CarBEN Model -- 1/24th scale model and 3D computer model for EV

[NeilBlanchard]

New, revised animation video of the SketchUp model:

http://www.youtube.com/watch?v=SVptQ3tdMBs

Available in HD this time, too!

[GrandisMerlin]

Hi Neil,

It looks very interesting, I would just like to note here that you'd probably want to add some more head room between both, the ceiling and the windshield.
The first one (ceiling is just for comfort... and taller people) BUT the second one is entirely for safety.
It's a very common omission from us DIYers to basically delete any free space we find. Just imagine that head room in a 40mph crash... remember everything inside the vehicle will keep moving the way it was - in a straight line - to the windshield 15 inches away.
There are a lot of handy physics calculators in the web that could help you determine the inertia/momentum that the person has at the moment of the impact. That way you can calculate then the speed of the head of the subject when it makes the semi-circular travel from the original position to the driving wheel due to the waist being held by the seatbelt.

[Bicycle Bob]

Presumably, there wil be a chest belt as well. All those physics models show that if you are going to hit an interior part during a collision, you should do it as soon as possible to reduce the relative velocities. That's why we even tighten our seatbelts in risky situations.

[NeilBlanchard]

Yes, the 3D model of the seated figure is sized to be about my height (6'-4") but I have no control on the position it is sitting in. I like sitting upright, but this one is a little too upright, so I'm fairly sure that there will be enough headroom. The CarBEN design is pretty tall, and the batteries are under the floor, but it has ~4' of height where the driver is.

[GrandisMerlin]

You're completely right Bob. Although I didn't mentioned it, I assume too that the seatbelt is complete (including the chest belt).
Anyhow, the waist belt will be the "anchor point" for the whole body, unless Neil has a fancy pre-tensioner installed (the regular ones, although they do a good job in holding you to the seat as close as possible, perhaps some more clearance to the driving wheel would be welcomed
On a side note, your observation on the physics of collitions is, again, right Bob. I just wanted to add something to your comment... you do want that the thing you hit has the characteristics to:
a) hold you to it (not only keep you bouncing, like you correctly mention with the seatbelt tightening)
b) be soft enough (or absorbing enough, for that matter) to not hurt you when that thing, along with you, come to a stop... because at some point that thing WILL stop (and most likely, it will be harshly)

Keep the great posts! And good luck with your very interesting project Neil!

[RobertSmalls]

While putting my Insight back together, I had the occasion to study its SRS. The system has a single input: An accelerometer bolted to the frame of the car near the firewall, inside the SRS computer. At some number of g's of deceleration, it fires the seatbelt pretensioners. At some higher threshold, it fires the airbag inflators. It's an incredibly simple system.

The 2000 Civic SRS adds "impact sensors" in each front fender, and newer cars get insanely complex with more sensors and more bags.

For people who are inclined to add soft, pretensioning seatbelts to a homemade car, I believe you can do that very easily, by installing a junkyard SRS system minus the airbags. If you want to add airbags, that will add considerable risk and complexity, and you'll need a donor car with matching seating position, distance to the steering wheel, and roughly similar deceleration during a crash.

[NeilBlanchard]

It was really great to be there at the X-Prize -- being able to see all the vehicles and to get to talk to the people who made them was invaluable. I think that the X-Prize is getting an important thing going, but I also wonder about the emphasis on near perfection; rather than on achieving ultimate efficiency. It's clear that electric drive is the only way to go:

The average of the 12 vehicles using electric drive MPGe (I'm including the FVT in this) was 134.7MPGe
The average of the 6 hybrids (not including the FVT) was 61.2MPGe
The average of the 5 internal combustion drive cars was 82.9MPGe

So, I am continuing work on my CarBEN design (which would be a mainstream 5-seat design, that is less than 14 feet long, and I think the aero could be equal to or better than anything at the X-Prize!), and I would like to plan on using FVT's EiG batteries and electric drivetrain.

CarBEN Concept EV: An Open Source Project - Vox

Initially, I want to try to meet or exceed the mainstream range as an EV. And if I can fit a really big battery pack (40-60kWh) then I would like to at least plan for this. The intended location for the battery pack is under the floor (the shaded 4'x'4'x6" box on the drawing) and this could be altered/enlarged.

I like the direct drive, but I also think that 8-10s 0-60mph would be plenty! The CarBEN chassis would be best (I think) as a composite foam sandwich (which provides thermal insulation along with good strength) and I think it will be light weight.

I will start making the section ribs out of aluminum sheets (like the Sonex plane my friend is building) and then I need to recruit some help for the fiberglass/composite shell. Maybe a local shop, or possibly someone like Dave Cloud (he's in Washington state) and he built the amazing Dolphin car, which just set the range record (over 200 miles!) for a lead acid EV: http://ecomodder.com/forum/showthrea...hin-13142.html

After I get a chassis built (notice I did not say "if"! :-), I would love to have FVT do the battery and drivetrain installation. After *that*, I hope to implement some "open source" ideas like using both the shock absorbers and hydraulic *motor* brakes to collect pressure in a small hydraulic accumulator, which would drive a small genset. And to be clear, I am not including the FVT components as open source; just the CarBEN design and the other efficiency ideas I have listed on my blog. More ways for auto makers to build more efficient vehicles - Updated 29 June 2010! - Vox

If anyone would like me to send drawings, and/or computer files, I'd be happy to do this.

[NeilBlanchard]

I now have several versions of the solid model of CarBEN! I have a .STEP, .STL, .CGR (and a 3D PDF, too) -- if anybody can do a CFD test using these, I would greatly appreciate it!

[NeilBlanchard]

Here are some renderings, done for me by C. Michael Lewis, from Portland ME. Proving it is a small world, he works both in architecture (and has mutual friends) and he races in the Electrathon series, and he currently holds the speed record of 62 Miles in an hour; while getting 2,249MPGe!

(My model is fairly rough...I need to have it made in a solid modeler.)
Link to my blog: http://neilblanchard.blogspot.com/20...e-project.html

[davidgrey50]

I just came across this thread. NeilBlanchard, I applaud the scope of your vision. However, you are proposing to construct an entire road-worthy passenger vehicle from scratch which is an undertaking of the Most Extremely Large variety. You are creating a chassis including suspension and steering; bodywork, including interior fittings, windows, HVAC, all safety requirements; an electrical system for propulsion, lighting, and ancillaries; and so on and on.

Some little experience tells me that dull stuff like door-hinges and suspension calibration and keeping water out will occupy a startling amount of time and effort. I don't know what your financial and temporal resources are, but I hope they're substantial.

I'll continue to follow this thread with great interest, and leave you with one-and-a-half bits of free (It's worth what you paid for it) advice: developing and testing of sub-systems - and sub-sub-systems - is the only way you will maintain your sanity, as fifty small nightmares are so much easier to handle than one great big one. And second, I'd heartily agree with those who have suggested a donor chassis. Small pickups (Ranger, S-10) seem to come very close to being the right size.