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

[safas]

Suspension is a huge can of worms. We dipped into it once, with no resolution and lots of agro, so I've been leaving it alone for now. I don't want to open up the whole can of worms again. But I am curious to know whether military hydro-pneumatic suspension systems have capabilities similar to a Citroen DS, or HWH's Active Air? If anyone reading this knows the answer, please post!! Hydro-pneumatic suspension seems to be a "big thing" in contemporary military vehicles, so it would be good to know more about it, and what it can and can't do, in its military versions. safas?....

While I find the topic quite interesting, it's not interesting enough to make me go out and search for info, sorry.

Sure, there may be roughly two tons (200 KW) of Proterra's Nickel Magnesium Cobalt (NMC) batteries packed between and around the ladder-frame rails, but that's a different story.....:sombrero:

I don't see any specs for energy density of the battery pack, but the 100 W/kg from your calculations is a good result, which nevertheless could be much improved.
Tesla gets 156 W/kg:
http://www.roperld.com/science/TeslaModelS.htm

 

[Libransser]

I don't see any specs for energy density of the battery pack, but the 100 W/kg from your calculations is a good result, which nevertheless could be much improved.
Tesla gets 156 W/kg:
http://www.roperld.com/science/TeslaModelS.htm

Speaking of Tesla's battery pack, another benefit I haven't seen being talked about is the packaging of the batteries.

Proterra is doing things right by designing the bus from the start to be an electric vehicle. Tesla did the same, instead of adapting an existing vehicle platform they designed their own from scratch allowing them to carry a bigger battery pack than any other platform-adapted electric vehicle in the market. Which may be the reason why Proterra is able to achieve that range without needing a break-through in battery technology. Although selection of battery cell types may very well be another key reason.

While other car manufacturers use bigger & costlier specialized/custom Li-Ion battery cells, Tesla uses a lot of small, cheap & common Li-Ion 18650-type battery cells, like the battery cells found in laptops.

Tesla's battery pack solution is very elegant. Space is greatly maximized, weight balance is a non-issue, cost is relatively low, it works as another structural element, it has built-in safety features, it's potentially swappable & upgradeable, and small batteries can be arranged more easily to make use of small spaces available in the chassis.

Here are some answers for a Quora question about advantages of small batteries vs. bigger batteries:
https://www.quora.com/Tesla-Motors-...-large-battery-to-power-the-electric-vehicles

Here's an article talking mostly about the batteries cost for the Tesla Model S (the comment section is good too):
http://www.greencarreports.com/news...a-tesla-model-s-battery--and-what-it-may-cost

Here's an interesting thread showing the dismantling of a Tesla's battery pack with pictures (I just started reading it):
http://www.teslamotorsclub.com/showthread.php/34934-Pics-Info-Inside-the-battery-pack

And here's the most interesting article about "What makes Tesla's batteries so great":
http://www.torquenews.com/2250/what-makes-tesla-s-batteries-so-great

 

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Hi Libransser, safas,

Libransser, fantastic leads for Tesla!! I didn't know much about Tesla; now I know much more.

The energy density of Tesla's batteries really struck me. The last article you referenced stated 233 Wh/kg, which is quite astonishing, even better than the 156 W/kg that safas just quoted. Suppose for the sake of mathematical simplicity that circa 2018 the energy density of Tesla batteries will be at least 250 Wh/kg, which means 4 kg per KW. A 200 KW battery pack would then weigh just 800 kg!! Which might tempt one to have the TerraLiner carry 300 KW of batteries weighing 1200 kg, for even longer noise-free glamping.....:ylsmoke: .. I also liked reading about how Tesla's batteries are fast discharge/fast charge, because that will be important if the TerraLiner needs to suddenly rely on a big boost from the battery pack when driving up steep 6, 7, o 8 % mountain roads, inclines that do exist, and that do exist on 4-lane highways where trucks can legally drive 120 kph....

I finally finished the posting series with the power calculations -- see posts #2127 - #2129 at http://www.expeditionportal.com/for...w-6x6-Hybrid-Drivetrain?p=1974110#post1974110 and following. safas, you may want to take a look at those posts, because in the final ones I took your advice, and got a bit less "conservative" with the basic assumptions, like the drag co-efficient (I am now assuming 0.41, the drag coefficient of the MAN SkyLiner), the frontal area (9.7 square meters, an oft-quoted, standard figure for large 4 m high x 2.5 wide trucks), and air-desnity (1.26, which is the density of air at sea level at 6 degrees Celsius). The power figures that I then get for the TerraLiner become very different.

Before, using Iain's very conservative assumptions, for the TerraLiner to sustain a given speed on flat terrain without a headwind, I got:

90 kph	182.3 KW
100 kph	227.4 KW
110 kph	280.4 KW
120 kph	341.8 KW
130 kph	412.8 KW

Whereas using more realistic assumptions that posit good TerraLiner aerodynamic design, more realistic air pressure, and 9.7 square meters of frontal area, I get:

90 kph	130.6 KW
100 kph	156.6 KW
110 kph	186.0 KW
120 kph	219.4 KW
130 kph	257.0 KW

At 130 kph there's a huge difference: roughly 150 KW. And even at 90 kph there's a difference of 50 KW. This matters, because the size of the primary generator needs to be set to handle most "normal" driving situations, including driving through flat or hilly country where 120 kph is the legal limit, and there's a 20 or 30 kph headwind.

Yes, yes, I know that in some countries like Germany 90 kph is the legal limit for trucks and 100 kph is the legal limit for buses. But Germany is not the world -- no country is -- and as already shown earlier in the thread, legal speed limits vary widely across the planet, even for trucks and buses. Canada and the United States allow 120 kph in some states and provinces, Australia allows 110 kph outside built-up areas, Pakistan and Romania the same, and some countries report variable figures such as 100 - 140 kph (UAE) or 60 - 120 kph (Venezuela) -- see https://en.wikipedia.org/wiki/Speed_limits_by_country .

Regenerative braking and power boosts from the batteries will take care of the ups-and-downs of driving through low-lying hills, so the figures for travel on a flat plane are the most important. That's why I now think that the TerraLiner will probably need a primary generator that can produce 300 KW, or 400 HP, which means that the diesel ICE that powers it probably needs to be roughly 450 HP. That's still much smaller than the standard engines that are now being installed in premium 45-foot Class A motorhomes, for instance a Cummins 600 HP in Newell motorhomes, or the equivalent Volvo engine in Prevost-based motorhomes (because Prevost is owned by Volvo) -- see http://www.newellcoach.com/features/specifications/ , http://www.newellcoach.com/wp-content/uploads/2014/06/NewellNews_Vol34Iss1.pdf , http://www.volvotrucks.com/TRUCKS/NA/EN-US/PRODUCTS/Pages/trucklanding.aspx , http://www.volvotrucks.com/trucks/na/en-us/products/powertrain/Pages/powertrain.aspx , http://www.volvotrucks.com/SiteCollectionDocuments/VTNA_Tree/ILF/Products/D13/D13 Family.pdf , and http://www.volvotrucks.com/SiteCollectionDocuments/VTNA_Tree/ILF/Products/D16/D16 Family.pdf .

Here I should note, however, that even if the TerraLiner were driving at 120 kph with a 30 kph headwind for 5 hours, and consuming roughly 300 KW per hour, if the generator were rated for 280 KW, then the battery pack would be drawn down only 100 KW (20 KW X 5). So it might be possible, given the percentage likelihood of various driving scenarios, that a generator somewhere between 260 and 300 KW would be more appropriate. Only a truck engineer who has experience designing for global markets would be able to guess the ideal "sweet spot" size for the primary generator, given a certain size of battery pack. All that I've done so far is suggest some of the scenarios that need to be taken into account, and give rough ballpark estimates of the power requirements.

For instance, check out my calculations for ascending the final 13 km of the Eisenhower pass, a 7 % grade where 120 kph is legal. It's a 4-lane highway, so 120 kph would be possible for a TerraLiner that had sufficient power: slow vehicles on the right, and vehicles that can handle the slope at high speed on the left -- post #2127 at http://www.expeditionportal.com/for...w-6x6-Hybrid-Drivetrain?p=1974110#post1974110. I was still using Iain's more conservative assumptions, and assuming a 200 KW primary generator combined with the Pratt & Whitney APS 5000 turboshaft APU producing 450 KW. But even the combined power of the two generators -- 650 KW -- was not enough to climb this slope at 120 kph with a 20 kph headwind. An additional 60 - 70 KW boost from the battery pack seemed necessary. I need to redo those calculations with newer, more realistic assumptions regarding the drag coefficient, air density at 3000 m, etc., and assuming a 300 KW primary generator instead.

safas: Here once again I really want to thank you for encouraging me to take another look at turbines. Yes, I know that installing a Boeing Dreamliner APU might seem excessive and slightly "science-fiction", but Ian Wright at Wrightspeed is into turbines, and I could imagine him loving the idea. Again, the turboshaft APU"s primary purpose would be to serve as a massive "power booster" so that the TerraLiner will be able to ascend long, steep inclines without a problem, like the 3 % sustained slope from Dolalghat in Nepal to the Tong La Pass in Tibet, a continuous ascent that's 151 km long; or ascend short, sharp, very steep slopes (6 - 8 %) that can be found on various 4-lane highways. See posts #2124 onwards, from section #38 onwards, at http://www.expeditionportal.com/for...w-6x6-Hybrid-Drivetrain?p=1974106#post1974106 .

Apart from such turboshaft-boosted scenarios, the TerraLiner should prove quite fuel-efficient at "normal" highway driving speeds (55 - 65 mph), when powered by just a 300 KW generator -- and hence, probably a 450 HP ICE -- and with massive regenerative braking. "Quite fuel efficient" at least in comparison to the average large Class A motorhome. Large, 40 - 45 foot Class A motorhome typically get 6- 8 miles per gallon, so I think the target for the TerraLiner should be 10 mpg in "normal" driving -- see post #2129, section 49, at http://www.expeditionportal.com/for...w-6x6-Hybrid-Drivetrain?p=1974540#post1974540 . If the TerraLiner were equipped with a 1500 liter diesel tank (i.e. 396 US gallons, the legal limit), then at 10 mpg it could drive 3,960 miles without refueling.....:sombrero:,,,We'll see.

Again, streamlining and reducing the drag coefficient is paramount, and Libransser, it was interesting to read that Tesla is now fitting Titanium plates to the bottoms of its roadsters, to prevent the possibility of a battery fire in a crash -- see http://www.nytimes.com/2014/04/10/a...olution-to-preventing-model-s-fires.html?_r=0 , http://www.treehugger.com/cars/tesl...ld-and-aluminum-deflector-plates-model-s.html , and https://www.teslamotors.com/blog/te...-shield-and-aluminum-deflector-plates-model-s :






It seems that the TerraLiner should do likewise, turning the entire underbody into one enormous "skid plate", as you suggested a while back.

But otherwise, Titanium will not be a realistic building material for most of the TerraLiner, as I will explain in the next few sections.


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1. Some Thoughts on Titanium and the TerraLiner


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For instance, one of the problems with a Titainum space-frame is that although theoretically one might save on weight, in actual practice, the tubes have to be thick enough for good welds, so weight savings are negated. This point is repeated again and again on web-forums; see for instance http://www.sccaforums.com/forums/aft/38675 :

....you could build a [roll] cage out of titanium with the same ultimate strength as a steel cage, but in order for it to be as rigid, the tubes would be either thicker (no longer a weight savings) or larger diameter (clearance issues). If he want's a super lightweight cage, that's stiff and strong, I suggest heat treated, butted chromoly tubing.

But that doesn't mean a Titanium roll-cage is not being tried. Ariel, a manufacturer of what look like track-day cars (although they are not just that), in co-operation with Caged Laser Engineering, has been developiong an all-titanium roll cage for its “Atom” model:






See https://www.facebook.com/pages/Caged-Laser-Engineering/147414068707402 , http://www.arielmotor.co.uk , http://www.arielmotor.co.uk/atom/ , http://www.arielmotor.co.uk/nomad/introduction/ ,
https://en.wikipedia.org/wiki/Ariel_Atom , http://www.pistonheads.com/news/ph-britishcars/ariel-atom-titanium-chassis-new-details/29186 , http://www.slashgear.com/ariel-atom-to-get-even-lighter-thanks-to-new-titanium-chassis-25275159/ , http://www.autocar.co.uk/car-news/new-cars/ariel-developing-titanium-chassis , http://www.autoblog.com/2013/03/25/ariel-developing-titanium-atom-chassis/ , http://www.motoroids.com/news/next-gen-ariel-atom-to-get-lighter-with-titanium-treatment/ , http://www.worldcarfans.com/113032455613/ariel-working-on-a-titanium-chassis , http://www.topcarrating.com/topspeed.php?brand_id=186 , http://www.topspeed.com/cars/ariel-atom/ke564.html , and http://www.topspeed.com/cars/car-news/ariel-working-on-a-new-titanium-chassis-ar151126.html .

But as one article about this Ariel/Caged Laser Engineering project states, even in the world of Titanium manufacturing for airplanes, the barometric chambers where titanium components are welded in an oxygen-free environment, are still only about a half a meter square – see https://connect.innovateuk.org/web/...-40-chassis-weight-saving-in-arial-sports-car . Whereas when constructing a completely integrated titanium roll-cage and/or chassis for a car – in the Ariel Atom, they are one and the same thing – the barometric chamber would have to be “3.5 m long by 2m wide by 2m high - four times larger than the world's biggest such chamber ….”

And for the TerraLiner? Building a 12 m x 4.5 m x 3 m barometric chamber just so that the TerraLiner can have a Titanium welded space-frame is simply out of the question.


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2. Welding Titanium


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This is what titanium welding looks like in an argon-filled barometric chamber:






Yes, car manufacturers are beginning to use Titanium for smaller components – see http://www.engineerlive.com/content/titanium-some-light-relief . But a full integrated and properly welded Titanium space-frame or roll-cage is an engineering challenge of a completely different order of magnitude. Remember that when fitting together large Titanium components for fighter jets, or Aluminum components for airliners, manufacturers like Boeing and Airbus have traditionally used rivets, and not welding. See http://www.reddit.com/r/explainlike...why_are_airplanes_covered_in_rivets_and_cars/ , http://aviation.stackexchange.com/questions/6312/why-are-airplanes-riveted-and-not-screwed , https://howthingsfly.si.edu/structures-materials/materials , and http://zenithair.com/kit-data/ht-86-12.html .

Riveting has a lot to be said for it, which is why aircraft -- even the parts made out of aluminum -- have long been riveted. See the excellent discussion at https://www.reddit.com/r/explainlik...why_are_airplanes_covered_in_rivets_and_cars/ . Airstreams are still riveted, just like they were 50 years ago, and old aluminum Landrover Defenders were riveted. Now that aluminum welding has become much more sophisticated and cost-effective, welded aluminum is usually the material of choice for large sailing and power yachts (the only real alternative is carbon fiber); and of course aluminum cars are mostly welded. And yet airplanes are still riveted, for all of the various reasons explained in that excellent discussion thread just referenced.

I've then read that what's true for aluminum, is all the more true for titanium: that outside the well-controlled, oxygen-free environment of an argon chamber, it's very difficult to weld titanium properly. I can't quite imagine what a "bolted" together titanium space frame would be like, and surely the whole point to something like a roll cage, is that the entire thing would be welded together to form a structure that's unbreakable and unbendable.


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3. The Problem with Rivets: Why the Boeing Dreamliner 787 Uses Composites


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In any case, this is the main reason why Boeing and Airbus are trying to move to composites instead. There's the weight factor, of course, but the main issue here is the riveting: a 747 will contain literally millions of rivets to hold all of the aluminum (and sometimes titanium) pieces together. Which means millions of man-hours of labor. Whereas the large composite panels and complete fuselage tubes of the Boeing Dreamliner 787 eliminate a huge percentage of rivets, and the man-hours required to install them – see http://www.airspacemag.com/flight-today/inside-boeings-787-factory-94818438/?no-ist , http://www.boeing.com/commercial/787/ , http://composite.about.com/od/aboutcarbon/a/Boeings-787-Dreamliner.htm , http://www.dailymail.co.uk/home/mos...-building-new-787-Dreamliner-plane-built.html , http://www.mirror.co.uk/lifestyle/travel/inside-the-dreamliner-factory-a-tour-of-boeings-1174074 , and http://www.3mb.asia/the-use-of-composites-in-the-boeing-787-dreamliner/ :






But even still, Boeing has not completely eliminated all “rivets” (or “fasteners&#8221.… – see http://www.airliners.net/aviation-forums/general_aviation/read.main/3404578/ and http://www.homebuiltairplanes.com/forums/composites/10603-787-uses-riveted-composite-skins.html . In the first video, also notice that the Dreamliner's windows do not have shades, and use Smart-Glass instead to dim the windows. So any of you who were skeptical about the use of Smart Glass in transportation applications…..



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4. The Problem with Rivets: Leaking Airstreams


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In short given the current levels of various transportation technologies in play, I figure that TerraLiner will be built much like a Newell coach: a super-rigid torsion free under-chassis made out of stainless steel, and built like a box-struss structure; and a welded-aluminum space frame on top of that, with body panels fully welded as well.

Why not riveted, as per Air-stream?

Well, Airstreams do have their problems. See the excellent blog post at http://livingstingy.blogspot.com/2012/07/airstreams.html for a thorough discussion of the “Problems with Airstreams.” For whatever reason, since I read this post last, the writer has taken it off the web. This is a real shame, because it does a better job of summarizing everything that is wrong with Airstreams than anything I have read anywhere else, in print or on the web. I hope I don't get in too much trouble for reposting it here. After all, anybody can recover the article if they know how to use the Internet's "Wayback Machine".

Furthermore, as anyone who has read this thread knows, I am a huge fan of Airstreams. But no product is ever perfect, and the criticisms made in this article are really good ones, and they are well-written. I believe in learning through discussion, debate, and criticism, and when the criticism is articulate and well-organized, it deserves to stay in print. So it would be a tremendous shame if this were lost to posterity:

Airstreams

Pretty to look at, but expensive to own and difficult to maintain. An Airstream is not really a very cost-effective form of RVing.


We have looked at dozens of Airstreams over the years - maybe over 100, I am not sure. We keep thinking about buying one, but usually something stops us from making the purchase. They are an American Cultural Icon, and like with a Harley-Davidson, people tend to pay more for the cache than they do for the physical equipment.

So what keeps us from buying one?


1. Price: The price of these things, new or used, is staggering. A new Airstream like the one shown above, can cost over $50,000. This is a lot of money to spend on a recreational toy, for anyone in the middle-class. It is not as bad as, say, a $300,000 motorhome, of course. But when you throw in another $30,000 for a tow vehicle, you are looking at close to $100,000 to go camping. That is a lot of money.

Used trailers are slightly less, of course. But often they need expensive repairs - we'll get to that later. As a result, they can be a real money-pit, over time, if you want to keep them in good repair.

2. Weight: While advertised as a lightweight trailer (due to the aluminum construction) their very size makes them heavy, aluminum or not. To safely tow a 22-27 foot unit, we would want to have an F-250 at the very least. And this would not be cheap, nor would it get good gas mileage.

What sort of mileage? Well, like with penis size, men lie about gas mileage all the time. I've seen guys blow by me at 80 mph (which is not safe, for any trailer) towing a 31-footer, and then later claiming they are getting 20 mpg, which is an outright falsehood, as the underlying tow vehicle is not capable of such gas mileage.

The low teens or even the single-digits are more the norm, particularly for gas engines. Diesels fare a little better. But 20 mpg? Not in your dreams!

This adds up, over time, if you want to travel a lot. We drove 10,000 miles last summer, to Labrador and back towing our tiny Casita with a BMW X5. At an average 17 mpg, that comes out to 588 gallons of fuel, which at about $4 (including Canada) works out to $2353 in fuel. At 10 mpg, which is what our pickup truck used to get, towing a 27-footer, we are looking at 1000 gallons of fuel, costing $4000. It is a lot of gas!

You might be able to tow a Bambi with a medium-sized SUV (I've seen them towed with Range Rovers and BMW X5's) but the height and width of the thing means you will have a lot of wind resistance. And that is the smallest Airstream they make, and it still costs $50,000. The folks with the Range Rover I met, had $100,000 of car and camper parked at their site. Kinda expensive for camping - at least for us middle-class schmucks. And while they might think they can afford it, in reality, well - that is what this blog is all about, middle-class people bankrupting themselves buying bling.

If you want to buy a larger Airstream, you'd better buy a big pickup truck and be prepared to pay a lot of money for gas.


3. Size: Even the smallest Airstream (the "Bambi") is large, compared to our present Casita. It is taller and wider and thus is harder to maneuver into smaller spaces. The larger rigs are even more so. While having "space" in a camper is nice, you have to tow this (weight) and maneuver it (size). Sometimes less is more.

For example, we like to go up the Blue Ridge Parkway, and the campsites there were created back in the days of car-camping. For larger campers, the options are limited. But we can wedge ourselves into the tiniest of spaces. It is handy. And cheaper than staying in an "RV Resort".


4. Clear Coat: Airstream trailers are not bare aluminum, but rather aluminum coated with a clear paint. As they age, this clear coat scratches, yellows, and then starts to peel off. It looks like holy hell. At that point, you have two choices: Buff all the clear coat off the trailer and polish it, like an old airplane (which will be so shiny as to blind other motorists), or take it back to the factory (or a skilled repairman) to have it re-coated. Both are time-consuming and expensive processes. Lesser trailers, which are painted or fiberglass, don't seem to have this problem - or if they do, can be inexpensively repainted at any body shop.


5. Dents: The heartbreaking part about owning an Airstream isdents. The aluminum dents easily, particularly at the corners. Our regular "square" trailers had no problems hitting the occasional tree branch when backing up. Our motorhome was hit on the side by a runaway trailer tire coming in the opposite direction and suffered little more than a black tire mark. Our fiberglass Casita hits tree branches all the time - with the result being little more than a scratch that buffs out.

But with an Airstream, you just touch it to something, and thatabsolutely prefect exterior now has a heart-wrenching dent in it. I met a nice lady the other day with a year-old Bambi. I didn't ask how much it cost, but they are in the mid five-figure range, brand new. She was off to a special repair shop to have a small dent (and resultant leak) removed. A slight impact with a tree branch had marred the "perfect" exterior of the Bambi.

Sadly, this cut short her camping season, as the repair shop needed over a MONTH to remove the dented panels, replace them with new ones, re-rivet and re-clearcoat the trailer. She e-mailed me later:

"I picked up my Airstream Sept. 16 from Knoxville, TN and she looks like new. Thank heaven for insurance because the total repair cost 8,000.00 as there was more damage then I first thought."​

Ouch. $8000 is what I PAID to purchase my secondhand Casita. And insurance notwithstanding, the costs are not "free." File a few claims like that, and well, your insurance will skyrocket, over time.

Notice the rock guards on the front of the unit shown above. Airstream had to add these, as the tow vehicle throws up rocks and gravel, which over time, pits and dents the trailer (this happens with our Casita, but most of the time, it just means buffing out the fiberglass). The idea is, the rock guards can be replaced easily, without having to replace the underlying trailer panels.

I have an idea - why not cover the entire trailer with these guards? Then, you can easily replace them when the trailer is dented! Oh, wait, that makes no sense at all, does it? And neither do "rock guards".

Repairing such dent in panels is problematic. You have to get the exact same panel from the factory, and it has to be buck-riveted in place, which means accessing the interior, which means tearing out cabinets and interior walls to do the job right (blind rivets, of course, just won't do!).

And when the new panel is in place, well, you have to seal and re-clear-coat it. Sounds like a practical design, no?

As a result, you see older Airstreams with dents in them, as the owners cannot afford to make repairs, and even if you do repair them, you risk causing....


6. Leaks: Airstreams leak, over time. The design uses a number of panels riveted together, and over time, they start to leak at the seams, the windows, the doors, etc. The entire design relies on sealant and caulking to keep tight, and that is not a good design. Sealants dry out, caulking cracks, and as the unit goes down the road, joints flex and let in water.

Since the shape of the trailer is like a twinkie, water rolls down the sides, and hits every seam and crevice in the trailer. Eventually, it finds a way in. (Our Casita has the same shape, but being made from one piece of fiberglass on the top, there are no seams to let in water).

Square trailers can leak, of course. But since the walls are vertical, the water runs off the roof and doesn't tend to run down the sides, seeking ingress at every window or door joint. And since most have single-piece fiberglass panels and roofs (or rubber roofs) there are fewer joints for water to find.

Water causes a musty smell, creates mildew, and eventually rots out the floor, in the rear of the trailer, or by the front door (we've seen it all!). This is staggeringly expensive and difficult to fix, as the "Belly Pan" has to be removed, in many cases, to get at the wood flooring.

Of course, if you kept your Airstream indoors when not in use, you could reduce the incidence of leakage, and preserve that expensive clear-coat. But that can be hard to do, as they are...


7. Hard to Store: When we had our barn in New York, we set it up with a bay for a large motorhome or trailer. Most people don't have such storage facilities handy. For the average suburbanite, it is simply out of the question. The alternatives are to store the unit outdoors, in your yard, or to keep it outdoors at a paid-for storage yard. In either case, the unit sits outside, the clearcoat oxidizing, and rain running down the sides of the thing, looking for an entry point, 24/7.

And if you bought a truck to tow it with (which you will need) you need a place to keep that. For us, the idea of having a giant pickup truck blocking our driveway just seems, well, impractical. We store the Casita in a storage locker (indoors) and the X5 fits in the garage. It is a lot less hassle and wear and tear.


8. Layout & Space: Many Airstream folks tout the increased size of their units as an advantage over other kinds of rigs. But the layout of many Airstreams leaves a lot to be desired. Square trailers, which are very cheap to buy and own ($15,000) have far more headroom, flat walls, more cabinet space and more storage space underneath.

The Achilles heel of the Airstream is storage, and many folks complain there is not even a place to put a folding chair, in an Airstream. There are few, if any, outside storage compartments.

Inside, in addition to the sloping wall problem (which cuts into cabinet space), is the lack of a place to eat. Even our 17' Casita has not one, buttwo dinettes. Most Airstreams, particularly older models, have none. We looked at a 31-footer the other day, and it had no dinette. You are expected to eat on the couch in the front, and you know how handy and comfortable that would be.

Some newer units have dinettes, as people have complained about this long and loud, over the years.

And many older units have twin beds with a center aisle. Very Ricky-and-Lucy, but not practical for a modern age.

But what about bigger units? The 31-footer we looked at has the same layout as smaller trailers - they just give you a giant closet to fill up the space. Who needs 8-feet of closet in a camper for chrissakes? It makes no sense. Eight feet of closet and no dinette. And no, a closet is not a handy place to store your folding chairs and barbecue grill, unless you want your clothes smelling like charcoal.

And despite their enormous length, they sleep few people. The 31-footer had rear twins (which were not really full-size twin mattresses, but more like bunks) and could theoretically sleep two more on the pull-out couch. Thirty-one feet and it sleeps four. Our 18' Prowler slept six!

Clearly, these are not the choice for a family with more than two kids.


9. Parts: You can go to Camping World or go online and find parts for your RV all day long - unless, of course, it is an Airstream. For example, I just bought a new stove vent housing for $7.99 on eBay. It was also on Amazon and several other RV parts places, as well as from the original manufacturer of the part.

But for an Airstream? Many parts are "special" to the marque, and nothing else "fits" on an Airstream. You want to add a fantastic fan to your camper? Not a problem, if you have a regular camper. Oh, wait, you have an Airstream. You need the special Airstream model, as they decided to use a different sized vent opening than everyone else.

And so on, down the line. Simple parts that cost a couple of bucks for a regular trailer, are special-order pieces for an Airstream. Even the awning is different, as the arms have to have a "bend" to them to fit the side of the trailer (sort of). Nothing is simple!


10. Keeping it "Perfect": The Airstream has a "perfect" exterior, and if kept spotless - no dents, no scratches, no peeling clearcoat - it will hold its value and not depreciate too much. This is not to say theydon't depreciate. If you look at NADA guides, you can see that a $67,000 23-footer, after five years, is worth about half as much (that old "depreciates half in value every five years" rule of thumb).

This is in contrast to our 1988 Prowler 18' which we bought for $4000 and used for several years and sold for $4000. Or our 27' Wilderness 5th Wheel, which we bought for $6500, used for several years, and then sold for $6000. And the Casita, which we paid $8000 for, might fetch $6000 - or more - today. And with a cheaper trailer, even if they depreciate down to nothing, you don't lose much.

But in order to keep even the value that an Airstream has, it has to be kept original. You cannot modify it or use non-Airstream parts on it. They detract from the value, considerably.

And yet, over time, the interiors wear out - and the tambor doors for the cabinets are either NLA or horrendously expensive, so people "restore" an older Airstream using non-stock cabinets and appliances (some folks put 110V refrigerators in them!). Many become lakeside camps, and are never run again.

While a classic Airstream in excellent condition, with all-original configuration will fetch high dollars, a gutted-and-redone trailer, "modernized" and updated, may be worth a lot less.

With other types of trailers, this is not so much a concern. I am not running a trailer museum, just going camping. So, if I want to drill a hole in the side of the camper and bolt on something, I am not "desecrating" a "classic RV" or anything.

Camping should be about camping, not keeping some talisman of an icon in perfect condition all the time. When you worry about tracking dirt into your camper, maybe it is time to give up on camping. I'm just saying....

* * * ​

So why do people buy Airstreams? Well, they look cool, to be sure. And it is a cult product - you can go on Airstream Caravans, camp at Airstream parks, and join the Airstream club and lean the secret handshakes and all of that nonsense. It is retro, it is funky, and it has cache. But is cache worth spending money on? Not to me.

Like with a Harley, you can fantasize about how cool it will be to cruise down the highway in your shiny new Airstream, with everyone looking on in envy. But of course, that is sort of a ridiculous reason to buyanything isn't it? And yet we all do it, don't we? We all want to have the baddest or best whatever-on-wheels to show off our implied wealth and sophistication.

And of course, it goes without saying, that it implies status. The fellows I met towing a Bambi with their Range Rover weren't making a sound economic choice, they were making a status statement. And the statement is, "Look at me! I am better than you! I can afford to spend $100,000 to go camping!"

That sort of thing gets old really quickly. It takes no talent to go deeply into debt for status. And the ability to borrow is not a sign of real wealth. I could afford, right now, to buy 17 of such rigs. I choose not to. The cost of buying "brandy-new" is just too staggering. And frankly, what is the fun in that? It takes no talent to go to the dealer and write checks (or worse yet, take out a loan). No one is "impressed" by your ability to go into debt to acquire consumer goods.

(Some people really think this - that their ability to borrow to buy bling is a sign of their wealth, which they measure in terms of monthly income and credit score. Borrowing is not wealth, it is anti-wealth. And anyone with a W-2 and no common sense can go into debt up to their eyeballs to buy just about anything. It is not a sign of wealth or sophistication, but often poverty and stupidity).

It would be fun to restore a vintage Airstream from the 1960's and tow it with a restored International Travelall (with fake wood on the sides, of course). But then again, the reality of the costs involved make me realize that it would be an expensive fantasy, and the reality of driving an older vehicle and an older trailer, well, it would have its challenges.

But for me, the allure of RVing may be wearing off, quickly. Event the maintenance on a "small" trailer like we have, gets to be a lot, over time. I have spend the last four days repacking wheel bearings, fixing a refrigerator door, steam-cleaning the carpeting, and tightening screws and replacing loose rivets. Keeping even a lesser RV in good working order is, well, a lot of work.

Just driving somewhere and staying in a rented house or B&B starts to look more alluring than dragging your house with you, all the time. And maybe in a few years, that is what we will do.

But the thought of spending tens of thousands of dollars on an RV? It is just not in the cards, even if I could afford to "pay cash" for one - and I can, but I choose not to. Maybe if I won the lottery. But then again, if I won the lottery, I would have a private jet and a limo, right?

There. Permanently preserved in the vault that is ExPo. Note that I grabbed the very last copy of this article that the WayBack machine snapped, the one snapped on September 15th, 2015 -- see http://web.archive.org/web/20150315000000*/http://livingstingy.blogspot.com/2012/07/airstreams.html and http://web.archive.org/web/20150322011237/http://livingstingy.blogspot.com/2012/07/airstreams.html .

For our present purposes, the basic issue is that because the outside aluminum skins of Aistreams are still riveted, and not welded, sooner or later they begin to leak, horribly. This is not an argument against aluminum, so much as it is an argument against building a trailer out of aluminum sheets merely riveted together. When Air-stream first began building its trailers, riveting was the only cost-effective technology available for working with aluminum. But as already stated, aluminum welding has come a very long way in 50 years:






Here again I want to emphasize that throughout this posting series I have shown tremendous enthusiasm for Airstream, mainly because I like their curvilinear metal exteriors, and I like the interiors of Airstreams designed by Christopher C. Deam specifically (not all Airstream interiors are/were designed by Deam). But the excellent blog-post just referenced and reposted in its entirety, has gotten me thinking, and it has to be admittetd that a single-piece carbon-fiber or aluminum roof is much preferred to a roof made out of any other material, because in principle it can't leak, except (maybe) where it would be perforated by hatches. Or by tubes where we would want it to leak, to collect rainwater…..

So in the case of Airstream, it has to be admitted that they've come to fetishize not just a material (aluminum), but a seriously outdated construction technique, namely, riveting.

Here it's worth noting that Livin Lite (owned by the same company that owns Airstream) also sells aluminum-framed campers. But the aluminum pieces in Livin Lite campers are welded, not riveted – see http://www.livinlite.com/camplite-overview.php :






Futhermore, LivinLite campers combine aluminum space-frame, cabinet, and flooring construction, with composite side-panels, roofing, etc. This seems more the way to go for the TerraLiner, at least for the end-caps where more complex geometries might be desired, as per Newell. Otherwise, again as per Newell, a welded aluminum skin everywhere else.



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5. Not Letting Structure Over-Determine Design


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Just a word of caution, however. To my mind Livin Lite’s visual fetishization of its aluminum-framed construction seems a bit cack-handed and clumsy, at least from a design point of view. I don't see any reason why the aluminum-framed construction actually has to be visible. LivinLite seems to think it necessary to show the aluminum structural framing on each and every one of its drawers, cup-boards, tables, and beds:








The contrast here would be with how Kimberley builds its kitchens, for instance:

"No Timber" cupboards and drawers. All the Kimberley drawers and cupboards and structured in aluminium alloy and generally powder coated. The exception is the underbed storage drawers in the Kamper which are stainless steel because of the wide open size.

Sorry, but the image with all the drawers open in the Kruiser T’s kitchen, showing their aluminum sides, was the biggest such image I could find on the Kimberley website. It’s very low-resolution, but demonstrates the basic idea. Then second image is the aluminum-honeycomb solid-surface benchtop from the smaller Kruiser S-class.

And yet, even though the Kruiser T’s kitchen’s is constructed out of aluminum, Kimberley still laminates its cuboard and drawer fronts in cherry wood – see http://www.kimberleykaravans.com/lightweight-innovative-materials , http://www.kimberleykruiser.com/timber , and http://www.kimberleykruiser.com/cooking-appliances-kitchen . In other words, even even though like LivinLite, Kimberley is committed to aluminum-framed interior consruction, Kimberley does not feel the need to visually fetishize that fact. If you hadn’t seen the image of what a Kimberley Kruiser T3 kitchen looks like prior to the application of laminates, you might never know that it is mostly aluminum behind the cherry wood façade. You might mistakenly assume that Kimberley’s kitchens are just made out of pine or plywood, as per the kitchens in any number of low-grade American campers and motohroms. Kimberley goes the extra mile, combining great engineering with great aesthetics, and the TerraLiner should want to do the same.

Here I should note that the LivinLite interiors are not aesthetically "bad". They are not "grandma's kitchen", like the interiors of so many American motorhomes. They even have a kind of hyper-functional logic, and a certain degree of elegance. But they're still nowhere near as beautiful as Kimberley's kitchens.

Moreover, Kimberley’s camper shell is not just sandwich composite panels glued together, as per so many expedition motorhomes. Rather, it’s a combination of aluminum and fiberglass:

Rolled and curved Fibreglass profile. This gives maximum strength for the minimum amount of fibreglass material. Complex to make but so strong once made, the multi-dimensional corners and alloy inserts result in the lightest designs. Despite rollovers and accidents, Kimberley is not aware of any fibreglass component that has failed.

See http://info.kimberleykruiser.com/of...uminium-material-technology-like-range-rover/ . In other words, just like Blissmobil, Kimberley sees the wisdom in combining a metal frame with fiberglass; in the case of Blissmobil, composite sandwich panels that are 60 mm thick – see http://www.blissmobil.com/en/products-en/20-foot-body-en/the-body-20ft.html :







But needless to say, both companies thoroughly understand that despite the metal framing, the camper shell has to be completely free of thermal bridges. In the case of Blissmobil, all potential thermal bridges are insulated using aerogel and finished with polyester trimming. And yet the Kimberley Kruiser still manages to achieve a wonderfully curvilinear external appearance, despite sharing similar construction characteristics with Bliss Mobil.

This is intelligent engineering, combined with first-class design.s


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6. Not Fetishizing Any One Kind of Material


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To my way of thinking, it's a bit foolish to get too caught up with the question of materials. All materials have their uses, their advantages and disadvantages. Only sophisticated engineering analysis can determine what might be the “best” material for a given element in the TerraLiner's design.

For instance, Kimberley looked into the possibility of an all-aluminum, more lightweight chassis on which their camper shells might sit, but found that:

In the off-road industry, many manufacturers have tried all aluminium trailers and chassis with dismal results. Fatigue cracking of off road chassis will get the better of an all aluminium solution in the 1-2 tonne trailer weight.

See http://info.kimberleykaravans.com/b...onsumption-with-Lightweight-Off-road-Caravans . So at one point Kimberley had settled on continuing to build an all-steel chassis http://www.kimberleykampers.com/chassis-suspension , and http://www.kimberleykaravans.com/offroad-caravan-chassis-and-suspension .

More recently, Kimberley has developed a Hybrid steel-aluminum chassis – again, see http://info.kimberleykaravans.com/b...onsumption-with-Lightweight-Off-road-Caravans , http://info.kimberleykruiser.com/improve-your-fuel-consumption-with-lightweight-off-road-caravans/ , and http://www.kimberleygroup.com.au/im...-caravans-Brochure-pages-20052015-low-res.pdf . This most recent design actually uses a combination of three metals:

There are 3 principal metals used by Kimberley [in its chassis]:

• Hot dipped Galvanized Steel,
• 6061 or 6060 Marine Grade Aluminium and
• 304 Stainless steel.

The Chassis which includes the drawbar, the chassis rails, the suspension “hangers”, and the rear tie plate are all hot dipped galvanized.

Similarly, Kimberley will use a combination of stainless steel and aluminum in its outdoor kitchens. Stainless steel for the sink and work surfaces, and aluminum for the drawers and understructure:

Pre-stressed alloy and stainless steel drawer and hatch combinations. This combination of stainless and aluminium needs carefull fastening for vibration proof durability. The result gives you both ultra light weight and a durable low maintenance surface. Kitchen slides, hatch doors, rear hatches and storage drawers use the combination cleverly.

See http://www.kimberleykaravans.com/offroad-caravan-cooking-options-and-layouts , http://www.kimberleykampers.com/cooking-options , and http://www.kimberleykaravans.com/lightweight-innovative-materials .

Along similar lines, although most of the Kimberley Kruiser T's interior kitchen is constructed out of aluminum, the lowest and biggest drawers that have to carry heavy pots and pans are constructed out of stainless steel. So too, the big drawer underneath the bed in a Kimberley Karavan is stainless steel, because it's so large.


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7. Matching the material to the actual requirement: TerraLiner Security


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There are other possibilities when it comes to materials, and a number of times in the thread some have asked about bullet-proof glass, or armored plating.

Armored motorhomes have been created -- see http://www.huenerkopf.de/en/wohnmobile/prevost-besprechungsmobil/galerie and http://www.huenerkopf.de/en/archives/187 . And Merkavim Transportation Technologies in Israel produces a special armored passenger bus, called the "Mars Defender" -- see http://www.merkavim.co.il/en/Project/34/Mars-Defender , http://www.moital.gov.il/cmstamat/Rsrc/ICA/Automotive 2104/pdf/Auto_099.pdf , and http://www.defesanet.com.br/en/e_la...veal-the-World-s-Best-Protected-Armored-Bus-/ :










But all the heavy steel plating and bomb-proof glass that Merkavim installs in its buses would be completely unnecessary for the TerraLiner. The Mars Defender is basically a transit bus designed to drive through a war-zone, where the possibility of attack by an IED is imminent and real. The potential threat to the TerraLiner when underway is much lighter than that, more like the threat that motorists in Brazil encounter: small-arms fire. Basically, the bullets of pistols and guns, not a rocket attack, grenade, or bomb.

So in post #2179 at http://www.expeditionportal.com/for...w-6x6-Hybrid-Drivetrain?p=1987764#post1987764 , I noted that cars in Brazil are now being sold factory-equipped with a lighter kind of protection, a form of Kevlar made by Dupont called "Armura" -- see http://www.dupont.com/corporate-fun...es/protection/articles/better-protection.html , http://www.dupont.com/corporate-fun...otection/articles/brazil-life-protection.html , http://www.dupont.com.br/dpt/armura/dupont-armura-home.html , http://www.dupont.com.br/dpt/armura/dupont-armura.html , http://www.dupont.com.br/dpt/armura/modelos/blindagem-audi.html , http://www.dupont.com.br/dpt/armura/modelos/blindagem-bmw.html , http://www.dupont.com.br/dpt/armura/modelos/blindagem-honda.html , http://www.dupont.com.br/dpt/armura/modelos/blindagem-mitsubishi.html , http://www.dupont.com.br/dpt/armura/modelos/blindagem-toyota.html , http://www.dupont.com.br/dpt/armura/novidades.html , http://www.reuters.com/article/us-dupont-brazil-idUSBRE83E06I20120415 , http://www.reuters.com/article/uk-dupont-brazil-idUSLNE83F03720120416 , http://uk.reuters.com/article/uk-dupont-brazil-idUKBRE83F0FB20120416 , http://www.philly.com/philly/blogs/...or-the-middle-class-not-available-in-USA.html , http://www.lipstickalley.com/showth...-Are-Paying-12-000-Per-Car-For-Bulletproofing! , http://www.nytimes.com/2009/05/04/world/americas/04brazil.html?_r=0 , http://www.boston.com/business/articles/2011/11/30/bulletproof_boom_armored_cars_in_latin_america/ , http://www.carscoops.com/2015/11/failed-brazilian-carjacking-would-make.html , http://www.telegraph.co.uk/sport/fo...killed-in-attempted-carjacking-in-Brazil.html , and http://estadodeminas.vrum.com.br/ap...-blindagem-automotiva-em-belo-horizonte.shtml :










Granted, "Armura" is much cheaper than the kind of stuff installed by Texas Armoring, because Armura is not being aimed at Brazil's rich elite, but rather, at Brazil's middle-class -- see http://www.texasarmoring.com . But because it's Kevlar and not steel, it's far lighter; and because the "sentry glass" is designed to stop bullets, and not bombs, it too is much lighter.



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8. The Range of Materials that Texas Armoring Uses


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Actually, Texas Armoring doesn't use steel very much either: for the list of of its armoring materials, most of them plastics and composites including kevlar, see http://www.texasarmoring.com/armored_vehicle_bulletproofing_materials.html ;










Armoring with steel is actually simplistic and crude, and armoring with lots of heavy steel is the "cheap" route offered by less reputable companies:

---

What's the difference between "all-steel" and "lightweight" armoring?

Many companies are offering bottom-of-the-barrel armoring packages at deeply discounted rates. These packages usually employ all-steel armoring, sub-standard bulletproof glass, and armor that may or may not truly meet ballistic standards. In contrast, we offer lightweight composite packages that utilize space-age composite materials and cutting-edge installation techniques for maximum protection coverage. All-steel armoring packages are considered second rate and will typically weigh 1,500 lbs more than our lightweight packages. This unnecessary added weight has a severe impact on the maneuverability and overall lifespan of the vehicle, basically negating any cost savings associated with such a package.

---

How much weight will you add?

Weight added will depend on the level of armoring requested and the type of vehicle to be armored. We will add between 400-1,500lbs on a typical SUV for our most common armoring packages.

See http://www.texasarmoring.com/texas_armoring_faq.html .

As I wrote before, when designing the TerraLiner, it seems to me that the "target" should be to make it potentially usable in a country like Brazil. Brazil is a middle-income country with excellent super-highways, the Peace-Index maps locate Brazil somewhere in the middle, travel advisories classify Brazil together with China, and only Brazil's slightly elevated Mexican/Russian/Peruvian/Namibian rate of homicide will give pause for concern. Carjacking and kidnapping is now a common problem in Brazil, to be sure. But that doesn't mean that one needs to drive through Brazil in the motorhome equivalent of a tank. If one were driving the TerraLiner through the Palestinian territories where there is a constant risk of IEDs, then sure, a steel-plated heavy behemoth like the "Mars Defender" bus would be necessary. But countries with that level of threat should be avoided to begin with. In Latin America, this may include avoiding Venezuela, Colombia, and Honduras. And in Africa, it may include avoiding South Africa, while visiting Namibia, Botswana, and Zambia instead.

There are intelligent ways to use materials and construction techniques to create a globally capable motorhome/mobile house, and then there are "evangelical,", "cultish", "paranoid", "militant" -- or simply overly emotional -- ways to use materials. The incorporation of layers of lightweight Kevlar behind the TerraLiner's aluminum skin strikes me as an excellent idea, as long as it does not add more than 500 kg to the motorhome. And reasonably bullet-proof glass for the cab also seems a good idea. The "Armura" kits sold by Dupont in Brazil cost 12,000 USD (which is a lot of money for someone Brazilian and middle-glass), but they weigh only 200 pounds, or just 90 kg. That's just for a car. In the TerraLiner, depending on the weight, it's possible that all of the sides of the vehicles might have aluminum skins backed by Kevlar; or it's possible that only the front Cab Area will.

Similarly, there does not seem to be a good reason for the camper box (as opposed to the Cab Area) to have bullet-proof glass, although shatter-proof (i.e. burglar proof) glass is now standard for expedition motorhomes, and is quite lightweight. Only the front Cab Area would need the stronger, truly bullet-proof windows and windshield.

The overall idea is that it's important to be realistic about the level of threat the TerraLiner might encounter, and about where the TerraLiner will, and will not, want to go. And to then design various kinds of protections proportionately and differentially. It makes no sense to armor and protect the entire vehicle, for instance, to the same level that one armors and protects the Cab Area.


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9. Underbody Blast Protection?


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The only other major security issue that might be worth designing for, is underbody blast protection. In many parts of the world conflicts have left behind minefields where even those who put in the mines no longer know where they are. This was already discussed in post #83 at http://www.expeditionportal.com/for...w-6x6-Hybrid-Drivetrain?p=1565461#post1565461 .

Here too one quickly enters very exotic territory, and it's easy to get lost in the details. I simply wanted to mention again an interesting German company called Drehtainer, whose blast-proof Medical and/or Command vehicle was described earlier in the thread, in post #75 at http://www.expeditionportal.com/for...w-6x6-Hybrid-Drivetrain?p=1564913#post1564913 . Drehtainer is a company specialized in the fabrication of hi-spec containers, for instance, modular camp containers and medical evacuation containers – see http://www.drehtainer.com , http://www.drehtainer.com/company/about-drehtainer.html , http://www.drehtainer.com/products.html , http://www.drehtainer.com/products/vehicle-components/functional-areas.html , http://www.drehtainer.com/products/defence.html , http://www.army-technology.com/contractors/field/drehtainer/ , http://www.drehtainer.com/products/vehicle-components/mobitainer.html , http://www.drehtainer.com/products/vehicle-components/functional-areas.html , http://www.drehtainer.com/uploads/media/Brochure-blast-resisting-buildings.pdf , and http://www.drehtainer.com/uploads/media/brochure-mobile-employment.pdf

But Drehtainer has also developed a particular speciality in manufacturing containers for use in the field by militaries -- see http://www.drehtainer.com/products/defence.html , http://www.drehtainer.com/products/defence/expandable-container.html , http://www.drehtainer.com/products/defence/military-camp.html , http://www.drehtainer.com/products/defence/command-post.html , http://www.drehtainer.com/products/defence/gvtc.html , http://www.drehtainer.com/products/defence/multi-purpose-cont.html , http://www.army-technology.com/contractors/field/drehtainer/ , and http://www.miltechmag.com/2015/02/idex-2015-drehtainer-sophisticated.html .

And within that container sub-speciality, it has developed containers that are blast-proof or IED-proof -- see http://www.drehtainer.com/products/vehicle-components/anti-mine-anti-ied-protection.html , http://www.drehtainer.com/protection/blast-protection.html , http://www.drehtainer.com/products/industry/blast-resistant-building/protection.html , http://www.drehtainer.com/protection/ballistic-tests.html , http://www.drehtainer.com/protection/anti-mine-anti-ied-protection.html , and http://www.drehtainer.com/uploads/media/Brochure-Protection.pdf .

When I first posted images of Drehtainer's MFD, or "Modular Flexible Drive" concept vehicle, I mainly posted them because:


(a) the MFD is based on a Tatra 8x8 backbone tube
(b) it very nicely demonstrates that a fully integrated "camper shell" can be built on top of a Tatra backbone tube, because the tube is so torsionally stiff
(c) the MFD looks kinda cool


The MFD is basically a modular vehicle system that can be quickly configured to be set up, say, as a field hospital – see http://www.drehtainer.com/nc/news/p.../weltpremiere-des-mfd-auf-der-eurosatory.html , http://www.drehtainer.com/news/dreh...ewsdetail/article/modular-flexible-drive.html , https://www.yumpu.com/en/document/view/7014595/data-sheet-modular-flexible-drive-drehtainercom , and https://www.yumpu.com/de/document/view/7607981/saving-soldiers-lives-drehtainer-gmbh . Once the vehicles are aligned and connected, staff can move easily from one vehicle to the next, and enjoy full protection:










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For additional pictures, see http://filterman.funpic.org/09-secours_camion_pc_drehtainer.htm , http://www.commercialmotor.com/big-lorry-blog/awesome-armoured-fighting-vehi , and http://forum.bernard.debucquoi.com/viewtopic.php?f=11&t=4833&start=60 .



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10. Zero-Shock Blast Protection


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When I first posted the pictures above, I did not fully appreciate that the main "concept" behind the MFD's underbody blast protection, something called "Zero Shock" -- see http://www.drehtainer.com/products/vehicle-components.html , http://www.drehtainer.com/products/vehicle-components/anti-mine-anti-ied-protection.html , http://www.drehtainer.com/products/defence/zero-shockr.html , http://www.drehtainer.com/uploads/media/Data-sheet_zero-shock_02.pdf , http://www.readperiodicals.com/201304/2988153521.html , http://www.adjacentgovernment.co.uk...vgam-100-protection-mine-blast-effects/11959/ , and http://www.army-technology.com/products/zero-shock-system/zero-shock-system1.html .

It's a fascinating system in which the shockwave from an underbody blast is almost completely mitigated by releasing the main floor of the container, and letting it drop. This may seem insane and counter-intuitive, unless one thinks through what an underbody blast actually does. An underbody blast wants to "push" the whole vehicle upwards. So it transfers an upwards "shock" to all the furniture and components in the vehicle. By having all of these sitting on a secondary floor that can suddenly be put into free-fall, the shock of the blast only affects the underside of the vehicle and of course the walls. The upwards thrust is not transferred to the furniture or the components in the vehicle, because they are sitting on the secondary floor that has now been released into free-fall.

It's super-cool when you think about it, but I can't explain it any better than that. Here are some images:








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A system this complex obviously can't be used in the TerraLiner, if only because it consumes a considerable amount of extra height. Even if only 10 cm were required, 10 cm would be too much. But Drehtainer is an interesting company, and seems to have thought long and hard about blast protection for large vehicles.



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11. A Titanium/Fiber/Ceramic Underbody Blast Protection Shield?


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When one first thinks of underbody blast protection for the TerraLiner, one thinks of a big steel plate. But that's out of the question, because it would be too heavy.

However, given that the TerraLiner might want to follow Tesla's lead, and fit a series of Titanium plates to its underbody to protect the batteries against fire due to debris impact, perhaps Titanium plates alone might afford sufficient, lightweight, albeit very expensive blast protection? I don't know the "blast protective" properties of Titanium, but they must be considerable, because Titanium's melting point is higher than steel, Titanium has higher tensile strength, and Titanium will "stretch" or elongate much further than steel before it breaks. On the other hand Titanium is only 56 percent as dense as steel, and that might be a negative when thinking about blast protection. Titanium is also half as stiff as steel for a given weight, so if "stiffness" or "density" are important factors in blast protection, then Titanium might offer few advantages over steel.

On the other hand, blast protection is also about energy absorption, and given Titanium's ability to flex further before it breaks, this might make it a good material. I honestly have no idea -- see http://www.ibiscycles.com/support/technical_articles/metallurgy_for_cyclists/the_titanium_advantage/ and http://www.garelicksteel.com/pdfs/Melting_Points_of_Common_Metals.pdf . Titanium probably has not been tried much as a material in a blast protection shield simply because it's so expensive. But given that the name of the game in blast protection is usually energy absorption or energy dispersal, it's possible that Drehtainer has developed fiber or ceramic forms of underbody blast-protection that could be combined with a thinner, outer layer of Titanium, to create a blast-protection underbody shield that's just as good as a thick steel plate, but weighs just 1/4 as much.....

Only one thing seems certain: simply installing a big, thick, heavy steel plate is out of the question, for most of the length of the TerraLiner. The only possible exception might be the Cab Area. But even there one would want to talk with companies that offer more "sophisticated", lightweight, and proven blast-protection products. Unfortunately, unlike Texas Armoring, Drehtainer seems to provide no information about the various types of materials that it uses for blast and bullet protection.



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12. Protecting the Cab Area


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With that said, one of Drehtainer's more interesting products is a custom-built protected driver's cab -- see http://www.drehtainer.com/products/vehicle-components/protected-drivers-cab.html :







Recall that earlier in the thread when discussing how Rosenbauer builds firestruck cabs and bodies out of aluminum, I expressed some admiration for the beautifully sculpted, very impact resistant, and crush-proof "Commander" cab -- see post #1886 at http://www.expeditionportal.com/for...w-6x6-Hybrid-Drivetrain?p=1955691#post1955691 for the previous discussion:







If I have one criticism of Newell's construction technique, it would be its use of fiberglass for the end-caps. I understand why Newell does this, and has to do this: only by using fiberglass molds can it cost-effectively get the wonderfully rounded detailing of the end-caps as designed by Porsche. Newell could try doing the end-caps in hammered aluminum instead, but that would cost a fortune, and Newell coaches are already pricey enough as it is. Again, there is a terrific gallery of Porsche's exterior design work for Newell at http://www.caranddriver.com/photo-gallery/newell-p2000i-rv-review-feature#5 and following.

But somehow, a fiberglass end-cap that looks something like the following images does not inspire much confidence:







This end-cap is not from a Newell coach. But it provides a good idea of what a fiber-glass end-cap looks like. I don't know if Newell installs additional steel roll-bars in the Cab Area, or protective steel bars in front of the driver's and passenger's seats. I would be very surprised if it did not, because if a fiberglass end-cap like this were the only thing separating me from a head-on collision, I'd be very worried. Newell coaches cost over a million USD, so one imagines that they've developed some kind of steel roll cage for the Cab Area, even though the encasing end-cap is fiberglass for stylistic purposes.


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13. A Panoramic Bullet-Proof Cab Area


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So I figure that if Rosenbauer builds the Panther, and if Rosenbauer is extremely comfortable sculpting aluminum Cab-Areas for fire-trucks in any case (which it does seem to be, and then some....), then why not have Rosenbauer construct the Cab Area of the TerraLiner, perhaps in consultation with Drehtainer? The Drehtainer cab is no doubt completely blast-proof, but it's rectilinearity leaves much to be desired. Notice, however, that the windows in the Drehtainer cab are not that small:







They are flat, which is a good thing from the point of view of replaceability. If a large rock damages the front windshield, for instance, of course the rock won't go through (the windshield is bullet-proof and shatter-proof), but the crackle impact that it leaves behind will obstruct visibility. So if the TerraLiner were stuck in the middle of nowhere, what would be wanted is the ability to replace the front windshield with very ordinary, flat, easily available auto glass. That way the TerraLiner could still drive around until the replacement bulletproof glass arrives.

My thinking is that in principle there should be no reason why the Drehtainer cab could not be redesigned so that another large flat pane of glass joins at an angle with the front windshield overhead, to provide more of a Rosenbauer Panther type of viewing experience:









Or perhaps three flat panes of glass join together to form the same kind of large curved windshield we see above in the Rosenbauer Panther.

Furthermore, where the lines in the Drehtainer cab don't have to be straight (for instance, the lower body), those too could be more curvilinear like the Panther. The reason Drehtrainer's cab interests me, of course, is because again, I suspect that it's not merely fashioned out of steel in any kind of simplistic way. I suspect that Drehtrainer is using much more sophisticated kinds of blast-protection materials and technologies, in order to save on weight as well as improve protection. But once again, unfortunately, Drehtainer seems to provide no information on-line about the kinds of protection materials it uses.

Another vehicle that I've mentioned a few times and that I find inspiring is the Burstner Panorama -- see posts #100 and #101 in the "Camper Thermal Engineering Thread" at http://www.expeditionportal.com/for...Arctic-Antarctica-Tibet?p=1669493#post1669493 and following:







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So expressed as a rebus (see https://en.wikipedia.org/wiki/Rebus ), what's basically wanted for the TerraLiner Cab Area is some combination of the following:





..+.. ..+...



...+..... = The TerraLiner Cab





The important thing to remember here is that the TerraLiner's Cab Area -- if it needs "underbody blast protection" at all -- would only need blast protection from below. Our concern would be an undetonated mine somewhere in Nambia or Zambia near the Anglolan border. Our concern should not be an IED set up to do maximum damage by blasting a vehicle from the side, 4 or 5 feet above the ground.

So when it comes to the windows and sidewalls, what's needed is merely protection against small firearms, i.e. pistols, rifles, and shotguns. The TerraLiner's Cab Area does not need windows and side-walls that can protect against rockets, missiles, or grenades. And furthermore, the Cab Area needs the most ordinary kinds of protection of all: excellent protection against a head-on collision, a side-collision, and against a rollover.

So getting the balance "just right" in the equation spelled out above for TerraLiner cab design, might prove a rather complicated task!! It's certainly possible that the very idea of a "Panoramic Bullet-Proof Cab Area" is an oxymoron, a contradiction in terms. I've done lots of concept drawings, but realistically speaking one could only take things to a more definitive level in CAD via consultation with companies like Drehtainer and Texas Armoring. In a nutshell, it's all about the windows: what kinds of windows will protect one against a certain level of small-arms threat; how large such windows can be; and whether they can be arranged in a limited number of flat sections to create a "panoramic" Cab Area, while preserving excellent TerraLiner aerodynamics.

A complicated design problem indeed! :wings:


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Well, returning to Titanium and Tesla, Titanium does seem like it might be the perfect material for the massive underbody "skid plate" that you proposed a while back, Libransser; a skid plate that would run the length of the bottom of the TerraLiner..... It was a good idea for skid-plate reasons, but turns out that it's a good idea for battery-protection reasons, too. And as written previously, it's also a good idea for aerodynamic reasons: having a completely smooth underbelly will dramatically improve the TerraLiner's drag coefficient. But again, the Titanium would probably be fastened in a series of removable sections.

Using Titanium anywhere else in the TerraLiner? Probably not.


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Also check out some of these interesting details on a Miilenium Coach: the radiator and the exhaust are mounted on the roof; and Millennium advertises its chassis made by Prevost as "torsionally rigid" -- see http://www.millenniumluxurycoaches.com/features/ .

I just wanted to get in these thoughts about TerraLiner construction here, because grizzlyj raised some construction issues, to which I responded, and these posts add a bit more to that discussion. But now back to batteries, power calculations, and the drivetrain.....:sombrero:

All best wishes,



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