Thrifty Alternatives ..Building Foam Campers

[redveloce]

Not necessarily the shape, but that's the right idea.

[wagondude]

Are you talking like doped fabric over a stick type airframe with the foam instead of wood sticks? I would think it could be done (very little if any weight savings). The only concern I would have would be puncture resistance of the unsupported canvas.

[KCStudly]

I'd be just as concerned about the foam snapping. The foam is very strong in compression if the load is spread over a large area. It doesn't do as well in tension or with point loads, which is essential what you would be doing by making it into thin flat slats.

It is also very flexible, so I am guessing that the structure you are envisioning would warp easily from the shrinking effect of the drying canvas.

If you look into the theory of what we have been doing here, the skins are the strength in tension and the foam holds the skins separated from each other by providing a large area to resist the compression forces from the skin being in tension. This is somewhat different from an airplane fuselage or Conestoga wagon where the tension in the outer skin is resisted by the compression of an arch like (or round) structure. (Well, not really, but the arch/round shape is inherently strong when compressed evenly.)

For the shape that Redveloce has proposed (flat paneled box like insert) I don't think that thinner, more sparsely placed foam sticks will provide the compressive strength that can be achieved with broader panels or an arch shape.

Now, if you were to wrap each "foam strip" in canvas and glue/paint, making each stick a tubular strength member, then it might work. However, my experience with TPCE would suggest that just because a thing is doable, and even though it may be a novel and theoretically lighter method of construction, does not mean that it is practical or recommended. (Translation: sounds easy but takes a lot more effort than it seems on the face of it and may not be worth the extra effort for the amount of weight it saves.) Spruces spars could be just as light and would be far easier and quicker to build accurately using same tools; much more rigid, linear in strength (i.e. long grain fibers), and quicker to fab. Another option is tubular aluminum frame work.

I'm not poo pooing foamies (the simple premise has been proven to be valid). I'm just looking at my own experience with hybrid methods, having some hands on experience with the foam, and I have come to realize that what seems easy, is often times more complicated.

Perhaps I am just discouraged by all of the people who have started and finished more traditional TD's while I am still fitting and gluing backer blocks into foam. Then again, even elegantly simple things can become complicated... if you let them.

[Jack B.]

I too won't poo-poo the idea, but it seems to a solution to a problem that doesn't exist. I don't see much weight savings but I do see a lot of strength loss.

I've been thinking of the Sopwith Camel/Conestoga Wagon concept with a stick frame with painted fabric stretched tight for an ultra light tent type trailer to be bicycle pullable(sp). Keep the weight down, be waterproof and avoid sleeping on the ground. I had at first thought about a bike foamie but the bulkiness seemed to be a wind resistance issue. And since I'm building a tadpole recumbent trike with a possible motor-hill-climb assist . . .

Jack

[GPW]

What about a PVC pipe frame (light ) covered with canvas in traditional aircraft fuselage style ? You can heat bend PVC to most any shape you want ...
Won’t rot, lighter than wood . STRONGER than foam ...

[Jack B.]

PVC pipe is my first choice for the bike trailer. Frame, wheel mounts - everything from various dimension pipe. My experience is that once you put those two pieces together with the pipe glue on it, it's a forever thing.

There are some interesting YouTube videos of various ways folks have come up with to bend PVC pipe. Some involve filling the pipe with hot water, filling with sand to maintain it's tubular shape during the bend and even a machine for spinning the pipe over a localized heat source to distribute the heat while you bend.

Jack

[GPW]

We’ve been using a HF heat gun to bend PVC for making bows (Archery) , quick and easy ... an outside activity due to fumes ... We can heat it till it’s like a wet noodle , and bend it by hand or shape over a form ... When re-heated the memory of the material makes it turn back into a straight pipe ... (in case you bend it wrong)

Here’s where we got the idea ... http://www.youtube.com/watch?v=95Buzpjllgo

Ps. i’ve made several PVC Bows , they shoot as good as a wooden bow , and cost a dollar or two ...

[Bogo]

Greed has always been mankind’s worst disease ...and likely then reason for it’s demise ...

http://www.sciencedaily.com/releases/20 ... 194259.htm
Cheating Favors Extinction, Yeast Study Finds: Feedback Between Population and Evolutionary Dynamics

Cooperative behaviour is widely observed in nature, but there remains the possibility that so-called 'cheaters' can exploit the system, taking without giving, with uncertain consequences for the social unit as a whole. A new study has found that a yeast colony dominated by non-producers ('cheaters') is more likely to face extinction than one consisting entirely of producers ('co-operators').

It's an interesting study.

The researchers studied a cooperative species, Saccharomyces cerevisiae or 'baker's yeast', focusing on two strains: one which had the SUC2 gene that produces the enzyme invertase (the co-operators), and one lacking SUC2 (the cheaters) making it unable to produce this enzyme. Invertase breaks down sucrose in the environment to liberate glucose and fructose that can be used by all yeast cells in the colony.

"We were very surprised by the fact that the total population size for the mixed group (consisting of both co-operators and cheaters) was about the same at equilibrium as the total population size in the absence of cheaters (i.e. purely co-operators). We didn't expect that," Dr Sanchez explained. "If it weren't for the fact that the co-operators and cheaters were labelled with different colours, it would have been very hard to tell whether the population contained any cheaters or not."

This was the case when the environment was benign. But when those stable populations were suddenly exposed to a harsh environment, all of the pure co-operator populations survived, while just one of six mixed populations adapted to the fast deterioration in conditions, the researchers found.

[GPW]

One only has to study History , to see how it works .... The rise and fall of great civilizations ...

But then , they didn’t have Foamie trailers eh ?

[GPW]

Just a consideration .... One of the airplane guys reported the Gripper (well dried ) not being waterproof ???? Spilled on a surface , easily removed... with water... More testing !!! ...

[wagondude]

As long as the top coat is water proof, it shouldn't be a problem. Although, even some oil based paints (testor's for instance) can be softened by water if you soak them long enough.

[Jack B.]

So would spar varnish or marine varnish hold up as a waterproof top coat? Or a good latex outdoor glossy or semi-gloss paint? If the paint works on a house . . . Marine grade stuff gets pretty spendyish in my experience.

Jack

[GPW]

Jack, it would appear now , through experience and time tested , that common Gloss Latex house paint works just FINE , and is the logical “thrifty alternative” ... We used the cheap Wal-Mart house paint , it was C**P paint , but has lasted a while now out in the elements , Hot hot sun, hail , storms, etc. etc. ... Still looks decent, starting to dull a little ...could use a re-paint , perhaps with some new colors ? No rush though , it’s probably good for a couple more years till it chalks out ...
Just getting around to re-painting the House and Studio exterior now after 13 years ... not a bad run for a paint job ... but I used Good paint for that ...


I’m really not worried about the Gripper at all , sometimes the airplane guys go “overboard “ with the destructive testing ... I’ll only be using the Gripper to adhere the canvas to the foam ... and as a simple primer (thin) ...

[Wolffarmer]

An idea I have thought about to build a trailer body is to build it using thin wood strips in a geodesic pattern. Heck they built a lot of WWII bombers with it. And other airplanes. Don't know how one would really insulate it. Maybe just give up and cover it with fabric for a 2 season very light camper. They found during WWII that those planes could take a lot of damage and still make it home. One part of the structure would be destroyed but other members just took up the stress and the machine kept going. Much like the structure of the internet. Ramblings of a mad man.

Randy

[Jack B.]

For what it's worth I'm residing my house this week. 20 some years ago we put up "plastic" siding and the only parts that really went bad were on the south side where it got brittle from constant sun exposure. So what we need is a thick paint made from the same stuff they use in the making of siding.

Jack