Unusual Designs Found on Internet

[WizardOfOdds]

Ok, this is really may be a traditional box trailer design, but it has a very unusually feature: it is two story. Many teardrop builder claim: '... the roof is strong enough to stand on...’, but here he makes use of that over built roof by putting a tent on top for extra sleeping room! No lack of detail on this one, he includes lists of parts, lots of pictures, and a very long video.
https://www.instructables.com/Teardrop-Camper-Homemade-With-Plywood/

[WizardOfOdds]

Be sure to check out the foam builds at doityourselfRV.com
https://www.doityourselfrv.com/foam-campers/

[WizardOfOdds]

When building a flat panel folding top, bi-folding walls provide a lot to like, including:
- there is less exposure to rain while opening & closing
- the folded sides need not overlap to attain max height expansion
- since the sides need not overlap, the build is more symmetric
But there also several problems, not the least of which is maintaining stability during erection & lowing the walls/roof: there are too many rotational degrees of freedom for one person to reliably control, even in the absence of a strong cross breeze. It is much less of a problem if the unit is not too large and two people share the erection task, but even then, locking out some hinges is a big help.
Even Mike M’s erection system uses a pole brace to keep things stable...

Here is a solution used on an ice shanty that seems to be adequate for units of reasonable size. It uses pins to eliminate rotation of the bi-fold hinge of the opened wall, and he uses 4 to look both bi-fold hinges while opened.


Perhaps the most stable is a corner brace as illustrated here ...
Notice his method locks the bi-fold hinge as in the previous approach, but also cross braces the opened wall into a vertical position. That is it eliminates two rotational degrees of freedom rather than just one. However, that locking requires slight lifting of the other (still closed) wall which must be considered.

[OP827]

I see one little issue with the last two designs. Since the roof is lifted one side a a time the roof sides need some flexible overhang to shed water during storage and towing and both designs do not have that. They seem both to be created for winter time usage with no rain, just snow. It is possible to solve with some heavy flexible membrane/rubber strip that is wider than two bifold side walls thicknesses together to weather seal the hinge between roof and side wall section. What do you think about addressing that gap?
Overall it is a viable design, especially the second one that has a benefit of increasing the width at the expense of overall towing height.

EDIT: the last design has a link to original sale advertisement and the builder did use a tent cover over the roof to address the roof side gap during storage and transport:

[WizardOfOdds]

I see one little issue with the last two designs. Since the roof is lifted one side a a time the roof sides need some flexible overhang to shed water during storage and towing and both designs do not have that. They seem both to be created for winter time usage with no rain, just snow.

Thanks, very good point.

My post was really intended to focus only on the need to lock out one or two hinges during erection to avoid instability, and the 2nd video had just that focus. I added the others (repeats of earlier posts) to illustrate how 2 other builders addressed the issue.

As much as I like simple bi-folds, I fear the curse of over-sights. In particular, in order for the roof and pairs of panels to lie horizontally flat upon each other requires pretty exact dimensions and pivot locations. For example, take a perfect configuration and make the roof a fraction of an inch less wide, then you do not get a nice flat stack. Likewise, slight differences in side panel widths (heights when erected) want to force the stacked pair away from horizontal. I suspect (in practice) these small mismatches place heavy stress on the joints when folded, and that is what should be avoided when using foam construction. Hinges with a bit of “give” might be a solution.

And then there is the evidence of time. If simple bifolds really are a great option, there would be lot more of them! I am sure all the issues can be solved, but doing so with a very light foam objective might not be so easy.

Thanks for the comments, they add a lot of value. And it is always painful to discover flaws the hard & expensive way.

PS edit:

It is possible to solve with some heavy flexible membrane/rubber strip that is wider than two bifold side walls thicknesses together to weather seal the hinge between roof and side wall section. What do you think about addressing that gap?

I think your suggestion of using a flexible overhang to cover the edges of the folded panels is a good one.

However, I would consider another possibility: Use rigid overhangs, but slant one of them. This sounds a bit crazy, but read on.

A slanted overhang is great for dripping rain, but can it be effective traveling down the highway? Now consider this: only one of the four overhangs needs to be slanted (the one opposite the side first raised). So if you move the bi-folds to the ends (rather than the sides) then only the rear overhang needs to be slanted (provided you raise the front first). Although I worried that a rear slanted overlap in motion could cause a suction that would draw rain, I never had any such problem with over 30K miles on the Tip Top Tier Drop. Was this just luck??

PPS edit: I should add that a rigid overhang is really only practical for a height of a few inches. That should be adequate for the top 2 trailers shown above. The 3rd design has a folded bi-fold stack of a foot or more (to provide increased width when opened). So I think his tarp type travel top is the better solution for his case. Further, not everyone will want the bi-folds at the front/aft.

BTW: I do not have any info why he installed the tarp hood on the 3rd trailer, but I would have guessed it was to cover the ends more than the sides. They look to be far more susceptible to rain: the video starts with a front end view and shows a gap of about 2 inches between the layered bi-folds. If the ends present the only problem, seems like a complete hood is over kill, so maybe he had leaks on the sides too (???).

[WizardOfOdds]

Plans for a pop up trailer are sold at this url
https://www.etsy.com/listing/909628385/pop-up-tent-camper-trailer-building
It is not clear if the plans are for fabric or solid sides, or if the author actually built one.
The camper features an unusual external lift that might be easier to repair "in the field" than the more common "hidden" approaches. It appears to use a fore-to-aft shaft to synchronize reeling the front and rear cables. I suppose the four poles are removed during transport. It is not clear if they are the only support for the roof.

Let’s compare this with another simple approach: a hidden cable between the upper shell and base walls. It lifts the top by pulling up the lower lip of the top tier toward the upper lip of the base. That is not a good idea for walls of marginal strength as it burdens the walls with lift forces at their weakest points. It also can only raise the top by the height of the base.

The lift above does not place any forces on the walls, only the floor and roof. Also, the poles could be telescoped rather than removed during travel. However, the poles would need to be manually extended (which would unreel cable from the spools) before the crank is turned. If the poles are rigid enough to be the main (sole?) support it might be a reasonable alternative for a tent-side solid-roof arrangement

[tony.latham]

It is not clear if they are the only support for the roof.

I think the images are computer renderings. It makes me wonder if the designer ever made a prototype.

I surely wouldn't want to spend a night in an unvented box without windows.

Tony

p.s. Where do you suppose water will end up running down the walls?

[Pmullen503]

It is not clear if they are the only support for the roof.

I think the images are computer renderings. It makes me wonder if the designer ever made a prototype.

I surely wouldn't want to spend a night in an unvented box without windows.

Tony

p.s. Where do you suppose water will end up running down the walls?

My thoughts as well.

It's easy to design things in CAD that don't work as well as you thought they would or are difficult or impossible to actually build. I'd really like to see a prototype constructed and used for a time to work the bugs out of the design.

If what you want is a canvas sided pop up, they are many good ones available where they have spent decades optimizing the design. The types of lifting mechanisms you see in pop ups evolved because they work. If there was a simpler, cheaper, or more reliable way to do the job, I think you would see the commercial producers use is.

The ropes or cables they appear to use won't guarantee that the top won't tip side to side as its raised. Might work OK for a hinged top.

[RJ Howell]

I am a big fan of lifting tops! Travel small, camp tall!

I love seeing the different approaches. Mine has canvas (duck cloth) sides that did takes several layers of coatings to water proof (well fully repel anyway). I like the folding sides, especially the segmented sections, only issues becomes weight and fold/unfold smoothly. Mine is a single ribbed foam roof and so light it does require gas struts. I have found that it works great for most conditions including light snow. It's the heavy wet snow that causes an issue.. My next will have a aluminum frame for the roof to get past this. That will add weight and probably then require the gas struts. I do hope not... Back to designing!

[flyweight]

I hope this hasn't been posted before, but it's new to me. Behold the Lipov Waggon (Belarus) Food Truck

121738206_736104686945340_2688793657573098974_n.jpg (305.33 KiB) Viewed 6810 times

121812488_3467299926690786_6684857801296129437_n.jpg (314.56 KiB) Viewed 6810 times

121719867_984041042093901_19385771762289043_n.jpg (379.35 KiB) Viewed 6810 times

Sauce: https://www.instagram.com/p/CGhqO3KhNrU/

[WizardOfOdds]

Thanks for the comments. I considered them carefully and here are a few additional thoughts...

“I think the images are computer renderings. It makes me wonder if the designer ever made a prototype.”

Fully agree, as I said "It is not clear if the plans are for fabric or solid sides, or if the author actually built one.”

I surely wouldn't want to spend a night in an unvented box without windows. ...
Where do you suppose water will end up running down the walls?

Agreed, but again, it is not clear what his full plan is. The image is just part of an ad. I would want more detail before purchasing a plan, but $10 is pretty cheap.

If what you want is a canvas sided pop up, they are many good ones available ..... The types of lifting mechanisms you see in pop ups evolved because they work. If there was a simpler, cheaper, or more reliable way to do the job, I think you would see the commercial producers use is.

Yet interest in DIY solutions persist! What if you replace “canvas sided pop up” with “tear drop”? I suspect the list of reasons many of us choose DIY over commercial is pretty long.

The early tent trailers with solid tops that I remember used external bi-fold struts. Today, most are larger and use 4 hidden telescoping struts with three sections each. With all the struts, cables, shafts and cranks, the new ones are far more expensive. Can it be that commercial designs are largely driven by what justifies a bigger price tag (profit)?

Further, is the most appropriate solution for commercial production the most appropriate for DIY? Twenty-five years ago I built an experimental 3 section PVC portable antenna pole that used the same techniques as the expanding struts. I was actually surprised how well it worked, but rejected it because it depended on a tight cable to stay fully erected (it was difficult to lock the sections 10 & 20 ft up in the air). Frankly, I did not find it simple, cheap, or reliable. I have the same attitude toward using them for a trailer. If you find commercial struts at all, they are probably replacement parts with very limited size and load selection. And I doubt anyone will consider them cheap. Without access to special metal working tools, they are not simple to fabricate. And I question how reliable/maintainable they are. What do you do when the cable comes off a pulley wheel that’s internal to a strut which is internal to the trailer wall?? How easily can you “jerry-rig” a fix at the campground? How do you fix a bent strut (will the sections ever slide smoothly again?)?

“The ropes or cables they appear to use won't guarantee that the top won't tip side to side as its raised.”

Yes, unless he has sliders around the poles attached to the top (not clear in figure). For a trailer with fabric sides/ends, that is exactly what I anticipate. Going up I would expect the side near the crank to lead the other side. Going down might reverse the tilt. I can imaging at least 2 ways to limiting tilt, but why is that important?? The early commercial tent trailers were opened by fully raising one end first. A tilted roof during erection was “part of the plan”.

For a telescopic top, the top can not tilt much until it is nearly raised off the base, but it can bind (jam). That’s one reason I said “...it might be a reasonable alternative for a tent-side solid-roof arrangement.” I didn’t intend that as a strong endorsement.

“It's easy to design things in CAD that don't work as well as you thought they would or are difficult or impossible to actually build. I'd really like to see a prototype constructed and used for a time to work the bugs out of the design.”

Yes, I fully agree. I would not have posted this for lack of information, but decided his unusual lift mechanism was adequately described by his CAD rendering. As such, I probably picked a poor title.

“I am a big fan of lifting tops! Travel small, camp tall!
I love seeing the different approaches.”

Fully agree, that’s what I see this thread as being all-about. I posted this because I found the lift mechanism “unusual” - not totally unique or one of great genius, but interesting. I tried to point out advantages, limitations, improvements, and issues some builders might want to consider. BTW - Love the wrap-around screen. Great work!

[OP827]

What I like about this design is the use of simple rectangular wall and floor panels to create over 4 times the living volume from its transport volume, very well done. This one gave me an inspiration, thinking of my #2 future build.
Hope to hear everyone's comments here about the practicality of this design.

https://youtu.be/Q2YVfy9CnRE

[OP827]

Another simple lifting roof and tent wall trailer.

[WizardOfOdds]

I encountered this video a long time ago, but it seems I failed to post a link.
This one is truly impressive. The pop roof and unique slide out is just the beginning.
Check out his curved cabinet doors, unique screen door, and much more!
Many a commercial unit pales compared to this DIY. Very well done

[WizardOfOdds]

When I first posted links to the Camper 365 (http://www.tnttt.com/viewtopic.php?f=5&t=64495&start=105#p1254111 bottom of pg 8 of this thread), I did not find much detail. One of the most interesting "features" was the adjustable wheel width. Well, here are some new links with a bit more detail. Hope you find them interesting.