Oh I wasn't suggesting giving up the aluminum box! But aren't most Wal-Marts
near a body of potable water, otherwise known as a "gas station"? And, you
know, balance of nature probably required that you lose something in return for
all that education; be glad it was just the fur on your head and not your
thumbs!
So instead of building a whole new titanium frame, could one scab a titanium
c-channel onto the middle parts of the frame? Do titanium and steel weld
together?
Or would the differential bending strength make the whole assembly only as
strong as the weakest piece of it, i.e., the steel that, in bending, would take
the titanium along with it or break the weld, in either case probably messing up
something (poking a tire, jabbing through the floor ...)? And, isn't titanium
more brittle than steel? Or is it just prohibitively expensive?
re the waterbeds and HUD standards, well, not to get too far off subject, but
the frame under my waterbed is a 12" high box (of some flimsy stuff, not even
plywood, sounds like a ripe melon when you tap on it) about 1' smaller all
around than the mattress frame; then the mattress is supported on top of that by
a piece of 3/8" masonite or some similar material that also supports the 2x10
mattress frame. It's heavy all right, I sure couldn't see picking it up and
moving it like you can a bed, but the load on any one part of it can't be
thought much of a problem considering the materials supporting it. Granted this
is not a four-point load on the floor but I've never seen a waterbed that's on a
conventional bed frame. It's probably the equivalent of the early '70s holding
tanks: calculated to spread the load but still too heavy overall for frame
tolerances given bouncing forces on the road. Clearly the air/water mattress
would be a big improvement if it has the same comfortingly elemental quality,
which I'm willing to be convinced of with a proper demonstration.
Okay, so, I guess we have our design together then?
--Sarah
PS, so helium in the walls wouldn't lift the whole thing up and float it over
the frame, huh? It could replace all that wet fiberglas and the mice nesting in
it though. With perfect electronic seam sealing & then never moving the thing,
at least.
"Dr. Gerald N. Johnson, electrical engineer" wrote:
> Helium is hard to hold in without very good welded seams and then it
> leaks easily. Its often used to test welded seams in electronic
> components. Even if helium weighed nothing, it would only reduce the
> vehicle weight by the volume of air displaced, which in the Airstream
> walls, isn't much.
>
> The simplest concept in doubling frame strength would be to double the
> frame member thickness, increase the frame member height (both requiring
> wholesale replacement of the frame and lower skin), or most simple to
> add another channel the same size as the original to make a box or I
> beam. Scabbing another piece of the same sized channel to make a box or
> I beam is the most simple technique.
>
> When a bedroom floor moves when I walk across it, it might not like the
> total weight of the early water bed. I hear they make them lighter these
> days to solve many of those structural problems. It makes a big
> difference in the floor load whether the water is 18" or 4" deep. And it
> makes a big difference to the house floor structure whether the bed sits
> on four points or is a distributed load. A floor made to minimum HUD
> specifications can be kind of wimpy.
>
> The frame would benefit the most from added material near the middle at
> the axle(s). There's where the bending moment from distributed or point
> loads is the greatest. Its like a see-saw. I've never seen one break
> anywhere but at the pivot. That's because that's where the stresses are
> the greatest. A trailer frame is a see-saw. Doubling up the frame
> material out at the back or up close to the hitch isn't quite as an
> effective use of added material.
>
> Trouble with the body of potable water is that we make it less potable
> by crapping in the woods. Might not need the aluminum box, just a cover
> to keep the rain off and a sleeping bag, carry it all on our backs, sit
> on logs (if in a country side that has trees to cut into logs). Been
> there, tried that (at Uncle's orders, and a little on my own), I think I
> rather like parking the A/S and being ready for bed or supper in minutes
> instead of hours. Besides its hard to set up posts on a blacktop Walmart
> parking lot that might hold up the rain cover. And I don't grow fur on
> top my head well anymore.
>
> Gerald J.
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