(New?) Composite Panel Construction Technique

[StrongFeather]

I’m working on what I believe is a new construction technique. I’ve eluded to it in my build journal, but haven’t gone into any detail because, at this point, it’s all theory. I hope to begin “prototyping” (for lack of a better term) in a few weeks after finishing the trailer frame, but I thought now might be a good time to start a new thread on the technique itself. I’ve put a lot of thought and research into it, but at this point it’s all theory and a lot of details either haven’t been completely worked out or will change as the project progresses.

The idea involves first building strong and lightweight composite panels made of fiberglass, Kevlar®, carbon fiber, or a combination thereof. The panels will be made using a vacuum infusion process (rather than vacuum bagging and/or wet layup), which will also, hopefully, allow me to create an automotive quality finish. The panels can be made to any size/shape up to about 4’ wide by 7’ tall, including curved roof sections. Once all of the panels are made, they’ll then be assembled to create the outer shell. Foam insulation and an inner skin will added to create what I hope will be a very strong, lightweight sandwich composite structure that is not only stronger and lighter, but easier and faster to assemble than traditional construction techniques.

Assembly option A would be to assemble the each individual outer wall and the roof first and then assemble those larger panels on the trailer frame. You’d do this by epoxying the composite panels together first, then add the foam insulation and finally the inner skin to make the wall (or roof) assembly. This method would give the builder the option of vacuum bagging the interior skin to the outer shell and avoid mechanical fasteners altogether. I estimate that two people could assemble one wall panel in a day – most of that time will be spent waiting for epoxy to cure enough to move onto the next step. If you have enough room, you could certainly do multiple panels at once by working on other assembly(ies) as you’re waiting for epoxy to cure.

Assembly option B would be to create the entire outer shell first by epoxying the composite panels together on the trailer frame, either one panel at a time or in larger sections. The insulation and interior skin would then be added in a more traditional way from within the shell – most likely requiring mechanical fasteners (screws) to “clamp” the skin to the outer shell.

I think I’m going to leave this as it is for now – a high level overview, rather than a complete nuts and bolts explanation of everything that’s in my head . I’ll add more detail as the thread progresses so that certain aspects of the technique can be discussed by themselves, e.g. vacuum infusion vs. vacuum bagging vs. wet layup.

Sorry, no pictures yet.


Steve

[John61CT]

Excellent!

I think also a "central hub" thread for DIY composite panels in general - other than foamie / PMF - would be great, just a quick list of links people can explore from.

I see lots of valuable stuff buried in very long general-build threads.

[aggie79]

Have you given a thought about making the insulation part of your exterior shell vacuum infusion? Boat hulls built using vacuum infusion usually have (structural) foam as part of the resin infusion process.

[StrongFeather]

I’ve considered using core material as a bulker for the outermost skin, and as a “frame” for the panels, not as insulation or to makeup the panels total thickness.

Adding foam insulation (XPS) to the infusion would come with some added complexity in the infusion, but also in assembly of the panels, e.g. running wires or conduit, etc. Whereas if the wires or conduits are run first, the foam just gets trimmed away wherever needed prior to being epoxied in place.

It may make more sense if I try to paint a picture of what a panel will look like. Imagine a painters canvas - a thin layer of material stretched across a perimeter frame with the back open. By itself, a panel won’t be super strong, but as a complete structure, it should be very strong.

Steve


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[John61CT]

Thought of using this idea to lighten up a dinghy, increase its floatation and resistance to damage, maybe ease of repair? Compared to standard ply anyway.

http://www.cruisersforum.com/forums/sho ... ?p=2788988

[noseoil]

I like the idea, but I'm wondering about the cost in terms of labor & $$$. It would certainly be a light build, but the cost might not be worth the effort, unless multiple builds were done as a production run. The skill level is way up there, but I'd like to see one just to watch the progress & technique come together.

[tony.latham]

This sounds about as easy as making your own plywood. (This is coming from an old kayak vacuum bagger --from the days we built them from s-glass and kevlar.)

But I'm with Noseoil, it'll be an interesting build to watch if you move forward with it.



Tony

[StrongFeather]

I like the idea, but I'm wondering about the cost in terms of labor & $$$. It would certainly be a light build, but the cost might not be worth the effort, unless multiple builds were done as a production run. The skill level is way up there, but I'd like to see one just to watch the progress & technique come together.

...and...

This sounds about as easy as making your own plywood. (This is coming from an old kayak vacuum bagger --from the days we built them from s-glass and kevlar.)
But I'm with Noseoil, it'll be an interesting build to watch if you move forward with it.
Tony

Will the juice be worth the squeeze?? That's a great question that I think we all ask in the beginning, and I think we get as many answers as there are unique builds on this site. For me, this build, or any project that I embark on, is just as much about the challenge of doing something new/unique/different, rather than doing it as fast, easy and cheap as possible. Luckily for all of us, others have a similar point of view, otherwise we wouldn’t be able to admire incredible pieces of work such as The Tuscan Tortoise, or this… (Credit Tony)… or my personal favorite, Astroliner. There are so many incredible builds on this site and I suspect that the vast majority of them, at some point, made at least one decision in at least one part of their build, to do something that was a little harder and/or a little more expensive - otherwise, we would all be admiring foam boxes with painted canvas on HF/NTE frames. Not that there’s anything wrong with that. I admire anyone who takes on a project like this, no matter their means, skill-level or desire.

This technique certainly won’t be the cheapest, in fact I jokingly called it RMF the other day – not that I’m rich by any stretch of the imagination – I just thought it was funny. It also won’t be the easiest, at least not for me because I have the burden… actually the privilege of countless hours of research, planning, development, designing, testing, playing and so on. Not to mention the added cost of development and equipment that will not actually become part of the build. In spite of all of that, I’m not only willing and able, I’m honored to have great folks like you following my journey so that I can (hopefully) pass some of my experience on while learning a great deal from you as well. The ultimate complement would be for someone to use this technique to build a trailer of their own someday.

Regarding the skill level involved in making the panels; some members of this site already have the skill and ability to build them, and many of you could certainly take on the challenge of learning how. Although I haven’t made any panels yet, if my vision for building them works, it should be pretty streamlined and relatively easy to produce them. For everyone else, there are still traditional building techniques or the option of finding someone that is willing and able to make some panels for you. Once the panels are built, regardless of who builds them, I’m hoping one of the biggest advantages of this technique will be the relative ease and speed of assembling the shell.

Thank you all for following me on this journey, and thank you all for your input, suggestions, comments, questions and critiques.


Steve

[John61CT]

The Tuscan Tortoise

Did I miss that, trailer? or do you just mean Barton Perreira's glasses design?

Completely agree, science or art for their own sake are noble goals, beyond cost or even practicality.

Just need to be clear from the outset what motivates a given design. . .

wrt your technique, I want to learn, for building a nesting dinghy. . .

PS link to Tony's build please? google ImageSearch no help

[Atomic77]

I'm pretty interested in this concept, mostly because I've done a lot of infusion. I have built many custom parts for race boats and infusion is a very interesting and enjoyable process for me. I too considered doing something like this when building the Astroliner. I mean, I have the skillset, training and expertise to do it. Unfortunately, that's all I had. I did have access to the vacuum pumps and other necessary tools, but I always built parts on someone else's dime. Carbon fiber isn't cheap, infusion epoxy and resin isn't either, and all the molds I used were built, gel coated and finished by a very long, expensive and painstaking process. I would need molds, release wax, carbon fiber, (4-6 layers depending on cloth weight) boat cloth, infusion spray, infusion epoxy resin, EnkaMat, scales, guages, hoses, spiral tubing, pumps, release film, foam core, bag material, resin traps, pumps... the list goes on. In the end, the $$$ just kept adding up and the cost and labor of the molds alone was too prohibitive. So I went in another direction. But again, I find this thread interesting and am looking forward to what you figure out! Good luck!


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[StrongFeather]

First of all... Love those boats and Astroliner, Michael. I'm looking forward to any expert input you may have on this.

Just to touch on a couple of things you mentioned.
**Molds... I plan on using sheet glass to create the smooth finish for the outside surfaces. Glass is cheap, flat, has a high-gloss and its reusable, so I won't have to make a new mold for every different size panel. A curved roof might be a challenge, but my vision is sheet aluminum with ribs on the outside to create the profile. I also plan on using an in-mold gel coat (if fiberglass) or an in-mold clear coat (if carbon fiber), which I hope will nearly eliminate the post mold processing.
**Lay-up... For those that don't know, the layup is the layer of materials hat make up the finished product, e.g. carbon fiber(CF), fiberglass, synthetic core material, etc... It will take some experimenting to get a good mix of adequate strength for a reasonable price. 6 layers of carbon? Probably not due to cost. So, if CF is in the cards, it'll probably only be the outermost layer or two. I'll be experimenting with some other materials such as Soric, Coremat, and maybe even 18oz plain weave fiberglass that I found for pretty cheap. In all, without having done any tests, I'm thinking that the infused skin will be 2-4mm thick, but that's is only a very loose assumption at this point. If anyone knows the layup and/or thickness of a standard RV, or other things, I'd be interested in knowing that.

I have to keep a couple of things in mind when doing this. First, it's not a boat. Second, the panels are only one piece of the structure. Alone they won't be strong enough, but together with the rest of the structure, they should be stronger than a foamie Seriously, though, I'm not picking on the foamie's. I love them. My point is they're strong in spite of using, well, weak materials and I'm of the opinion that most people significantly over-build their trailers. Again, there's nothing wrong with that. My goal is simply to build something that is only reasonably overbuilt.


Steve

[AzAv8r]

If you can find a copy of "Advanced Composite Techniques: Lightweight Moldless Techniques for the Aircraft Homebuilder" by Zeke Smith (out of print, but there are sellers online), you'll see he recommends using plastic laminate panels sold to cover bathroom walls as the surface to lay your glass on to get a finished surface. It is flexible, so you can create curved parts. Lots of "build your own tools" material in the book also.

[StrongFeather]

Ordered! Thanks for the tip.


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[Thomcat316]

If you'd like to steal some of my experiences, feel free - ultralight teardrop build in my sig, seven years built and still getting miles put on!

[saywhatthat]

léger, Presque

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