Stainless/foam/luan sandwich walls?

[videographer]

Hi all. I'm kinda new here, but have read many threads about building a TD, and the foamie option really appeals to me. (Dream outcome is to tow it behind a Tesla electric car, so light weight and slippery aerodynamics are key.) I don't think I've seen what I'm considering, though - a stainless/foam/luan sandwich wall and roof system. Am I crazy? Is canvas covering really the only way to go?

I was imagining routing a 1"x1" slot in the bottom of the 2" wide foam, and before gluing the wood in, drilling in several holes with T-nuts on the top to bolt the wall down with (and of course, glue isn't out of the question.) And roofing it would be a challenge for sure. I was hoping to get at least 5' wide - does anyone cantilever out over the sides of a (for example) HF 4'x8' trailer?

Lots of questions, interested in your reactions! Thanks in advance -

[GuitarPhotog]

Why stainless? It's really heavy compared to aluminum, not to mention hard to cut, drill, bend, and work in general.

The object of a foamy is light weight, why counter that by using stainless?

<Chas>

[dales133]

Yea stainless is a bastard to work with if you don't have to and alot heavier than alloy.
Why not float aluminium over canvas, my roof will be done this way most lukly

[Fred Trout]

+1 on stainless is a beast to work with. And very expensive too.

[Jack Olsen]

videographer, I'm also new here, and looking into something similar. One thing you'll have to consider would be thermal expansion rates for different material. It's the reason people frequently 'float' the aluminum skin over the teardrop so that the adhesive between the wood and the metal doesn't oil-can the skin.

If you look at this thread I recently started, I list some of the comparative material weights -- I've been looking at aluminum, foam, FRP and also Aluminum Composite Panels (which sandwiches polyethylene with aluminum).

There are also a lot of other options in the sign-supply industry, where weather resistance and light weight are often an issue. There's honeycomb-centered composites, polygal (a material you see in a lot of small signs like political ones in peoples lawns), PVC, and other materials (and mixes of materials).

There is nothing cheaper or lighter than foam and canvas, in what I've looked at so far. But there are other options out there.

[videographer]

OK, you guys have already educated me, stainless is not a great plan (although working it shouldn't be that bad - there is a sheetmetal shop in my town with a waterjet cutter.) So aluminum it is.

So the overall thought, though, is that fabric & glue is required to generate enough rigidity to make a foamie workable? I will admit that I have a bit of an Airstream jones. Should I toss that plan right out of the gate?

Also, I have been looking around on Craigslist locally for a donor (read: cheap) trailer. Has anyone converted an aluminum snowmobile trailer? I've seen some as wide as 6' 6" for not a lot of money, and they do seem light.

So many questions, thanks in advance!

[dales133]

Fabric and paint are just an inexpensive way to make a very strong structure from foam.
There isn't any reason why you couldn't make San witch pannels with anything you want inside or out though.
From when I started mine I've changed tack numerous times as to what I'd use on the sides, just use what your comfortable with but use the resources here as a guide

[Fred Trout]

So the overall thought, though, is that fabric & glue is required to generate enough rigidity to make a foamie workable? I will admit that I have a bit of an Airstream jones. Should I toss that plan right out of the gate?

Also, I have been looking around on Craigslist locally for a donor (read: cheap) trailer. Has anyone converted an aluminum snowmobile trailer? I've seen some as wide as 6' 6" for not a lot of money, and they do seem light.

Canvas, foam and TightBond II is a well tested best solution for lower cost foamie construction. Has all the rigidity you would need, is more easily repaired than aluminum and pretty resistant to dings and punctures - more so than aluminum. Construction with foam panels is easier and more forgiving than plywood in general. For instance, I cut a panel too short and just glued a piece back on to fix it - works fine. The secret is the same as unibody construction - the whole structure reinforces the build - the canvas creates a giant glue surface the size of your teardrop.

Aluminum trailers should be fine and lighter than steel as long as someone can make any needed alterations. Check this thread for your foamie airstream jones solution:

http://tnttt.com/viewtopic.php?f=50&t=62852

pix from the thread:

[videographer]

Wow, that's really impressive.