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Custom 54mm Fiberglass Airframe

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REK

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After constantly seeing lots and lots of custom hand laid fiberglass and carbon fiber airframes. I wanted to get into the fun of making my own as well. I did lots of research on what type of weave style to use in terms of strength and weight. The 8 Harness Satin weave was my best choice. I found a good source that had it on special for $2 a yard. I ended up buying a wopping 3 yards from Coastal Composites https://www.coastalcomposites.com/ , which has a lot of great fabrics available on special. I got the fiberglass and now I am all set. I have already cut out the amount I am going to work with. I measured wrong, but it looks to me like it should turn out fine. The amount of wraps came out to be four wraps. The fiberglass will be laminated with Aeropoxy laminating resin (don't have it yet).

I then began to look up the best way to finish the lamination. Many use peel-ply, but I don't like it for the main reason that it leaves behind a raised ridge. Which is something I do not like, because of the fact that I have to sand it down flat. Instead I will be trying a different approach. I stumbled upon Soller Composites Heat shrink tubing material. I have some available and I have already tried it on a previous lamination that did not turn out too well, because I ran out of epoxy (was using 20 minute laminating epoxy). I discovered one unique advantage to this approach. When heating the heat shrink tubing, you also heat up the entire lamination. This gives the epoxy a heat cured process. Allowing for quick removal of the mylar and heat shrink tubing material.

Once I get the Aeropoxy laminating resin, I will post more pictures and steps to follow this procedure. I will be using my Cesaroni Pro54 2G motor as a mandrel. I will end up getting a good 9 inches of fiberglass airframe. Here are some pictures of the fiberglass and the heat shrinking material.

image.jpgimage.jpgimage.jpg
 
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While I do not have the Aeropoxy laminating resin yet. I have an opportunity to ask some questions about it. Since this is a 3:1 mix ratio, what is the best way to get the overall amount needed for the 3:1 mix ratio?
 
its a 100 to 27 mix ratio. use a scale. I am assuming you got the 120 minute not the 20. 20 wont give you much work time. If you want a smooth finish you could try using a silicone caul but it would be tough on a wet lay tube. You may also wont to look into dunstone shrink tape.
 
Actually, the Aeropoxy laminating resin is 100:27. I would recommend a digital scale with a tare feature. You can search the forum for scales, since that has been covered pretty well.

The first part of a successful layup with respect to epoxy is getting the ratios right. That's where the scale comes in. I made this handy reference table:
Aeropoxy Laminating Ratios.jpg

The second part is mix the two thoroughly. For me, I chuck a craft stick in my drill press and let it do the work for a minute or two. However you stir it, you need to do it thoroughly.

Getting these two things right will get you on your way.

Greg
 

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  • Aeropoxy Laminating Ratios.pdf
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While I do not have the Aeropoxy laminating resin yet. I have an opportunity to ask some questions about it. Since this is a 3:1 mix ratio, what is the best way to get the overall amount needed for the 3:1 mix ratio?

Use auto painter mixing cups; they come graduated in various combinations including 3:1.
measuring.jpg
 
All this talk of Aeropoxy has me thinking. I recently purchased some and have not had great luck getting it to cure. Measured on a TBB at 100:27, and it's still tacky. Thinking it could be due to high humidity, despite the fact I have a dehumidifier running constantly in the basement...

Hijack over!
 
All this talk of Aeropoxy has me thinking. I recently purchased some and have not had great luck getting it to cure. Measured on a TBB at 100:27, and it's still tacky. Thinking it could be due to high humidity, despite the fact I have a dehumidifier running constantly in the basement...

Hijack over!

Were you using the 3660 or 3665 hardener? My experience is that the 3665 can stay tacky if not curred initially at a slightly elevated tempearture. Haven't had any problems with 3660 at room temperature.

Jim
 
the mix is by weight not volume.

SDL watch out for the bulge at the end of the CTI case where it is formed it might trap your layup.

Watching for the bulge is no concern since the mylar stretches out of that area. Thus allowing for the fiberglass to settle flat over the mylar. I've tried it and it is no issue.
 
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its a 100 to 27 mix ratio. use a scale. I am assuming you got the 120 minute not the 20. 20 wont give you much work time. If you want a smooth finish you could try using a silicone caul but it would be tough on a wet lay tube. You may also wont to look into dunstone shrink tape.

I am getting the 2 hour working time, since I really want to take my time in soaking all of the glass. 20 minute epoxy seems deceiving, but really it takes about an hour for it to harden.
 
Glad to see many great responses. My next question leads me to ask if it is possible to make the epoxy more thin in viscosity? I found a video describing that you could microwave the 20 minute epoxy's resin and hardener in a microwave for 10 seconds to give it a more water like flow. I do not know if this would be possible with Aeropoxy, so is there any other alternative that could work?
 
Glad to see many great responses. My next question leads me to ask if it is possible to make the epoxy more thin in viscosity? I found a video describing that you could microwave the 20 minute epoxy's resin and hardener in a microwave for 10 seconds to give it a more water like flow. I do not know if this would be possible with Aeropoxy, so is there any other alternative that could work?

Why do you want to do that?

The viscosity is this enough as it is. Much thinner and the epoxy will migrate due to gravity (it does that anyway unthinned, but it's negligible).

Greg
 
you can heat it but you will lose work time. Be careful heating quantities of resin you may lead to an exotherm. You could also cut it with acetone. I would not recommend this action for laminating.
 
Yep. The only time I thin epoxy is if I'm doing something non-structural, like a thin coating on a carbon fiber layup. Like Flynfrog said, you can heat it (and I do often - especially in the winter), but the epoxy will kick within minutes.

20 minute epoxy seems deceiving, but really it takes about an hour for it to harden.

After 20 minutes (or even sooner depending on the temp) the epoxy will lose it's ability to properly wet out fiberglass. It may not be hard yet, but at that stage it is pretty much useless.

Alex
 
Why do you want to do that?

The viscosity is this enough as it is. Much thinner and the epoxy will migrate due to gravity (it does that anyway unthinned, but it's negligible).

Greg

Since you have experience with it and you see no reason to thin it even further, then I do not see a reason why I should thin it out more.
 
I can get on board with the 399. Did you see my 399 project? That was one fast flight! Melted the paint, that is pretty awesome for a 29mm.
 
Not much, a few bucks maybe? The biggest "cost" was the time spent rolling a few dozen of them on the floor to find the straight one.

Jim

That way I can go get me one. If not I can always get ARR's 29mm full length coupler.
 
Now since the questions are out of the way. I will be getting the two hour kit. I will place the order next week and then there is the 3-4 days shipping time so probably in two weeks I should have the resin ready. Thank you all for your responses.
 
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