Newbie design questions

[Prem]

beej wrote:

I wanted to ask you another question, for the curved roof/walls. I like the idea of using the 1/8th sheets laminated together w/ epoxy and fiber because I could put the curve in before installing. Do you have any idea how much extra curve I would need to put in so it would maintain the correct curve after removed from the rig?

I can't picture what you're talking about here, but I highly suggest that you build directly onto the trailer with nothing curved prefabricated...including the galley hatch. (You cut the hatch out later. It's perfectly formed.)

Prem

[TD Beej]

Sounds like by using the term "space frame" you mean "exoskeleton." The problem is thought, that a trailer chassis has to support those gravity and flex points where the spring hangers (or torsion bar plates) are attached.

Space frame is the correct term, it is an internal structure integrated into the shell. And yes I've considered issues of the stress points and they should not present an exceptional challenge. B^)


On the precurving the plywood, there are few benefits for the idea. Parts would be uniform, each side would match perfectly. Spanning seems could be done by offsetting the panels increasing the size of panels that could be used. The panels would then fit with a minimum of bending reducing stresses on the fasteners and need for supports to retain the correct curvature reducing weight and complexity.

Thanks,
Beej

[Prem]

There's next to zero stress on moderately curved 1/8" plywood. It's all gone once it's laminated with another sheet on top.

We tend to follow the Keep It Super Simple methods.

Prem

[TD Beej]

There's next to zero stress on moderately curved 1/8" plywood. It's all gone once it's laminated with another sheet on top.

Yes, but any sags or non-uniform curves will have to be dealt with to get a nice result before the second layer goes on and or more supports to maintain the correct shape. It also means cutting two pieces to fit instead of one and trying to work around the rest of the structure rather then in isolation during lamination. Plus, it might be possible to use a vacuum to make the strongest laminations possible by working with one part at a time. May be a case of "six of one, a half dozen of the other" but at the moment I think it will be easiest to get the best results by doing the curves off build then installing.

We tend to follow the Keep It Super Simple methods

I usually start from the design objective side and work back to how to do it the easiest way. My objectives are to be big enough to act as support for a family of 6, comfortable sleeping surface, fast setup (lunch on the run, getting to campgrounds late...), be the most effecient towing (we covered thousands of miles on every trip so far and gas is not getting cheaper), be the most stable and secure on the road (my wifes driving scares me already w/o towing anything). These are the whys of the choices I've been making in this plan.

Thanks,
Beej

[Prem]

Understood. Your situation and needs are specific.

Prem