Alto(Pop-Up) Inspired Foamie - Build Progress

[M-88]

Definitely following this! I'm planning on building a teardrop to pull behind my 2011 Focus (5 speed, though). I am hoping to have it be just as wide as the car, though. I don't want to kill gas mileage too much with the trailer.

There are a few things you may want to look into when towing with a Focus. I would definitely have an auxiliary transmission cooler installed - it will extend the life of the transmission a lot when towing. Also look into airbagging the rear suspension.

You will have tongue weight in order to tow the trailer safely. The problem is, the rear suspension on the Focus is designed to get negative camber (not the end of the world) and toe OUT when compressed. It acts as a means to give 4 wheel steering under hard cornering. It will make quick work of your rear tires, though.

When I move forward with this on my Focus, I am going to be adding rear airbags to mine to avoid destroying the rear tires.

[thelastlokean]

That is true about Ford Focus alignments, I have 'REAR SUSPENSION CAMBER SHIMS - Moog' that I added some time ago that levels out the rear tires, I didn't add them for any towing related reasons, at the time I was already experiencing rear tire uneven wear and noise even with very regular tire rotation.

I just got a mechanic to make my rear tires near 0, I don't drive aggressively and would rather take turns slower then have terrible tire wear...

Here's a link for what I'm talking about: http://www.moogproblemsolver.com/_pdf_E ... 002_En.pdf

I added an inline transmission cooler, I've also been using a bluetooth OBD2 scanner that lets me keep an eye on the gearing and transmission temp. Haven't had any issues yet. So far my Focus towing experiences have been wonderful. I ended up holding off on teardrop construction, as my workshop has moved to a larger location that I get to use for free, but I first had to clean out the worlds messiest garage... So I ended up using my trailer as a utility trailer for dozens of trips to local dumps, electronic recycling places, goodwill, salvation army, etc. I have certainly pushed it with the towing limits, once with a 1,200 lb load of servers and monitors, the only issue at that point was braking limitations...

Going forward, I plan on finding a way to get brakes added to the trailer... Most likely, I'm just going to swap out the axle to something a bit more heavy duty, a little bit longer, and with the needed flanges to mount electric brakes.

I have had much time to reflect on my designs though! I even found a dealership that specializes in tiny trailers and teardrops, so I got to tour a bunch of them. I will be building over the winter, as I have setup heat in my newly acquired garage space... Photos to come.

[thelastlokean]

Some Build update information:

I found out about a bunch of pretty cool materials and stuff at a fiberglass workshop I went to and has inspired me to modify my build.

Dacron Heat Shrink Fabric: Amazingly tough stuff, I'm going with this instead of canvas. I bought the 2.97 oz stuff from aircraftspruce, its intended to cover the outside of airplane frames... Also, it really isn't much more expensive than canvas.

Mesh Braided Fiberglass: A picture really does this justice, also available in carbon fiber blends... It reminds of a Chinese Finger Trap, greatly able to expand and shrink.

mesh braid.jpg (55.11 KiB) Viewed 1500 times

carbon fiberglass weave.jpg (154.92 KiB) Viewed 1500 times

I plan on building a frame with PVC tubing, heat bending it to shape, then reinforcing the frame with braided fiberglass. Then I will build the frame like a plane, with heat-shrink dacron fabric, wetted out with epoxy or aircraft dope. I plan to fabric inside and out of the frame, filling the void with a foam insulation.

Some edits to my basic design, I've decided I want to keep the rear-hatch kitchen, its just so nice and promotes organization.

[KCStudly]

Although very ambitious ( ) this sounds like a real challenge, for sure!

I would reconsider your build sequence, unless you plan to have the insulation professionally blown in after the Dacron outer skin has been applied. if you do the Dacron first it will have a faceted look and placing extruded foam might make things lumpy. If you build the frame and set the foam in chunks or panels, then you can carve/sand the foam to a pleasant shape, and the Dacron should conform nicely. Unless you are going for that fabric covered airplane look.

Of course this all presumes material compatibility; does epoxy bond to PVC? (IIRC, I think the answer is no.) Is commercial spray foam compatible with the Dacron?

Doing a whole camper with those little (sometimes unreliable, and expensive) cans of spray foam would really be... let's just say tedious.

Here's a think tank question for you: does the PVC even need reinforcement? I understand the excitement of new materials and how one can be enthused by a sales pitch, but doing all of that layup on a jungle gym of thin spindly tubes will add considerable cost in materials and build effort over not doing it, or even choosing other options. Even as a "lightweight" composite, adding glass and epoxy adds weight. (Ask me about my foam tongue box with 2 plies of 6oz cloth; I would guess that it has close to doubled in weight since glassing it.)

Doing things in a novel way does have an intrinsic value and appeal. I chose a unique path on TPCE, but it is never as easy as it sounds and can add significantly to the build time and expense. If I had chose to build in a more traditional manner using standard methods and materials I might have been done by now, and maybe have been closer to my original budget goals (maybe ).

More power to you if you do decide to commit to this. It would certainly be interesting to watch, but be careful what you wish for. There have been times during my build when I questioned why I had thought that something would be just as quick and easy (routing out and gluing in what seemed like a never ending succession of recessed anchor blocks comes immediately to mind).

All that being said, please take another look at GPW's FoamStream build and compare that technique to what you are proposing. If ultra light weight is a design goal, a similar but lighter method would be to make the (wooden) ribs/forms be temporary, then glass the shell inside and out, removing the wood form(s) during the process.

[Pmullen503]

I'm with KCStudy on most of what he said. What is the goal you hope to achieve by using non-traditional materials and methods? (Doing something differently for it's own sake is a legitimate goal in my opinion, I do it all the time.) You should choose materials and methods that get you to your goals.

If you really want a lightweight, fabric skinned structure spent some time here: http://www.gaboats.com. This will give you an idea of what's possible with a lightweight fabric covered structure. I'd use wood over PVC for the ease of gluing and you can work with rectangular members which will be easier to insulate. Bend or laminate the wood for curved members. You can also use a heat activated adhesive to apply the fabric which will be much easier than trying to glue fabric to PVC. I'd go with foam slabs cut to fit the openings of your framework; cheaper and you could sand them to get smooth curves or hotwire them to get a faceted look.

[GrenDesb]

I'm wondering if the hinge is worth it.

Safari Condo has put out a new Alto that doesn,t pop up. It uses the same roof with higher sides so that the finished profile is the same as the pop-up model once open.

The end result is that the gas consumption to tow the pop-up one and the new higher profile one is approximately the same.

The thing is that the aerodinaic advantage of the pop-up one is negligible compared to the added weight needed for the top to pop-up and for the camper to hold together without the walls being attached to the roof. A non-pop-up can be much sturdier with a lighter structure.

They are local ro me and I visited their facility. It is a very wel tought out and nicely built product but I would opt for the new higher profile one. If I was to build a custom camping trailer, I,d rather go with side or front/rear slide outs than pop-up roof.

But I like your ideas so I'll sure follow this build and I hope to see this coming to a successfull end.

[thelastlokean]

I do appreciate some critical input, as always everything you try to do has hidden and unforeseen details. I wasn't expecting so much criticism, or I would have put more detail into my initial post.

I'm certainly not going to give up on the two hinging roof pieces. Worth mentioning, the original alto fills the wall gap with glass or plexiglass, I plan on filling the gap with a layer of mesh screen and a layer of insulated fabric (recycled ice house material), held in place with velcro. It won't add nearly as much weight and will minimize some of the complexities of the hinging roof. Just personal preference, but the ability to fully stand up is critical in my opinion.

I also plan on minimizing windows, just one port window on the door, as a large section of the roof can be window if desired.

I've been lightweight tenting it for years, a large part of the goal is the ability to stand. Also, from what I know of aerodynamics, if the tow vehicle is wider or taller in cross-section than that of the lead vehicle there will be large increases in drag, I could see a taller profile working out well if towing with an SUV or even a mini-van, but I'm talking about towing with an economy car like a Ford Focus... Anything I could stand upright fully in, including ground clearance would be much taller than my car.

I do see where your coming from with the slide out concept, I just don't think its for me on this build. Time will tell how things work out.

Regarding the dacron and insulation. These are my original thoughts on build order: First, I was planning to build and glass the entire frame, including hinges and all. Then applying dacron to the outside with iron-on heat glue. Stage 1 shrinking with an iron set to 50% shrinking. Then tape up the seams. Then continue to iron until pulled tight like a drum, wasn't expecting faceted look, or inwards bow. (might have to experiment with that). Anyways, then I was going to seal the dacron with pre-tested to be compatible adhesive. After hardening, I was planning on adding insulation of some form, then putting up the inside lighter weight dacron, heat-shrinking, and then sealing.

Regarding material compatibility, there are some epoxies specifically designed for and specified to be compatible with pvc and fiberglass, however I'm not sure I'll be using them.(not rigid enough, to flexible) Also, a light sanding followed with an acetone scrubbing leaves the pvc surface porous and able for a strong mechanical bond. I have done some testing(still ongoing), making multiple 3' rods with various 1/2" plastic tubes and the carbon/glass fiber braid, when the surface is prepared properly adhesion is quite solid even with the adhesives that are theoretically only mechanical. I tried one with titebond 2 instead of an epoxy and it was surprisingly stiff and strong, one of the best strength/weight ratios. They have all been aging under load for the last few months, I'm excited to see how they hold up when some of the lower temperatures start setting in, I plan on attempting to break them all sometime this winter.

I also made a set of tubes, bye filling the inside with foam insulation for tubing with a slit, and some 1/4" rigid copper as the core and removed the core after glassing. Removing the core was a PITA, and would likely be nearly impossible for 'curved' pieces. I've decided to live with the 1/2" pvc core permanently stuck inside the tubes for a variety of reasons. I also did a small set of experiments with pex tubing instead of pvc. At this point, I have made more than 20 test pieces, the strongest and lightest one is going to become my framing material.

I've done a bit of research into the skin on frame boats/canoes/kayaks, and have seen what is involved with bending wood pieces (steam box, board selection, prices, etc.) and I have decided to build the frame out of carbon/glass fiber with a plastic core instead.

I might build a mountain bike frame or a small skin on frame canoe first, just to get some more hands on experience and familiarity in working with the braided fabrics. If all of my ideas are going to fail for some reason, its best to find out on a test piece or smaller scale project. I'm not new to glassing, and one of my largest appeals in the braided tubing is the ability to pull both the ends tight and cause the fabric to pull on tightly, I've seen some great results with some proper technique and tricks that eliminate the need of vacuum bagging.