrel with a layer of non-porous Teflon or Mylar...

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Can we use wax paper on the table in lieu of the butcher paper for the whetting ? Also what thickness mylar did you use for the final wrap/compression .02 or .05 ? This big project is a 4 inch tube that is 22 inches long..but have two LOC 2.56 inch , 34" tubes to wrap behind it - if we get exceptional results may want to roll that size on a mandrel without the paper tube to start for an almost min diameter rocket.

Thanks for sharing, enjoy your videos and use Thrustcurve,org almost everyday !

Kenny

JimJarvis50 said:

I think the next time I roll a tube, I'm going to try this. For the sake of my mandrel, I hope this isn't a "crushing" experience. Using tension, the extra cloth is mostly removed. Another thing that helps is that most of the excess epoxy is removed too. I think this will allow using less breather, which should give a smoother surface. For bagging fins, I use breather directly over the peel ply. I guess I would try it that way for a tube too.

Jim

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One way that's more feasible for applying tension on small layups is using the peel ply to provide the initial compaction once you've finished the layup.
Two tactics I've used:
Diagonal peel ply strips work okay to apply tension, but if the initial layup is too loose you can end up with diagonal kinks.
Better is using multiple wraps of peel ply. It's easier to pull very tightly, and then just wrap it with blue tape. Then you can just toss it in the vacuum bag.

KenRico said:

Can we use wax paper on the table in lieu of the butcher paper for the whetting ?

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I don't see why not. I like the butcher paper because it comes on large rolls, but waxed paper should be a find option if it's large enough.

KenRico said:

Also what thickness mylar did you use for the final wrap/compression .02 or .05 ?

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I used 0.005 Mylar (the thicker stuff from Tap Plastics).

JohnCoker said:

FWIW, I wouldn't bother hand-rolling a tube in a standard size. You won't get better results than a commercial fiberglass tube (and I doubt you'll save money at least until you perfect the process).

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I think after this very long discussion, this is pretty much exactly what I will be doing.

Thank you all for your input though.

JohnCoker said:

FWIW, I wouldn't bother hand-rolling a tube in a standard size. You won't get better results than a commercial fiberglass tube (and I doubt you'll save money at least until you perfect the process).

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I think It's well worth it. I can make a fiberglass tube for about 125% the cost of a cardboard tube (all consumable materials). For most people it really doesn't take much practice to roll your own tubing. Follow a guide, don't stray too much from it and you can make decent tubes first try.

Alex

Alex, what he is saying that is "until you get the hang of it, it is not worth the money". I have tried a few FG or CF tubes, and all of them turned out to be utter failures. Of course, trying to laminate a 29mm tube with structural epoxy and no peel ply doesn't help my case...

blackbrandt said:

...all of them turned out to be utter failures. Of course, trying to laminate a 29mm tube with structural epoxy and no peel ply ....

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Aksrockets said:

Follow a guide, don't stray too much from it and you can make decent tubes first try.

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I rest my case...

Alex