Those designing their own high MPGe cars.

[smilingcat]

hi Dave,

No just my machine is expensive. Software is open source meaning its free. When I get the software ported over to run on Tesla GPU, I will have 500Gflop (500 billion double precision arithmetic calculation per second capability) My simulation time would be reduced to about 20% or less than otherwise. Going from 60 hour simulation to 12 hours or less is the goal.

And I'm no stranger to 120 hour CPU time for simulation runs. Getting old and not that patient for results.

I'll keep you informed.

Thanks

Shawn

[PatQ562]

Maybe I'll build a 1/6 scale model and run it on top of my PU to see if I am on the right track.

Such thoughts occur to me too. Even better, one might find an empty straight road and tow a test body (wheels and all) which would give a good idea of road and wheel turbulence effects. If it weighed little (foam model) the drag would be almost all aero which is the hardest term for us amateurs to measure.
If however, one of us gets simulation going, it's a lot easier to make and test changes.
It also seems possible to test shapes by poking them out a window, with some kind of scale to measure drag.
Pat Q

[smilingcat]

Have two new machine:
bigboy: dual xeon (6-core) with 48G and RAID-10 disk array around 1.5Tbyte with cheap GPU installed to run CUDA and openCL.
os: Mandriva 2011 fall edition 64 bit

desktop: typical PC. ATHALON II (three core) 4G memory with 500G drive.
os: Mandriva 2011 fall edition 64 bit

I connect from the desktop to the big boy by VNC software. Written by TEAMVIEWER.

-----------
It turns out SALOME6.4.0 has a solid modeller based on Open Cascade so no need for FreeCad. SALOME has a built in mesh generator for FEM simulation. It can generate 20+million polygons. So it is a real system.

To load SALOME6.4.0 on Mandriva, you need to load the following "packages" software

http://rpm.phone.net/index.php3/stat....i586.rpm.html
software are: libicuuc.so.42, libicui18n.so.42, libicudata.so.42

from same http://rpm/phone.net download libjpeg.so.7

then load SALOME from www.salome-platform.org

I'm in process of loading CFD program decided to use CODE_SATURNE rather than using OPENFOAM for now. CODE_SATURNE is closely tied to SALOME. Also there is a structural analysis program called CODE_ASTER.

Code Saturne requires additional software packages and I'm going through them now. It needs ZLIB, SIP, PyQT, METIS.

Salome solid modeller looks very powerful. It is based on OpenCascade. bit of learning curve though.

This sort of things take time to sort out but once its sorted out, it's pretty quick.

[PatQ562]

Since this is a more appropriate thread, I am reposting some numbers I crunched on the Solarworld GT thread. The tables below compare the performance of the Solarworld GT (2 passengers, 660 lbs) and the Edison2 (4 passengers, 1000 lbs). Both of these are all-out efficiency efforts and their results can serve as a basis for calculations for those designing similar high efficiency cars.

It looks like the SolarWorld GT is a commendable exercise in high efficiency transportation for two. The weight (approx 660 lbs) speaks for itself but the all-important CdA (equivalent frontal area, directly proportional to air resistance) is 0.1372 x 1.72 m^2, = .235 m^2. Projects with heavier bodies, larger tires, and greater frontal areas WILL use more power.

800W @ 31mph equates to 26 wh/mi. Given their peak solar cell output of 830 W, and using an approximation that a full day's sun equals about 2/3 of a day of noontime sun, it appears they can run about 8 hours per sunny day, or about 250 miles.

Inquiring minds ask, "what about other speeds?". Since Edison2 published their power-vs-speed results for their "VLC" about two years ago in their blog, we can use their results to extrapolate the Solar Car's results, since the vehicles are generally similar.

POWER IN kW vs SPEED
Note:
"VLC" numbers are actual power required expressed in kilowatts (kW)
"Cor" numbers are VLC numbers, at 88% efficiency, to obtain actual electric consumption.
"Solar" numbers are based on their stated consumption of 800W at 31 mph.

Spd VLC Cor Solar
30 0.94 1.07 0.77 (extrapolated from 0.80 at 31mph) = 28% less than VLC!
40 1.65 1.88 1.35
50 2.63 2.99 2.15
60 3.95 4.49 3.26
70 5.65 6.42 4.63

This little table is invaluable for students of high efficiency vehicles who want to live in the real world. We have here results from two all-out efficiency vehicles of somewhat different sizes, weights, and passenger loads. As an approximation, one can look at a proposed design, factor in its weight, streamlining and surface area, and arrive at a reasonable estimate of power requirements. For example, a Leaf weighs 3-5 times as much as these two cars, has a larger frontal area, and approximately half the streamlining (Cd about 0.28), so we should expect it to use several times the power, ie 250-300 wh/mi.

Knowing the power lets you readily calculate motor and battery requirements and estimate range.

To obtain range, we need the wh per mile (wh/mi).
To obtain wh/mi, divide the power used by the speed.

For EDISON2 VLC (at 88% efficiency):

30 mph, 1.07 kW, 36 wh/mi = 277 mi range for 10kWh
40 mph, 1.88 kW, 47 wh/mi = 213 mi range
50 mph, 2.99 kW, 60 wh/mi = 166 mi range
60 mph, 4.49 kW, 75 wh/mi = 133 mi range
70 mph, 6.42 kW, 92 wh/mi = 109 mi range.

The range number of course applies to "usable" capacity. It probably requires an 11-12kWh battery to ensure 10kWh of usable capacity, or you can deduct 10-20% from the ranges shown. The reader will note that the VLC somewhat exceeds the performance touted by the early Aptera (85-100 wh/mi), let alone their final dismal numbers of about 180 wh/mi. You will also note the major impact of speed on range.

SOLAR CAR
Spd kW
30 mph, 0.77 kW, 26 wh/mi = 384 miles, on 10kWh
40 mph, 1.35 kW, 34 wh/mi = 294 miles
50 mph, 2.15 kW, 43 wh/mi = 233 miles
60 mph, 3.26 kW, 54 wh/mi = 185 miles
70 mph, 4.63 kW, 66 wh/mi = 151 miles.

As before, take "usable" battery capacity into account. But we have a new champion in the category of high efficiency, freeway capable, closed-cabin personal transportion.

For a nominal range of 200 miles at 50-60 mph, we could use a 12kWh Flux Power battery, at 100wh/kg, weighing about 264 lbs. The more advanced Tesla type batteries might cut this to 175 lbs, let alone some of the developments we keep hearing about.

"It can be done!"

Pat Q

[NeilBlanchard]

It can be done! That is the take away. Thanks, Pat!

[smilingcat]

Very interesting set of numbers.

And its quite telling that everyone working is close to the brick wall with available technology.

Thank you for the numbers.

[rayfellow]

'I'm beginning to see the light'. Thank you Pat for putting this together. I'm a non tech dude, but I guess all my lurking is paying off.

It's an exciting time in the personal transportation / cottage energy development business.

Thanks

[dfbvt]

I like your extrapolation of the empirical data that we now have had the good fortune to have obtained. This information will be most useful and encouraging for others working on designs near the leading edge of technology.

Thanks for your efforts Pat,

Dave Bowles

[smilingcat]

Update on the software front.

There is a much easier way to get the suite of software loaded onto your computer. Very little knowledge is required. If you were to follow the instructions, which I will list down below, you will have a geometry modeller, FreeCad, Salome or Open Cascade. You will also have a mesh generator for the finite element analysis, a computational fluid dynamics simulator, Code-Saturne or Open Foam, a structural analysis program called Code-Aster. And several other very useful software tools.

-----
1. You will need to download unetbootin software. http://unetbootin.sourceforge.net/ and install the software. It's just a simple download and install. Follow its instruction.

2. You will download p7zip software. I think you can use 7zip for windows if your computer is window based. (microsoft based os). Follow its instruction on download and installation.
for 7-ZIP http://www.7-zip.org/
for P7-ZIP do a search for your particular OS, there are Debian, Ubuntu Mandriva, Redhat, Fedora packages available for automatic installation.

3. Download CAELinux from http://www.caelinux.com/CMS/
this will take several hours. 4Gbyte file. After you've downloaded the file, its best to use a md5 checker to find its checksum. http://www.softpedia.com/get/System/...-Checker.shtml

If the checksum matches to 9d788406fe59de7c4aac40e0102d6f84 then you have a clean download.

4. Get yourself a 16G or bigger USB2 or USB3 memory stick around $34.00.

5. startup the unetbootin by double clicking on unetbootin icon.
select have iso disk radio button. On the right hand side of the window straight across from iso disk button, click on browse button. Go to where you have your caelinux2011.iso file and click. My case I had it downloaded to /Downloads/caelinux2011.iso

6. In the unetbootin window, last thing you will do is select USB drive and you may have to fill in Drive, select the appropriate USB drive then hit okay.

7. Go for about an hour break.

8. If everything went okay, your USB memory stick will be the liveDVD where all the software is loaded.

9. Shutdown your computer. Hard shutdown!! restart your computer, hit del key to enter setup and change the boot sequence.

select USB as the first boot device then your hard drive.

save and exit.

10. When the computer comes up with the USB stick still attached to the computer, you will see a screen with several selection. Select LiveDVD and click or hit the enter key.

Follow its instruction and your computer will be running ubuntu 10.04.4 LTS operating system and in the menu of the ubuntu, you will find all the software.


----------------

If you have any problems, I can assist you in getting the system up and running. Ubuntu software will NOT destroy your windows, or Linux OS you currently have on your machine.

And with this, I think we've come to a reasonable conclusion for the engineering software. If you are still interested, please feel free to contact me.