Quote: If you tried to support the cabover weight only on the walls (if you had some weird open-air camper) the walls would twist and the cabover would sag, but adding the front wall and roof plus structural timber prevent that twisting...
Hi Steve (and others):
Actually, have a look at the Outfitter Apex pop-up extended-cabover models; the cabover section is roughly the size of a massive hot tub for 10 people, and supports the roof, too, via the front steel lift stanchions (Apex roofs often have 300~400 LBS of gear and options up on them + the weight of the roof!). I'd guestimate that the Apex's front extended cabover section weighs (with the roof stanchions bearing down on them, too) 500+-LBS (and up to 700-LBS with full gear and food and mattress load packed in it's massive storage cavity), and quite well over 1150-LBS with 2 large sleeping people up there.
The only thing supporting this massive cabover extension are the 2 vertical side walls; a single composite structure with some rather huge aluminum beams the entire length of the camper, nose tip to rear wall. That's it
Outfitter Manufacturing once had a photograph of their entire factory assembly plant workforce and the owners all carefully standing like sardines standing on the cabover section of an unfinished Apex pop-up, and with absolutely no support from under (and the roof of the camper un-mounted, of course), I remember seeing at least 7 to 10 full-grown adults having a party up there (I guestimate with the ~~10 adults + cabover weight = ~1700-LBS) supported solely by the composite sidewalls. The non hard-side non-roofed pop-up sidewall (much, much, much less sidewall area than any hard-side roofed camper) can support basically the weight of another camper perched atop it no problem. This is thanks to a space-age composite wall design that could probably handle WAY more "live load" and forces from winds under-way (60, 70, 80 miles per hour down the highway).
The design issue for this kind of static and live load dynamic is: how and where to transfer the load path to the bottom of the tub, so that the tub doesn't end up level with the cabover bed
The pop-up, and in the extreme, the huge Apex cabover section would offer a remarkable (and the ultimate) FEA exercise for Mike to understand seemingly structure-defying strength from a relatively thin wall supported on the inside by just a few lateral struts.
The front of my S&S is built differently than most TC's. As with others there cabover frame is cantilevered into the structure. My S&S is done quite different, the sides of the cabover are solid 7/8 plywood from the nose to well into the main "box" distributing the force to the whole structure in the front. I dont think that S&S still does this since everyone has now gone to aluminum frames.
If you look at the nose construction you will note the RIGHT angles where the nose (overhang) meets the camper box. Yet the exterior is actually a radius curve. Want strength then follow the radius curve in the alum, rather than a right angle. I would not depend upon the overhead stringers for strength.
I would go with a combo monocoque construction on the top half and a rigid alum frame on the bottom half. They would join up in a clam shell configuration at about the upper middle around the window line extending to thru to the floor of the nose. This could be incredibly strong and unbelievably lightweight at the same time. Going with a clamshell config we can eliminate the leakage around front seams and ROT! You would need very little wood and what wood I would use would be exterior grade treated.
Here the key would be to reduce the weight load on top where possible. Biggest savings, AC, move it to the basement. In fact I would move everything I could to the basement to lower the CoG. I would design the basement to be fully accessible for repair and replacement.
I think the cantilever design is (in this case) outdated with the technology we and materials we have. Were I building wood, for sure its needed, but the strength of fiberglass construction is extremely strong.
Too many years in too many Corvettes and too many wrecks have shown me that survivability when I wrap my azz in fiberglass is very VERY good. Cost to repair is not only inexpensive but often can be done in your driveway by anyone in many cases.
Don
17 Oaks Ranch, Texas
US Army (RET)
'11 F350 4x4, CC, LWB, DRW, Lariat
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Vietnam Combat Veteran
noxinnhoj wrote: Lance sent me a full set of plans for how my 915 is framed and built,it amazes me how the extended cabover stays extended with just wood framing.They have been building them for a long time,all we have to do is maintain them so they dont collapse,lol.I think as long as you dont have more than one partner with you in the north south bed all will be fine,lol...
As long as you don't have more than one partner with you in the north south bed all will be fine,lol.
There you go limiting me again.....
Uh huh.....what were you thinking? I was thinking about the dog sleeping in the bed too.
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All the descriptions sound good for the cab over part in a standard camper but what about popups with no real side walls or connection to the roof. Just the shallow storage bin under the bed to hide all the superstructure that makes it all work.
(Edited)
Was behind on the tread when I posted the above and I see the Outfitter was discussed, but I have a Palomino and I think it is all wood.
JimBollman wrote: All the descriptions sound good for the cab over part in a standard camper but what about popups with no real side walls or connection to the roof. Just the shallow storage bin under the bed to hide all the superstructure that makes it all work.
(Edited)
Was behind on the tread when I posted the above and I see the Outfitter was discussed, but I have a Palomino and I think it is all wood.
Same concept, just shorter.
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