OP827 wrote:Are you familiar with this method: http://www.tnttt.com/viewtopic.php?f=2&t=52750#p1145889? It seems to be very light and not hard to do. It could even work with canvas instead of dacron, as TB2 glue causes the fabric to shrink while drying. This would need some testing of course. That might work, I would put some synthetic insulation in the voids, as it will also help with blocking the light where unwanted. It might look pretty nice showing the structure of your design. Rounded corners can still be made with foam.
As for lifting mechanism on my build, I did cables and pulleys system actuated by a single screw similar to a popup trailer, but simpler. Cable routing can vary, of course. I can report that it works on my build.
tony.latham wrote:The Rutan aircraft guys and fiberglass boat boys might be rolling their eyes if they come across that.
OP827 wrote:I agree with Tony. Best way to decide is to see other campers made with PMF and FG and/or do your own test panels and then decide what is best for your build .
Pmullen503 wrote:I would just make the top with foam. It would be easier to round the corners.
But if you want to go the skeletonized plywood route I would fill the voids with foam. Not too heavy and you don't have to bridge to voids. Glass cloth/epoxy doesn't shrink and it will be tough to get it tight over the voids. Canvass and glue will shrink tight over the voids but I would still fill them with foam.
Years ago I build a 4x8' lifting bench and used Acme rods in the four corners with a long chain and sprockets to turn all four in unison. The posts were just metal pipes with flanges and Acme nuts welded to the tops. I had a gear motor and sprocket to move the chain but you could use a crank for a "no power" solution.
timm wrote:Yeah, that's pretty much the plan. My thinking is that aircraft used to use a similar technique (canvas and dope) and it worked very well. Admittedly dope is a better sealant than exterior paint, but aircraft also move significantly faster than my car. A freak hailstorm would definitely do damage, but a hailstorm would do damage to a teardrop regardless of what the roof was made of, at least my roof can be repaired very quickly and inexpensively.
I can add foam for the reasons you mentioned, but I think the canvas and paint would be ok alone.
If you want a poor man's version of aircraft covering and finishing, try to find information on Fisher Aircraft. They are a low cost kit aircraft company. I dont know for sure if they are still around.tony.latham wrote:I built a "rag and tube" aircraft decades ago. It was covered with aircraft grade dacron. It was finished with nitrate dope, and then silvered butyrate (because of the UV problem) and finally butyrate paint. It took a roll of duct tape to get home after a bad hail storm in Pierre, South Dakota ––but N716TL is still flying even though I don't own it.
They quit using cotton for aircraft in the late fifties. You can buy aircraft (shrinkable) dacron from Aircraft Spruce along with the dope and powdered aluminum. There should be plenty of Youtubes on how to apply it.
Andrew is spot on with the rock chips.
Tony
Andrew Herrick wrote:It's obvious you're putting a great deal of thought and care into your project. As I said, I'm no aircraft guru, and the unsupported PMF might do just fine. If worse comes to worst, you could always renovate your camper later. Or you could do it for $50 and an afternoon's work the first time :p
timm wrote:
It has an 18" stroke and since PVC has such a high pressure rating (around 1200 psi for 1 1/4" schedule 40) I can basically lift as much as weight as the seals can take without leaking like crazy.
KTM_Guy wrote:I was looking to run PVC air lines in the garage so didi some looking online. First click was a guy that was working in his garage and without notice his air line exploded. He had photos and X-rays from the ER of his posterior neck with a 8" shard of PVC stuck in it.
I'm not using PVC for air.
Todd
Andrew Herrick wrote:KTM_Guy wrote:I was looking to run PVC air lines in the garage so didi some looking online. First click was a guy that was working in his garage and without notice his air line exploded. He had photos and X-rays from the ER of his posterior neck with a 8" shard of PVC stuck in it.
I'm not using PVC for air.
Todd
Do you know if it was cellular/foam core PVC or solid core PVC pipe?
Don’t recall. But was pointed out was when pvc fails it’s not a slow thing that you’ll notice. It’s a catastrophic failure with no notice.
Todd
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