Dynarawr/Dynasoar: Fiberglass PVC Foamie Truck Expedition Camper

Discussion in 'Fiberglass and Composite Boat Building' started by Mowgli, Oct 28, 2021.

  1. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Here is a typical US camper. The truck backs under the unit. The wheelwells are avoided by making the camper narrower. This one was lowered after the truck drove away and is raised before the truck backs under it. The entire camper bottom is supported by the truck bed.

    In order to have the wheel wells in the camper body; the jacks would need to raise the camper up super high.

    It may be difficult to see, but the camper body typically uses the spaces on the well sides for storage, which would not be done on a chassis only truck.

    It is easy for me to become confused because we have thousands of these where I live and none of the campers are made to sit directly on the chassis.

    C02D702F-4039-40EC-BF36-BF60E2B9C191.jpeg
     
  2. fallguy
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    Location: usa

    fallguy Senior Member

    Most US truck campers are made from 3/4" plywood bottom with some plastic lining glued to it to slide a bit, prevent water damage, if the truck base or water touches it.

    For a chassis only design, using 3/4" plywood is a bit light as the camper sidewalls and roof loads would not be well supported.

    So, adding a beam across the camper inside helps the structure.

    See my red line. This could be a short stub wall inside the structure. If there is no internal support; the base just needs to be stronger, heavier I'd say, intuitively.

    871E3AF7-EAFB-42F2-B979-48CFA7266ADE.png
     
  3. fallguy
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    fallguy Senior Member

    The stub wall could be a 6-7" step up to a dinette settee, for example.

    Otherwise, one may need to develop a box like base or simply a stronger base with something like glass over 3/4" plywood.

    But no way is low density pvc gonna work on the camper bottom. I would not even use coosa bw 26.

    Two sheets of 3/4" plywood and glass each side is 8'x8' inside and the weight is going to be running like ?? 200 pounds or more just for the bottom. The glass would need to be on the inside and outside absent internal structure because the inside glass would provide the tension..

    I'll wait to see a reply from OP. Hoping this stirs the conversation. Even wheel wells cannot be made from pvc and glass because rocks will delam her easily. They would be plywood and herculiner.
     
  4. Mowgli
    Joined: Sep 2021
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    Location: Senegal

    Mowgli Junior Member

    [​IMG]


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    Having trouble getting dimensions to show in plan view with Sketchup Web... sorry
     
  5. Mowgli
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    Location: Senegal

    Mowgli Junior Member

    We're definitely in what you've classed as C roads. Think off-road open sahara desert, the edge of jungle in the rainy season, etc.
     
  6. Mowgli
    Joined: Sep 2021
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    Location: Senegal

    Mowgli Junior Member

    Here’s my truck when bought at auction:
    [​IMG]


    Here it is ready for camper buildout:
    [​IMG]
    [​IMG]
    Original subframe can be seen well here. It’s going to be expanded significantly to support the floor. This I welding and metalwork I can do myself.


    Here are subframes and mounts that have seen extensive use in either the Outback or literally all over the world, including North Africa:
    [​IMG]
    The link below is the short read build page for the truck shown above with the galvanized subframe.
    2010-06-27 https://www.epicycles.com/Truck%20Blog/2010-01-01/2010-01-01.htm
    Their floor is 50mm PVC core with wood batten reinforcements. I’ve talked extensively to the builder and one of the others that helped construct it and travels with his own overland truck built from PVC foam panels as well.

    The following truck has used glassed wood. Wheelbase is identical to mine, with a single cab. Their roof is a pop-top as well.
    Subframe https://rollingstudio.wordpress.com/2011/01/08/subframe/
    [​IMG]
    [​IMG]

    [​IMG]

    [​IMG]

    My subframe mounts will be modified to add springs and lateral movement plates like below (it's currently only fishplated to the chassis rails):
    [​IMG]

    As for construction experience, I’ve built a competitive amateur rallycross car suspension by hand, fabricating my own struts, building and molding spring mounts, joints and linkages etc. to lift the vehicle while also increasing droop. Considerable math, geometry and dynamics evals went into that design and build to obtain better than oem handling and suspension travel and still return perfect alignment. In a past life I built ropes and climbing courses professionally, as well as roofing and general construction work when the right jobs came up. I’ve done a fair bit of rough wet layup work on kayaks, canoes and other human powered craft.
     
    Last edited: Nov 21, 2021
  7. Mowgli
    Joined: Sep 2021
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    Location: Senegal

    Mowgli Junior Member

    The truck has a 5L diesel, hi/lo transfer case with selectable 4wd and a crawl gear. It's payload as shown is 3000kg (not lbs). It's actually a Hino Dutro 300 that was/is co-produced as a Toyota Dyna XZU372.

    The dinette area becomes a double bed when the table drops down to fill the footwell area. The cutout area underneath is where the fridge/freezer unit goes directly on the floor as it's very heavy and is then accessed when standing on the lower floor. Two bunks come off the upper walls over the kitchen area for my boys and the rear wall counter folds out to a cot for my daughter. The interior design is the result of countless iterations and living 200+ days a year in vehicles and tents for more than 5 years.

    The camper is to be permanently mounted to the truck. No need for jacks or on/off mechanisms.

    Also, although it's counterintuitive, pickup truck tubs are terribly weak especially when stressed by extended loads. Being able to build directly onto a tailor made subframe on the chassis rails is preferred by any/all builders unless the original capabilities of a pickup have to be maintained.
     
  8. fallguy
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    fallguy Senior Member

    You first need to declare the subframe support structure and dimensions and then determine the wall and roof loads(weights). Once that is known, it is a piece of cake for someone like rx.

    A 2" or 50mm deck with wooden inserts makes a lot of sense because that essentially is my red line in multiple places and it affords a place to bolt to the chassis, although that could be done from the side.

    give the dimensions length for m aft, transverse width and what any additional metal frame might be like and see what rx says.....he can plug this into spreadsheets
     
  9. Mowgli
    Joined: Sep 2021
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    Location: Senegal

    Mowgli Junior Member

    This Swiss constructor is a big inspiration for my build:
    C est partis mon kiki mais est ce raisonnable ? - Page 2 - Casa Trotter https://www.casa-trotter.com/phpBB3/viewtopic.php?f=12&t=8395&sid=a18acdcca87ce7030adc1d74dd12fa20&start=25
    (open in Chrome and use the translation function if you cannot read French)

    [​IMG]
    [​IMG]

    Fabrication cellule composite sur Toy - Casa Trotter https://www.casa-trotter.com/phpBB3/viewtopic.php?f=12&t=10548
    [​IMG]
    [​IMG]
    Cutouts are for wood or Coosa inserts for mounting or heavy load points.

    Finished camper box
    [​IMG]
     
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  10. Mowgli
    Joined: Sep 2021
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    Location: Senegal

    Mowgli Junior Member

    Thanks fallguy. This is where I'm struggling. Without knowing how/what the camper body is constructed of (core weight, thickness, etc.) it's near impossible for me to determine the wall and roof weights. I can estimate the roof's load carrying requirement based on the solar setup.
     
  11. Mowgli
    Joined: Sep 2021
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    Location: Senegal

    Mowgli Junior Member

    Subframe will be laid out like these. I'll get a drawing together tomorrow with dimensions. It'll be built most likely with 1.5" square steel.
    upload_2021-11-21_23-56-22.png
     
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  12. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    I am not a fan of coosa here for the inserts, based on the roads. Coosa is fine for many things, but it is not the right product for bolting loads. Overtime; it will crush and the laminates will fail.

    The compressive strength is simply not there. Make no mistake, coosa is a great product for screws and screw holding. And many things can be bolted with even 12# density cores and single layers of laminates, but the bolts are under quite a bit of strain here when the chassis goes over uneven roads.

    If you have access to g10, I'd plan to use it where you make the hardpoints for the chassis bolting. If you do not have access to it; you can use wood, but wood, when it gets wet; expands and changes dimensions, so you will need to overbore any wood holes and fill them to avoid your camper being impossible to lift off..should you ever encounter water intrusion. G10 is the best way to go. You could also make your own solid frp hardpoint inserts, but it takes quite a bit of time. The g10 inserts would not need to be 50mm thick, but you'd need to transistion to them.

    The subframe changes the game for the needs for the base. I don't understand why you'd need 50mm thick with the steel. None of the pictures appear to be a 2" thick floor. Most of them appear to be 12mm thick; I could be wrong. Report back here on the two variations. One with the yellow corecell and the other woth the green pvc what thicknesses they used. That will help if @rxcomposite is willing to give you a spec. Also, if you already know the laminates from these builds; please share.

    For me, I really see no reason to build the walls ultralight. And so, you can load design the walls using 600/225 and a 12mm m80 core, which is the heaviest they'd ever be... I don't like that glass here, because it is too heavy for the value, but you can use it for load calcs.

    The rooftop is trickiest. It needs to be larger than the camper walls to shed water. It needs to be stiff enough to not sag across the middle. The ideal roof would have a wee bit of crown in it for rain loading. If you want rain catchment; that is done with ridges and some angles to the back, say. But the water will be dirty at first... the top I'd want either air gapped or thick. You could air gap with say a 12mm core on top and 25mm wood battens and a 6-12 mm inside core. I gotta go for now..
     
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  13. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    Some of the problems and choices you make are incomprehensible to me. You know enough about the loads to design the subframe, but you don't know enough about them to design the shell. Once you have a subframe, floor laminate design is governed by impact and abrasion because the unsupported span is small.
    Want to put solar panels on the roof? Design a grid the same size as your panels, laminated on the outside of the roof. This will do 3 things, stiffen the roof, provide mounting points for the panels and an airspace for solar insulation.

    Why transport a steel structure? Steel tubing is available everywhere, it makes more sense to transport the welder, angle grinder, consumables and paint.
    Similarly, just pack a few boxes of foam, a roll of fiberglass and a barrel of resin. Everything you don't use can be sold locally at a premium. I am also pretty sure you can buy polyester resin and fiberglass in Senegal, so I would only import the foam. Best way for that would have been to put the the boxes into the trucks cabin, or strap them to the frame.
     
  14. Mowgli
    Joined: Sep 2021
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    Location: Senegal

    Mowgli Junior Member

    Well noted on coosa and wood for inserts. I had planned on using G10 as a backing plate. What thickness or configuration should be used for mounting inserts as proposed?

    The Swiss builder uses only a high density foam (unspecificed-he keeps his secrets) for his mounts:
    [​IMG]



    The subframe vs all-composite mounted floor is an ongoing debate and I have not found a good answer. I had initially hoped to avoid the metal frame myself but it’s darn simple, easy to work with and obviously the well traveled route.


    The epicycles build referenced above did indeed use 50mm core for their floor.

    [​IMG][​IMG]



    His compatriot has a composite camper as well on a truck (an Oz-only produced OKA) that is a considerably stiffer boxed frame, a la the landcruiser also shown above, and they are about to start a build with the composite floor to be just glued directly onto the frame rails.

    He challenges sandwich panels naysayers and describes his mounting: “Our sandwich panel vehicle has been on the "road" now for 16 years and has experienced many km of serious stress without the slightest detriment. The body is glued to the cab and 12 rubber blocks attached to the chassis. They have a maximum of 10mm of possible movement.”
    <iframe width="640" height="360" src="https://www.youtube.com/emb
    ed/9cJg8JoTA9s" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

    Here is another glue and pad only:
    “It is a Defender chassis. The body is Sikaflexed to the top and rear of the cab and bolted and glued via multiple rubber blocks direct to the chassis. 100% successful in that time. Cab only is Discovery, chopped off behind the "B" pillar. Chassis, engine and mechanicals were Defender (note the wheel base - Discovery is not that long).”

    [​IMG]


    My truck has an extremely thick unboxed C chassis rail. The most common cabover truck used like this is the Fuso Canter which is a bit of a different beast as it has a stepped frame that both tapers and narrows rail thickness and height throughout the chassis. Epicycles and the New Rolling Studio are both Canters; most of the length of their chassis rails are 4.5mm thick. Isuzu’s offering uses 6mm rails. Mine come in at 7mm. A newish Toyota Tundra is 3.8mm and a 70 Series Landcruiser is 4mm but both are boxed. My Dyna has the highest payload of any above referenced (~3000kg), but this doesn’t necessarily translate to frame stiffness. Odds are it’s less torsionally stiff than a Landcruiser when unweighted due to the open C rails, but still far stiffer than the Canters.

    For the yellow Corecell and green Airex floor/bases I do not know the exact thickness; the Swiss builder doesn’t wish to ‘share his secrets.’ Comparison of photos with premade wall panels (34mm finished depth) joined to the floor shows the floor to have a core of at least 38mm. As an answer to the concerns mentioned about rocks, debris, road wear/tear, the floor can be seen here with an undercoating. Note the thickness of the green core seen from the side.

    [​IMG]


    Of the laminate schedule I know little. His walls are built with a 1.8mm skin which is adhered to a 30mm core, but that isn’t exactly what we need to know. For the floor he offers only the following: “the base fabrics which are 750 gm” and “layout the high density airex (green) then install compression inserts for fixing, the wheel arch is structural reinforcement in biaxial glass fabrics 3300 gr which will serve as a composite chassis frame for the distribution of torsional forces because on the toy the strongest 4 points are just on each side of the wheel arch, they will certainly be bolted on its 4 points the rest while floating.” The laminate over the wheel arches ends up being 3mm thick apparently. The floor as pictured weighs 45.5kg finished before assembly if that helps at all.

    Noted on the load calc with the 600/225. You think 12mm m80 to be sufficient even if the sides of the shoebox roof/lid are essentially hanging off the roof and the roof is only supported by 4 actuators in the corners?
    I’m not sure I agree about the rooftop being a larger dimension than the walls. While this would be ideal for shedding water and eventually snow, I can’t quickly thick of any rv/camper/overland build commercial or diy that doesn’t have a roof that matches the wall’s outer edges. Perhaps I’m not understanding what was meant.

    2” of foam has been a minimum recommendation from many builders specifically for equatorial areas to provide sufficient insulation from sun and heat. I do not care about rain catchment; not planning to hobo camp for multiple weeks. Noted regarding crown - most recent drawings posted yesterday show an updated roof with curvature.

    I understand the air gap would help to keep the roof weight down, but am concerned about keeping out as much of the aforementioned heat as possible. Solutions that maintain at least 50+mm of foam core?
     
    Last edited: Nov 23, 2021

  15. Mowgli
    Joined: Sep 2021
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    Location: Senegal

    Mowgli Junior Member

    Thanks for asking more questions Rumars. I should have been more specific in saying that I have enough skill to construct a very strong and moderately light steel subframe that is similar to what others have used with success. I do not know how and cannot design/build a subframe for specific loads or loading - that is far beyond my capabilities.

    With regards to the grid for the roof, are you proposing a metal structure or something else? It is definitely prudent to include an airspace as you directed, and I had expected to use aluminum stock to support the panels.

    Nobody else that I know of is building these things with the kind of attention to detail or loads as the accomplished folks do here with their boats and watercraft. Accordingly, things like roof loads are usually just estimated and then later some kind of rack structure is bolted on for better or worse. I realize now that you're point out how I could use the panel mounting framework to in fact reinforce the roof panel. Thank you for that idea/advice.

    The steel subframe that is pictured on the truck is overkill but is already on the truck and will be shipped with the truck at no cost to me. Hard to believe, but there is no constraint on how much vehicle weight is shipped on my behalf, only that anything attached or in the vehicle needs to be permanent (Thule roof bars, hitch mounts, tools and rescue equipment for example must be removed). That subframe used to support a 2500kg pumper body (also shown) and I can easily build it out to support the floor and weather the twist and other forces it will experience. I cannot however keep it light doing that, as I simply don't have near enough data or acumen at present for that kind of analysis and design.

    I would have loved to have stuffed everything into the truck for shipping. Unfortunately, I had to leave the truck behind in Seoul earlier than planned and as just mentioned can only ship it with permanently affixed items.

    My major push now for building at least the panels pre-move is that I have a good work space available, access to a fully stocked carpentry shop's tools and help from a family member who has actually both built and repaired both wood and fiberglass sailing boats, skiffs and other craft. Said family member is however and rightfully so, not willing to do this part of the design and prep legwork for me.
     
    Last edited: Nov 23, 2021
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