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

[biotect]

..

Assuming we cater for Ian's 450kw calculation on power requirements in LifePO4 running at full power (won't all the time, but makes for an interesting exercise).

Hi Joe,

I think Ian just recently revised his power estimate down to 248 KW. It would also be interesting to hear from Haf-E or egn, what their estimates might be, given the current TerraLiner specifications.

The only really useful calculation, would be what kind of battery bank would be necessary to serve as a "buffer" in fully serial hybrid mode. The TerraLiner is not intended as an all-electric vehicle, and it does not need to have an extended all-eletcric range. It only needs to be able to drive all-elecrtric for an hour or two at best, and perhaps even less than an hour?. The TerraLiner only needs the battery bank merely to act as a kind of "power reserve" when climbing inclines.

So right off the bat I would say that if 2 hours at 450 KW means an 11.6 ton battery bank, then 248 KW for 1 hour means a 3.1 ton battery bank. If 1 hour is enough, then that's what I'd go for. And if 30 minutes were enough, then I'd go for that instead. Furthermore, I'd want to investigate whether even lighter and more advanced Lith-Ion batteries are available.

I appreciate the value of purely theoretical exercises, but they can also have a rhetorical impact that leads to false conclusions. If someone reads "11 ton battery bank", and they don't realize that you were engaged in an extreme all-electric-for-two-hours sort of hypothetical exercise, they may conclude that thinking through a TerraLiner hybrid drive-train is not worthwhile. I think it is worthwhile, so if possible, it would be great if you might be wiling to run your numbers again for the parameters as stated in the following summary:

12 m long, 21 - 23 tons, 24 tons maximum, 6x6, two Jenoptik diesel generators producing 240 KW, and some size of battery bank, so that the TerraLiner might travel on electric power alone for 1 - 2 hours at most, perhaps as little as 20 - 30 minutes, and not more. Probably at least 90 % of the time or more the TerraLiner will be driving in full hybrid mode. Also, don't forget that the TerraLiner will also be towing a three-axle draw-bar trailer.

With that said, that sure was a really nifty set of calculations!!! It left my head spinning in quantitative bliss, and my heart laughing with auto-geek glee! :wings::wings:

Also: many, many thanks for playing the game of "argument and evidence" so tightly. Your post was packed with links, and all your reasoning was explicit and clear. Your post could serve as an exemplar for what all of the more "technical" or "engineering" posts should be like in this thread. Very, very much appreciated!!


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


Now even 3 tons sounds awfully high. I wonder how big the Wrightspeed battery bank is? Or I wonder how much the Proterra battery bank weighs, per KW?

Proterra claims that it has the most efficient battery bank on the market, so it would be interesting to rerun your calculations using Proterra's data as a starting point. See http://www.proterra.com , http://www.proterra.com/product-tech/product-specs/ , http://www.proterra.com/product-tech/product-portfolio/ , http://www.proterra.com/wp-content/uploads/2015/05/Tearsheets_FastCharge.pdf , http://www.proterra.com/wp-content/uploads/2015/05/Tearsheets_ExtendedRange.pdf , http://www.proterra.com/proterra-introduces-extended-range-electric-bus-flexible-battery-system/, https://chargedevs.com/newswire/pro...xr-battery-enables-ranges-of-up-to-180-miles/ , http://www.greencarcongress.com/2015/02/20150224-proterra.html , and http://gas2.org/2015/02/25/proterra-announces-extended-range-electric-bus-180-mile-range/.

Proterra is not very forthcoming with details in any of the above, but if you read the following PDF in particular, you'll see that it states that Proterra's extended range battery pack weighs 770 lbs -- see http://www.proterra.com/wp-content/uploads/2015/05/Tearsheets_CatalystPlatform.pdf . Let's just assume for the sake of argument that Proterra's extended range battery pack, for this weight, will deliver 257 KW, because it's the same battery pack that was tested in the following video. It may not be, but let's just assume that it is:






The video does say that its current fast-charge battery pack delivers 100 KW, and we know from the PDF that the fast-charge battery pack weighs 524 lbs. For further discussion, see post #1918 at http://www.expeditionportal.com/for...igid-Torsion-Free-Frame?p=1959999#post1959999 .

So reasoning very simplistically, if Ian's 248 KW figure were correct, then two such Proterra battery packs should last two hours, and would weigh only 1540 lbs, or roughly 700 kg. Which is a lot less than 11 tons!!

However, here I am also assuming that the PDF, when it lists the weight for a battery pack for given size of bus, is describing the battery weight for a bus with a standard configuration of 8 battery packs. I am assuming that 750 lbs refers to the total weight of 8 packs combined. If instead it refers to the weight of just one battery pack, then 8 battery packs would weigh 6000 pounds, or 2,721 kilos, delivering 257 KW. That would still be better than 3.1 tons for 248 KW, but not that much better. There is some ambiguity in the PDF, and it's difficult to know for certain what is being stated.

In any case, the key when estimating battery pack size and weight for the TerraLiner is not to use the statistics on Lith-Ion batteries that are common, widely available, and that have technology that's 5 years old. Rather, the key is to seek out info about battery pack solutions at the very "cutting edge" of the market, and extrapolate from there. Note that Proterra's 257 KW extended range battery pack is nickel-magnesim, and not Lith-ion. Lith-ion may not be the most promising technology possible, and even more efficient battery packs may emerge based on other technologies. After all, the target date for TerraLiner fabrication is 2018 - 2020, not 2015, and not 2010. It seems reasonable to bank on the possibility that if Proterra achieved 257 KW with a 750 lbs battery pack in 2015, then by 2020 the same battery weight should be delivering perhaps double that, at the "leading edge" of the market. Or that if the figure is more like 257 KW with a 2,721 kg battery bank composed of 8 extended-range packs, then by 2020 at least that figure might be cut in half, down to 1,360 kg, with 257 KW delivered by just 4 Proterra extended range battery packs.

And who knows, maybe even 1 hour of all-electric travel time is unnecessary? Even if Ian's 248 KW figure were accurate, perhaps to act as a successful peak-power buffer the battery pack still only needs to be 100 KW? And perhaps all-electric travel time only needs to be 1/2 an hour, or as little as 20 minutes?

There are a large number of variables in play here, and it's easy to construct an "alarmist" scenario because one assumes a value for one of the variables that one does not need to assume. I'd like to research MAN's Lion City Hybrid, for instance, to find out just how much all-electric run-time it has; how big the electric motors are; how big the diesel generator is; how big the battery bank is; how large a typical Lion City bus is; and how much it weighs. There are Lion City buses that are much longer "articulated" vehicles, in other words, "bendy buses" up to 18.75 m long -- see https://en.wikipedia.org/wiki/MAN_Lion's_City . The 18.75 m buses do come in hybrid diesel-electric format. Although an articulated city bus is not an off-road motorhome, a bus of this kind would provide a much more accurate precedent regarding what the TerraLiner actually needs, and how the various variables should be optimally set. It would suggest the size of a battery pack sufficient for accelerating or climbing inclines, for instance.

I'd like to do the same research into the Volvo 7900 bus, in its hybrid version, and not its all-electric version. I am still not sure what would be the exact equivalent in IVECO hybrid technology, but here too, a hybrid bus should give us at least some base-line "realistic" variable to work with: motor size, generator size, battery size, all-electric run time, etc.

Right now I have to focus on other things. But if anyone wants to do the research and post it here, by all means, please do!!! For very comprehensive summaries of manufacturers of hybrid buses worldwide, see post #1911, at http://www.expeditionportal.com/for...igid-Torsion-Free-Frame?p=1959802#post1959802 . Still haven't uploaded all the pages in those PDFs to the thread (uploading PDF pages is particularly time-consuming), but the links to those two excellent PDFs are there in that post.

All best wishes,



Biotect

 

[nick disjunkt]

Hi Biotect,

you might find the MV Hallaig interesting. It's a pioneering hybrid ferry built to sail between the Scottish islands on the west coast.

I learnt about if from the life at the end of the road blog that Paul keeps about his off-grid existence on Raasay.

A few of Paul's posts give some technical information but the one below has some great photos.

https://lifeattheendoftheroad.wordpress.com/2014/12/31/the-office-party/

If you have the time to search through his blog there's information about who supplied and commissioned the drive systems, and more about how it works.

Nick

 

[biotect]

Hi Nick,

What is it about "wordpress"? I have a very fast, very powerful computer, and a great internet connection. Literally every website on earth opens up for me without a problem, unless it is dead. But to be blunt, "wordpress" websites suck. Less than 20 % of the time do they open up for me on the first try. I get the feeling that many people created webpages and blogs on wordpress simply because doing so is free. Unfortunately, you get what you pay for, and if you create a website on a free platform, the quality of your website will be substandard.

One possibility is that the wordpress has not kept up with providing enough hardware to support user volume, and maybe that's why it gets so horribly bogged down. There may also be problems with the basic code of wordpress, which apparently is a mess, PHP is a terrible language, and no website built on wordpress is ever going to be as fast as a properly coded "custom" website, or a static HTML page -- see https://tommcfarlin.com/hate-and-vitriol-of-wordpress/ and https://premium.wpmudev.org/blog/wordpress-aint-perfect/ . Maybe all the plug-ins and themes that some users load into wordpress are the problem. I don't know; all I do know is that occasionally wordpress links open up for me, but more often than not they don't. It's gotten to the point where if something is a wordpress link, I won't even bother to try opening it up, because doing so involves too many attempts, and too much hassle.

I tried opening your link above, but as usual, it wouldn't load, and my browser gave up. If you like, please feel free to post some images from that website here, if you have the time. As for me, I'll try giving it a few more attempts, but by attempt three of four, I will once again conclude that wordpress sucks, and it will no longer be worthwhile to continue trying to access the link.

All best wishes,



Biotect

 

[Iain_U1250]

Let me start with what I think is the current "Architectural" design for Terraliner. The truck iis going to be driven by electric motors, possible one per wheel, and at least one per axle. The power for the truck will primarily come from two 120kW generators, which will all the time when driving, and then for a few hours each night to charge up the trucks drive battery banks, which will need to be around 200kWh for 0.5 - 1hr of driving.

The truck will be 2.5x4mx12m, and weigh 24 tons. It has a 8 ton trailer (which only needs two axles - three would be a waste of time) and the truck will be covered in solar panels, have three slide outs, and some roll out awnings, all to maximise the amount of solar panel area available.


The power train you are proposing is a diesel electric with a battery bank as a buffer. I was thinking you were planning on something which has a diesel motor to drive the truck, coupled with a smaller auxiliary electric motor for extra power/torque when needed and for a "stealth mode" on pure electric. Either way, the power calcs remain the same, just the method is up for question.

The power calculations I have done are the absolute minimum. It think your costing of $500K to $1M is a little bit light, given the amount of cutting edge equipment your are looking at, and your prototype cost of $2M is more likely a realistic price. The end users of such an expensive vehicle is unlikely to be happy of having to crawl up hills at 20kph and slow down to 60kph if there is a headwind. Your drive motors will need to be around 450kW in order to be able to drive up hills and into headwinds. This will not be a rocket ship, more like a Toyota Prius, just "adequate", Next is to decide on how much electric power you will need to install to drive the electric motors. This power will have to come from gensets. The question is how much generating power is require. You will need more than 240kW, that is a given as other wise you will be stopping constantly to charge up the batteries if you have a headwind. I did some more calculation adding headwinds and grade to the equations. A 40kph headwind adds and 120kW a 5% grade, adds a massive 300kW ( if you want to keep the 100kph) That's why trucks have such big power plants. To be able to drive up a hill with a strong headwind and keep 100kph requires around 660kW or just short of 900bhp. Now that amount of power would be overkill, but I think you get the point. There will be occasions that you won't have enough power, so you will slow down, and it doesn't take much slowing down as reduce power requirements but it also does not take much of a grade to increase power requirements. So basically you need to decide what "Performance" your want from the Terraliner. For the target market of "old retired couple with lots of money" does not need a rocket, but they won't like to struggle up a hill either if the battery buffer starts to run out. I think a third 120kW generator ( or two bigger ones) will be required, to be able to keep up with real world scenarios. You also need a large enough battery bank to provide the shortfall in power.

I am not sure whether your are proposing one motor per wheel, one per axle or one per truck. Larger motors are more efficient, but also have a fairly limited rev range, and will require a transmission, so that kills of any efficiency gained. If you were planning on regenerative breaking charging the battery down a hill, then one motor per wheel would be best, for but again the overall drive train will need to be designed properly for the use. This will not be a simple exercise, and won't be cheap, our $2M estimate could easily be spent just getting the drive train sorted out. Fitting a large electric motor to an existing proven would probably be a lot more cost effective, but that's part of the "Engineering" you will need to do. Unless you can buy a chassis/drive train from something existing, your budget not even close for a prototype, given all the testing and safety requirement you will need to comply with, probably by a factor of 10 at least.

Oshkosh have something under development:


In the end, going a full electric drive / diesel generating hybrid is going to be expensive, especially in R&D. A modern diesel powered drive train, even with an auxiliary motor is possible now with minimal engineering. Any transmission with a direct drive power take-off ( my old Unimog has one) can take an auxiliary drive motor.

The discussion has strayed a long way from trying to drive on electric power for 10 hours, and re-charging overnight on a genset, to having a diesel electric drive unit, and there is not point having anything more than the just the buffer battery bank of maybe 120kWh. The size of the battery bank will depend on the technology, and in 5 years time, things might be smaller, solar cells might be a lot more efficient, and we may also have one of these

 

[biotect]

Hi Ian,

Excellent post, and really nice summary. We are now very much on "the same page", so to speak, and your summary captures the state of play perfectly.

Note that I personally never had any commitment to the idea of the TerraLiner driving all-electric for 8 or 10 hours. thjaktis simply fielded that article about Brighsun's publicity stunt, driving Melbourne to Sydney on a single charge, and that then motivated me to investigate all-electric technology. Which I am very glad that I did, because it seems apparent that in larger vehicles hybrid technology has so far advanced the furthest in buses, and electric trolley buses in particular. The "red herring" of Brighsun was worth exploring, if only because it led to the wonderful specialized world of electric trolley buses, for which -- incidentally -- the Jenoptik diesel generator was originally designed.

Now your suggestion that the best solution for the TerraLiner might be merely going parallel hybrid, with a supplementary electric motor to provide regenerative braking and power take-off, is most definitely on the cards. That's the solution that MAN thinks is best for long-haul trucking. However, long-haul trucking is not quite the same thing as long-haul motor-homing, especially if the motorhome already needs a reasonably large battery pack in any case (100 KW or larger), because it has massive solar.

Your thoughts about the expense involved in developing a prototype are also very, very well taken. Glad that at least one thread-participant is on the same page as me when it comes to the question of R&D costs.....:sombrero: This is one of the reasons why I simply have no interest in a fully tubular space frame construction, and why I remain very interested in the torsion-free ladder frames built by MAN and IVECO-Astra.

With that said, thjakits had a useful suggestion. Why not begin with a MAN or IVECO-Astra ladder frame, and firmly bolt a tubular space frame that forms the camper body on top of that:

Here is another option.......select the chassis you want and then BOLT a Space-Frame box to it and you should also get a super-rigid structure (if this is still the goal....)

The observation that no ladder frame is ever 100 % torsionally stiff is not that interesting, because needless to say there are no absolutes in mechanical engineering. But the MAN-KAT frame is stiff enough, and a while back egn suggested that all that might be required is minimal springs or even rubber spacers, to separate a camper body from the (relatively) torsion-free frame of a MAN SX-44.

Thajakits is then suggesting here, "Why not go further and design the camper body so that it works in concert with a ladder frame, to create an overall engineering design that ends up working much like a tubular space frame?" I like the idea, because it allows one to continue separating the manufacturer that provides the base chassis and drive-train, from the manufacturer that builds the camper body. A camper body manufacturer like Newell is already thoroughly familiar with tubular space-frame engineering, because that's how it builds Newell coaches, from the ground up. But I wouldn't trust Newell to build an off-road capable, non-twisting chassis that also has a hybrid drive-train. That's MAN's area of competence, or IVECO-Astra's.

So thjakits' idea represents a nice "split the difference" solution, and is an excellent friendly amendment. Have a motorhome fabricator like Newell work in concert with MAN or IVECO-Astra, so that once bolted together, camper body and base chassis work together, just as a single-piece tubular space frame would have.

What do you think?

As for the R & D expense of developing a fully serial hybrid drive-train, I hear you. Again, that's why I've become so interested in researching MAN and IVECO specifically. If any companies might be able to combine their expertise in hybrid buses and trucks, with their expertise in designing 6x6 truck frames for challenging conditions, it would be these two. Volvo might also be worth looking into, because Volvo seems very committed to hybrid busing. But as near as I can tell, Volvo doesn't advertise competence in creating 6x6 trucks that have frames that do not twist. The only time I have ever encountered such competence advertised, is on MAN, Tatra, and IVECO-Astra websites. Unfortunately, Tatra's backbone tube fuses chassis-stiffness and a drive-train into a single unified solution, and Tatra doesn't seem to have any particular competence in emerging hybrid technologies.

So I figure that if one went with either MAN or IVECO, although the R & D costs would still be there, they would be drawing upon lots of expertise and technology already developed in-house.

I discuseed Oshkosh at length earlier in the thread, but as near as I can tell Oshkosh is not that interested in true serial hybrid. Instead, Oshkosh advertises what it calls a "pure diesel electric" solution, akin to a diesel-electric locomotive. In Oshkos's "PROPULSE" system there is no battery intervening as a buffer, but instead, a large ICE motor powers a generator that more or less directly powers electric motors (there's some intervention by super-capacitors). So the ICE motor in an Oshkosh vehicle has to be big. Oshkosh also doesn't have much of a track record in transit hybrid buses, or commercial, non-military hybrid technology. So that's why I've found myself less interested in Oshkosh of late. The TAK 4 suspension is pretty cool, and I covered the military vehicle shown in the video that you posted at length, in posts #671 - #673, at http://www.expeditionportal.com/for...igid-Torsion-Free-Frame?p=1670213#post1670213 and following. But again, Oshkosh's "PROPULSE" technology does not seem to be exactly what's needed.

On the subject of three or six electric motors, I still haven't decided. From everything you've written, hub motors seem increasingly attractive, if only because they would also eliminate the complexity of cross-axle transmissions. Albeit each would still need an individual gear-box, for very low speeds, as Haf-E suggested.

So here is a request. Would you be wiling to do a power calculation for the following:


(1) TerraLiner + trailer as already described, trailer with two axles, TerraLiner weighing 22 tons, etc.


(2) Climbing a 5 % grade with moderate headwind, for 1 hour. Here I am thinking of the highway that runs through the Sierra Mountains from San Francisco to Reno. I was towing a not-very-large U-haul trailer, but somewhere around Lake Tahoe my transmission was just destroyed. I had good insurance, so I got a tow into Reno, where I spent the next 2 weeks bored out of my skull, because I don't gamble. I should have caught the problem early on, but I guess I was enjoying the mountain scenery so much that I simply wasn't paying attention. It was a really, really long incline, perhaps even longer than an hour. But let's estimate climbing such an extended incline with the TerraLiner for an hour.


(3) If climbing such an incline at 100 kph would require 660 KW, then what would you say would be the right "balance" between battery pack size and diesel generator size, in order to meet that power demand for an hour? A 600 KW battery pack is out of the question, because if Proterra is anything to go buy, and if 257 KWH worth of batteries weigh approximately 2,700 kg, then 600 KW of batteries would weigh 6,303 kg, or a bit more than 6 tons. But generators much bigger than two Jenopotiks would also weigh more. So a balance needs to be struck here between heavier generators and/or heavier battery pack. The battery pack needs to be imagined as draining down on this incline, even though the generators keep topping it up. The two need to be conceptualized working in tandem, so neither one needs to actually be 660 KW.

To get crudely simplistic (and my math is no doubt completely wrong here), on the face of it one might think that a 330 KW battery pack + 330 KW of generator power would suffice, in order to meet your overall 660 KW requirement for 1 hour of climbing. Over the course of an hour, the battery would be draining, but only half as fast because the generators would be constantly feeding it more juice. After an hour there would be nothing left in the battery, but hopefully by that point the incline would be over.

If this crude estimate were roughly accurate, then one might say that the following drivetrain would suffice:


(a) three Jenoptik generators, producing 360 KW, and weighting 350 kg x 3 = 1050 kg

(b) a 330 KW battery pack, which scaling up from Proterra's info, might weigh as little as 3,493 kg, or 3 1/2 tons


Giving total drive-train weight of 4 1/2 tons, which clearly is quite a lot.

If instead one could find two generators that weigh 700 kg each, and produce 220 KW each, or 440 KW in total, then perhaps the battery bank could remain as small as 257 KW. So total system weight would be 700 kg + 700 kg + 2721 = 4,121 kg, or a bit more than 4 tons. Not much of an improvement over the previous calculation, but still a bit better.


(4) The power calculation should assume six electric hub motors. If 660 KW were needed, then presumably each hub motor would need to be rated for 110 KW?


(5) One specific request: if it's not too much trouble, would you be willing to post your spreadsheet and explain your calculations in some measure of detail, i.e. how you arrived at the power requirement of 660 KW when the TerraLiner is climbing an incline? And so too, your similar calculation that allowed you to arrive at 248 KW driving flat, with no headwind?

Your power figures will be cited by others, and I would prefer that they be subject to a bit of scrutiny first. For instance, Joe has already cited your exaggerated initial estimate of 450 KW for driving flat. Above I also took your 660 KW figure as "given", but quite honestly, I did not like doing so. You may be wrong, and your figure of 660 KW may be too high. If that turns out to be the case, but only after we've all wasted lots of time bandying about ideas using your figures as merely "given", then we will all feel a bit foolish. And we will also become a bit pissed off at you.....:sombrero:

In other words, before this discussion goes much further, it would be great if you might be wiling to display your calculations and/or spreadsheets, and explain all your assumptions, showing how you arrived at your power figures. That way your figures might be subject to scrutiny by others. That would help advance the discussion tremendously.

Sure, I know that it's more fun to just assert 248 KW, or just assert 660 KW, and enjoy feeling authoritative when others don't question your math. But at present, your power calculations are still merely assertions for me, and will remain so, until people like egn, dwh, Haf-E, and campo have had a chance to examine your spreadsheets and assumptions. Once again, I am a trained philosopher, and I've taught courses in Critical Thinking and Epistemology. So for me only evidence and argument are ultimately convincing in areas of knowledge such as science and engineering. I also very much believe in the value of critique. Science does not progress because any one scientist in particular, as an individual, is particularly rational. Rather, science progresses only because the intelligence of scientists considered collectively, is vastly greater the sum total of their individual brains. Scientists are smarter together above all because they subject each other's work to merciless and unforgiving critique. Without peer-review and criticism, there would be no science.

Finally, I should once again repeat that my main interest in having the TerraLiner go serial hybrid, is the problem of repairability, and designing for fail-safe operation. The parallel hybrid solutions that Bosch, MAN, and others are now developing for long-haul trucks are all fine and good, but they don't solve the repairability conundrum, and they don't allow one to build fail-safe redundancy into the drive-train system.

All best wishes,



Biotect

 

[biotect]

Hi all,

Thought I should also remind everyone about campo's power-related questions, questions that still have not been answered:


1. Does it make sense for the TerraLiner to carry fuel cells in addition to a lith-ion battery bank? See posts #1935 and #1936 at http://www.expeditionportal.com/for...igid-Torsion-Free-Frame?p=1961416#post1961416 and http://www.expeditionportal.com/for...igid-Torsion-Free-Frame?p=1961416#post1961416 , for this question elaborated in detail.

2. What exactly is a "fuel cell hybrid bus"? How might it prove superior to an ordinary diesel bus? How might it prove superior to a "lith-ion battery bank hybrid bus", of the kind that MAN makes, i.e. its "Lion City hybrid" line of buses?

3. Could all of the TerraLiner's batteries be condensed into a single, unified loth-ion battery bank, as proposed by campo? Could a single lith-ion battery pack serve to start the two diesel generators, as well as power camper systems? Or would it still be better for the diesel generators to have their own, separate start-up batteries?



All best wishes,



Biotect

 

[Iain_U1250]

Here is a summary of the force involved on a vehicle. My spreadsheet is just a series of formula which will take a lot of time for me to pretty it up for others to use. Probably best if they make their own.

Rolling resistance, going uphill, forced required to actually accelerate which I discounted that as I have no idea how fast you want to accelerate past 100kph and it in reality, you use all the available power for accelerating when there is not much wind resistance, and the accelerate less when you go faster.

The total force require to drive around is:

Ftotal = Froll + Fslope + Faccel + Fair

and

Froll = cr m g where:
cr : coeffidcient of rolling resistance and can vary a lot ;
m : total mass of truck and trailer in kg;
g : 9.81 m/s2


Fslope = s m g where:
s : upward slope, ( 5% = 0.05)
m: total mass of truck and trailer

Faccel = a m where:
a : acceleration rate required in m/s2
m: total mass of truck and trailer

Fair= (r cd A v (speed + headwind wind)**2 )/2 where:
r is the density of air: 1.29 kg/m3 at sea level, less as you get higher but we will start on the beach,
cd : drag coefficient - typical truck/trailer is 0.96, a more streamlined bus is around 0.8, so I used that assuming you would make it as good as possible, but the typical expo truck with all the stuff on the roof, sand ladder on the side, etc, will be a lot higher.
A : projected frontal area in m2 - I just used the width x height, as you don't get that much air flowing under the truck, and it is difficult to calculate properly given the things that will be hanging down under the truck, the tyres, mirrors, and other things hanging off the side.
v air : Is the total of speed + any headwinds in m/s. This is a gross simplification as the wind at 45 deg to the direction of travel will be acting on a much bigger area ( but at a lower velocity - much like a sail on a boat, and can add a lot of resistance depending on the direction.

The total power required for each different scenarios is:

P = Ftotal v/h v : velocity in m/s
h : drivetrain efficiency, which depends on the configuration


It would be good for someone to put this into another spreadsheet and do all the calcs again.


I ran the figures for my little truck - (Cd 0.96) A = 3.3 x 2.2m and m=7500kg. In order to drive up a 5% slope in a 40kph headwind at 100kph, I need 374 kW, which is a lot more than the 160kW I have, doing a few iterations, looks like 70kph will be my max speed up the hill with my foot flat.

My "flat road no headwind maximum speed" is around 110kph. I will hopefully get to test that out soon.

 

[thjakits]

Hi Bio, hi all,


QUOTE: "Furthermore, a fully integrated interior design is still a requirement, and thjakits is simply wrong: this kind of long, fully integrated camper shell can only be built on top of a rigid, comparatively torsion-free frame."


- just to make the point: Bio, YOU are wrong assuming that a flexible frame would not work. It's just you don't want to give it the thought it would require.
[DA again....even if you prefer/like the rigid frame approach, due diligence requires that you sound out ALL possible solutions, incl. flex frames - and be it just to positively rule it out - with sound technical/engineering arguments]

- WHAT makes you think a flex frame could NOT support an "integrated cabin"? Just because we never saw one yet, does not mean it cannot work.
Just so happens, that UNIMOG mostly does NOT NEED the driver section be aligned with the cargo/work section. That's where all the fantastically crazy looking pics come from where the driver cabin goes one way and the cargo bay the other....

As a result of the UNIMOG design (which was NOT particularly made for an "integrated camper" build - not really needed either as the UNIMOG cabin is rather useless for anything but operating/driving)

- IF you put anything on a UNIMOG frame you HAVE TO use a rather well articulating 3-point or 4-point suspension (cargo/work unit to frame).
As it goes, most UNIMOGs come with a cabin and leave it to the customer to get the work unit.
HOWEVER, WHAT makes you think you could NOT extend your RIGID "Integrated Camper/driver"-unit with a 3- or 4-point suspension all the way to the front onto a UNIMOG frame??
BTW - there is now fairly long UNIMOG frames in production......

- And last but not least: Did it occur to you that the UNIMOG frame is actually rather stiff - in definite planes - and just PRECISELY flexible in others?
Look at it as the frame being an ACTIVE part of the wheel/axle suspension!
What does that do?
SAVING HUGE amounts of space! Empty volume!
IF you wanted the full suspension travel of the UNIMOG (just the perfect example, but applicable to any design - have a look (again) at Wotahellisthat...
That frame has some serious twist to it too, but the box is rather solid on top.
ESPECIALLY on a long vehicle like Wotahahell or Terraliner, a twisting/flexible frame will save lots of suspension space (or increase suspension articulation - anyway you want to see it)

To be more blunt: If you need a wheel travel of 1m relative to the diagonally opposite wheel, you either need to make space for that meter or you make space for 40 cm and let the FRAME do the rest - 60 cm SAVED!

99% of the time you won't need that travel, but to get off the beach, out of the farmers mud bog, or over the rockline that separates you from the beach - you will...
The 40cm is MORE than enough (just a number now for the example...) for ALL road travel - 99% of the time....

Did you ever look at EXTREME articulation machinery? There is LOADS of empty space in the wheel articulation universe! Incl. the MAN-KAT, which doesn't really articulate that much anyway....

YOUR truck, YOUR decision - YOUR mistake if you do NOT investigate ALL possibilities....

[Frankly I find it quite arrogant from you to just decree, that a flex frame will not work on a "integrated" design! By your own admittance you are not an engineer, but a Industrial Designer, no? - So HOW do you come to the result to just call it off WITHOUT any substantiated argument - you never even THOUGHT it through.... I did, and it would work just fine! IF it makes economical sense at the end is a different analysis, but from a technical point of view it is rather simple....]
YOU may not LIKE this approach from your present point of view, but you still should think it through - ...that's just the professional approach.



The other thing: I didn't ask you to explain your present design details (forthcoming in this thread as you said...), I offered you to explain to me per PM, where YOU think I went of track, philosophical, prose-wise or "literature"ly in my previous to last post!??

What I can/could read out of your following post is something like "Watch your tone, I don't need blablabla rants!"
That's where I said: Either you misunderstood my whole post or you are mixing up things posted (wouldn't be the 1st time...)

I STILL would like you to explain to me WHERE YOU think I stepped on your toes - You can do that here or via PM (if you want to keep this off the thread)

In MY opinion I only posted valid concerns, different view points and suggestions and real world experience data.....
(I just don't like/accept to get called on anything without explanation or chance to refute....)

I may be behind the curve of your constant design changing, but my posts are still about everyday/common sense/real world things/concerns...
AND by the way - reread your own posts, YOU are changing quite a LOT! I remember when 10m length was still a upper limit - "and no way you will go longer because of maneuverability and what not!" - I still remember clearly arguing that going to the legal limit would not make ANY difference to the maneuverability. Where are you today? 12 meters! And there is loads of this (...weight is another) - and mostly it is YOU coming around to opinions, suggestions and facts made the more experienced posters on this thread. And I would suggest, a good number BECAUSE I threw arguments on the thread over and over again....
(I maybe wrong on this one - just not in the mood to reread the last pages - I seem to recall, that you now also will build in some slide-outs!?? Weren't these strictly OFF the list a few months ago, too??)

Which is the whole idea about posting? - Getting YOU to see our concerns with your latest brainchild - BUT isn't it curious/fun, that you FINALLY and MOSTLY end up right where we (most posters here) argued many MONTH ago??

So - where did I step on your toes again?


- And lastly: It may NOT be your idea or plan, but experience of those that actually HAVE rigs on this thread, told you before, mostly all of the offroad prowess is - at the end - more an emergency/safety net - NONE would likely drive onto a beach (unless heavy gravel or rock) to float a boat - you JUST DON'T risk your HOME like that.....especially if you have a boat with wheels on it anyway......

Probably you live to far away from the beach, to see cars, 4x4s, etc. getting stuck and washed out on the beach regularly, to consider to NOT drive on it.
On many beaches you only have a very small window to actually drive on before tide concerns will hit you ....
Once your rig is "salted" - ...forget it.


thjakits

 

[Iain_U1250]

I definitely plan on driving up and down beaches regularly, over here, there are beaches that are actually gazetted roads with speed limits and traffic cops

You have to watch the tide though, especially on the West coast, there are some 7-9m tides,

Small planes land on this beach

With a proper 4 point mount system, you can fix a long rigid body to something as flexible as a Unimog, it has been done plenty times before, but the 6x6 are extremely rare, and I think they are now outsourced.

This is something done locally, not sure how well it actually performs.

http://www.drive.com.au/motor-news/perkins-swaps-racetrack-for-outback-20110525-1f4vs.html

 

[biotect]

thjakits,

Do you pay much attention to where a given discussion is going, and what the current theme of the thread might be? The current topic is power. The previous posts in the thread have been mostly been about power. After this post I will re-post Ian's excellent summary of his formulas and assumptions, and I will also repost my suggestion that the focus right now should be power, and only power. I should not have to do this, but oh well.....


1. This thread is about "Torsion-Free Frames"

To address your post as succinctly as I can: I have already made it clear that I have no interest in doing the work required to figure out how to "scale up" the Unimog solution to a 12 m length. Furthermore, I think it would be idiotic to pay a company millions of dollars or euros to try to do the same. The R & D involved here would be a money-sink. A perfectly good alternative exists: simply buy a torsion-free chassis frame from MAN or IVECO-Astra, and bolt on a tubular space-frame camper body made by Newell or an equivalent fabricator. So why bother spending millions trying to develop something else? It would be foolish, and it does not make any sense.

There's also the not-so-small matter of the title of this thread: "Fully Integrated MAN or TATRA 6x6 or 8x8 Expedition RV, w Rigid, Torsion-Free Frame." That's the title of the friggin' thread, and I have absolutely zero interest in debating the title of the thread with you further. If you are incapable of reading the title of the thread and respecting it, then please, stop posting here. I do not want to debate Unimog versus MAN here, because I have already made my choice. This thread is not the place to have the kind of debate that you want to have. If you want to have that debate, please start another thread. Please do not take up space on this thread with pre-occupations that run contrary to the title, pre-occupations that were excluded right from the beginning, in the very formulation of the title.


2. This thread's design-process is program-driven

As for my design parameters changing, again, I simply disagree. I think the thing that his been changing is your understanding of what I have been saying all along. Slide-outs were never ruled out, ever, and I posted examples of off-road vehicles with slide-out very early on, long before you arrived on the scene -- see post #115 at http://www.expeditionportal.com/for...igid-Torsion-Free-Frame?p=1566713#post1566713 . I just did not want to talk about slide-outs in the same moment that I was talking about pop-ups, because although the Kirivan has both, very few other vehicles do. I did not want to deal with a riot of howls of "impossible" or "impractical" coming from the peanut gallery, and so that's why I did not talk about both. As for the overall length of the TerraLiner, yes, it has increased to 12 m. But it is exactly because people like you are so fixed on arbitrary, merely quantitative design limits like "length" and "weight", that I have been so thoroughly reticent about posting any of my design work.

My way of thinking about design is program-driven, and it was not very clear to me until recently what exactly the TerraLiner's program should be, at a detailed level, beyond the fact that I wanted to design a Class A, globally-capable motorhome for wealthy, retired couples. It may seem obvious to middle-aged participants here on ExPo what the program must always be for any expedition vehicle, because they simply assume that any such vehicle should be mid-sized, and should strike a compromise between adventuring and sojourning. You yourself, thjakits, have made precisely this assumption repeatedly throughout this thread, most noticeably in one of your better "devil's advocate" posts -- see post #1163 at http://www.expeditionportal.com/for...igid-Torsion-Free-Frame?p=1740093#post1740093 . In that post you kept repeating the word “exploring”, and it was your implicit assumption that a capacity to “explore” should be a central feature of any and all globally capable motorhomes. I should thank you for that post, if only negatively: because you kept dogmatically insisting upon “exploring”, I found myself asking, "Should exploring be a necessary feature of a globally capable Class A motorhome that functions mainly as a base camp?" And I realized that the answer to that question was, "Absolutely not." So on occasion your dogmatic stubbornness seams to have some value, if only because of the strong negative reactions that it engenders.

In short, the more I thought things through, the more that the assumption that a Class A motorhome needs to be able to "explore" came to seem eminently contestable. Really thinking through the program, and thinking through how the program might be realized in an "aesthetically satisfying" package, has always been much more important to me than arbitrarily fixing things like "length" or "weight". It's obvious to any designer worth their salt that details like length and weight should be program-dirven, and not the other way around. And only once the program has been thoroughly explored, can such things be nailed down with some degree of precision.

You might also note that from the very beginning of the thread that I pushed back hard -- very hard -- against participants like grizzlyj, who were hoping that the thread would become a forum in which they might discuss their ideal conception of a motorhome, namely, a mid-sized Unimog. From the very beginning, I made it clear that I had zero interest in designing a vehicle that could do lots of off-road rock-crawling. Mañana, which appears very early on in the thread, was held up as design exemplar precisely because it is fully integrated, and is designed not to rock-crawl. Mañana also happens to be 10.72 m long, which is not much short of 12 m.

Now granted, I needed a bit of time to figure out what kinds of implicit and unreflective assumptions some thread participants were bringing to bear, in other words, their conception of what an ideal globally-capable motorhome should look like. And I needed time to further clarify how my own thinking is radically different from theirs. And how I have absolutely zero interest in designing for them, and their middle-aged wants and preferences, and their need to travel fast, as per one country every 15 days. So I simply view the thread as a process in which my conception of an ideal motorhome --a motorhome designed very specifically for just one age-cohort and financial bracket, namely, wealthy retired couples -- has become more clear. And it has also become more clear how the ideal globally-capable motorhome for retired, wealthy couples, will be radically different from the "fixed Platonic ideal" of the "ultimate expedition motorhome" circulating inside the skulls of many middle-aged participants here on ExPo.

So I would offer that it's you who has been changing, thjaktis, and not me. Gradually you have been realizing that I am not designing the TerraLiner for you, and perhaps that's the reason why you are lost, and cannot seem to follow the thread.

I also very much disagree with you that I've ended up where "everyone else" was a month ago. You are simply wrong about this, and here too, it seems clear to me that you still just don't get it.

I expect that very few people on ExPo will want or can afford a 12 m motorhome designed primarily for sojourning, one that tows a TOAD garage containing an SUV intended to do the exploring, and the grocery shopping. I expect that very few people on ExPo have entertained the idea of trying to transfer as completely as possible, to a global context, the "Class-A style" of motor-homing that is now very common in the United States. This is a style of motor-homing in which the primary Class-A vehicle functions mostly as a base camp, and the TOAD does all the exploring. That's where I currently am. If other thread participants want to claim that they were already there a month ago, my hat goes off to them. Unfortunately, there is no evidence of that in the thread.

Furthermore, I have never seen anyone propose such a thing anywhere else. I have only seen mid-sized expedition motorhomes carrying motorbikes, and a handful (less than 5) that carry super-small SUVs inside the main camper body. Because the SUV garage is in the camper body, it thereby cuts down even further on the availability of living space that is already in short supply, in non-integrated expedition motorhomes.


3. Many others have contributed at least as much to this thread, and in some cases, much more

You also give yourself way too much credit. Yes, you have provided a few valuable contributions, mainly the idea of a Chinese 6x6 axle arrangement, and you've alerted me to the problem of windshield breakage. That's about it. Personally, I consider the contributions of egn, Haf-E, campo, dwh, and Joe Manigna to be at least as significant, and most probably more significant.

It was egn, for instance, who first suggested that I start this thread -- see http://www.expeditionportal.com/for...es-and-mounting-campers?p=1558661#post1558661 . It was egn who provided the best and most informed answers to the questions that I posted in the other thread where it all began, in "pivoting frames and mountain campers", the thread where I first broached the possibility of a fully integrated design. See post #332 at http://www.expeditionportal.com/for...es-and-mounting-campers?p=1499067#post1499067 where I first posted my questions, and for egn's responses, see http://www.expeditionportal.com/for...es-and-mounting-campers?p=1557972#post1557972 , http://www.expeditionportal.com/for...es-and-mounting-campers?p=1558044#post1558044 , and following. It was egn who confirmed that I was reading MAN SX-series literature correctly, and that MAN KAT and SX frames twist only very little, especially when compared to TGS or Unimog frames. It was egn who admitted that the non-twisting character of a MAN KAT frame had also suggested to him the possibility of exploring a fully integrated design, if only because he and his wife had previously owned a more conventional, fully integrated, "Liner"-type German motorhome.

In this here thread, it was also egn who first proposed investigating a hybrid drive-train, and who provided a link to the Jenoptik generator. That's just the tip of the iceberg: egn's contributions to this thread are too numerous to mention. Just read the first 50 pages. I owe egn a world of thanks, and it is to him that I feel "most" grateful, although I also do feel very grateful to at least a half-dozen other participants. By the way: Victorian and Iain were also very early participants, the very first to respond to my query -- see http://www.expeditionportal.com/for...es-and-mounting-campers?p=1499124#post1499124 and http://www.expeditionportal.com/for...es-and-mounting-campers?p=1511588#post1511588 . But if egn had not encouraged me, this thread would simply not exist.

It was then Haf-E who seconded egn's thoughts about hybrid, and who added many of his own, proposing various solutions. And it was dwh who first suggested that the primary engineering goal of the TerraLiner should be maximum "autonomy", in terms of power, water, and sewage, and that designing for autonomy is much more important than designing for geographic reach. That basic, fundamental conceptual move has now become absolutely central to my design thinking. I am now designing the TerraLiner for maximum autonomy, and not for maximum geographic reach. Whereas some of the less constructive proposals early in this thread kept going on and on about the importance of geographic reach, the importance of being able to go slumming in desperately poor 4th-World African countries, and hence, the importance of designing on the chassis of a mid-size Unimog.

My reaction was swift: from very early on, I made it clear that geographic reach did not strike me as the be-all and end-all of expedition motorhome design, as it seems to be for many ExPo participants. Just read the first 15 pages of the thread. Most recently I've suggested that for many ExPo participants, striking a compromise between exploring and sojourning in a mid-sized expedition motorhome is only important because they are on a tight clock, they are middle-aged, they still have to work, and they don't have much leisure time on their hands. Mid-size also suits their budget better, whereas Class-A motorhomes in the United States are typically bought by retired couples who have money.

dwh also provided useful leads about the EcoJohn, and it was dwh who first proposed AWGs, or atmospheric water generators. Although wayno briefly mentioned Blissmobil, it was dwh who made a strong case for taking a look at Blissmobil's solution to the problem of water, in post #1450 at http://www.expeditionportal.com/for...igid-Torsion-Free-Frame?p=1859291#post1859291. I feel an enormous debt of gratitude to dwh as well. I also found dwh's posts about independent suspension very useful, and as you yourself now (finally!) acknowledge, you were wrong in thinking that all independent suspensions have "junk" in the center that prevents them from having good center-line clearance. Dwh won that debate, but it was very painful to watch, because your stubbornness and dogmatism prevented you from actually listening to the good arguments that dwh was making.

There's also safas, who posted very useful information about thin-flim flexible solar cells made by Alta Devices; nick disjunkt who gave us the British expression "Chinese Six", an economical way to refer to strange 6x6 trucks that have the tandem axle up front; and campo, who gave me tons of useful feedback in another thread, about Camper Thermal Engineering -- see http://www.expeditionportal.com/for...old-amp-High-Altitude-Arctic-Antarctica-Tibet . Needless to say there have been many other participants, too numerous to catalog here. Please Note: if I have failed to mention anyone who also thinks that they have made a significant constructive contribution, my apologies!!

Last but not least, there's Joe Maninga, whose postings of exceptionally relevant examples of Australian expedition motorhomes have been singular moments of design inspiration.

Here too there is an object lesson: you misinterpreted Joe's posting of the Paradise Motorhomes expedition vehicle as an argument for mid-sized. That was never Joe's intention, and that's also not how I read his post. Joe posted this vehicle because it had a fully integrated, well-lit interior, and a super-cool drop-down deck. The Paradise Motorhomes expedition vehicle has had a huge impact on my current design trajectory, and if Joe had not posted it, I would not be now designing something very different from what I was designing 6 months ago.

Your insistence that my design should not change dramatically, is also quite telling. I have made it clear from the outset that I view this thread as a place where I can explore, grow, and change my mind. From the very beginning I have made it clear that I want to design a globally-capable, Class-A sized motorhome for a wealthy retired couple. But that, aside from this very general design objective, I wanted to explore as many possibilities and considerations as I could, especially logistical and programmatic considerations. And that I wanted to leave things as "open" and "loose" as possible, at least in the beginning, because I did not want to repeat the mistake of Bran Ferren, whose design team pumped out more than a hundred useless drawings and useless CAD for a year, because not enough thinking had gone into basic operational requirements, and basic logistics.


4. Insistent, aggressive repetition is rude

I appreciate your contributions to this thread, but trying to wear people down via pig-headed repetition is, well, just plain stupid. It's also very aggressive and rude.

When other participants on the thread suggest design or engineering ideas, they suggest them tentatively, and they are happy to "let go" of their suggestions, if further exploration indicates that the idea might not be that good or feasible after all. For instance, dwh proposed Capstone turbines as an alternative to diesel generators, but as I posted more and more material about Capstone turbines in transportation applications, gradually dwh realized himself that these might not be such a good idea. Others do not cling to their ideas and opinions as strongly as you do. Confucius said, "He who never changes his mind, loves himself more than he loves the truth". Other participants are also content to merely suggest, and not dogmatically and repetitively insist, recognizing full well that this here is my design project, not theirs.

So too, other thread participants have been willing to respect where I am going programatically, and they have understood that there probably would be a market for a globally capable Class-A motorhome, one that glamps on farmland in the Second and Third World, and not the Fourth World, i.e. not central Africa. Perhaps they understand market basics, like the fact that the majority of motorhome sales in the United States are Class A's, and not B's or C's. The least number of motorhomes shipped in the United States are actually the smallest ones, mere van-conversions called Class-B's. And yet some participants at the beginning of this thread were making very dogmatic and absurd statements to the effect that I would be designing for a much "bigger" market, if I designed smaller. With all the dogmatism of those who think that their own little bubble of personal experience gives them complete access to universal truth, they then very strongly insisted that if I wanted to be "realistic" or "practical", I should be designing on a Sprinter or small-Unimog chassis. This was a factually wrong claim, as I demonstrated just recently when I provided abundant evidence to the contrary, in post #1941 and following, at http://www.expeditionportal.com/for...igid-Torsion-Free-Frame?p=1962442#post1962442 . I provided statistical evidence based on actual market shipments, whereas those who are "experienced" typically tend to know only the tiny bubble of their personal needs, wants, and preferences.

Think of it this way. Iain is a relatively new "regular" participant on this thread. As already mentioned, Iain was one of the very first to respond to my queries in the other thread, and then he inexplicably disappeared..... Iain also personally owns a Unimog, so if anyone might be biased in favor of mogs, it would be him. And yet Iain has come up to speed very quickly, and corresponding with him has been a blast. He very quickly understood the "Class A base camp" concept, and the idea of glamping for months on coastal farmland and beaches. Just above he posted some wonderful photographs of the same. When Iain made the mistake of assuming that the TerraLiner had to be 30 tons, he quickly corrected it, and re-did his calculations. When I asked him to present all of his numbers and calculations in a way such that others could review them, he posted the relevant information immediately. Iain knows what it means to "play well with others", and I can imagine that his contributions to this thread will also prove significant.


5. I will post more further along. In the meantime, you will have to wait.

thjakits, that is all that I can post right now. I have other priorities. I will post something much longer further along in which I explain ad nauseum why you've been rubbing me the wrong way. For now, you will just have to exercise some patience, and you will have to wait.

I also very much do want the current discussion to continue exploring Iain's power calculations, and I would like the current discussion to address campo's questions. I really do want the current discussion to be about power, and I absolutely do not want the current discussion to be further correspondence between you and I, unless the topic is the TerrraLiner's power requirements, and nothing but the TerraLiner's power requirements. If you have anything further to say to me, please write to me by private message. I very much hope that you can find the restraint to respect this request, and allow the thread to continue uninterrupted with a discussion of the TerraLiner's power requirements.

I am sorry that I have been so harsh, but the frustration has been building for a while.

All best wishes,





Biotect

 

[biotect]

Hi all,

Thought I should also remind everyone about campo's power-related questions, questions that still have not been answered:


1. Does it make sense for the TerraLiner to carry fuel cells in addition to a lith-ion battery bank? See posts #1935 and #1936 at http://www.expeditionportal.com/for...igid-Torsion-Free-Frame?p=1961416#post1961416 and http://www.expeditionportal.com/for...igid-Torsion-Free-Frame?p=1961416#post1961416 , for this question elaborated in detail.

2. What exactly is a "fuel cell hybrid bus"? How might it prove superior to an ordinary diesel bus? How might it prove superior to a "lith-ion battery bank hybrid bus", of the kind that MAN makes, i.e. its "Lion City hybrid" line of buses?

3. Could all of the TerraLiner's batteries be condensed into a single, unified loth-ion battery bank, as proposed by campo? Could a single lith-ion battery pack serve to start the two diesel generators, as well as power camper systems? Or would it still be better for the diesel generators to have their own, separate start-up batteries?



All best wishes,



Biotect..

 

[biotect]

Here are Ian's formulas again, for TerraLiner power requirements just rolling on flat ground, as well as driving an upward slope, and for acceleration. If anyone wants to have a go at these formulas and revisiting the power calculations, please do!!

All best wishes,


Biotect


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


Here is a summary of the force involved on a vehicle. My spreadsheet is just a series of formula which will take a lot of time for me to pretty it up for others to use. Probably best if they make their own.

Rolling resistance, going uphill, forced required to actually accelerate which I discounted that as I have no idea how fast you want to accelerate past 100kph and it in reality, you use all the available power for accelerating when there is not much wind resistance, and the accelerate less when you go faster.

The total force require to drive around is:

Ftotal = Froll + Fslope + Faccel + Fair

and

Froll = cr m g where:
cr : coeffidcient of rolling resistance and can vary a lot ;
m : total mass of truck and trailer in kg;
g : 9.81 m/s2


Fslope = s m g where:
s : upward slope, ( 5% = 0.05)
m: total mass of truck and trailer

Faccel = a m where:
a : acceleration rate required in m/s2
m: total mass of truck and trailer

Fair= (r cd A v (speed + headwind wind)**2 )/2 where:
r is the density of air: 1.29 kg/m3 at sea level, less as you get higher but we will start on the beach,
cd : drag coefficient - typical truck/trailer is 0.96, a more streamlined bus is around 0.8, so I used that assuming you would make it as good as possible, but the typical expo truck with all the stuff on the roof, sand ladder on the side, etc, will be a lot higher.
A : projected frontal area in m2 - I just used the width x height, as you don't get that much air flowing under the truck, and it is difficult to calculate properly given the things that will be hanging down under the truck, the tyres, mirrors, and other things hanging off the side.
v air : Is the total of speed + any headwinds in m/s. This is a gross simplification as the wind at 45 deg to the direction of travel will be acting on a much bigger area ( but at a lower velocity - much like a sail on a boat, and can add a lot of resistance depending on the direction.

The total power required for each different scenarios is:

P = Ftotal v/h v : velocity in m/s
h : drivetrain efficiency, which depends on the configuration


It would be good for someone to put this into another spreadsheet and do all the calcs again.


I ran the figures for my little truck - (Cd 0.96) A = 3.3 x 2.2m and m=7500kg. In order to drive up a 5% slope in a 40kph headwind at 100kph, I need 374 kW, which is a lot more than the 160kW I have, doing a few iterations, looks like 70kph will be my max speed up the hill with my foot flat.

My "flat road no headwind maximum speed" is around 110kph. I will hopefully get to test that out soon.

 

[campo]

I am sure that you can get close to reality with Ian's formula or spreadsheet approach to determine the HP needs for Terraliner.
.
The other possible approach is to use more the practical side.
How do manufacturers do today ?
Some 30 years ago the maximum in Europe was 380 Hp for trains with 38/40 or even 50 ton in Holland. That was the best at that time for all types of on and off road situations.
Today you can buy the biggest Scania engine for the same purpose:
V8 Volume 16.4 litre max power 730 hp (537 kW) at 1900 r/min
Maximum torque 3500 Nm between 1000 and 1400 r/min
The today's biggest Volvo has an 16 litre diesel engine with 750 HP and 3550 Nm
.
With that sort of figures you seem to have more than enough reserves even the best !
And that's also the more than sufficient traction, speed and power you want for a magnificent Terraliner.
But remember Ian's words it will still not feel like driving a sports car.
Today's race trucks have 1000 HP for 8 Ton weight.
700 HP for 30 tons Terraliner on 5 or six axles will definitely not feel like a race vehicle.
.
The other question that will determine the electrical range is how much kW you need to keep up rolling 30 tons for 2? hours on only electric.
EGN's is right with his remark's that the generator does only need to cover average demand to top up the battery bank again, and the battery bank has to assist in shorter top power and speeding situations or uphill's. A good balance is necessary. We'll need to know how much electrical power is minimally needed to drive for example 2 hours at speed 50 km/h to cross some cities at reasonable cruise speed without noise.
.
From my driving experience I think that I can maintain on the flat a modern truck combination of 30 tons at speed 90km/h with something between 200 to 250 hp. I did never measure it.

 

[Iain_U1250]

Just ran the numbers, and you are spot on, the formulae come up with 154kW (206hp) to run a 30 ton modern truck (Cd 0.08) on a flat road with no headwind


The 5% grade and 40kph headwind are design extremes. 5% is the "Desirable Maximum Grade" for a highway, from the road design manual (I was design manager on a few highways in the past ) There are not many places in the world where you will rise up 5km in 100km of travel

The 40kph headwind is the worst constant headwind I have ever experienced, travelling from Mt Isa to Longreach (650km). We were in our Land Rover Defender on a camping trip, we struggled to hold 100kph, luckily it is pretty flat out there but we had to drop down to 90kph up any hill or the engine temperature would start to rise and used our entire tank of fuel (127lt) to get there, almost double what we normally use and I had my foot flat most of the way. The wind dropped down on the next day, but I remember it being 40kph (21 knots) with gusts up to 30 knots on the weather report.

Biotect needs to decide on the 'Performance" of the Terraliner, what do the ORCWPOM expect from their $2M truck? The Newell guys have as their standard 450kW (600hp) so most likely, this is the power output that will be expected of Terraliner. This is the "Drive Power", and includes the transmission losses of around 30% ( as an aside, can you mow see why trucks tend to blow transmissions more often than they do engines - 150kW of heat needs to go somewhere, maybe someone can invent a means of recovering the heat to use in charging batteries)

If an electric drive is more efficient, then you don't need as much "Drive Power" This is the power the electric motors have to have. The "Generator Power" could be less, given that you are very unlikely to have to drive for more than an hour at 5%, and can use the battery bank as the buffer. If we stick with the 240kW gensets, which is just enough to hold Terraliner at 90kph into a 40kph headwind, then we now need to decide how much battery buffer we need to go up a hill now and again. The assumption that a 5% grade for 100km ( 1 hour of travell) is going to be the extreme, then you need to make up the 210kW shortfall from the battery bank. This means a 210kWh battery bank. Changing the assumption to 33km of 5% means you need only 1/3 of the battery bank for that example. What needs to be done is to work out what "all electric" range we want, how fast do we want to drive with the gensets off, and I think the 2hrs @ 50kph sound reasonable. To work out the power requirements, the "Faccel" part of the equation, as this will likely be the most significant contributor to the power requirements. Typical acceleration/drive/stop profiles need to be worked out for Terraliner, but I'm sure the guys with the buses will have done this all this in order to work out their own battery requirements - I think their bus will be less than 30 tons all up though), so we could just use their battery bank and scale it down from a 8 hour trip to our 2 hour trip and proportion the relative weights ( 15 ton bus vs 30 ton Terraliner) I think we will come up with around 200kWh which is just what we need for the other scenario


Next stage is to do the power requirements for all sorts of different scenarios, and see if there are any where we are not able to maintain the required performance. For example, up a 15% grade ( which we will find on some mountain passes) we could only sustain 40kph with our "Drive Power" and our ORCWLOM should be able to live with that, all the other trucks on that road will be going just as slow. Going up a winding mountain pass for an hour is quite likely. What if our battery is not 100% charged at the bottom of the pass because we have been driving through a city. Then when it comes to the pass, we will only have the genset power which will limit out speed to 25kph. Is this acceptable? This is where battery management systems can come into their own, maybe our driver can program in the route using GPS, and the truck's computer will work out when the gensets are able to be switched off.


The next thing to look at is what the expected battery performance is going to be like over time. My own experience with little LiPo drone batteries is that the degrade with use. We should in reality, be designing for the case where the batteries are just at the end of their useful life, and it is time to replace them. Maybe this will be a 75% or 50% drop in actual capacity, I don;t know. In our remote gas well sites, we designed for 50% of initial installed battery capacity. So, maybe we need 400kWh of battery bank. This is what the "Architect" needs to decide, then the "Engineer" can tell him whether he can make it fit. This is the Architectural to Engineering part - or as I call it - "Fantasy to Reality" part of the design.

 

[thjakits]

Bio,

quote: "I will post something much longer further along in which I explain ad nauseum why you've been rubbing me the wrong way."

Don't bother ......save your time.

Good Luck with Terraliner.


thjakits out