Fiberglass Bodytubes

[Tamago231]

Hello everyone,

I'm just getting back into rocketry, I used to make them all the time as a kid and now I've discovered the glory of custom rockets. Anyway, I've read alot about the fiberglass body tubes and I have a few questions. Know first that I haven't gotten around to actually making any yet, I'm just waiting until i can get some.
My first question is if i put wax paper on my mold then i should be able to slide the finished product off of the mold (in theory), but my only problem is that i'd have trouble glueing any motor mounts inside the tube.
Thats really my biggest idea so far, and i'm sure whenever i get to experiment i might find something that works.
If anyone has any comments or advice on this topic i'd appreciate any help. Also i'm working on a college student budget...

Thanks for any help

 

[phaar]

Well, I can only give you advice on using Aerosleeves(www.aerosleeves.com), which I recommend if this is your first time. They are just "socks" that slip over you mandrel. As for the wax paper thing, ours did not stick to the wax paper. We greased it up with extra wax from a candle. We also made sure the wax paper was secured tightly to the mandrel(a full length coupler in our case). Doing all that, it should work out fine. I think others could give you a little more advice though, as I have only done this once. I hope I could give you some help!

BTW, welcome back to the hobby and welcome to the forum. I know you will love it here.

 

Welcome to TRF! If anyone can help ya, these guys can...

 

[Tamago231]

Alright huge update here, I finally got a hold of some fiberglass cloth and epoxy from an independent business (only to find out an hour later Lowes had everything cheaper...). Anyway i got to experiment with this stuff and found a great way to get the final product off of the mold very, very easily.
First you simply wrap your mold (in my case PVC) with normal kitchen wax paper. Just wrap it around as tight as you can and you don't have to tape it, or you can if you want. Now apply the epoxy and wrap the cloth like normal, its easier with two people i found, just to keep things together. Now this is the best part, after it dries you'll notice that the whole thing will slide right off the mold because of the wax paper, and you should have your tube with wax paper on the inside. All you do now put your finger in the tube grap some wax paper and spin it so that it peels from the inside (the paper has a very weak bond to the epoxy). This should leave you with a completely smooth inside (except for the over lain spot, but it is a very tiny jump).
Hopefully this should help some people with their releasing problems, and also i hope this isn't old news...

 

[gerbs4me]

welcome to TRF
I'd use aerosleeves, until you get the hang of things

 

[GL-P]

Welcome to composites!

I'd use sleeves too. You can find cheaper ones than what Aerosleeve sells tho.

I've used the same technique but instead with window film. It's heat shrink so I can get it real tight, it's reusable and epoxy doesn't stick to it.

 

[Micromeister]

Wouldn't one of the many spary on epoxy mold releases be easier to deal with than trying to hold wax paper on a mandrel? I've never tried this method but it seems awful bulky and awkward to work with. I've used several release agents that always worked well for me on single wrap ultra light competition bodies, one is a Mcmaster-Carr product #1409K61 in a 16oz aerosol about 6 buck a can. It's a synthetic wax based Non-Silicone material, I've used it on tapered sealed wood, PVC and metal mandrels.
I've also found the easiest way to " Break the seal" on these laided- up bodies is to throw the whole cured thing in the freezer for about 10-15 munites. The body usually pops right off

 

[George Gassaway]

I learned the hard way that wax paper has tiny pinholes in some spots, which allows some epoxy to bleed through. So it takes a few wraps of the wax paper to be sure that the epoxy does not end up bleeding through several layers via pinholes.

Spray-on wax mold realize is really nice. But it does not like to let the part just slide off nice and easy. The tube and mandrel has to be heated up enough for the wax to turn to liquid, so the wax is more like grease, then the tube can slide off. But if it is heated up too much the wax will migrate away an the tube can be a lot harder to remove from the mandrel.

My experience is limited to smaller tubes, mostly for FAI contest type rockets and a few NAR contest models. Some info on how really lightweight fiberglass tubes are made can be found on the spacemodeling.org website:

https://www.spacemodeling.org/new/

Click on the “construction, Supplies, and Technical info” link at the left of the page, and on the resulting new right hand page go down 4 links to Dave O’Bryan’s article on making lightweight fiberglass tubes.

The tubes are usually made so lightly, with so little epoxy that the tubes have hundreds of pinholes, which would let the epoxy vent out of the tube. That is solved by adding an outer layer that will hold the gases in. Either 1/4mil mylar, or Japanese tissue which has had epoxy squeegeed onto it before applying to the mandrel, with excess epoxy removed (the original bare tissue itself would let air go through it).

Here is a photo of 40mm (1.58”) diameter FAI type rocket as used for Parachute, Streamer, and Helicopter duration (the one in the photo has a folding helicopter rotor system inside). Next to an old big Bertha for comparison.

https://members.aol.com/GCGassaway/FAI/OtherFAI/S9_1.jpg

The tube itself (no fins) weighs about 5.5 grams, and that’s not as light as some people have been able to make them. The red color is from red Japanese tissue being used for the outer pressurization wrap.

I know this is not exactly the size or strength that you have in mind making. But it doesn’t hurt knowing of other methods for making things like this.

- George Gassaway

 

[Const Star]

Originally posted by Tamago231
Hello everyone,

I'm just getting back into rocketry, I used to make them all the time as a kid and now I've discovered the glory of custom rockets. Anyway, I've read alot about the fiberglass body tubes and I have a few questions. Know first that I haven't gotten around to actually making any yet, I'm just waiting until i can get some.
My first question is if i put wax paper on my mold then i should be able to slide the finished product off of the mold (in theory), but my only problem is that i'd have trouble glueing any motor mounts inside the tube.
Thats really my biggest idea so far, and i'm sure whenever i get to experiment i might find something that works.
If anyone has any comments or advice on this topic i'd appreciate any help. Also i'm working on a college student budget...

Thanks for any help

im sure a good epoxy would hold that sucker in place, but u should swab the inside good regardless, if the wax thing is what u end up doing

 

[George Gassaway]

I wrote:

>>>>>
Spray-on wax mold realize is really nice.
<<<<<

Meant spray-on wax mold RELEASE.

- George Gassaway

 

[aksarben10]

Originally posted by George Gassaway

My experience is limited to smaller tubes, mostly for FAI contest type rockets and a few NAR contest models. Some info on how really lightweight fiberglass tubes are made can be found on the spacemodeling.org website:

https://www.spacemodeling.org/new/

Click on the “construction, Supplies, and Technical info” link at the left of the page, and on the resulting new right hand page go down 4 links to Dave O’Bryan’s article on making lightweight fiberglass tubes.

- George Gassaway

George, those are some very nice aticles. Thanks for the links.

Scott