Kim's "Puff" the magic dragon 4Hx7.5WX12L foamie camper

[QueticoBill]

George, was that foot of snow, what was the span? Near 8' ? Since bending is proportional to the square if the length, 8' needs to be around 2.5 times as strong as for 5'.

[ghcoe]

George, was that foot of snow, what was the span? Near 8' ? Since bending is proportional to the square if the length, 8' needs to be around 2.5 times as strong as for 5'.

Span would have been 4 foot on my #2 and 5 foot on my #1.

What I am saying is that PMF foam is much more stronger than just picking up a piece of foam board at the hardware store. This is where people get the idea that foamies are not strong.

If 3 of the four sides of the foam where supported, leaving the fourth side open for a span, would you still need 2.5 times as much strength?

[QueticoBill]

I'm apologize but missing 3 of 4 sides. If you mean adding beams - joists - and I thought your detail was excellent and elegant - that obviously changes things. Still, for 8', at least a 2x3, if not a 2x4, and adhering the joust to the foam so they work together, like a concrete "T".

I thought arching or curving top of joists to achieve positive drainage was a good idea, approaching my vardo suggestion. I think a curve the other way, and imagined the hobbit design that pops up here, would help the span.

So you don't build in the sag of foam over 8' , would you put the pmf on the foam - what will become the ceiling - flat upside down?

I haven't built a foamie teardrop but have designed and built lots of foam core structures, probably all with a rigid skin like ply, hardboard, or plastic laminate, but I believe engineering holds.

[ghcoe]

I believe anything over 4' should probably have some sort of extra support. That is why I prototyped the supports into #4 as a test bed. My next build will be 5' again so I will be adding some extra support for the roof since it will have a longer span front to back than #1. I will also be adding a slight curve in the roof line (front to back) and I find the foam, if not kerfed, will bow slightly in the middle. With adding the supports (rafters) this tends to help with the bowing.

[tomhawk]

I like the idea of actual I-beams. I made this out of 1/4" plywood scrapes. I used my angle grinder with a flap disk to scarf together some strips so the length can be whatever you desire. I might use this for a strut on my PMF foamie roof that will be 5' wide. I am not sure if it was worth the effort but it seems quite strong and light. The commercial manufacturers of these things claim you need special techniques so maybe this is not a good idea.

ibeamA.jpg (150.88 KiB) Viewed 1570 times

Tom

[ghcoe]

The commercial manufacturers of these things claim you need special techniques so maybe this is not a good idea.

ibeamA.jpg

Tom

The only thing different between yours and theirs is a engineer signed off on it....

[kimphan]

Thank you, I have been sleeping on the extra wall and really dislike it... I am contemplating making a modified folding caravan with shorter walls approach (5 feet high when unfolded) and make my trailer less than 2 feet height when folded with a strapped down roof for extra safety.

[TinkerTailor]

Hi Kim -

TinkerTailor here. I responded to your post on my build thread and just skimmed through yours. I'm sure you're aware of this, but making it a folding design will make for a much longer, much more complicated build! My wife often asks when it will be done. I respond that I don't know and then think to myself that it would have been done a long time ago if I did a simpler design. I don't regret it, but there it is.

Good luck with the project!

[kimphan]

Thank you so much for your kind words...

I've been observing your post and it has been a long time coming... So many things that you did is so cool and I'm really into all the tinkering to make it possible.

I'm hoping to dedicate a year for this folding build... luckily I live in the suburbs and a sloped house gave me a big empty basement that allow me to work on my build without hogging the garage.

For me, this means trading complicated and time consuming build for a more roomy camper and safer transport.
Just the safer transport is selling itself as I need to sell this to my husband, it is quite a risky pet project what I'm doing.

[kimphan]

Quick update...

I just finished installing the trailer hitch on my Honda Accord for $100 myself.

Turns out to be quite an adventure because I was clumsy with the fishwire and one of the square washer bracket was stuck in. The cool thing is I called Curt and they sent me the part in less than a week for 2 square washers and HomeDepot actually sell Curt's wishwire for $2 with a one week delay free delivery.
We also experimented with a cell phone endoscope snake and got great visual confirming the stuck washer are not going to cause issue, but could not use the endoscope's hook to move the stuck washer from the frame, oh well, my car will make music wherever it goes.

One interesting thing is that I did it without taking off the exhausted since could not get that thing off with my chopstick arms.
Another tricky part is to align the heavy hitch to the dangling bolt, remove the fishwire, put the nut on the bolt while holding the heavy hitch, I had to get help from my partner, constantly worried about how the bolt will get lost if we made a mistake and accidentally push it back on the frame. So we tie a rubber band around the bolt to pull it down while aligning the heavy hitch and it worked like a charm.

Money saved, lesson learned. Etrailer is the best site for figuring out the best hitch. Curt's hitch's fit my car like a glove.

Another win is I also finished installing the wiring harness for the hitch, Curt's part was spot on, just ground, plug in and test. I can't believe the trailer service place wanted to charge me $200 to get it done when it cost my $40 for the part.

There is an adapter that adapt the 4 way flat pole to a 7 way trailer pole, it's on the way, can't wait to test everything.

Kim.

[pchast]

Great job Kim