Teardrops n Tiny Travel Trailers

Okay, maybe not super unique, but very different from anything I have seen thus far.

My plan is to build a monocoque shell which simply bolts to a Harbor Freight 4x8 flat bed trailer. I need the trailer for work and only have room for one to be parked, so I plan on building a stand that the Teardrop will sit on and park the trailer underneath it when not in use.

My plan is thus: make 1-1/2" wide strips out of 1/8" lauan/underlayment/doorskin flim flam and also make the lofted arcs (1-3/8" wide) of the same. These will then become the lofting forms after they are glued into I-beam shapes. I will then take the 1/8" sheets and rip into 1/2-3/4" strips (probably 3/4, less cutting, maybe even more if I can get away with it, it's a rather gentle contour) and strip the whole thing on the exterior, just gluing (with standard PVA yellow glue) and stapling them for a clamp. (Like a cedar strip canoe). On the interior I will spray 1-1/2" of CCSPF (closed cell spray polyurethane foam). This will then be sanded with my 7" sander/polisher with an 80 grit paper. With my lofts being 12"o.c. I think I can get it pretty smooth. I will run a few 1/2" PEX tubes for electrical chases prior to the foaming. I will then finish the exterior with a good sanding, bondo for the cracks, and a thin 2.5 oz fiberglass layer with epoxy to make it watertight. On the interior floor I will lay a sheet of the 1/8" lauan, but for the walls I will just do what many people are doing for cheap floor resurfacing; 1:3 ratio of elmer's glue to water and paper mache torn pieces of heavy weight rosin paper. After a layer of that I will do a layer of maps and then coat the final surface with polyurethane. The outside will be painted with [automotive](assuming I want to pay for that...) paint. There will be a middle bunk in the hemisphere at the front of my teardrop (I have a young daughter) that will be 1/8" lauan on bottom, then foam, then the mache on top (unless compression loads will cause it to fail requiring me bump it up to the lauan). My bulkhead will be the same. In fact, my bulkhead may be mache on both sides as it does not have a downward force in the middle like the bunk.

My shell is currently, after doing a modeling in SolidWorks, about 200 sq ft of surface area (when I include the fenestrations), so about 350 board feet of foam, so that is about $350. (Of course the bulkhead and the bunk and the countertop(s) will also need it, so that adds another $200...) The doorskin/lauan/underlayment stuff is 32sqft/sheet, so I will need about 18 of those between the lofts, countertops, fenestration rims (another design feature I have yet to model, it is only on graph paper as yet), and exterior skin; that adds another $180 or so. I hope to get the bulk of the structure costing less than $800 or so, and weighing about 250 lbs. (50lbs foam, 250lbs in lauan (accounting them to be about 11lbs/sheet, which I need to verify somewhere...)

I plan to run some strength tests on this sandwich configuration in the next little while and let people know how it goes. I won't be building until February at the VERY earliest. I will be in school again and still very broke, but we will see where things are at.

Any thoughts and comments are appreciated. Thanks for looking. I will try to post the pictures of my design (haven't tried to do pictures yet). I will try to update this later with the fleshed out component locations (as yet it is still in graph format), but I may post it to start my build journal in a while. I mostly wanted to start the conversation on this type of construction here.

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Xanthoman

Interesting construction. It's going to look like a Flying Guppie, and I mean that in the best possible way. Are you going to form and finish the shell first, then cut out your doors and windows and try to maintain that shape?

I will maintain that shape in all aspects. Both side doors and the back hatch will use gas pistons and be hatch style opening. I designed a curved rim that will attach to the exterior prior to the foaming so they will be made the same way as the rest and just have the perimeter cut out after.


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More power to you! It would be unique, for sure.

Couple of other thoughts come to mind:
Shaping/sanding the inside will be a messy chore for sure.

Important point made^ here; you will want windows, vents and a few other small penetrations that, unless you custom make everything to very closely fit your 3D shapes... well, even that would be very taxing. Most readily available components won't "fit" w/o some sort of flat church or recess. Some people manage to integrate this type of thing (such as star gazer windows in a roof radius), but as soon as the curves get in to 3-axes and/or less than very gentle radii, it becomes incredibly difficult to keep everything transitioning smoothly, still looking good and weather tight at the same time. Good luck on that one. Even door and hatch hinges are going to be an issue (the only way I can see to do that and maintain the smooth outer shape is with large 'C' shaped hinges that work from inside, like the hinges on a car trunk lid; those take up a lot of interior space, will still need flat/parallel surfaces to reference off of, and will likely have to be custom fabricated out of metal in order to be strong enough w/o being too huge).

Neat idea with plenty of opportunity for light weight, but very impractical to build, IMO. With any of these things (TD's in general, foamies, hybrids, etc.) the trouble isn't in the basic concept, it is always in the details. What may seem like a fast and efficient method may end up being confoundingly complex and timely in the end.

Having built a dozen cedar strip boats, I would suggest you rethink the 1/8 Luan in favor of 1/4" solid wood. Cedar or even poplar. Those will be easier/stronger to edge glue and will give you enough wood to blend your seams. Think about it, if your seams are 1/16" out with 1/8" ply you won't be able to sand them flush without breaking into the inner plys. Solid wood will not delaminate either. Cheap ply will have voids and other defects that make it hard to get a smooth curve for the tougher bends.

Either way, you'll want to cover the outside with fiberglass or canvas. Otherwise you are relying on miles of edge glued seams to stay watertight for years.

I think you'll want plywood on both sides of the foam floor; it will probably dent if you kneel on it with just canvas or paper mache.

I wonder if you could build a stripper with foam strips.........

I don't even plan on edge gluing the strips. Just glueing them to the loft rims. The thin outside layer is just to give the foam a backing to be sprayed against. Since I am not going for the wood look ( as a kayak or such) it can go through all the layers of the ply if it wants to! I don't care about that in the slightest! I agree with the floor idea; definitely ply on both sides there.


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External hinges would not take up any interior space. If it was achievable on the Atomic Camper, I'm sure it can be repeated.

That's a sweet camper! ...my doors need to be vertical hatch doors for other reasons, I will have more pictures in my build journal when I get to it. I plan on salvaging hinges from a minivan hatch at the same time as I am taking gas lifters. $7 for hinges and $3 for lifters at the junk yard. My doors fly out and act as the tops of a shower and a dressing room on either side. I designed them already and will start a proper build journal to post the pictures on.


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Let me know if you need any help when I'm over that way

clip wrote:Let me know if you need any help when I'm over that way

When are you coming this way? I am in Rexburg, Idaho. Most people don't come by here except to visit Yellowstone...


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Well I guess I thought you were in Pittsburgh for some reason, I ll be in Nebraska next week but that's no real close either.