Hybrid Foam Teardrop Build With Plywood Skeleton

[Chefsonora]

Hey everyone, Im Brett. I've been planning this concept in my head for years. Wanted to build some sort of teardrop camper and because im a glutton for punishment, I've incorporated some difficult design elements (that I partly blame on the Foamie influence for ease of structure).
I'm starting with the standard 4'x 8' trailer and sticking to the single sheet plywood as my size limit(high and wide). My standout feature is a sort of bullet nose cone capped with a large dome skylight. That comes back to meet the body with coved front and top edges (15" radius). Flat or slightly sloping roof with rear hatch and galley. I kept it straight to incorporate a bunk for my 2 daughters (7 &5). Incorporating a lot of modular/ adjustable elements. It will have a plywood skeleton (mostly 1/2", some areas with 1/4" glue laminated on) with stringers notched together with the coved shaping ribs (of 1/4" plywood) all walls and ceiling will be 2" purple foam. Coved areas will be blocked in with chunks of foam and gaps will be filled with expanding foam to bond it all together, then shaped to the curves. All PMF skin inside and out.
Bunk will be supported by ribs tied together with stringers. It will be a kind of canvas sling between tubular aluminum struts running on tracks of t-slot aluminum track embedded in plywood and backed by an aluminum plate with riv-nuts. Galley will be modular/ removable, tying in to the same t-slot track on the sides as well as on the floor. Floor will be a foam sandwich of 1/2" plywood, with the PMF wrapping under the edge. All plywood will be treated (edge and face) with penetrating epoxy with fiberglass at stress points. All mounting points through the floor will have polyurethane bushings embedded in and isolated/ sealed with epoxy. Frame will have strips of epdm rubber to reduce friction/ wear.
Roof vent will be framed in between roof ribs and have a built up flange to avoid leak potential. Building a tongue box to tie in with the curves that will have battery & propane). Balancing that with weight to the rear, 3 section galley with fridge/cooler, water jug and a pull out counter/stove area. Adding external t-slot track at the corners for a attachable kick leg table, galley bag hanger, potentially shower/curtain attachment. Planning on t-slot roof racks to tie in a vestibule tent and solar. Planning on primarily 12volt system for lights, fan and charging with power hub behind the tongue box.
I probably missed a couple of things, but that's what im working towards. If anyone has experience with the hybrid ply skeleton/ foam build any tips on bonding it all together would be greatly appreciated! Wish me luck!

 

[Chefsonora]

Me and ChatGPT worked up some rendering ideas.

 

[Tony Latham]

Interesting concept. There are two things that caught my attention. First, the suicide doors. Sooner or later, you'll drive off with the door unlatched. Not a big problem if the hinge faces forward.

But more importantly, an adult and two kids in a 4' wide camper.
That may work for now, but someone once told me that kids grow up fast. Pull out a tape measure and look at what 48".

A 5' wide trailer will give you an extra mile.

Quick question: No sheathing, inside or out?

Either way, you and your little guys are going to have fun.

Tony

 

[Chefsonora]

Interesting concept. There are two things that caught my attention. First, the suicide doors. Sooner or later, you'll drive off with the door unlatched. Not a big problem if the hinge faces forward.

But more importantly, an adult and two kids in a 4' wide camper.
That may work for now, but someone once told me that kids grow up fast. Pull out a tape measure and look at what 48".

A 5' wide trailer will give you an extra mile.

Quick question: No sheathing, inside or out?

Either way, you and your little guys are going to have fun.

Tony

No sheathing, just PMF inside and out with canvas. Size wise I'm doing this as a proof of concept for a first build, planning on a larger one down the road. I figure its a good way to try out my modular system ideas without overextending my capabilities and budget. The rounded corners would get tricky and it's my design step before I commit to fiberglass. I'm glad there are so many epoxy options these days, I can still smell the polyester resin my parents used on our kit boat when I was a kid!

 

[Chefsonora]

And the suicide doors is one of my many little arguments with ChatGPT. It's only one door, not suicide and a small hatch. Thanks for the input!

 

[Tom&Shelly]

I'm glad there are so many epoxy options these days, I can still smell the polyester resin my parents used on our kit boat when I was a kid!

Know just what you mean! My Dad made radio-controlled airplanes with polyester resin.

Tom

 

[Chefsonora]

First cuts made for the framework! The hoops are for the radius/ coved corners that will tie in to longitudinal stringers. Will be reinforcing in areas for the bunk bed (will be a sliding system of bars across with a canvas sling between) it will slide on a t-slot track and lock into place. Galley will also tie in to the t-slot, with some in the floor as well(making the galley modular/ removable as well.)
Will also be beefed up in the upper area where a roof rack will go

 

[Chefsonora]

Stitching together the Harbour Freight folding trailer. Took the caster mount piece of angle iron and drilled and bolted across the break in the frame where it folded. Had to cut the end foot off of the angle as well as trim a little over an 1/8" off the cross member to accommodate the angle iron piece. Will be welding all joints once completely assembled.
By my calculations to hit the 60/40 weight/ axle placement I moved the mount back 3-1/2".
Will be adding a center spine of 2" x 2" x 1/4" square tube down the center, adding about 8-12" in the front to attach the hitch to and terminating at the stern with a section of 2-1/2"x 2-1/2" x 1/4" as a hitch for a bike rack(or stern support for long things on the roof rack)