Montana Mod-u-Foamer - The Corto Series

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Montana Mod-u-Foamer - The Corto Series

Postby jim_manley » Tue Aug 08, 2017 9:42 pm

For those who aren't into reading, please just move on, this is a build journal, but an effective one starts with describing perceived needs, designs that address them, rethinking based on the results of experiments, and only then actual building will take place. Now, that's not to say that I won't be building for months, or even years, as some have here, sometimes due to analysis paralysis. I've already got my Harbor Freight (HF) trailer kit under construction and my initial foam, interior/exterior laminates, adhesives, and fasteners in hand.

I'm also spelling things out with their acronyms for the newbies, so please excuse the pedantry if you're a Teardrop Master, mod(erator), or whatever other levels are above Teardrop Inspector. Many builders just jump in with inscrutable terminology in their journals, often confusing the non-annointed who think a TV is something on which you watch the DIY Channel, Tiny House Nation, etc. (for the newbs, it's a Tow Vehicle ;)).

I'm cursed/blessed by being both an engineer and an educator, so I try to be precise without too much hand-waving, but precision generally also means providing details. Unlike a typical TV episode, where there are only 21 minutes of content and nine minutes of commercials per half-hour episode, it's all content here, and it may be a while between posts, depending on real life (family, the real jobs, discretionary money, discovery of better methods/materials, etc.). Bear with me though, as I do try to use humor, although I usually bomb more than the majority of the time that even professional comedians do. As a wise old Navy Admiral once admonished me after a very difficult, dry, highly-technical briefing, "Damn it, son, if you can't be informative, at least be entertaining!" :o :roll: :thinking: :applause:

I've been planning this build for many years in bits and pieces, and I'm finally at the point where need is overcoming all of the other barriers, including available time, physical stamina, and especially money (I'm limited to the salary of a pre-tenure teacher in a tiny K-12 school of 35 students in one of the most rural areas in the country). I originally just wanted to build a simpler variation of the Safari Condo Alto:

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I've built half-a-dozen wood-framed/paneled flatbed and box utility trailers on Harbor Freight 1,720-pound and 1,195-pound kit frames, and I've used fiberglass over foam to build experimental aircraft. Being 6'3", I was drawn to the Alto design because of the ample headroom through most of the trailer when the roof is raised, as well as the ample light that can enter through the windows along the roof line. Room for plenty of amenities added over time for longer-term living is also a nice option, and I've been interested in clever space efficiencies being developed for tiny homes (THs). The more I thought about both TDTs and THs, the more I began to think about how it might be possible to combine the techniques used to construct them.

Expanded styrene (XPS) foam panels such as Owens Corning Foamular or Dow's products were an obvious starting point for their light weight and compressive strength when used as the core of a composite sandwich. Two-inch thick 4 x 8 foot Dow panels cost about 25% less than Foamular in my area and are plentiful, and Polywall is about three-quarters of the cost of fiberglass reinforced panels (FRP). I'm experimenting with Polywall non-fiberglass reinforced plastic (NRP) sheets cut and adhered to the foam with Glidden Gripper primer or an adhesive that doesn't dissolve the foam or require evaporation since foam and Polywall are both essentially impervious to vapor escape.

I was going to use 5 mm thick birch plywood for the inside skins of the panels, but they were out of stock. I had originally wanted to use Polywall on interior and exterior panel surfaces to eliminate any chance of rot, but they cost about 25% more than the plywood. So, I'm going to wind up with a very-easy-to-keep-clean and bright interior that will be completely worry-free when it comes to water, whether due to precipitation or spills inside - there's nothing like being able to hose out your RV after a rainy, mucky trip, right? I can always apply other materials to the interior surfaces selectively as utility and aesthetics indicate. I'll initially just be using plastic organizer containers for supplies stowed in the Corto, and at some point (aka when enough discretionary cash and time are available), I'll probably fabricate foam-core, wood/Formica/etc.-veneer cabinets.

My variation of the Alto I'm calling the Corto, since the former means "tall" and the latter means "short" in Spanish. My initial configuration was going to be a 4 x 4 x 8 foot (H x W x L) teardrop with a maximum height of six feet inside with the roof raised. However, I'm now thinking about making as many of the sandwich panels 4 x 8 feet as possible and using adjustable-pressure latches on the interiors and exteriors to lock the panels together.

The simplest initial configuration that would require no foam cuts could be made up of eight 4 x 8 foot panels arranged with one as the floor, one as the roof, two on each side, and one on each end, with the aft panel able to pivot from the left side corner (keeps everyone from walking into the street without really trying). Flexible vinyl foam-core seals, such as those used along the bottoms of garage doors (Thrifty!), could be used to deflect precipitation away from joints, and if the compression latches aren't able to keep water from penetrating the joints, the joints could also have thin foam seals in them.

It took me a long time to figure out what terms to use to find on the Web what used to be professionally called "slip hinges", but I finally discovered the right magic phrases include "detachable hinges" and "lift-off hinges". I knew they existed, because they've been used on boats forever, as having an opened door swinging around in heavy seas is not a good idea at all (especially when they're made of solid oak, maple, etc.). Here's what one looks like, in case you're not a nautical cabinet-maker:

Image

These are very useful for construction of prototype as well as production/self-built trailers, especially when the alternative is trying to read a good book in a trailer being towed at high speed over boulders with unsecured cabinet doors swinging all about (what should be an unnecessary caveat, but we apparently live among a majority of In-DUH-viduals: NEVER RIDE IN A TRAILER BEING TOWED, AT ANY SPEED!)! I plan to use them to slip panels together along their edges, two per long dimension and one along each short dimension. It's amazing how much strength is suddenly achieved when even three otherwise-floppy panels (e.g., < 1/8th-inch luan plywood) are fixed together just at the centers of their edges to form a corner.

When six faces are formed into a rectangular solid from panels using the same method, the strength of the resulting structure is incomprehensible, even when calculations are performed correctly to predict the outcome. Here's what a whimsical cube constructed of twelve 4 x 8 foot foam panels, secured by 24 slip hinges on the centers of each four-foot section of each edge:

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The more mechanically inclined might notice that there aren't any hinges in the two back corners and that's because you can't slide panels along more than one axis, as once you've engaged one pair of hinges along an edge, you can no longer slide that panel into another set of hinges along a perpendicular edge. That means that at least two pressure latches will need to be installed between the side and back panels in each of the back corners. Another option would be to use removable-pin hinges, but having used those before, that can be tricky as, even if you drill and tie them off to the hinges with fishing line, the pins always wind up lost in the mud or the bowels of the tow vehicle (TV) in torrential rain and wind late on those Friday nights when we seem to wind up camping :roll: :thumbdown: :o

It should also be noted that the vertical corners are point-edge-to-point-edge, which, although seals can be situated where they meet, will succumb to Murphy's Law, and water will make its way inside. The same is likely true in the roof joints, although I would put thin, compressible seals in them prior to assembly. Even though it would probably only be a few drops, that's enough to demoralize all but the stoutest-of-heart, eventually (e.g., visitors one might be trying to impress! :D). Me, mmm, water's something to be cherished, especially given the extensive droughts Out Here and the following fires. Maybe not in a sleeping bag, but that will lie on top of several layers of impervious closed-cell foam mats and mattresses, while leaks would most likely run down the joints and drops collect toward the corners - nothing some of those quick-dry towels couldn't handle and be wrung/snapped essentially dry.

Don't worry about the HF trailer frame I'm showing in my drawings, as any structures wider than six feet, more than four feet high, not aerodynamically faired, and reinforced with many more additional fasteners won't be towed with the panels erected. Also, support legs would be deployed at the outer corners of the frame attached between the shell and the trailer frame to ensure solid stability when moving around and materials stowed inside (the edges of the frame can be seen protruding a couple of inches along the bottoms of each side panel).

This is strictly a static, non-towable experiment for the foreseeable future, and another reason for the simple box experiments is to gather experience with building larger structures and the much more numerous interior features at a TH scale. Eventually, some panels will be cut/kerfed to establish a curved teardrop profile to allow towing with the panels assembled using more mechanically-substantial fittings, or at least a larger number of fasteners spaced more closely than the two feet in this very rough prototype. Here's how the panel layout for the concept could be applied to a teardrop-faired version with more-than-adequate inter-panel connections and structural reinforcement:

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While this is based on a simple 8 x 8 x 16 foot box made from 4 x 8 foot panels, I've drawn in a teardrop outline (generated in about a minute using the SketchUp arc tool) across the side panels to show where the cuts could be made in four panels on each side. However, I would more likely cut the upper or lower two panels on each side down to 2 x 8 feet wide to result in a six-foot-high shell, and the outline would be scaled vertically appropriately. In the structures being towed, I would incorporate some form of reinforcement extending (all the way?) through the width of foam sandwich panels that would take the structural load off the foam and provide sufficient compression on seals along joints to prevent any water intrusion. Occasional drips in a vehicle intentionally taken out into the wild where you're kayaking, hiking, cross-country skiing, fishing, sailing, and doing a bunch of other messy stuff is one thing. Getting splish-sploshed on with a laptop where it was designed to be, on your lap, perhaps while lying in bed, and plugged into AC power, is something completely different - potentially shocking! :? :shock: :frightened: :cry: :worship:

So, there it is, the first installment of my version of Homer's "Odyssey" ... or Homer's "Idiocy", as in the yellow Simpsons character, depending on whether you're a literary or TV critic ... or a Teardrop Master! :thinking:

More to Come, So Stay Tuned ... unfortunately for The Unsuspecting Public! :shock: :R :FNP ;)
"Education isn't the filling of a pail, but the lighting of a fire." -- Plutarch ... or W.B. Yeats ... or ...

"In theory, theory and practice are the same ... in practice, they aren't!" -- Some Engineer

"Just when you think you have all the answers ... they change all the questions!" -- Murphy of Murphy, Dewey, Screwem, and Howe, LLP


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Re: Montana Mod-u-Foamer - The Corto Series

Postby jim_manley » Thu Aug 10, 2017 1:34 am

Here's what the teardrop versions of the 8x8x16 foot (HxWxL) "Fatty" and the sportier, lower-profile, much more aerodynamic "Heat-Sleeker" 6x8x16 foot versions of the Corto look like, carved out of the 8x8x16 foot "Boxer" prototype.

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I really like how the Heat-Sleeker profile looks! At nearly six feet high inside at the peak with the roof down, and its gradually-increasing slope fastback, the Heat-Sleeker would provide over seven feet of headroom along over half of the shell length with the roof rotated up, ala the Alto.
"Education isn't the filling of a pail, but the lighting of a fire." -- Plutarch ... or W.B. Yeats ... or ...

"In theory, theory and practice are the same ... in practice, they aren't!" -- Some Engineer

"Just when you think you have all the answers ... they change all the questions!" -- Murphy of Murphy, Dewey, Screwem, and Howe, LLP


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Re: Montana Mod-u-Foamer - The Corto Series

Postby jim_manley » Fri Aug 11, 2017 1:33 am

Glen's wish is my command after he commented that my Corto concept trailers would be big ... and varying size has been part of my plan from the beginning. Below is a cutaway view, with the right wall removed, of the Mod-u-Foam concept for the roof of the Corto Heat-Sleeker variant. Two-foot-wide left and right slide-outs could be fabricated, allowing the width of the shell to be expanded from four to up to eight feet after arrival on-site. I didn't show the detail (yet :twisted: ) for how the deck and support subframe (attached to the HF trailer) could also be extended to ensure proper road handling at highway speeds. Also, recall that the side and roof panels could be made up of modular sections that are held together with hinges and/or positively-locking adjustable-pressure latches, allowing the length and height of the shell to also be adjusted in size, all the way down to 4 x 4 x 8 feet (H x W x L).

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Plenty of room to expand to welcome the friends and relatives of poor, dearly-departed, little Mr. Toad to visit 8) :lol: :thumbsup: :applause: Enjoy!
"Education isn't the filling of a pail, but the lighting of a fire." -- Plutarch ... or W.B. Yeats ... or ...

"In theory, theory and practice are the same ... in practice, they aren't!" -- Some Engineer

"Just when you think you have all the answers ... they change all the questions!" -- Murphy of Murphy, Dewey, Screwem, and Howe, LLP


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Re: Montana Mod-u-Foamer - The Corto Series

Postby aggie79 » Fri Aug 11, 2017 8:23 am

Interesting... :thinking: I've always admired the Alto and will be following this.

I'm curious as to:
1. How the lift-off hinges will attach/anchor in a NRP/XPS/NRP sandwich?
2. How will you form the curved composite roof panels...
a. Perhaps with a female or male mold/buck?
b. Will you kerf a full width thickness of XPS or will you laminate thinner layers of XPS?
3. What type of adhesive you will use for the low surface energy NRP?
4. How will accommodate the typical variation in thickness of an XPS panel?

I look forward to your experiments and build! :thumbsup: :applause: :thumbsup:
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Re: Montana Mod-u-Foamer - The Corto Series

Postby tony.latham » Fri Aug 11, 2017 2:24 pm

I'm wondering how you're going to keep it dust and water free?

Tony
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Re: Montana Mod-u-Foamer - The Corto Series

Postby QueticoBill » Fri Aug 11, 2017 3:52 pm

tony.latham wrote:I'm wondering how you're going to keep it dust and water free?

Tony


Me too. Looking at youtube of the model for this, it sure seems more feasible if the part that rises is the "outside" and kind of sits on and over the lower fixed walls. Then at least I'd have a chance.
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Re: Montana Mod-u-Foamer - The Corto Series

Postby jim_manley » Fri Aug 11, 2017 10:14 pm

aggie79 wrote:Interesting... :thinking: I've always admired the Alto and will be following this.
I'm curious as to:
1. How the lift-off hinges will attach/anchor in a NRP/XPS/NRP sandwich?
2. How will you form the curved composite roof panels...
a. Perhaps with a female or male mold/buck?
b. Will you kerf a full width thickness of XPS or will you laminate thinner layers of XPS?
3. What type of adhesive you will use for the low surface energy NRP?
4. How will accommodate the typical variation in thickness of an XPS panel?

Per the Star Trek episode, "The City on the Edge of Forever" (in which McCoy changes history after jumping through a time portal into the 1930s that results in the Enterprise and the Federation ceasing to exist), as The Guardian time portal device said, "Time has resumed its shape. All is as it was before. Many such journeys are possible. Let me be your gateway." Yes, I am A Guardian, and many such journeys are possible, but, I hope with less dramatic results than those where the Nazis won WW-II!

1. I intend for the hinges to be bolted through the sandwich with oversized washers, lockwashers, and nylock nuts, counter-torqued nut pairs, or Loc-tite (to prevent loosening), as the ability of the NRP to constrain bolt movement is satisfactory without significant wear, and XPS resists compression sufficiently. At least, that's my story and I'm sticking to it! :FNP

2. Gluing/Great Stuff to bond multiple layers of 1/2-inch XPS is Plan A for the XPS curved sections; kerfing and glue/Great Stuff/etc., in the kerfs for two-inch thick XPS is Plan B; and wishful thinking that there's some way to heat-bend 2-inch thick XPS without melting it is Plans C through Z ... :thinking:

3. Adhesives that can successfully bond NRP to XPS - ahhh, the 64-million dollar question! In theory, contact cement that doesn't melt XPS would be ideal ... except that the only ones I've been able to obtain with those properties are water-based (e.g., latex) ... and hence take forever to dry (if ever) . Glidden Gripper is supposed to be legendary, but that's also latex-based, AIUI, so, there's the drying issue again. The FRP panel adhesives are designed to bond non-porous FRP panels to porous concrete, wood, etc., so, those are apparently out. I don't have access to a small quantity of 3M™ Fastbond™ Contact Adhesive 30NF yet, but it appears to be suitable for bonding foam, as well as NRP, and other non-porous materials.

4. The NRP is stiff enough to make up for any variations in XPS thickness, and if there are any significant depressions (which would cause voids/gaps), Great Stuff is probably the right solution.

QueticoBill wrote:
tony.latham wrote:I'm wondering how you're going to keep it dust and water free?
Tony

Me too. Looking at youtube of the model for this, it sure seems more feasible if the part that rises is the "outside" and kind of sits on and over the lower fixed walls. Then at least I'd have a chance.

Hi Tony and Bill!

I probably won't be showing the details for seals until everything else is nailed down, so to speak, because every decision made before seals are installed changes everything about how seals need to be implemented (no actual nails will be used in the construction of the Corto, per PETA demands, or somebody like that, I'm sure!). Having said that, I'm quite aware of the Winter Warrior outside-wrap raised-roof design, but it's based on woody techniques, and as we all know, woody designers and builders don't seem to care anything about weight and cost, or at least not nearly as much as Foamie builders. The Alto uses some pretty clever (and expensive) materials and techniques to reduce weight, but to nowhere near what our beloved foamies weigh or cost, as they use a very costly, but high strength-to-weight, aluminum-and-something honeycomb-like composite-based panels. That weight and cost disadvantage of the Alto extends to how they provide windows and seals, but fortunately, the latter can be pretty readily reproduced with very affordable seal materials readily available from DIY brick-and-mortar and on-line suppliers such as Home Depot, Lowes, Do-It Centers, etc., and even Walmart.

My original thought was to cut down the width of the roof sections for the 4 x 4 x 8 foot (H x W x L) minimal-size Corto from 4 x 8 feet foam panels to about 44 inches wide. That's because they would be fit between the two-plus inch thick side walls that would be mounted on top of a 4 x 8 foot sandwich panel. However, the full width of the exterior NRP sheets would be adhered to the roof panels, with two inches extending over each side wall. The overlap would keep water and dust away from the sliding joint as the roof panel dropped into the lowered position. When raised, I would use some of the tricks used in the Alto that aren't obvious from the videos I've seen, but become apparent when examining one in person.

However, I decided to keep the roof panels a full multiple of four feet wide so that the side walls would be attached to the base panels along the side edges of he base. This eliminates the need to make difficult, eight-foot-long rip cuts that, if screwed up, can make it difficult to get the NRP bonded without a lot of Great Stuff or other filler, sanding, etc. I absolutely hate two things - sanding and painting, which is why I'm using the NRP sheets on the exterior. Since this would eliminate the built-in overlap of the aforementioned method, I would make up for that by bolting a separate stiff flap along the edges of the roof-to-sidewall joints, with a compressible foam seal on the underside that would rest on the top edges of the side walls.

The main technique the Safari Condo Alto manufacturer uses is a wide, stiff overhang along the roof edge with a compressible foam seal on the underside to keep dust and water away from the roof-to-sidewalls joints. They also have a flexible flap that wipes against the inside surface of the outer wall panel and pops out just as the roof reaches the raised position. That causes water coming off the windows suspended under the roof edge to drain away from the joints, and the underside of the seal is a compressible foam that spans the area from the joint, outward toward the edges of the side walls, providing a wide sealing area. I'm going to test garage door bottom seals for this, as they're compressible and flexible enough, and are available in long enough single pieces to extend along the entire length of roof joints on the Corto from the 4 x 4 x 8 foot to 6 x 8 x 16 foot (H x W x L) variants.

I'll show these details in some Sketchup drawings over the next few weeks. If all else fails, I'll just stretch a darned tarp across the top, or set a waterproof pop-up above the trailer and retire to the interior of my nice, warm, dry Foamie to enjoy some hot beans and franks, and cold root beer! :thumbsup: :applause: 8)

Thanks for the interest and questions - I'm in a holding pattern beyond planning at the moment because of a screw-up in being paid consistently through the Summer. I'll be fully funded starting in September, so I'll be able to get back to acquiring materials and building during the rapidly-dwindling outdoor building season this close to the Arctic Circle (well, OK, a 50-mile strip of Nothern Montana and the entire Province of Alberta stands between me and that latitude). Another advantage of the modular approach is that I can build panels indoors, albeit in a Dexter-style kill room lined on all surfaces with plastic sheeting and sealed with duct tape, to keep the foam dust and adhesive fumes out of the rest of the house! :shock:
"Education isn't the filling of a pail, but the lighting of a fire." -- Plutarch ... or W.B. Yeats ... or ...

"In theory, theory and practice are the same ... in practice, they aren't!" -- Some Engineer

"Just when you think you have all the answers ... they change all the questions!" -- Murphy of Murphy, Dewey, Screwem, and Howe, LLP


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Re: Montana Mod-u-Foamer - The Corto Series

Postby ssuuki19 » Sat Aug 12, 2017 12:20 am

Hi just wanted to say I found this post really informative, and funny. Especially your sig :) The Alto design fascinates me and on this forum I've now seen at least three designs that had a folding door to accommodate a shape change. Looking forward to seeing where you go with the ideas.

How does sealant get on my triceps and then my car seat?? more than once??
Aluminum is almost as fascinating as wood.
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Re: Montana Mod-u-Foamer - The Corto Series

Postby jim_manley » Sat Aug 12, 2017 3:27 am

Here's another cutaway view of the Corto with dual two-foot slideouts to either side, stowed within the four-foot-wide central outer shell, resulting in a 6 x 4 x 16 (H x W x L) teardrop volume:

Image

The view of this drawing is what you'd see through a very wide-angle lens, so there's some significant perspective distortion. That can be seen in the odd angle of the right tire, the apparent depth of the shell in the cross-wise direction looks much shallower than it really would be, and the 4 x 8 floor panels appear to be of vastly different sizes, when they're actually identical, It's not clear whether the 6 x 16 (H x L) teardrop profile would present too much sideways sail area when towing in heavy crosswinds, given that the standard track of the wheels is about five feet between the outside edges of the tires.

Plus, the center of side wind force on the shell would be about 3.5 feet above the road, but the lateral center of gravity should be within about 2.5 feet off the ground. The more weight, lower down inside the shell, the more stable the trailer would be, and that will be easy to accommodate when internal foam-core cabinets, camping equipment and materials (including a porta-potty or lightweight flush or composting toilet), food, drinks, potable water, and gray/black water.

Here's what the 6 x 4 x 16 (H x W x L) Corto would look like from below, showing how much lateral support is provided to keep the trailer upright in high crosswinds:

Image
Last edited by jim_manley on Sat Aug 12, 2017 5:01 pm, edited 1 time in total.
"Education isn't the filling of a pail, but the lighting of a fire." -- Plutarch ... or W.B. Yeats ... or ...

"In theory, theory and practice are the same ... in practice, they aren't!" -- Some Engineer

"Just when you think you have all the answers ... they change all the questions!" -- Murphy of Murphy, Dewey, Screwem, and Howe, LLP


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Re: Montana Mod-u-Foamer - The Corto Series

Postby jim_manley » Sat Aug 12, 2017 1:14 pm

ssuuki19 wrote:Hi just wanted to say I found this post really informative, and funny. Especially your sig :) The Alto design fascinates me and on this forum I've now seen at least three designs that had a folding door to accommodate a shape change. Looking forward to seeing where you go with the ideas.

Hi ssuuki19!

Glad you enjoyed my rambling mumblings ... or mumbled ramblings ... if "Seinfeld" is "The TV Show About Nothing", then this is "The Journal About Nothing", at least nothing beyond a spindly HF utility trailer until I begin making those cuts and gluing that can't be reversed with the Undo option, like I can in CAD software :cry:. Cut once, measure twice, and swear at my own stupidity at least three times ... because I did the first two steps in the wrong order! :x
"Education isn't the filling of a pail, but the lighting of a fire." -- Plutarch ... or W.B. Yeats ... or ...

"In theory, theory and practice are the same ... in practice, they aren't!" -- Some Engineer

"Just when you think you have all the answers ... they change all the questions!" -- Murphy of Murphy, Dewey, Screwem, and Howe, LLP


What I'd love to build: ... What I'll probably wind up with:
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Re: Montana Mod-u-Foamer - The Corto Series

Postby jim_manley » Sat Aug 12, 2017 11:45 pm

Here's a quickie drawing that I feel really captures what I want the Corto to ultimately be and, while it won't be simple to build, what TD is, once you start cutting curved pieces? :?:

Image

The most amazing thing is that the back opening is actually an inch taller than I am (6' 3") and the peak interior height is 8' 3"! Plus, the height will be well over my head over the entire length of the interior all the way to the leading edge of the sidewalls :thumbsup: :applause: :D. The look with the raised roof is even more spectacular than that of the Alto, due to the forward roof hinge being on a deck panel.

Anyone astute enough to realize that the roof hinge has to be only attached to the center roof section will know that something will need to be done about the gaps at the forward bottom edges of the slideouts, both for waterproofing as well as bugproofing. That bridge will be crossed, as they say, in the very happy situation that I've been able to get the build done that far :worship:. I suspect that it will make a nice entry for cool air down low in the shell as part of natural or powered circulation.

Note how the center roof section creates an opportunity for a rear vent as there's a gap formed between it and the slideout roof sections along their aft edges. That will need a screen and possibly a small panel to control or shut off air flow through the gap. Given that most Foamies induce heavy breathing and the sweats if there's no air flow, I think the forward low intake and high rear gap exhaust will work out pretty well. A roof vent/fan will still be needed, of course, but that's just another detail I would have to construct when I get to that point (unless I can find one in good shape from a junked RV), since the professional options cost about as much as my HF trailer!

Some have questioned whether the Corto design violates the Safari Condo Alto patent claims, and it just so happens that I'm very experienced with patents as I conceived of, was awarded, successfully defended in court, and obtained licensing fees for a patent (although it was for software). I'm both a software and hard-stuff engineer, so I'm pretty well-acquainted with the issues that could come up in a mechanical design.

It turns out that Safari Condo's main claim is for a hinge at the leading edge of an aerodynamic trailer shell that allows the roof to rotate upward. My hinge would be at the bottom edge, several feet below the leading edge, which is at the very forward-most extent of the shell. Safari Condo also makes other claims, but my design doesn't involve any of those. It doesn't appear that they claimed the folding rear wall because I'm sure that concept has been in use for many decades on lots of folding-wall RVs.

One of the things I love about the Alto is the amount of light that can come in through the windows, which I included in this drawing. The Alto (as with any RV with any size window), includes tracks along the upper edges of the windows for curtains to be drawn, along with tie-backs to control light entry and privacy. The Corto would also have that feature, especially if I don't otherwise cover the gap between the forward edges of the side walls and the aft edges of the front of the roof slideout sections when the roof is raised.

It's possible that the rear wall will be shorter, I just "raised the roof" as far as I did to see whether a door could be included in the aft wall, and whether I could stand up within the entire length of the interior. The 22.5 degree angle shown here just happened to be my first That Looks About Right (TLAR) engineering (aka "gut feel") guess! ;) I will be one very happy camper (literally!) if I can pull off this build as drawn here, but there are a lot of "ifs" between here/now and there/then, aka the hairy details. Details, ohhh, like the frames holding all those window panes, which may be acrylic or polycarbonate (if I win multiple lotteries) and, as someone has already asked about, a plethora of seals (the rubber kind, not the performing sea mammals! :pictures: ). I'll keep doodling until I'm able to continue fabrication and assembly, but I'm now even more motivated than ever to build something as awesome as this would be. My Mileage Will Vary, of course, but hey, as Shakespeare said, "To dream, perchance to sleep", or words to a more iambic pentameterish rhythm :applause:
"Education isn't the filling of a pail, but the lighting of a fire." -- Plutarch ... or W.B. Yeats ... or ...

"In theory, theory and practice are the same ... in practice, they aren't!" -- Some Engineer

"Just when you think you have all the answers ... they change all the questions!" -- Murphy of Murphy, Dewey, Screwem, and Howe, LLP


What I'd love to build: ... What I'll probably wind up with:
.....Image................ Image
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jim_manley
Teardrop Builder
 
Posts: 28
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Joined: Wed Jun 21, 2017 3:20 pm
Location: East Glacier Park, Montana
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