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

[biotect]

Hi optimusprime,

Propane is a good example!

I haven't really decided about propane yet, specifically. Earlier in the thread I asked whether or not having propane on board just to fuel an outdoor barbecue might be a problem. I was wondering if just a cylinder of outdoor barbecue propane would suddenly throw one into the "1000 liters of fuel on board, or less" category. Recall that egn said that according to German regulations, as long as you don't have propane on board, you can carry up to 1500 liters of diesel fuel. But with propane, the limit drops to 1000 liters, with any propane carried counting for three times as much as the diesel carried. So you could carry, say, 800 liters of diesel, but only 66 liters of propane, because propane would count for 66 x 3 = 198 liters.

I also asked whether one could design a vehicle in which propane is an option, but one still has a 1500 liter tank for diesel anyway. When one carries propane, one simply does not fill up the tank to full. Instead, one fills up to 800 liters, or 900 liters, or whatever the limit would be, depending on how much propane one is carrying.

But I did not receive a response to these questions, so the issue of "propane" is still open for me.

I like the possibility of propane at least as an option. But I can appreciate the good arguments for going "all diesel", as per the DeLeoni MAN KAT, or egn's Blue Thunder. The Tatra GTC 815 carried propane, for instance, and it had a propane stove. As as far as I know, the Tatra GTC 815 is the only really big, 6x6, expedition-grade camper to have travelled across both Tibet and the Bolivian Altiplano -- see posts #284 and #288 onwards, at http://www.expeditionportal.com/for...pedition-RV-w-Rigid-Torsion-Free-Frame/page29 . So the Tatra 815 GTC seems like a good reference point, even though it was built a bit more than 20 years ago, in the latter half of the 1980's. The Tatra GTC 815 had a very sophisticated electrical system, and lots of diesel available. And yet it opted for a propane stove. Perhaps because propane burns well at high-altitude? Or perhaps because electric induction stoves were not common yet, and not easily available behind the iron curtain, in still-communist Czechoslovakia?

In any case, I have been meaning to go through the entire thread, making a short list of still-unanswered questions. And clearly, if I still have not resolved issues like kitchen stoves and heaters, then the specification that I posted so far is quite incomplete. That's why I created the "Camper Thermal Engineering for Extreme Cold and High Altitude" thread, so that these questions might (eventually) get a reasonably good answer. But over the next few weeks I will try to create a collected list of "loose end" questions; questions that were raised earlier in the thread, and that have still gone unanswered.

All best wishes,



Biotect

 

[campo]

Hi Biotect.
Your research capacities are amazing.
And I every time find a lot of for me new information. Thanks.
In this case the difference between different tubular and real monocoque designs.
I have seen them before but did not realise the differences.
.
I have never focused on that aspects. But you do not mention real arguments why YOU would not
build YOUR modern concept vehicle that is close to a bus, on these monocoque principles instead
of just choosing the older and proven chassis with longerons constructions.
For me it would be more logical and based upon your own input directives.
Dont forget that your monocoque cell will have different internal walls (rooms dividers, furniturewalls and shower,..)
That will be reinforcing the box until it becomes torsion free and like it is also calculated and executed in my TGM construction.
.
View attachment SketchupinterieurV11.pdf
.
The effect is similar to a central cross in a shoebox
or the ties in the back of Dakar VEKA race trucks.
.

.
Only for your information. Look what we have already done ourselves on the side of classical 4 point subframe design.
It's my French friend who did the torsion calculations I just gave him some advice.
I can assure you that he went some CAD steps further than the today Uni$at and Ac$ionM calculations.
This TGM13290 is in construction right now. Consider it as a further development of existing 4P systems.
.
Best regards Campo
.


.

.

 

[biotect]

But you do not mention real arguments why YOU would not
build YOUR modern concept vehicle that is close to a bus, on these monocoque principles instead
of just choosing the older and proven chassis with longerons constructions.
For me it would be more logical and based upon your own input directives.
Dont forget that your monocoque cell will have different internal walls (rooms dividers, furniturewalls and shower,..)
That will be reinforcing the box until it becomes torsion free and like it is also calculated and executed in my TGM construction.

Hi campo,

There are a number of reasons.


1. First, I don't like the idea of just helping myself to any technology I can dream up. Because the vehicle then becomes too theoretical, too "futuristic". And remember, the goal here (as you put it so well) is innovative, and not futuristic.


2. Second, I really do wonder whether just a space-frame will be able to handle serious bad-road and occasional off-road travel. One of the virtues of the traditional approach to expedition motorhomes, where the camper is separated from the twisting chassis frame via a 3-point or 4-point pivoting sub-frame, is that this protects the camper box from structural damage. Whereas once the camper box becomes connected to the underlying frame, it is no longer structurally isolated from chassis stress. The damage that occurred to Peter Thompson's Mañana is a case in point – see post #212 at http://www.expeditionportal.com/for...pedition-RV-w-Rigid-Torsion-Free-Frame/page22 .

Now granted, Mañana was not built on top of a torsion-free frame like the the MAN SX-44 or SX-45. But it's still sobering to realize that even though Mr. Thompson did not really "push" Mañana, and even though he travelled mostly on roads (including some very bad roads), and rarely "off-road", even still his camper suffered damage.

One can certainly do lots of engineering calculations and try to determine how best to design a space-frame for a large 6x6, a space-frame that could withstand the stress of worldwide travel, including some serious off-road travel. But you never really know whether you got your calculations right until you build it, and test it. And in a monocoque or tubular space-frame design, damage to the chassis frame is damage to the camper box. That's a fairly risky proposition. Remember, even just the idea of building a fully integrated motorhome on top of an old, "technologically primitive" SX-44 or SX-45 ladder frame, is still innovative. Nobody has yet done it before. Indeed, aside from the vehicle whose picture appears at the very beginning of this thread, it does not seem that anyone has done a "fully integrated" design on top of a MAN KAT A1 either. Mañana really is one of the few large "experiments" in fully integrated expedition motorhome design.


3. Third, I want to be able to present this vehicle as a serious proposition: as something that a risk-taking individual with deep pockets might seriously consider building. Any such individual, if they are practical and have some sense, will probably suggest that before leaping to full space-frame or true monocoque construction, it might be best to try out a "transitional" design, a design that combines the Tatra backbone tube with a space-frame. Sure, one would not then be "testing" whether a full space-frame or true monocoque construction can work. But a risk-taking individual, even with deep pockets, is not MAN Neoplan, with the resources to sink millions into a true monocoque bus for ordinary city-service – the 1988 MetroLiner– a bus that then failed.

So too, it would also be nice if a major manufacturer of either mainstream or expedition motorhomes were to show some interest, once the design is finalized and published. As I wrote earlier to Thjakits, I am really imagining the TerraLiner as more of a mainstream production motorhome that is globally capable, as opposed to an expedition motorhome that is glamped out. I find myself looking to UniCat and Actionmobil for engineering inspiration, and in the case of UniCat, for the pop-up concept. But I made it clear long ago in the thread that I do not look to Actionmobil or UniCat for aesthetic inspiration. Rather, for aesthetic design inspiration I look to major German manufacturers like Hymer and Concorde; to premium German manufacturers like Ketterer and Volkner; and to premium American manufacturers like Newell and Millennium.

In the world of mainstream motorhome production more expensive design features like curvilinear forms are possible, because mainstream motorhomes are made in production runs where it becomes cost-effective to create curved molds, molds used more than once. Similarly, as just seen, major manufacturers like Prevost can afford to invest in the engineering and computing necessary to create a fully integral "space frame" chassis.

But even if Prevost were interested in the design, I am not so certain they would want to take a risk on a fully tubular space-frame design either. At least not in the beginning. They too might prefer to play it safe, at least initially, by incorporating a Tatra backbone tube.


4. Fourth, everything that I have read about space-frames and monocoque construction suggests that even in more "ordinary" kinds of vehicles, these are best supplemented by something like a ladder frame (as per those extra-heavy rails deep inside the Monaco/Roadmaster chassis), or a tube frame (as per the DeLorean). So if that's true for ordinary vehicles that drive exclusively on paved roads, then it would seem even more true for an expedition motorhome that drives on bad roads and occasionally off-road.


5. Fifth, combining a Tatra backbone tube (and just the tube) with space-frame construction would also be innovative. Here again, I don't think that anyone has done it before. I don't know how much the backbone tube alone weighs; this is something I need to research, probably by contacting Tatra directly. But I can imagine that the backbone tube just by itself weighs a fraction of total weight stated for a complete "Phoenix" truck or a complete 815-series military vehicle. The following pdfs give some indication of the weight, because they show a "chassis only" configuration, without the cab:





The 6x6 weighs 10,240 kg, and the 8x8 weighs 13,000 kg, and these figures include the weights of engines and transmissions. Whereas in a diesel-electric hybrid vehicle, it's possible (although not inevitable) that the total weight of a comparable power-train might be less. So it seems to me at least possible that the 6x6 pictured, reduced to just the backbone tube and little else, could indeed become the basis of a vehicle that meets your 16 ton weight limit, if a camper were then built up around it via tubular space-frame construction.


6. Sixth, it's hard enough trying to figure out the ideal "pattern" of interior space, without having to throw into the mix the structural considerations of a tubular space frame. This is probably the most important consideration of all: if the Tatra backbone tube absorbs all the stress of travel, no matter how bad the terrain, then the rest of the design becomes relatively "free", from a structural point of view. The camper body becomes a structure that only needs to support and account for itself, sitting on top of a "base" -- the backbone tube -- that remains rigid and stable.


7. Seventh, one of the reasons why ActionMobil and UniCat use self supporting sandwich plate fibre glass composite panels, pretty much just glued together, is because this eliminates "metal thermal bridges". Whereas a tubular space-frame skeleton strikes me as full of potential thermal bridges that would have to be addressed. But this would be less of a problem if the space-fame were just a "half-height", as per that one image already posted:





On top of this half-height space-frame one could then place a camper body that is true monocoque, made completely out of some kind of composite, with no metal thermal bridges.


8. Eighth, if the backbone tube and the space-frame surrounding it were doing all the structural work, then the monocoque composite camper would not need to be very heavy or robust. It would only have to support itself. Sure, a certain degree of thickness would remain necessary for insulation. But the whole thing could be very light. Again, as already indicated to thjakits, this will result in a low center of gravity, so that the expedition vehicle could do this:





Although UniCats and Actionmobils look very big and heavy, up top they are actually feather light. And that seems like a good idea.

Give me a few days, and I am sure that I will be able to think of 8 more reasons......:sombrero:

All best wishes,



Biotect

 

[egn]

Width and length are correct, but height....? There seems to be a difference of opinion in the thread whether an expedition motorhome should be 3.4, or 3.6, or 3.95 m high. egn's Blue Thunder is 3.95 m, and he seems to have seen more territory on planet earth with Blue Thunder than most overlanders.

There were several situations where we run into problems with our height in Albania:

On normal overland road with no height limitation we caught a probably illegally installed tv cable with the exhaust flap at speed of about 60 km/h. It was installed across the road an I saw it moving, but it was to late to stop. I just heard ping and it fell down. We stopped immediately and looked at the result. Two boys coming along with scooted stopped and we talked with them. They spoke a little bit English so we were told that this is was a TV cable. The cable broke at a connection and the repair should be easy. In the meantime the owner of the house, which was connected to the cable, arrived. I asked him what the repair would cost, but he immediately said that everything is ok and they will repair it immediately. We said goodbye and continued our journey.

The next issue was when we wanted to go a scenery route through the hills. There was a concrete tunnel below a rail road that didn't have a height marking, so we thought we can go through. It looked very tight so I drove very carefully into it. Our young daughter entered the cab roof to look and warn me when it is going to get tight. At the beginning it was ok, but we couldn't do the last 2 m. We scratched the protective rail of the PV installation.



So I had to go backward. We discussed the situation and we first thought we have to drop the idea of going this route. But with the help of local people we found a way around by going a different road. So we finally managed to go the scenery road and didn't regret it. We could top off our water tanks from a well and found a nice camp spot in mid of nature.



We had another issue when driving through side roads of a city. the cables are so low that our daughter had to look whether they go along the roof rails without getting caught. Some she had to lift to get over.



We also had a very tight situation on a road where on the right side where only a few cm space to a rock.



And at the left side we touched a power transmission cable.



But we also managed this situation.

So you see, there are problems when going with a high vehicle. But up to now we always found a solution. And if not, as all is holiday, we don't have to go a specific route.

 

[campo]

Hi egn
I do agree that height is a considerably bigger problem than length.
The 3,95m high vehicles had similar situations in Russia as you describe above.
I would rebuild my version 2.0 again on 3,4m height, just enough with the small tires to get 2,0m inside living height.
The roof pop out bedroom as biotect suggests is then the innovative solution for more comfort.
The 3,95 height gives you also higher gravity centre balance.
The gravity height problem comes a lot more in our compact 4x4 short 3,95m wheelbases than on your 6x6.

Gruesse Campo

 

[campo]

Hi Biotect
.
Interesting, now I understand better the reason why you would build on a classical truckframe.
I think it is only because your knowledge about monocoque possibilities and their advantages for your concept is still insufficient.
And as I read based on only 1 negative (Manana) story. Sorry to be a little hard.
.
The reason why I am pushing you hard in this other and more innovating direction is that we have already more practical
knowledge about expedition vehicles than you. As well on:
.
- truck based chassis with torsion fee sub frames, (like mine)
- truck based with integrated RV bodies (Stafco and Manana in 4x4),
- truck based with fixed driver cabins to body (horse trucks)
- and let’s call it bus monocoques without traditional truck frame (I did not see one 4x4 RV be they will come soon).
.
To be honest my version 2.0 could be one like you are only discovering in your mind.
I have a friend with a 9 year old MAN TGS 6x6 who will probably replace it by a 4x4 bus based expedition vehicle.
Other Belgian friends already possess a fully integrated 4x4 RV on truck base exactly like you want to build on the RX or Tatra.
They have it for already 20 years. It is quite unique and a proven vehicle with today 350.000 km !
So they did not have the problems of the Manana that was built by … a coach builder.
The 1 man workshop in Belgium who made it, the man’s name is Paul.
He is retired for some years now but I am sure that you can still visit him.
The driver/owner of this Mercedes LN2 917 AEF based (4x4) vehicle is one of my friends.
And now comes the good news: this integrated 917 did not break and the construction is off road proven.
Al sort of fire trucks are built like that and you can find the "half integrated" principle on Unimog minibuses.
.

.
.

.

.



So about the Manana Thompson Truck. I am not impressed. I am the owner of the same truck but then the new version called TGM N36 4x4 and with air suspension on the rear axle. I have built the most classical way a torsion free box as I did not have time, budget and energy to do it the Thompson way. Maybe my version 2.0 would be again on modern and light TGM but then the Manana or Stafco integrated way. It would allow me to get more living volume inside for the same compact outside dimensions.

If you keep in mind the concept car as you describe it then I suggest that you change “fully integrated” in only semi-integrated in the thread title.

Best wishes Campo

 

[egn]

biotect
In short, maybe a generator with a 120 KW power output like the Jepotnik is necessary; maybe not. I honestly don't know. I only know that Oshkosh installed a 6.6 L, 400 HP engine in the L-ATV, and not something smaller. And that hybrid trolley buses in Germany use the Jepotnik.....

A quick calculation shows that this power is necessary for a vehicle that is driving long distances. Lets assume an average diesel fuel usage of about 30l/100km at highway speed of about 100 km/h. So the vehicle would consume 30 l/h. At 35 % efficiency this calculates into 30 l * 10 kWh/l * 0,35 / 1 h = 105 kW. If you add the an optimistic efficiency of the electrical power train of about 90 % then you get about 120 kW. Q.E.D. :ylsmoke:

You can compensate that a bit by the battery. But think about going up a very long steep hill, like BT in Turkey, driving up from height 0 on Black Sea level to about 2000 m at a distance of about 150 km.



This adds about another 100 kWh in to the necessary energy. This additional energy has to come from the battery. You would have to have a very large battery otherwise you would have to reduce the speed considerably, just like BT in this case because of overheating the engine (has been fixed by additional oil cooler now).

Or think about driving through sandy roads in deserts or very soft roads. You can easily hit 100 l/100km in this case. It is an trade-off in this case. You either put more range extender power in or more battery. A range extender with enough power gives you unlimited range at a specific speed. More battery power gives you only limited range on constant speed, if the range extender is not able to provide the power necessary to keep speed.

Haf-E
The latest newest variant of LI batteries is now claiming 10,000 cycles at 80% depth of discharge - so the advantage of ultra-capacitors is less significant.

Newest Lithium Titanate cells go even better.

But the point is, that if your electric motors have a peak power 500 kW then your storage has to deliver the difference between the power output of the range extender. High discharge currents of more than 1C certainly reduce the life-time.

biotect
I figured that is pretty much covered in the standard specifications of expedition motorhomes that one finds on the UniCat and ActionMobil websites. Such vehicles are almost always designed to withstand the heat of crossing the Sahara, for instance. But what I really want to know is: can they handle -50 C in Siberia?

Yes, almost all expedition vehicles that can be seen are more designed toward use in hot climate. Me and my wife also like to travel into cold snowy areas. currently we a limited by school holidays, but in the future we will more travel to North Europe in winter, and finally to the East (Russia, Mongolia, Central Asia, North America, ...) in winter.

So BT was also designed basically to cover climates from -50° C to +50° C. The highly insulated box is a start. Calculations show that we would only need about 3000 W heating power at - 50° C. The fuel system is already adapted to low temperatures by having heated fuel tanks and heated fuel filter.

The air-cooled engine itself can be pre-heated by a high power diesel heater to allow start below -20° C. And air-cooled engines are able to cope with all temperatures by design. In the 70s Magirus delivered around 9.500 vehicles to Russia for construction use in cold climate.

We will test and improve the cold climate capabilities in the next years to come.

 

[egn]

The 3,95 height gives you also problematic gravity centre balance.
The gravity problem comes a lot more in our compact 4x4 short 3,95m wheelbases than on your 6x6.

The wheel base is relevant so far, that the chassis of a 6x6 is much heavier then of a 4x4. In total it is the ratio between chassis weight and cabin weight, and the weight distribution within the cabin.

Our 6x6 chassis totally stripped weighted about 9.5 t (metric). Fully loaded I estimate that the chassis weights about 13 t and the cabin about 5 t. The cabin alone has a very low center of gravity with all tanks, battery and other heavy items in the "cellar", which is about 40 cm high. The ladder frame is build into the floor.

So I assume that more than 3 t is within region of 0.5 cm cabin height. The vehicles center of gravity should be not much higher than about 1.5 m above ground.

 

[biotect]

Hi campo,

Many thanks for this. This is all very useful feedback. It's also good to see just how sympathetic you are to the concept of full integration: "more living volume inside for the same compact outside dimensions". You seem even more enthusiastic about the basic idea being explored by this thread than me!! And even more willing to push technological possibilities and boundaries. Thank you: I needed a kick in the pants.

As I said, I will be talking to some friends who have much stronger backgrounds in engineering than me, and who can help me with the engineering calculations necessary to imagine a vehicle that has a pure "tubular space frame" design. You are right to push me hard on this.

As you might have gathered by now, my strong inclination is more "aesthetic" and "humanistic". I am mainly interested in this concept because of the interior possibilities it opens up, as well as the social possibilities (see the "Magic Bus" video). Although I have a reasonably good background in science, and I respect engineers immensely, purely technical problems do not excite my attention as much as aesthetic and social ones. The technical calculations for a space-frame will be complicated and involved. Again, see the short engineering essays on the optimization of tubular space-frame design for (a) a student race car, and (b) a solar powered vehicle, using computer modeling, at http://mate.tue.nl/mate/pdfs/12814.pdf and http://www.fisita.com/students/congress/sc08papers/f2008sc048.pdf . These papers give a very good idea of the process of space-frame optimization, and how complicated it will be.

So here I should confess to a certain laziness. By simply stipulating a Tatra backbone tube instead, I can avoid having to think about stuff like:







************************************************







Sure, friends with automotive engineering backgrounds will help me with tubular space-frame optimization. But because interior design decisions will affect space-frame design, and vice-versa, ultimately it will be me alone who has to think it all through.

But I promise you that I now will.

Thank you,


Biotect

 

[biotect]

..

If you add the an optimistic efficiency of the electrical power train of about 90 % then you get about 120 kW. Q.E.D. :ylsmoke:

Hi egn,

This is good to know. Many thanks for doing that calculation! So something like the Jenoptik 120 KW flywheel generator really is necessary -- see post #673 and #674 at http://www.expeditionportal.com/for...pedition-RV-w-Rigid-Torsion-Free-Frame/page68 . Good thing that it weighs only 350 kg. And perhaps Styer makes a version of the engine that could be multi-fuel? Will need to give them a call.

Things are not looking so good for microturbines, by way of comparison. Just one Capstone C65 microturbine (i.e. 65 KW) weighs 1,121 kg, and two of them would weigh 2,243 kg. The next step up is a 200 KW microturbine, the C200, that weighs 2,776 kg. See http://www.capstoneturbine.com/prodsol/solutions/hev.asp ,http://www.capstoneturbine.com/_docs/datasheets/C65 & C65 ICHPLiquid Fuels_331038F_lowres.pdf, and http://www.capstoneturbine.com/_docs/datasheets/C200 Liquid Fuel_331049D_lowres.pdf .

Yes, almost all expedition vehicles that can be seen are more designed toward use in hot climate. Me and my wife also like to travel into cold snowy areas. currently we a limited by school holidays, but in the future we will more travel to North Europe in winter, and finally to the East (Russia, Mongolia, Central Asia, North America, ...) in winter.

So BT was also designed basically to cover climates from -50° C to +50° C. The highly insulated box is a start. Calculations show that we would only need about 3000 W heating power at - 50° C. The fuel system is already adapted to low temperatures by having heated fuel tanks and heated fuel filter.

The air-cooled engine itself can be pre-heated by a high power diesel heater to allow start below -20° C. And air-cooled engines are able to cope with all temperatures by design. In the 70s Magirus delivered around 9.500 vehicles to Russia for construction use in cold climate.

We will test and improve the cold climate capabilities in the next years to come.

Perhaps you have already communicated this information before. But if you don't me asking again: what are the wall thicknesses of Blue Thunder's camper? And what are the roof and floor thicknesses? And how did you calculate that Blue Thunder's camper box would be good enough to handle from -50° C to +50° C?

So you see, there are problems when going with a high vehicle. But up to now we always found a solution. And if not, as all is holiday, we don't have to go a specific route.

Many, many thanks for yet more terrific pictures of your adventures in Albania, and for that candid, honest admission of some of the problems that driving a 3.95 m high vehicle generates.

Hi optimusprime,

I haven't really decided about propane yet, specifically. Earlier in the thread I asked whether or not having propane on board just to fuel an outdoor barbecue might be a problem. I was wondering if having just one cylinder of outdoor barbecue propane on board would suddenly throw one into the "1000 liters of fuel on board, or less" category. Recall that egn said that according to German regulations, as long as you don't have propane on board, you can carry up to 1500 liters of diesel fuel. But with propane, the limit drops to 1000 liters, with any propane carried counting for three times as much as the diesel carried. So you could carry, say, 800 liters of diesel, but only 66 liters of propane, because propane would count for 66 x 3 = 198 liters.

I also asked whether one could design a vehicle in which propane is an option, but one still has a 1500 liter tank for diesel anyway. When one carries propane, one simply does not fill up the tank to full. Instead, one fills up to 800 liters, or 900 liters, or whatever the limit would be, depending on how much propane one is carrying.

But I did not receive a response to these questions, so the issue of "propane" is still open for me.

I like the possibility of propane at least as an option. But I can appreciate the good arguments for going "all diesel", as per the DeLeoni MAN KAT, or egn's Blue Thunder. The Tatra GTC 815 carried propane, for instance, and it had a propane stove. As as far as I know, the Tatra GTC 815 is the only really big, 6x6, expedition-grade camper to have travelled across both Tibet and the Bolivian Altiplano -- see posts #284 and #288 onwards, at http://www.expeditionportal.com/for...pedition-RV-w-Rigid-Torsion-Free-Frame/page29 . So the Tatra 815 GTC seems like a good reference point, even though it was built a bit more than 20 years ago, in the latter half of the 1980's. The Tatra GTC 815 had a very sophisticated electrical system, and lots of diesel available. And yet it opted for a propane stove. Perhaps because propane burns well at high-altitude? Or perhaps because electric induction stoves were not common yet, and not easily available behind the iron curtain, in still-communist Czechoslovakia?

egn, might you know the answer to these questions about possibly carrying propane? If you don't, no worries. But thought I should ask.

All best wishes,



Biotect

 

[thjakits]

Hey Bio,

....stole another pack of time! Below the edited/reshuffled quote with quote of Campo's post - I'll just rant a bit into that!


Quote Originally Posted by biotec View Post

So the concept vehicle being discussed here will be:


a fully integrated, German "Liner" style motorhome
with 3 axles, and 6x6 all-wheel drive
ideally below 16 tons, fully loaded; but torsion-free chassis is an absolute minimum requirement
constructed either on MAN SX-44 or Tatra 815 "Phoenix" torsion-free chassis
intended for a 2017/2018 release date

OUCH! Unless you build the REST of the Terraliner out of Unobtainium (probably not invented by 2018!) you can forget about the 16 tons!
Btw: 16 tons is 4x4 territory - IF you insist on 6x6, might as well design for max usage of the 3 axles ~26-28 tons for a "motorhome"

You already stated, that your design will NOT be OFF-ROAD, but ALL-ROAD capable, well, WHY then do you insist on MAN/KAT/TATRA chassis as a basis?
These machines are decidedly "military go ANYWHERE with a support team behind"!
Ask any of the gentlemen/ladies here that actually have machines based on the named chassis, if they really ever got themselves into places, where they needed the actual capabilities of their rigs? I bet, mostly not and the ones that did, would do everything to avoid doing it again!
As previously mentioned - one does not want to risk the only home/safe-place you have along!

Even guys like ENG, who takes/took his KAT up the river to get to a camping place, will do that now and very then - a river that wide and drive-able is that wide for a reason - FLOODS. You don't want to get stuck upriver! Then his tires took a beating - what if you blow one in the middle of it?

Another point to ask the guys with real experience is how much their 6x6 drives are really in use??
Most travel km will NOT need anything more than a lockable or LS rear drive - for all these km you will carry probably close to or over a TON of heavy metal around as ....ballast at best or fuel eater at worst (depending if you can freewheel)!

Also already posted - google up on MAN-hydro drive, RENAULT-optidrive, POCLAIN hydro-drive [the inventor and patent holder of this], MERCEDES is catching up too and VOLVO has something coming too [being the de-facto step-mother of Renault these days....] for every driven conventional axle replaced by non-driven axle with hydro-drive hubs you save roughly 400kg - maybe not for EVERY axle, I don't know if this number already includes the transfercase/drive.

You still can use the AWD-drive without a time limit, but when it is off you save weight/energy.

"Don't wrong get me - Love I do the MAN/KAT/TATRA builds, but for MAINLY road use destined they are not!"YODA"

Military HAS to expect that a countries main-roads will be the 1st thing taken out by the enemy - that's why they must have these chassis - economy is not even the 2nd consideration.....


front and rear wheel steering

engineering innovative, not engineering futuristic

Unless you grow legs on your ride, you will be hard pressed for "futuristic" these days!

...and even that wouldn't be too far off:

https://www.google.com/search?q=all...m=isch&q=plustech+all+terrain+walking+machine


designed with a view to "technology available now", but also "technology not yet proven" in an expedition motorhome application

intended for a well-off, recently retired couple, and used for full-time overlanding around the world
but with convertible seating and a pull-down bed, so that it could sleep 4 adults on a temporary basis

9.5 m long, 2.5 m wide, 3.95 m high
equipped with a motorcycle, stowed along with spare tires, in a "column" type hydraulic tail-lift at the back of the vehicle
and a small SUV runabout towed behind the vehicle, as per Petert Thompson's Mañana

If you are doing the 3.95m hight you might as well go to the mostly applied max length of 12m - as mentioned elsewhere, 3.95m hight will be the limiting factor much more often than the length. If you already specify - "additional modes of transport" - might as well make these go-anywhere and "moderate the home base".

equipped with an off-road capable, military grade, serial-hybrid power train
...see above

full serial hybrid, and not parallel hybrid
with either a diesel engine, or a microturbine, driving a range-extending electrical generator; still to be determined
possibly equipped with two generators, for redundancy
multi-fuel capable

At present battery technology - you will have to make some hard decisions about powering your Terraliner - the more power you want the bigger the battery bank, the heavier, the more power, the more battery, the heavier, .......you get the idea!
AS mentioned before - bat tech leaps everyday - by 2018 I think we will have the first cars with the same range of gasoline/diesel cars - probably charging times and charging station infrastructure will not be there to make it really an alternative yet....
Please observe, I wrote CARS not TRUCKS.....
For the proposed remote travel capacity I suggest you concentrate on DIESEL powered electricity production.
DIESEL WILL stay the main transport energy provider for MANY years to come - however SERIAL hybrid tech will arrive shortly, at least for on-highway longhaul. As the generator efficiency constantly gets better, the drive possibilities of e-drive will become an advantage over transmissions. Though I believe for AWD capability the Hydrodrive will still rule, .....unless they can make e-motors as light as hydro-motors!!
HYBRID will effectively only be useful for energy recovery, from downhill braking and normal braking [The hydro hub motors can be used to drive a hydro-generator to recover as well if the road surface requires....]
If you go for the Serial Hybrid System anyway - you probably don't need two generators - how many trucks (or even Specialty builds out there) have a 2nd ENGINE?? You design (effectively) a Diesel-Electric-System (In Locomotives and certain Ships, this is old news!!) - you call it Serial-Hybrid, just because it is an extension of the previous hybrid CAR systems - it's a little bit like turbines vs. diesel generators - just takes time to make SMALLER systems as efficient as the big ones!! (Btw - the biggest TransOceanCruiser - the Queen Mary 2 runs Turbine-Electric-Generators of 25000kw each, BUT also 4 DIESEL-Electric-Generators of 16000KW each - ALL to ELECTRIC-Drive-Pod-Systems, Turbine-Generator sets sit on the upper deck!!
Also Aux-DIESEL-Generators are still used....
Sooo - it seems the switch over point for EFFICIENCY advantages between DIESEL-piston engine and Turbine power is somewhere above 16000KW (...at least at the time the QM2 design was frozen - probably around 2000?). Most likely the threshold came down quite a bit by now, but I doubt it already reached the power-levels you will look for in the Terraliner.
The only justification you might get is, that a turbine-gen-set is significantly lighter than a diesel-engine. However looking at e.g. the weights of VW-TDI powered Gen-sets at the power levels you need vs. turbine powered will probably not outweigh the cost difference....

You will have to balance the battery size, between storage capacity for at least 18 hrs to operate the camped vehicle and charging technology so that you can take advantage of the most efficient output range of the diesel generator. Optimize for MAX DIESEL storage capacity (no matter if you use a diesel engine or turbine, a ROAD-destined turbine will hardly ever be Jet-fuel powered....).

Another one is if you can keep the batteries charged by solar-power only....

Multifuel-capability? FORGET IT! I don't know of ANY Multifuel-motor out there that keeps its efficiency compared to any dedicated-fuel engine.
Whatever you think you might gain by being able to buy cheaper alternate fuels you WILL loose on efficiency, complexity and reliability elsewhere!


top speed 140 km/h
normal driving speed 100 km/h
tires to be determined, depending on application; tire size either 14.00 R20 or 16.00 R20
equipped with CTIS, tire-protection shields, and possibly tire-protection chains (as recommended by egn)

Bio! If you are out travelling - you will HARDLY EVER want to go 140 - especially with a BIG RIG! I did 130km/h once with a 18m tractor trailer in old East Germany (don't tell anyone!) with brand-new Scania 143 - 400hp - just short of red line rpm - fantastic, I think this was 1989!! But this was a HIGHWAY-rig!!

I wonder what the average Touring/Travel speed of the Big-Rig-Owners here is?

I suppose if you plan for a max of 120 it will be hardly ever used - going electric of course has a lot of flexibility here.
Using the above mentioned Tires - I doubt these will like your speed proposal either!
Look up what a common tire/wheel-size is for the purpose - considering you WANT some serious ground clearance - probably some R22.5 - I assume....

Considering, that you already specify "additional mobility" - I suggest to stick to common and efficient tires, like High-Grip Road tires (Gravel pit trucks, etc...) though I would go for the tallest ones available.

Save the Michelin-Super-X for the trailered "additional mobility"!


equipped with a very large battery pack; either lithium-ion or ultra-capacitors, still to be determined
see above - you are not going VERY far yet on battery alone, nor would you efficiently charge them with your available solar power - better concentrate on energy recovery capacity from downhill coasting and braking and save fuel this way.


capable of traveling comfortably through a -50°C to +50°C climate range
and a 5500 m altitude range
covered in lots of very big, thermally advanced windows
constructed out of walls 6 m thick; roof and floor thickness still to be determined

You want to re-think those very big windows - see previous post!

.....and those 6m thick walls!! You probably meant 6 cm???


maximize solar panels coverage with fold-out panels when stopped, use them as shade/awning while at it!!


possibly equipped with slide-out for lounge area
and a full-length UniCat type pop-up
Pop-up will probably not help with the weight - but I do agree this is a great idea to make it roomy for longer stays.
But then get on it and do slide-outs too - properly designed they ARE reliable and not that heavy.


no garage in back.
equipped with a fold-down deck at the rear of the vehicle instead
a fold-down rear deck accessed by sliding glass doors, that run across the full width of the back of the vehicle
a fold-down rear deck that lowers with a "cantilever" type hydraulic tail-lift mechism

I think you need to add about 10 tons to your weight desires!!


not air-transportable; a vehicle for sojourning, not racking up overlanding miles

What I say - forget the 140km/h!!!

Mate!! NO worries - if you really want - I have the connections to get you air-transport for anything you can fit on a road (2.5 m wide and less than a 100 tons total)!! If you want to get brought in on the spot you can go bigger but need to stay below 20 tons.
Question is if you have the dough to pay the service and will survive seeing the invoice! :Wow1:


designed with lots of curves, in a "Retro-futuristic" style reminiscent of the 1930's and 1940's
designed so that it looks visually endearing, non-threatening, and lovable, as per the VW "Kombi" Microbus
but also designed with beauty, grace, and elegance in mind

Well "Mr. Colani #2" - I am afraid you will have to do a LOT off soul-searching - if you REALLY want to design something according to the discussed list - not exactly highly compatible wishes here!
The old VW bus might have been quite a ride and I had the pleasure to go places with one myself (not mine, but I drove it!), not exactly scale-able though.
Now take the newer Synchros - scale them up and you got - a very straight 'n square box again!!


So campo, many thanks for your message!! It had a good structure, and encouraged me to think in a very systematic, point-form way about some of the more important specifications of this concept vehicle.

Yeah - now let me hack through Campo's answers/ideas below!!:sombrero:



All best wishes,



Biotect

Hi there
Thank you for the many clarifying details on your thoughts.
Of course we have some more questions and sometimes also our own ideas...
.
From all your mentioned points I have one big problem with your basic idea.
The use of the old fashioned conventional truck base as a 6x6 SX44/45 or HX or Tatra 815
is not at all what I would call "a fully integrated" solution as you would like to see one for your innovating concept expedition RV.
.
These MAN and TATRA's 6x6 are built as easy selling platforms on which you can put as well a concrete mixer, a missile launcher as some sort of RV container.
Man and Tatra accept, if you wish to do so, that you take of the driving cab and put an "integrated" coach or RV bodywork on their platform framework.
.
Not very useful as a base for an "fully integrated" concept expedition RV.
The MAN/TATRA engine and driveline choice and position is only like that because it has been sold like this for many years.
The chassis forms are shaped like it is because you can build any kind of body on it.
The driver cabin is in the front, just taken out of the normal truck production.
So nothing new or innovative if you take this base idea.
.
I would imagine more a monocoque structure as an innovative base for your concept.
Look at cars/vans or on more heavy vehicles like the modern coach frames that are slowly becoming integrated vehicles.
On the best new coach examples you will have difficulties to find the old truck chassis structures.
You can also look at the Steyr Pandur 6x6 or Mowag Pirhana 6x6 who do not have chassis (but they are to military heavy).
These 2 construction ways are more innovating and matching better with your fully integrated idea.
I am sure that you know more monocoque heavy vehicles.

Totally agree with Campo!

Have a look at US-SCHOOLBUS tech (very old and simple) for a combined frame/monocoque/space-frame structure!!
Prevost is probably the most expensive COACH design in the US - NO frame at all! Don't like it, because a semi-serious accident will most likely compromise the whole structural integrity. US-SCHOOLBUSES are built as they are, because the HAVE to survive multiple flips/roll-overs and stay together - if you have a serious accident with a US-SCHOOLBUS you most likely won't be pretty anymore, but rolling under your own power!
.
If you use as base the MAN/TATRA 6x6 trucks you will end with a +20 ton vehicle like all the others.
Only your "integrated top body" will be slightly different from other 6x6 expedition vehicles.
If you take this existing MAN/TATRA chassis base idea it is just the most heavy proven chassis concept.
Strong like it has to be for a missile launcher, but the wrong strengths for the new exceptionally good integrated and lightweight 6x6 RV.
Your idea, and also mine, was to target for a not more than 16 tons 6x6 fully loaded RV.

I agree - see above! Looks GREAT, IS great and certainly NOT what you describe in your wishlist!

For sure the today's 6x6 MAN SX/HX and TATRA's are good and proven solutions for people building a normal expedition RV.
.
best wishes Campo
.
PS: Also the 14" or 16R20 tires are a more than 40 year old concept !?
.
But the rest in your summary is .... OK !!!!!!!!!!!.
.
Go for it.

YES - go for it!! BUT you WILL HAVE TO get involved in the technical design part too - just concentrating on the living quarters, visual art and trying to integrate social ideas about 2nd/3rd/4th world compatibility will never lead to anything near what you list above!

Your list still describes a fairly capable, serious machine - some of your artistic/social desires though will not fit into it.

If you are serious about the Terraliner, you will have to design on the very edge of everything!!
You want a vehicle that is built by the hundreds or even thousands - it HAS to appeal to a rather wide audience!

All the KAT/TATRA/EXPEDITION Crowd are rather VERY individual folks - I think you would be VERY hard pressed to find even ONE similar pair of trucks, let alone identical rigs among ALL of them (...talking about Serial Production). Even established builders like Actionmobil and Unicat will mainly build to and by order - .....one will probably over estimate how many of a certain model they actually sell.....

[These are all VERY serious HEAVY TRUCKS - not what I would call a mobile home...]

Go step by step:

a) What is the most extreme (driving, remote areas, stay on site) group you want to address - serial production already eliminates most of the unique-expedition-ride folks

b) Design for utmost practicality/survivability/self-repair-ability first! Aesthetics ("Art/Beauty") is the VERY last you should be concerned with!

You mentioned road-service/aid - you are building the rig to go places. Mostly no road-service available there!
Self-repair-ability is not only good for the owner/driver, but any help they might encounter out there, will appreciate also, if they don't need a specialist education to ....help out!


Sorry to be so apparently negative on a lot of your desires, but I always like to play the devils advocate!
If I can find a problem or a negative - you can work on getting it fixed!
If I cannot find anything to nag anymore - you are done designing and ready for production!! :luxhello:

I don't have any Explorer (but always liked them) - I decided a while ago, they would be too expensive for my intended traveling.
So, I don't talk from experience, but I do see frequently some of the folks on here coming through Panama - mostly on the way south...

[I also saw the amphibious 3-axle converted milk-tank when it was in Panama - ridiculous!! TOO hot to spend more than 3 min inside on a regular Panama-day, access only through roof hatches, by the time it made it here it was rust bucket......a mall-spectacle-show-piece at best.....
It looked good in magazine ads, but up close it is rather disappointing: too small wheels, too much stuff hanging underneath, off-road? Forget it! Waste of time and money! The fellow spent a fortune building it and loosing about all of it at the end]
...mentioned this, because you had a pic of it somewhere ON THIS THREAD....

I also traveled some of the more interesting roads in South America (really few, but INTERESTING!), most are transited by slightly elevated single/dual axle drive trucks (that would be the common rear-tandem truck axles). I doubt that you would seriously want to risk to go anywhere worse even with a KAT. From the point where the local trucks get stuck, to where you will get stuck with a KAT is mostly not that much further ahead - only, you will be the ONLY guy who got that little much further, no one else ......to give you a hand to get un-stuck!!
My advise to all is to keep the size of go-anywhere-hell-be-damned-rigs to a size that can be handled by human recovery-power only!!
MANY times that is all you will be able to organize! Enough people and cable/ropes and pulleys and you WILL rescue a Pinzgauer or Volvo C303/4/6 or similar.

I would like to see a documentation where you did that with a 20+ ton rig!!

(No cynicism here - it probably is possible, but at what effort!! ....and yes, if you have a reference to look at one rescue, please let me know, I really want to see that - that must be a master at work, one only can admire and learn from! :bigbossHL:

Certainly not a job for the "elderly retired couple"!!)



'nough said!

Off the box, eepwall:

thjakits

 

[biotect]

Hi thjakits,

As you know, I very much welcome critical feedback, just as long as it is reasonably well-argued, evidential, etc. So almost all of the points you made above are good ones, and worth considering seriously. Your "nagging" and "devil's advocacy" has been most welcome indeed. If only because I sense that, much like campo, egn, dwh, optimusprime, Haf-E, Amphibeast and others, you are in broad sympathy with the general idea of this project: fully integrated design for a large expedition motorhome.

I am now preparing for the return to Art College, so I cannot address your points in quite the detail that I would like. So the following is a bit "on the fly". Hope that's OK. Also know in advance that from here on out, my posts must reduce to a trickle..........So if I fail to respond in a timely manner in future, please do not take it personally. I will not be responding to anyone quickly in future! At least not between now and Christmas vacation.


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1. 4x4 or 6x6??


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Btw: 16 tons is 4x4 territory - IF you insist on 6x6, might as well design for max usage of the 3 axles ~26-28 tons for a "motorhome".

I can see your argument about 4x4 versus 6x6. Peter Thompson's Mañana, which in some ways is the nearest design-precedent for what I have in mind, is a 4x4 and not a 6x6:










And yet Mañana was still about 35 feet long, or 10.74 m overall -- see http://www.thompsons.au.com/motorhome/ . The base chassis of Mañana, a MAN L2000 18.284 4x4, has a gross vehicle mass (GVM) of 18,000 kg, and a GCM maximum of 30,000 kg. Needless to say, the fully integrated motorhome built on top eliminates the factory-supplied cab. The weight of the completed motorhome seems to place 7,100 kg on the front axle, and 11,500 kg on the rear, or 18,600 kg overall. I get the impression that this is the overall weight of Mañana, although I am not 100 % certain of this -- see http://www.thompsons.au.com/motorhome/ .

So again, I am inclined to agree with both you and campo that keeping the weight below 20 tons, and ideally nearer to 16 tons, should be a major design objective, for all the reasons you gave, including the problem of vehicle recovery.

And so yes, I am willing to consider a 4x4 format instead of 6x6. But the length needs to stay 9.5 m.


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2. The Problem of Turtling


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However: I also wonder about the problem of a 9.5 m long 4x4 "turtling" as it crosses a hill.

This problem is hard to describe in words. "Turtling" is what happens when a vehicle goes over a hill that is not broad and wide, but rather narrow and medium-sized: more of a "hillock" than a hill. The front wheels go over, and then proceed down the other side, before the back wheels clear the hillock. The center section of the MAN-KAT then scrapes its underside on the crest of the hill. In extreme cases it gets stuck, because both the front and rear wheels have lost traction.

A few months ago I saw a great video on YouTube of a MAN-KAT 4x4 doing just this. After far too much time spent searching, I finally found the video. It's long, about 9 minutes. Skip ahead 4 minutes, 25 seconds into the video, to see a MAN KAT 4x4 "turtle":




For a MAN KAT 8x8 then doing recovery on this turtled 4x4, skip ahead to 6 minutes, 30 seconds.

Here is another video of a MAN-KAT 4x4 turtling:


[video=youtube;0tbbhWqlOiw]http://www.youtube.com/watch?v=0tbbhWqlOiw&index=26&list=PLEAE9FCE044DFE4 96 [/video]


The video I posted earlier in the thread that shows President Obama's limousine getting stuck on a kerb in Ireland, is also a good example of "turtling":




This is why the distance between the first and second axle in a 6x6 is important not just for the turning radius, but also for driving on bad gravel roads that may go over "smaller" kinds of hillocks. If the vehicle were 9.5 m long, and 4x4, then the distance between the front and rear axle would be much longer than a vehicle of the same length that is 6x6 instead. The two rear axles on the MAN-KAT A1 and the SX series are 1.5 m apart (here assuming that the inter-axle distance in the SX is no different than a MAN KAT). So this extra axle in effect reduces the middle distance between the first and second axle by that amount. Sure, in a 4x4 one could also try locating the front and rear axles closer together. But this then creates problems for the approach and departure angles, at the front and back of the vehicle.

This problem of "turtling" (I don't know what else to call it???), seems to me one of the reasons why MAN-KATs longer than 9.3 m will be 8x8s, and not 6x6s. That, and the fact that an 8x8 configuration allows crossing ditches that are 1.8 or 1.9 m wide. The HX series can cross ditches 1.8 m wide, and the SX series, 1.9 m ditches:





See http://www.scribd.com/doc/17296072/The-Mobility-Elite , and post #3 at http://www.expeditionportal.com/for...-8x8-Expedition-RV-w-Rigid-Torsion-Free-Frame . It's the wide spacing between the two front axles, combined with the pair of rear axles, that makes it possible for 8x8 trucks to cross ditches.

But it's also the narrowing of the space in the middle of the vehicle, by adding the 2nd and 3rd axles, that also makes 8x8 trucks so capable. This makes them much less susceptible to turtling, as nicely demonstrated by the following video of a MAN-KAT 8x8 dune-hoppinng in Libya:




As egn admitted earlier in the thread, a 6x6 does not have the ditch-crossing capability of an 8x8, because it only has one axle in front. But a 6x6 is also not as prone to "turtling" as a 4x4 of equivalent length, because the second axle reduces the space in the middle.

Do you see the idea?


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3. Addressing the Problem of Turtling, in Blueprints


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To help illustrate this idea further, here are some MAN-KAT blueprints.

The MAN-KAT has been produced in so many different variations over the years, that no one set of blueprints should be considered normative. The HX and SX series are further developments of the MAN-KAT format, but it's difficult (or seemingly impossible) to find blueprints for these on-line. Even still, this question of deliberately shortening the middle-distance with an extra axle (or axles), so as to minimize the possibility of "turtling", is a spatial idea that cannot be technologically finessed. Either the extra axle is present, or it is not.

To start off, here are some blueprints for a MAN-KAT 4x4. The total length is 8.015 m; approach angle, 45 degrees; departure angle, 40 degrees; and the middle distance between the axles is 4.5 m:





Next, here are some blueprints for a MAN-KAT 6x6. The total length is slightly longer, at 9 m; approach angle, 45 degrees; departure angle, 42 degrees; but the middle distance between the first and second axis has now been reduced to 3.8 m, because of the addition of the second axle. Without that second axle, the distance between the front and the rear axle would be 5.2 m:





And notice how in this blueprint the 2nd and 3rd axles are not that wide apart: there is only 1.4 m between them. But that 1.4 m makes all the difference.

Next, here are some blueprints for MAN-KAT 8x8s. These blueprints describe two variations with different overall lengths, and with different wheel sizes. One variation is 9.380 m long overall; the second, 10.04 m. The first shorter variation, when using the bigger 16.00 R20 tires, has an approach angle of 40 degrees, and a departure angle of 54 degrees. The second, longer variation, when using the bigger 16.00 R20 tires, has an approach angle of 40 degrees, and a departure angle of 38 degrees. In the first variation, the inter-axle "middle distance" or L2 measurement is now just 3.3 m. In the second variation, the L2 measurement is 3.57 m:





The L3 measurement, i.e. the measurement between the two rear axles, in both cases is 1.5 m.

Here again one needs to remark that in the shorter, 9.38 m long version, if it were not for the second and third axles, the middle-distance between the first and last axle would be L1 + L2 + L3 = 1.93 + 3.3 + 1.5 = 6.73 m. And the middle distance on the longer, 10.04 m version would be even more: 7 m.

Finally, here is an example of a "super-compressed" 8x8, in which the middle-distance has been reduced to just 2.77 m, and overall length to 8.85 m:





So clearly, the middle distance is an important consideration. The less of a middle distance that a vehicle has, the more capable it will be when it comes to bad-road and off-road travel. This is no doubt why the distance becomes progressively shorter in ever more capable MAN-KAT off-road trucks. Of course, as per Peter Thompson's Mañana, I am now thinking of the TerraLiner only as a "bad-road" motorhome or an "all-road" motorhome, and not as a true off-road motorhome. So perhaps the middle distance and worry about the possibility of turtling should not figure too prominently as a design consideration? As you suggest, design is a series of compromises. And so if adding a third axle dramatically increases the weight, then 4x4 would be preferred to 6x6, for that reason alone.

But I also wonder whether adding a third axle, in a diesel-electric hybrid vehicle of the kind now being considered, really would add that much weight after all. For instance, perhaps this vehicle would still have differentials, or perhaps not. Perhaps it would have hub motors on each wheel; or perhaps just one motor for each axle, as Haf-E and egn suggested. So as I begin to settle on a particular power train, it will be interesting to see whether adding a third axle, and going with 6x6, really does add significant weight.

So too, it does seem important to try to keep the middle distance to 4.5 m or less, as per a MAN-KAT 4x4. And the only way to do that, in a motorhome that is 9.5 m long, is to introduce a third axle, and go with a 6x6 arrangement instead of a 4x4 arrangement.

Of course, no axle format is invincible. Here is a good video of a 6x6 caught in a watery hole:


[video=youtube;P8go63-pHIM]http://www.youtube.com/watch?v=P8go63-pHIM [/video]



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4. Using MAN SX-Series or TATRA technology selectively


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You already stated, that your design will NOT be OFF-ROAD, but ALL-ROAD capable, well, WHY then do you insist on MAN/KAT/TATRA chassis as a basis?

These machines are decidedly "military go ANYWHERE with a support team behind"!
Ask any of the gentlemen/ladies here that actually have machines based on the named chassis, if they really ever got themselves into places, where they needed the actual capabilities of their rigs? I bet, mostly not and the ones that did, would do everything to avoid doing it again!

As previously mentioned - one does not want to risk the only home/safe-place you have along!

Even guys like ENG, who takes/took his KAT up the river to get to a camping place, will do that now and very then - a river that wide and drive-able is that wide for a reason - FLOODS. You don't want to get stuck upriver! Then his tires took a beating - what if you blow one in the middle of it?

Another point to ask the guys with real experience is how much their 6x6 drives are really in use??

Most travel km will NOT need anything more than a lockable or LS rear drive - for all these km you will carry probably close to or over a TON of heavy metal around as ....ballast at best or fuel eater at worst (depending if you can freewheel)!

........

"Don't wrong get me - Love I do the MAN/KAT/TATRA builds, but for MAINLY road use destined they are not!"YODA"

Military HAS to expect that a countries main-roads will be the 1st thing taken out by the enemy - that's why they must have these chassis - economy is not even the 2nd consideration.....

Now very much agreed, literally adopting the "complete package" of a MAN or Tatra 6x6 would be a mistake. It would probably be overkill, given my design target: a "bad road" motorhome, and not a true "off road" motorhome.

But I have already been over this same territory with campo. Please if possible read the last few pages of this thread, from post #722 onwards. campo really pressed me on the issue of more innovative chassis design, and I responded with a long series of posts in which I demonstrated my awareness of possibilities like "monocoque" and "tubular space frame". As I then already indicated to campo, I am no longer thinking of adopting the "complete package" of a MAN or Tatra 6x6 chassis. This is not how I am currently thinking. Rather, I am currently imagining just using the Tatra backbone tube, combined with a "half-height" tubular space-frame below 1.6 m, and a composite monocoque shell above that. But a monocoque shell equipped with the necessary metal arches for rollover protection.

So again, please see my most recent exchanges with campo for further explanation, before addressing this topic further. That would save me the trouble of just repeating myself. ... My apologies for being so direct, but I don't really have time to repeat the same points over and over again, addressed specifically to each and every thread participant.......


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5. Height?


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If you are doing the 3.95m hight you might as well go to the mostly applied max length of 12m - as mentioned elsewhere, 3.95m hight will be the limiting factor much more often than the length. If you already specify - "additional modes of transport" - might as well make these go-anywhere and "moderate the home base".

As for your other points, I still find myself wanting to "agree to disagree" with you on many of them, although not all.

For instance, we will probably have to agree to disagree about height.

As you suggested in the quote just above, I will be thinking of the main vehicle as mainly an "all-road" or "bad-road" capable motorhome, and the supplementary run-about vehicle as the truly all-terrain "off-road" devil. Given that basic premise, perhaps the height of the main vehicle is then not such a big concern? For instance, perhaps egn and his wife only tried driving up that creek bed in Albania with their 6x6, or along some of the crazier and more narrow mountain roads in Albania, because they were not towing a TOAD?







In short, I tend to draw the opposite conclusion from you. If there are indeed "additional modes of transport" available (namely, a TOAD and a motorcycle), then the main home base could in fact be as long and as tall as Mañana, which again, is 10.67 m long, and 4.1 m high -- see http://www.thompsons.au.com/motorhome/ . Mañana is not a short or squat motorhome.

I see the main home-base or "TerraLiner" as traveling mostly on major paved roads and highways; and on gravel roads that are also used by very large vehicles, like the G219 in Tibet, or the Tanami trail in Australia:




If enormous Australian road-trains can use the Tanami trail, then there is no reason why a motorhome 9.5 m long and 3.95 m high could not do the same. The same as regards the G219 in Tibet: it is regularly travelled by large Chinese military and construction trucks. The above two videos make all of this manifestly clear. But needless to say, not just any kind of motorhome could travel the Tanami Trail or the G219. No mainstream motorhome could, because the corrugation would bust its axles.

However, reasoning this through further, one would probably not travel a road as soft and narrow as the Canning Stock Route in the TerraLiner. Here one would instead want to use the additional vehicle(s) provided.


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6. Towing a TOAD


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Now perhaps a TOAD need not necessarily be the smallest and lightest off-road-capable 4WD one can find, e.g. a two-door Jeep Rubicon, or the Jeep Wrangler that was towed by Mañana.

The TOAD could also be something like a Mercedes Benz G-Wagen, perhaps equipped with an Azalai camper? See http://psi-azalai.com/lazalai-tout-terrain/mercedes-g/ , and see post #152 and #153 earlier in this thread, at http://www.expeditionportal.com/for...pedition-RV-w-Rigid-Torsion-Free-Frame/page16 .

For more interior images of Azalais on the French website, see http://psi-azalai.com/lazalai-tout-terrain/interieur/ , http://psi-azalai.com/lazalai-tout-terrain/mercedes-g/ , http://psi-azalai.com/lazalai-tout-terrain/iveco-4x4/ , http://psi-azalai.com/lazalai-tout-terrain/toyota-hzj78/ , http://psi-azalai.com/lababouch-tout-chemin/interieur-2/ , and http://psi-azalai.com/nouveautes/ford-ranger-single-cab/ . And for the most spectacular galleries of Azalais driving through various landscapes, see http://psi-azalai.com/lazalai-tout-terrain/defender-130/ , http://psi-azalai.com/lazalai-tout-terrain/defender-110/ , http://psi-azalai.com/lazalai-tout-terrain/toyota-hdj80/ , http://psi-azalai.com/lazalai-tout-terrain/toyota-hzj-79/ , http://psi-azalai.com/lazalai-tout-terrain/iveco-4x4/ , http://psi-azalai.com/lababouch-tout-chemin/double-cab/ , http://psi-azalai.com/le-reve/egypte-2/ , http://psi-azalai.com/le-reve/les-images/argentine/ , http://psi-azalai.com/le-reve/les-images/nepal/ , and http://psi-azalai.com/le-reve/islande/ .

The Swiss-German Azalai website (based near Neuchatel) is also worth looking at. See http://www.azalai.ch/Azalai_de/Home.html , http://www.azalai.ch/Azalai_de/Bilder/Bilder.html , http://www.azalai.ch/Azalai_de/Bilder/Seiten/Azalai_aussen.html , http://www.azalai.ch/Azalai_de/Bilder/Seiten/Azalai_innen.html , etc. Both of the French and the Swiss-German websites are far more detailed and image-rich than the equivalent Azalai website in English. Strangely enough, the Swiss-German website has a collection of links to pdf articles written in English , that’s much more comprehensive than anything provided by the English website – see http://www.azalai.ch/Azalai_de/Presse.html .

Here are some Azalai videos:





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Or perhaps the TOAD should be a G-wagen configured with a much lower pop-up camper, like the XP Camper -- see post #152 at http://www.expeditionportal.com/for...pedition-RV-w-Rigid-Torsion-Free-Frame/page16 ?

Or perhaps the TOAD should be a G-wagen equipped with ORC's Camper Pro: see http://www.orc.de , http://www.orc.de/inhalt.php?bereich=Reisemobile&subnav=50&sprache=2 , http://www.orc.de/produkte/download/Catalogue_GCampPro201108.pdf , http://www.orc.de/inhalt.php?bereich=Reisemobile&subnav=50&sprache=1 , http://www.orc.de/produkte/download/Katalog_GCampPro_201108.pdf , http://www.orc.de/inhalt.php?bereich=Zubeh%F6r&subnav=13&sprache=2 , http://www.orc.de/produkte/download/Catalogue_MercedesGPur_de_eng_201403.pdf , http://www.orc.de/inhalt.php?bereich=Zubeh%F6r&subnav=13&sprache=1 , http://www.orc.de/produkte/download/Katalog_MercedesGPur_de_eng_201403.pdf , http://www.orc.de/produkte/download/catalogue_gpur_201104.pdf , http://www.mercedes-fans.de/inside/inside_artikel/id=3451 , http://www.mercedes-fans.de/galerie/id=1547 , http://www.mercedes-fans.de/picture/picture=48078 , http://www.adventuremedia4u.de/4x4fahrzeuge/fernreisemobile/orc-mercedes-g-camppro.html , and http://www.fourbyfourclub.com (I gave the links in both English and German, and direct links to the PDFs, because the ORC website is very badly organized, and the English PDF links sometimes do not work....)

Here are some videos:


[video=youtube;_snqzACvkIY]https://www.youtube.com/watch?v=_snqzACvkIY [/video]

Or perhaps the TOAD should be a G-wagen very well-equipped for expedition travel, but only with a Pop-Up tent, as per the G-wagen "Entdecker" put together by UniCat. See http://www.mercedes-g-entdecker.com , http://www.mercedes-g-entdecker.com/images_shen/pdf/ENTDECKER_en.pdf , , http://www.mercedes-g-entdecker.com/photo.html , http://expeditionportal.com/gelaendewagen-entdecker/ :


[video=youtube;gQfFO51TJh4]https://www.youtube.com/watch?v=gQfFO51TJh4  [/video]

What do you think? My own inclination is to go with a TOAD that has a hard-shell camper, or almost completely hard shell, like the Azalai, as opposed to just an RTT, as per the Entdecker. Because this TOAD should have the same climate capabilities as the main vehicle., and an RTT will simply not work in Siberia. Whereas the Azalai has long since been Sahara-tested, Tibet- and Himalaya-tested, and Siberia-tested.

I wonder what the maximum allowable size is for a TOAD, in various countries?

egn, if you are reading this, do you know what the maximum allowable size would be in Germany, for a vehicle towed by a motorhome?

So if the main "base camp" vehicle is really not intended for expeditions up creek beds, then I see no reason why it could not be proportioned more like a Newell or Concorde motorhome, approaching 3.95 m in height. But of course, this main vehicle still needs to be "bad-road" capable. It still needs to be able to drive Australia's corrugated tracks, like Mañana, or the G219 highway in Tibet. Which, I think we can agree, a Newell or a Concorde would not be able to do, without busting an axle or two.


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