TerraLiner:12 m Globally Mobile Beach House/Class-A Crossover w 6x6 Hybrid Drivetrain

biotect · Dec 18, 2014

Hi NeverEnough,

Excellent summary of arguments for "mongo IS" and 6x6, and a frank, candid admission that "turtling" is a potential problem. Why is lifting the middle axle on ordinary paved roads so critical for you? It has come up a few times in the thread. Egn was against a lifting axle, and he drives his 6x6 everywhere:

egn said:
A lift axle would certainly reduce fuel consumption, but the ride will probably not be as comfortable as with 3 axles on road, as the suspension has to be harder at same weight.

So why would lifting the second axle be important for you? Just reduced fuel consumption, or additional reasons? As things are panning out, it will indeed prove possible for the TerraLiner to weigh 18 tons or less -- after all, Peter Thompson's Mañana weighs this much, and Mañana is 10.74 m long (see http://www.thompsons.au.com/motorhome/ ), and was not constructed out of carbon fiber and titanium....:sombrero:

So again, just curious why you and a few others think that lifting one axle for road driving is so critically important.

All best wishes,

Biotect

dwh · Dec 18, 2014

I think that pic that was posted of an IS with some rocks was a bit deceptive. If you are building a hybrid and using one drive motor per wheel, even without a portal arrangement, then the center is going to have the same, or better, ground clearance as a Unimog. The suspension is simply going be IS by default because it wouldn't make any sense to add some sort of big tube to lock the left side to the right side.

If you are going to use one drive motor per axle, then it's a different story since you *must* tie the ends together, with either a big tube (solid axle) or a center gearbox + swing axles (IS), so you would have to make a decision on which way to go. This would also apply if using a conventional internal combustion drive-train.

But if you go with one drive motor per wheel, then that's that - the decision's already made. It is what it is.

LoRoad · Dec 18, 2014

This might be what NeverEnough is referring to. On a recent trip I backed my truck/camper into a tree, in my defense it was pitch black outside. The jolt was severe enough to shake the camper out of whack and the truck to tweak/tremble...if trucks can actually tremble that is. When the daylight came up all I initially saw as damage was that the dome over the shower had cracked. I thought I had gotten away with 'something' or at the very least I was super lucky. Sadly I couldn't have been more wrong. Immediately following that incident I spent several days traveling the washboard, if we can call them this, roads in Death Valley. Over that time here is what happened.

The tree torque had done way more damage than previously thought...notice how the tie down has come virtually completely loose from camper structure...this traversed the entire camper on both sides. Internally seams, covered by wall paper, were now showing signs of breaking apart and on the outside (pic below) the outside shell of the fiberglass had now cracked in two.

So I have to agree with those that say it's nice to have NICE, but what I really want is something that will survive the crap roads I'm planning on driving down and like a Timex can take a licking and keep on ticking.

NeverEnough · Dec 18, 2014

dwh said:
I think that pic that was posted of an IS with some rocks was a bit deceptive. If you are building a hybrid and using one drive motor per wheel, even without a portal arrangement, then the center is going to have the same, or better, ground clearance as a Unimog. The suspension is simply going be IS by default because it wouldn't make any sense to add some sort of big tube to lock the left side to the right side.

If you are going to use one drive motor per axle, then it's a different story since you *must* tie the ends together, with either a big tube (solid axle) or a center gearbox + swing axles (IS), so you would have to make a decision on which way to go. This would also apply if using a conventional internal combustion drive-train.

But if you go with one drive motor per wheel, then that's that - the decision's already made. It is what it is.

Thank you DWH, as always, for taking the time to give an explanation. Whether your motors are on the backbone/chassis (meaning a CV and possible portal) or in the hub, by default you're in the IS world if you want one motor per wheel. I'm very curious about what options can be put together for either configuration for a heavy truck with currently available market components. The unsprung weight of +100kW hub motor will require some special considerations in the suspension engineering and setup. And if you put the motors on the frame with CV's, then you've got to build some beefy shafts and joints. Either way, $$$$$$$.

NeverEnough · Dec 18, 2014

LoRoad said:
This might be what NeverEnough is referring to. On a recent trip I backed my truck/camper into a tree, in my defense it was pitch black outside. The jolt was severe enough to shake the camper out of whack and the truck to tweak/tremble...if trucks can actually tremble that is. When the daylight came up all I initially saw as damage was that the dome over the shower had cracked. I thought I had gotten away with 'something' or at the very least I was super lucky. Sadly I couldn't have been more wrong. Immediately following that incident I spent several days traveling the washboard, if we can call them this, roads in Death Valley. Over that time here is what happened.

The tree torque had done way more damage than previously thought...notice how the tie down has come virtually completely loose from camper structure...this traversed the entire camper on both sides. Internally seams, covered by wall paper, were now showing signs of breaking apart and on the outside (pic below) the outside shell of the fiberglass had now cracked in two.

View attachment 260618

View attachment 260617

So I have to agree with those that say it's nice to have NICE, but what I really want is something that will survive the crap roads I'm planning on driving down and like a Timex can take a licking and keep on ticking.

It's exactly what I'm talking about. Sorry about the bump, always a pain to bust something up, and it happens so fast. I've done some serious damage to RV's over the years, usually backing up. And the commercial units just aren't built to take a hit- any bump usually has a domino effect on the whole body and guts. The body, and internals, of my rig are doing great so far. Because of my proclivity for bumping into things, I also have something I can replace made of steel, aluminum, or 1/4" fiberglass pultrusion extending on all corners, so it takes the hit first.

NeverEnough · Dec 18, 2014

biotect said:
Hi NeverEnough,

Excellent summary of arguments for "mongo IS" and 6x6, and a frank, candid admission that "turtling" is a potential problem. Why is lifting the middle axle on ordinary paved roads so critical for you? It has come up a few times in the thread. Egn was against a lifting axle, and he drives his 6x6 everywhere:

So why would lifting the second axle be important for you? Just reduced fuel consumption, or additional reasons? As things are panning out, it will indeed prove possible for the TerraLiner to weigh 18 tons or less -- after all, Peter Thompson's Mañana weighs this much, and Mañana is 10.74 m long (see http://www.thompsons.au.com/motorhome/ ), and was not constructed out of carbon fiber and titanium....:sombrero:

So again, just curious why you and a few others think that lifting one axle for road driving is so critically important.

All best wishes,

Biotect

It's not critical or even that important, just nice to reduce the friction, especially if I'm in a range-extended EV. And it's easier to turn- oh, I forgot that this rig will have dual steer axles, I mean IS wheel pairs with hub motors. There, three posts in one day. That's what happens when I my flight gets pushed back an hour.

biotect · Dec 18, 2014

Good to hear from you, LoRoad,

First, let me express some sympathy for the damage done to your rig......

Agreed, "indestructible" and/or easily repairable on the outside seems very important, which is why I always wondered why ActionMobil and UniCat use sandwich plate fiberglass construction. The MaxiMog was covered instead by a skin of stainless steel, and the camper boxes of Beppe Tenti's 6x6 trucks seem to be built out of very strong corrugated metal -- see posts #222 to #221 and posts #231 to #235 at http://www.expeditionportal.com/for...pedition-RV-w-Rigid-Torsion-Free-Frame/page22 , http://www.expeditionportal.com/for...pedition-RV-w-Rigid-Torsion-Free-Frame/page23 , and http://www.expeditionportal.com/for...pedition-RV-w-Rigid-Torsion-Free-Frame/page24 :

If you check out these posts that cover Beppe Tenti's "Overland 12" expedition, you'll see the kind of beating these camper boxes could take in the middle of Africa.

Carbon-Fiber, although expensive, is notoriously strong, so I am banking on the idea that one can have "lightweight" and "indestructible" simultaneously -- see posts #865 - #867 at http://www.expeditionportal.com/for...pedition-RV-w-Rigid-Torsion-Free-Frame/page87 . And with Carbon-Fiber, one can also have "nice", which for me personally means "curvilinear design". As for the windowing, you might have noticed in recent posts that I am taking thjakit's thoughts about front windshield design very seriously.

But of course the type of suspension underneath is absolutely critical, which is why egn, thjakits, dwh, campo, NeverEnough, et al, have been debating traditional "straight-axle" versus "IS" (independent suspension); and why 4x4 versus 6x6 also seems an issue. More axles generally means a smoother, faster ride and less stress for the camper box.

I take it that you would now be a fan of IS, instead of traditional straight-axle?

All best wishes,

Biotect

LoRoad · Dec 18, 2014

biotect said:
I take it that you would now be a fan of IS, instead of traditional straight-axle?

Given that SherpAlypto is a 6x6, for me it's a non issue. But my 2cents is that your design, while in the end could very well work out just fine, might be too expensive for even the audience. That's one of the reasons why things are as they are now. I have come to this simplified realization having just finished a year of design work with SherpAlypto. We started out with an idea and ended up with something, we thing anyway, that is very useable and somewhat 'cost effective.' my 2cents.

dwh · Dec 18, 2014

biotect said:
Agreed, "indestructible" and/or easily repairable on the outside seems very important, which is why I always wondered why ActionMobil and UniCat use sandwich plate fiberglass construction.

Lightweight, stiff, good insulation (IIRC R7 per inch). lack of thermal bridges, uniform structural thermal expansion/contraction and also - easy to fix. Cut out the damaged area, glue in a new piece, finish off with standard fiberglass repair technique. Pretty much the same as repairing a boat, and not all that different from patching a hole in drywall.

The MaxiMog was covered instead by a skin of stainless steel, and the camper boxes of Beppe Tenti's 6x6 trucks seem to be built out of very strong corrugated metal

I sort of figured they did it that way to create a strong box that allowed them to delete the torsion-free subframe. The box is so strong, it looks to me as though it would reinforce and support the truck frame.

If you check out these posts that cover Beppe Tenit's "Overland 12" expedition, you'll see the kind of beating these camper boxes could take in the middle of Africa.

I think they crossed the line from "bad road vehicle" to "off road vehicle". Looking at some of that Africa footage, it looks like they spent significant time working as a road crew - either repairing roads, or making their own.

Stephen Stewart and the Silk Route club ended up doing road work in Tibet:

http://www.xor.org.uk/travel/china2002/20021012.htm

Carbon-Fiber, although expensive, is notoriously strong,

Not really. A strand of carbon fiber is notoriously strong "for its weight". At least in terms of tensile strength...not sure about shear strength. But the composite material of fiber strands + epoxy is not all that hard to break. Once it does crack or break, the repair procedure is pretty much identical to fiberglass repair.

so I am banking on the idea that one can have "lightweight" and "indestructible" simultaneously

Remember what happened to the tip "winglets" on the around the world Rutan Voyager aircraft.

biotect · Dec 20, 2014

dwh,

As always, excellent post.

Agreed, Beppe Tenti's 6x6 trucks were really "off-road" and not merely "bad-road" expedition vehicles, and you summed up the problem beautifully: "they spent significant time working as a road crew - either repairing roads, or making their own." That's in part why I have been adamantly insisting that the TerraLiner should not be thought of as a vehicle designed to negotiate mud-trucks in the Congo.

It's still interesting, however, that Beppe Tenti opted for such strong camper box construction. Whereas other supposedly "off-road" expedition motorhomes intended for use in the middle of Africa will have only much lighter fiberglass sandwich panels, whose merits you summarized well: lightweight, stiff, good insulation (IIRC R7 per inch). lack of thermal bridges, uniform structural thermal expansion/contraction and also - easy to fix. As you suggest in your post, dwh, a carbon fiber monocoque fully integrated camper shell would have pretty much the same properties: it would be even lighter than fiberglass, stiffer, also well-insulating, would lack thermal bridges, and would provide uniform thermal expansion and contraction. It would also be easy to fix, as per fiberglass: thanks for that video.

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1. Stephen Stewart on Mainstream, Conventional Campers in Tibet

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As for Stephen Stewart on the subject of Tibet, his short article was mostly a meditation on the limits of travel in Tibet by ordinary, mainstream motorhome. Stewart's point was that, although a 4x4 Unimog seemed like "gross overkill" for most his 25,000 kmh trip, in Tibet specifically the Unimog reigned supreme. But notably, unlike many expedition adventurers, Stewart is keenly aware of the limits of the standard expedition camper "box stuck on the back" format. Not just in this article, but throughout his writings, Stewart seems very aware of the design advantages of contemporary mainstream motorhomes. And it's notable that rather conventional, mainstream motorhomes were thoroughly adequate for most of the 25,000 kmh trip:

Whilst it is tempting to say this road is only suitable for 4x4s or trucks this may be too restrictive. The trouble with a big 4x4 campervan (like Mog) is that for 25,000km of this trip it has been gross overkill (as well as noisy, slow, relatively cramped, hard too drive and expensive to run). Only for the last 1500km has Mog been supreme.

See http://www.xor.org.uk/travel/china2002/20021012.htm . This short article is also a bit dated: written in 2002, or 12 years ago. My own estimation is that Tibet is really "bad road" country, and not "off-road" country, or "mud track" country, as per central Africa. So a 6x6 TerraLiner would be right at home in Tibet.

One of the central objectives of a TerraLiner is precisely to avoid the "design flaws" of they typical expedition motorhome, with its "cramped" camper box (Stewart's description), simply stuck on the back of a truck chassis. A central objective of the TerraLiner is to have the same spaciousness and light-filled interior that has become standard in the world of mainstream motorhomes; but in a 6x6 "bad-road" motorhome that would have no trouble in Tibet.

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2. Exterior Protective Piping: the Orangewerk MAN-KAT

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Now one possible way to avoid "catastrophic" damage to the fiberglass or carbon-fiber camper box shell, might be abundant exterior piping. The "Orangewerk" MAN-KAT conversion is covered with quite a bit of piping. See post #617 and #618 at http://www.expeditionportal.com/for...pedition-RV-w-Rigid-Torsion-Free-Frame/page62 for a complete set of pictures: