Teardrops n Tiny Travel Trailers

Hello all -

New member here. I have read a fair amount on the foamie forums - thanks for your experimentation, expertise, and generous and inspirational posting!

I have an (unassembled) HF folding trailer in my garage (the 1200 lb. version), and I'm plotting a folding hybrid foamie a la casita folding caravan, etc.

I aim to follow these vintage plans

http://tnttt.com/VintagePlans/foldingtrailer.pdf

in terms of the mechanism by which the structure folds and opens, including the 45 degree chamfers in the wall joints to prevent water intrusion, though my dimensions and outline will be quite different (I have drawings but need to sort out how to post them - the outline, however, will be similar to this: https://homedesignlover.com/architectur ... me-office/).
My plan is for the camper's external dimensions to be 11' long by 6'4" wide by 7' high when open and a bit less than 4' high when folded for traveling. It will be mounted on the aforementioned harbor freight 4 X 8 trailer when in use, and will be removed from the trailer and placed on its side for storage (inside my small garage). The trailer will also be folded up for storage when not in use.

I am planning on using primarily 2" foam, though perhaps 1" on the front and back walls to cut down on the height of the folded wall/hinge assembly. I want thick foam, though, as I will be using it for winter camping at ski areas around Lake Tahoe, as well as for general family camping and surf trips.

I plan on using a relatively light wood framing around the edges for the panels (for strength since there is no monocoque and also for the hinges) and I am leaning towards pmf inside and out, though I am still considering skinning the exterior with 1/8 plywood as well. If I do skin the outside with ply I will use pmf for the interior. I plan to make a sandwich panel for the floor with nrp panels on the bottom, 2" foam in the middle, and 1/4" ply on top, possibly with vinyl flooring over that.

Fixed plexiglass windows rabbeted and glued into the foam on the front and back walls, and openable plexi windows on the sides, either in the wiley or sash style. Standard vent up top. All-in-one diesel heater, propane stove, & a smallish electrical set up with a solar panel is the plan (these would need to be easily removed before turning the folded camper on its side for storage, with the exception of the solar panel itself). Bucket toilet and possibly a marine foot pump sink like the one seen here:
https://www.youtube.com/watch?v=D2604Le2k0A.

I have been making surfboards out of XPS foam and skinning them with poplar bender ply and cork flooring for a number of years, so I have some experience with similar materials, and I'm finishing a small XPS and pmf boat to get some familiarity with that process as well. The pmf application on the interior of the boat has not gone altogether well, but thankfully there won't be any compound curves in the camper, and only the internal radius in the roof in front and back will be visible.

Any thoughts, suggestions, or critiques would be most appreciated. I'm hoping to build this over the summer. Thanks much -

TinkerTailor

TT, sounds like you already know what to do.

Just fyi , on inside curves , the canvas tends to shrink away from the inside of the curve as it dries , so when applying the canvas , leave some extra canvas for shrinking room so it won’t be a problem … Tricky !!!

Sounds like a good plan except for storing it on its side. By the time it's done it will weigh several hundred pounds off the trailer. So not a trivial matter just getting it on and off. A foldable trailer is just not as stiff as a one piece body and flipping it on it's side may bend or break it.

Good point about the dangers of flipping it on its side. Very true. Unfortunately I don't have another storage option.

I was assuming that timber framing in the static lower section and also in the roof would provide enough support, but I'll have to think about beefing that up even more, or perhaps putting in some removable support beams between the walls that I can take out when it is in use.

Thank you!

I'd be worried most about racking. Maybe some big removable gussets on the corners or corner to corner struts.

Pmullen: Another good point about the racking. I'll think over how a removable gusset could work. I'm planning to install pulleys in my garage's ceiling so I can lift the cabin off the trailer more easily and then lower one side first onto a dolly setup so as to push it easily to where it will be stored. I think the pulleys and dollies will help make the turning-on-its-side process softer, but some extra support beams & gussets is a great idea to make sure things don't rattle apart gradually.

GPW: Great tip about shrinkage on the inside curves. I'll make sure to do the ones on the floor, which will be invisible, first to work some kinks out.

Thanks to you both!

I've read this a couple times now and man, you mind is further out there than mine!!! Don't know if that's a good thing or not.. What a challenge!

My mind goes towards 5 panels (4 sides and roof, floor being part of the trailer) and panels at least framed in wood to make up a slipping dovetail corner. Top would need the same to slide it on. Say sides are dovetailed and front rear are lap-joints. The 11ft long is doable, as is the 6'-4" wide. The 7ft high.. hmm.. hard to reach that roof when setup.

Quite the challenge buddy! Keep us posted as you proceed.

RJ Howell wrote:I've read this a couple times now and man, you mind is further out there than mine!!! Don't know if that's a good thing or not.. What a challenge!

My mind goes towards 5 panels (4 sides and roof, floor being part of the trailer) and panels at least framed in wood to make up a slipping dovetail corner. Top would need the same to slide it on. Say sides are dovetailed and front rear are lap-joints. The 11ft long is doable, as is the 6'-4" wide. The 7ft high.. hmm.. hard to reach that roof when setup.

Quite the challenge buddy! Keep us posted as you proceed.

Given your storage needs, I think RJ's idea of making separate panels makes more sense. I would also reconsider the size. What is the lowest roof height you can get away with? Putting the roof in place seems the toughest part of the job, especially working alone. You'd compromise the shape too, more of a box than camper.

Sliding dovetails would be nice but lap joints wouldn't require lifting the panels, they could be tilted into place.

Thanks for all the feedback everyone. Plenty to consider. Here are my sketches thus far, pretty much to scale except that I didn’t show that the 5” skirt is wider than the walls in order to slip over the walls like a sleeve.

My design for the roof component is, from top to bottom, 1’ 5”, so when the structure is open, the part of the roof I’d be grabbing would be about 5.5’ up, though with the trailer height it’d of course be higher. That is roughly on par with the height of the vintage plans. Nonetheless I’ll do some sort of mock-up to see how tricky it’ll be before building.

Thanks for the troubleshooting!Much appreciated.

TT, it may make things easier if you build a little scale model first … Scrap cardboard or foam meat trays work great for “visualizing” how things fit together , or don't …

I agree - will definitely do a little scale model and maybe a full size model of the folding wall assembly at a corner (not the entire walls, but just a chunk so to speak) to see how they would fold down & precisely how long the roof skirt would need to be to securely cover & tie everything together when closed.

I have written this then deleted twice now.. Thought just doesn't save much storing space, but I'll throw it at ya, let ya ponder and throw it away as you please. Maybe something in it helps.

I'm in the mist of a build off the back of my pickup. I want a sort of Earth Crawler to Overland with. I need it to fit in my garage so I'm doing a pop-top. Build is here: http://tnttt.com/viewtopic.php?f=55&t=72408, scroll to he last page and see the top. I have debated making solid panels to go in vs. fabric, yet found it a bit more involved for setup than I wish so I'm staying with fabric.

Thought was of doing the Front/Rear as hinged panels to lift the top and placing the sides once lifted. It would travel the same, just have two side panels inside I'd have to pull out and set.

Just doesn't break down enough for what you want for storage...

TinkerTailor wrote:I agree - will definitely do a little scale model and maybe a full size model of the folding wall assembly at a corner (not the entire walls, but just a chunk so to speak) to see how they would fold down & precisely how long the roof skirt would need to be to securely cover & tie everything together when closed.

Welcome to the board, TinkerTailor!
I am glad to see another folding hard wall and lifting roof design here, subscribed.
I also started with this very concept and then switched to more complicated design of my own in the end. Your design idea will work, but building light for roof and walls will be important to make setup and breakdown manageable, or you will need to add gas struts to lift the roof. I know a builder who already built two iterations of this a la Esterel/Gobur design. He has an engineering and design background and came up with a better solution (my opinion only) for gas struts to less interfere with the roof and make a better weather/dust seal than of the original Gobur or Esterel. He did an extension steel plate bracket fixed to the front and back walls to slip under the roof instead of a whole gas strut like in the original manufacturer design. You can check his second build video here and you can see how my build ended up working here.

As for sandwich panels I am quite happy with 6oz e-fiberglass and epoxy covering over XPS that I did on my build. It is light weight, stable and rigid. If I did that again I would consider other methods, but only after a good testing on samples.
Good luck!
Oleg

Thanks for that link, Oleg - a great job on that folding camper (and on yours - I've read through your thread before)! I'm a pretty solid craftsman, but the detail on both of those is beyond what I'll realistically be able to throw at this project (two small children, work, school, other projects, blah blah).

RJ Howell: I looked at your truck camper and that is looking great and very similar. Thanks for sending that along! Any tips you think might come in handy will be gratefully accepted.

That said, I've done a little scale-ish cardboard model, & it seems to me that the general vintage design will work with 2 " foam as the wall material. I'm planning to use 4 " L flashing on the front and back folding walls to create a lap joint that will hug the side walls when up and also when folded down. I'm thinking of using 2" foam on the front & back walls as well and then extending the roof skirt by another inch or two to sleeve over the additional folded wall material (the door will have to be shortened a bit to accommodate this, but I'd have to stoop to go through as it is, so not a big deal). I'll have some thin weatherizing gasket along the 45 degree chamfers on the folding walls as well as on the top of the folding walls where the roof cap will rest. The roof skirt or sleeve that slips over the assembled walls will be 1/4" plywood, perhaps with a clear finish as a contrast detail to the pmf. The roof cap itself will be mostly foam & pmf with a perimeter of light wood framing & a few light reinforcing spars in case of snow.

As for racking, I forgot to mention earlier that there will be a bed structure spanning the width of the back, and the galley structure spanning the width of the front of the static lower base, so that should help, though I may still need removable gussets for storing it on its side. We'll see.

As for the height, I want it to be a standie, but without danger of blowing over while towing in bad weather (and of course storable in my garage). Also, if I'm going to the effort of making this, I want to enjoy the aesthetics of it, so no boxy roof - it needs a radius up there! And since the roof and floor thicknesses are 2" and 2.5" respectively (if I use some vinyl flooring over the 1/4" ply on the floor), there are only 7.5" in play for me to maintain a 6' interior height...so I'll do some experiments to see how tough set-up would be, and maybe I'll shorten it a bit, or maybe I'll bring along a step stool. We'll see.

This thread is definitely helping me to think through the details. Thanks to all!

TT