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

[biotect]

Some commercial overlanding trucks also seem to have positively terrible departure angles; for instance, the vehicles used by Odyssey:





See post #978 at http://www.expeditionportal.com/for...pedition-RV-w-Rigid-Torsion-Free-Frame/page98 . But maybe I am wrong about this; maybe the camera angles in these images are not doing these vehicles sufficient justice?

Sure, I am still aiming for MAN-KAT level approach and departure angles (45 degrees), and I want the vehicle to be 6x6, to cut down on the distance between the first and second axle. But because the standard “two axles clustered in back” arrangement allows for long side-lockers between the first and second axles, I think that's what I will finally choose. Evenly spaced axles pretty much eliminate any possibility of side-lockers. But even with two axles clustered in back, the TerraLiner will probably end up with an inter-axle distance between the first and second axle that is much less than the inter-axle distance in almost all of the commercial overlanding trucks I've covered so far.

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A Visual Comparison of Inter-Axle Distance and Breakover Angles


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dwh, thjakits, optimusprime, Haf-E, egn, NeverEnough, etc.,

As you know, I've been worried for a while about the "breakover angle", inter-axle distance, and axle placement. For the fullest description of the worry, see post #886 at http://www.expeditionportal.com/for...pedition-RV-w-Rigid-Torsion-Free-Frame/page89 . But one salutary effect of researching commercial overlanding vehicles in depth, is realizing just how long their inter-axle distances tend to be, and how terrible their breakover angles must be as a consequence.

It's rather surprising that they do not constantly turtle:







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[dwh]

And that is because???


Whether central motor and full axle or hub motors - the suspension system has NOTHING to do with it.
WHY do you think a hub motor HAS to have a IS?

Because it doesn't have a differential, doesn't have center-to-side axles or half-shafts and doesn't *need* a big tube from side to side to house the power delivery mechanics.

Yes, you *can* stick a big tube in there between the hubs, but if you have a drive at each hub, you don't need it. If you put it there, it's not because you need it, it's because you *want* it for some other reason.

Which is why just about every drive hub setup I see on the net has IS.

 

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I was looking at images like these, that made me finally "relax" about the breakover angle, and made me realize just what a huge difference a third axle makes, even if only clustered in tandem in the rear. On paper, the added distance -- perhaps 2 m -- may not seem like much. But just compare the above images of 4x4 commercial overlanding vehicles, with the images that follow below, images of most of the 6x6's posted thus far in the thread. The difference is viscerally apparent: the breakover angles on all of these 6x6s seem much, much better.

Thought I would also use this as an opportunity to gather together in a single cluster most of the side-view images of 6x6s that have appeared in the thread, as well as those that have appeared in "Camper Thermal Engineering" thread. Think of this as a "hommage gallery" to the virtues of the 6x6, and as a purely "visual" argument as to why 6x6 is strongly preferable to 4x4.


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The gallery starts off with MAN-KAT 6x6 conversions, and egn's Blue Thunder:









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[dwh]

Well i've tried to be inclusive,make eveyone feel special!

Bucking for promotion. Watch your back there biotect, he's got his eye on your job.

 

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Next, some blueprints and images of the “raw” military version of the MAN-KAT 6x6:






And some images of the Doleoni MAN-KAT 6x6:







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Here's an image of a MAN-KAT 6x6 conversion that I found on the “Mountaineers of Iceland” website – see http://mountaineers.is/super-trucks/ , and post #19 at http://www.expeditionportal.com/for...p-High-Altitude-Arctic-Antarctica-Tibet/page2 :





The vehicle is used as a bus to ferry passengers on Iceland's glaciers, and notice just how fully, completely integrated the passenger compartment is with cab. This is probably the most “fully integrated” MAN-KAT conversion I've yet come across, but it's darned difficult to find additional information about the vehicle on the web.

And here is a sundry collection of other kinds of 6x6's, beginning with the Wothahellizat, and two Unicats, followed by Beppi Tenti's 6x6 and two Oshkosh 6x6s, and finishing off with the fully integrated 6x6 “Tonto”:








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[biotect]

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Next, here are some images of the Mongolian 6x6 Zetros conversions. For some reason, the breakover angle on these doesn’t look nearly as good as the vehicles posted above. Perhaps the tire size? Or perhaps these vehicles have been “stretched” beyond what would be sensible for a Zetros?






These are images of an "Armadillo" Zetros-based expedition motorhome, in which the breakover angle seems much better, perhaps because the chassis and wheelbase are much shorter? (Armadillo is a Chinese "upstart" company):







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On a vehicle like the Terrabus, the huge tires provide ample clearance even though the bus is very long, and there is substantial inter-axle distance between the first and second axle:







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Of course, there are all the Tatra 6x6's posted in the thread:









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And one more, a wild-lands fire-fighting Tatra 6x6:





The following are images of 6x6 rally support trucks that have not yet appeared in the thread, images that I found on the the “CaptainsVoyage” web-forum, at http://www.captainsvoyage-forum.com...side-cars-buses-trucks-trains/945-sporttrucks :








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Note that if you go directly to the "Captains Voyage" website, you can download these pictures in much higher resolution. Most of them were 4 - 6 MB in size, and had to be downsized to meet the 500 KB per image limit on ExPo.

Finally, here some images of the Armadillo MAN-TGA based 6x6, whose interior was exhaustively documented earlier in the thread -- see post #145, at http://www.expeditionportal.com/for...pedition-RV-w-Rigid-Torsion-Free-Frame/page15. For the original website, see http://translate.googleusercontent....v.com/&usg=ALkJrhiqKuUmnIyjt030tiBPVDEoOuJlQg , http://translate.googleusercontent....t.aspx&usg=ALkJrhhXH6gvo-XiJaJVc4Gd9sI3rmpq4Q , http://translate.googleusercontent....tID=18&usg=ALkJrhic-jU7ku_p2IKD7lvmmFkMoYtgVw , and http://translate.googleusercontent....ssID=3&usg=ALkJrhh7mvaM0mNrNKsTm5AXF1beywnzVQ . Of if you can read Chinese, see http://www.armadillo-rv.com/Product.aspx?BigClassID=1 , http://www.armadillo-rv.com/ProductDetail.aspx?ProductID=18 , and http://www.armadillo-rv.com/ProductImageShow.aspx?ProductID=18&PhotoClassID=3 :







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I particularly like the first row of images of this Armadillo, which show it “almost” turtling, as it negotiates the sandy edge of a steep hill/escarpment. The Armadillo can do so, clearly, because the edge of this escarpment is just pliable sand. But these photos show what turtling might mean for a luxury expedition motorhome. Although as thjakits keeps pointing out, and quite rightly, only the foolhardy or the very rich would ever risk their expensive mobile apartment doing crazy things that could eventuate in turtling.

What interests me in all of this is the comparative geometry. Many of these 6x6s are very long, too; the Unicats pictured, for instance, are well over 10 m. But somehow that extra axle makes all the difference in the world, and all of these 6x6s seem much less likely to “turtle”, than the 4x4 commercial overlanding vehicles shown at the very beginning. To compare visually, just open the previous page in a new window, at http://www.expeditionportal.com/for...edition-RV-w-Rigid-Torsion-Free-Frame/page107 .

Here are five of those images again, for comparison's sake:






The difference regarding inter-axle distances between these commercial overlanding 4x4 trucks (Acacia Africa, Oasis, Odyssey), and the 6x6s posted above, is really quite striking.

This then makes me wonder:

(a) Do 4x4 commercial overlanding vehicles often turtle? Or are their breakover angles reasonably sufficient for the routes they run?

(b) If 4x4s do have a problem with turtling, then why do overlanding companies not use more 6x6's? Oasis and Dragoman both seem to have some 6x6's, but otherwise the 4x4 format seems far more common.


All best wishes,



Biotect

 

[biotect]

Well i've tried to be inclusive, make eveyone feel special!

Bucking for promotion. Watch your back there biotect, he's got his eye on your job.

Honestly, if it's anything at all like my last job, he can have it!! My last job had me progressively bumped up to the managerial level, with much less time to engage in the "Art" or "Design" end of things. Responsible for 20 people, and everything they did wrong; would arrive in the morning and find 80 new emails in my in-box. I was a good manager, and they paid me handsomely for it. Every time I began talking about leaving, they'd offer me a raise. But it was a golden cage.

So I did the deliberately contrarian thing: made a conscious decision to leave security and status, and return to my true calling, as an artist and a designer....

The job of designer optimusprime can certainly have, too; the world needs more ethically committed designers, and optimus strikes me as a stand-up kind of guy. There is room for all of us here on Earth, and certainly in this thread. And beyond that, there is no question that the TerraLiner design has "shifted" in countless ways, large and small, because of the input of everyone who has contributed to the thread. In that sense, it really has become a team effort.

All best wishes,



Biotect

 

[dwh]

.perhaps IS might make sense because it might allow a long, uninterrupted space in the center of the truck. But even in IS, the links in the suspension function better when long, so one probably won't gain that much uninterrupted space in the center of the vehicle in any case. Sounds like a good enough argument to me.....:ylsmoke:

But, as I was pointing out - those long links don't necessarily have to be side-to-side, they can be fore-and-aft. So you could have the IS, and the extra travel, without the stuff cluttering up the center underneath the vehicle.

That makes sense if using a one drive per hub setup. Another thing, is that - like the GMC Eleganza - the suspension (and drives) would be easily accessible from the side - just pull off the wheels and there it is.

(2) PowerTrain

Sorry, dwh, but microturbines are out, at least for now.

Eh? I though you decided that long ago.

(5) No Portals.

Last but not least, no portals. The TerraLiner will be big enough, and its tires big enough, that portals are another unnecessary complication. The TerraLiner is a 6x6, so the largest inter-axle distance will be much smaller than any of the commercial overlanding vehicles posted a while back. And its breakover, approach, and departure angles will all be much better, even with the second and third axles clustered in back.

Think of it this way. I will want side-lockers between the first and second axles, of the kind pictured in these images of Zetros trucks:


View attachment 262565 View attachment 262566


In a standard staight-axle configuration with XZL tires, the center of the tire is either 58 cm (14.00R20) or 61 cm (16.00R20) above the ground. At least theoretically. When under load, or when deliberately deflated, it will of course be less. This then suggests that side-lockers could descend as low as just 80 cm above grade on either side, between the first and second axles, without significantly impairing the inter-axle breakover angle. In the following schematics of MAN-KAT 6x6s, the "peak" of the breakover angle between the first and second axles, seems no better than 80 cm above grade; not much higher than the wheel centers:


View attachment 262567 View attachment 262568


So if one wants side-lockers that can descend on either side to 80 cm above grade, then the only thing that portals might add, is an additional 20 cm of clearance, because the straight axles across the vehicle could now locate at 80 cm above grade, instead of 60 cm. That additional clearance may be important in a mog-sized vehicle that wants to rock-crawl off-road. But would it really be important in a bad-road expedition motorhome? I'd like to hear the argument that the additional complication of portals is really worth it, in a vehicle the size of the TerraLiner.

More on the topic of comparative breakover angles anon.


Hope that clarifies matters, for now.....

Actually, as you mentioned in a later post - properly designed portals might be very nice to have.

The portals aren't really about approach, departure and breakover angles - those can be improved simply with a higher suspension. The portals provide a higher clearance down the centerline of the vehicle. They also provide extra gearing right at the hub, which reduces the stress on axleshafts, differentials, driveshafts, etc.

But of course the also add complexity and unsprung weight.

Still, I think with one drive motor per axle, portals - at least for me - would be a serious consideration.

But I'd really have to spend some time trying to convince myself that they would be needed. Perhaps the extra gearing could be used to reduce the size of the drive motors. Certainly there would be a benefit in terms of centerline clearance.

But that might be perhaps offset by the loss of clearance on the sides where the portals are. If the drive motors actually fit within the wheels, then I probably would not add portals. But if the drive motors are outside of the wheel, then I might add portals.