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

[andylaurence]

Why don't you use pullrods or pushrods with bellcranks to actuate smaller dampers? That way, you save a bit of space. I'm confused as to whether you're planning a Macpherson or double-wishbone layout, though, so if the former, it's not really feasible.

[NeilBlanchard]

I want to use something that fits, and something that is available as a used part would be best. I think I will have to build the shell and see what kind of suspension will fit. Simple, light, with good alignment and good handling characteristics, are all important to me.

[NeilBlanchard]

I'm going to start building the full size shell for CarBEN EV this week! I just need 2" (actually it's about 1 15/16" thick) EPS foam sheets, and a gallon jug of waterproof yellow glue. Oh, and plotted section profiles of the 3D computer model... :-)

[CFECO]

Hey Neil,

I just came across your project, and I was amazed at how similar your car is to one I was building to compete in the Auto X-Prize competition. If my photos get up here you will see.
The front suspension I was going to use might be of help for you, as my "Cab-forward" design required I leave room for the foot well. I am using the lower torsion tube from a VW sand rail ( available in aluminum but I don't know if they are strong enough) with it's trailing arm and an upper a-arm link. The upper a-arms are "sprung" with a horizontal airbag running perpendicular to the car centerline, above the footwell. The car's ride height will be variable depending on speed. Raised for entry and around town visibility, and lower for less frontal area at highway speeds.
For frame structural material I am using 2"x4" "Pultruded" fiberglass tubing, very light and strong.
The clay model is the first design I had, but it has been refined, after talking with a leading aerodynamic engineer, the rear wheel pants are not efficient. Straight sides are better. The messy shop photo was where I was getting the general shape and dimensions.
OK, the photos are too large to up-load to this forum, I'll have to shrink them later, anyway, we need to talk!

Chuck

[NeilBlanchard]

Chuck,

Do you have a blog or a photo web page? You can PM me the links, and/or your email, and exchange ideas. Here's my latest blog post on CarBEN EV:

Neil Blanchard Designs: CarBEN EV Open Source Project part 4 [Updated 10 May 11]

I know that ride leveling is important for good aero. I'm hoping to look into using Levant Power regenerative shocks, along with foam-filled tires that would do 3 positive things:

Lower rolling resistance
Avoid flats and leaks and the need to monitor pressure
Transmit more motion through to the regenerative shock absorbers

The Levant shocks are able to be dynamically tuned, as well, so they should be able to be comfortable over bumps and still offer firm handling, too.

The FVT motors I am planning on using, are direct drive and so it maybe better to have FVT fabricate the front suspension, too?

[euromodder]

With just 1 post, Chuck can't PM nor post links.

Links without the "http://www." part will work though

[NeilBlanchard]

This is exactly what I need to build the shell of CarBEN!

Phlatprinter 3 Kit

It goes directly from the computer to the foam; which skips plotting on paper, then cutting out the paper, then gluing to the foam, and then cutting the foam. One step vs four...

It may have been someone here who first suggested the Phlatprinter?

[NeilBlanchard]

I can only buy the 2" thick EPS in 24" x 96" sizes, so the 27" width is fine. The sections need to be cut in segments to reduce waste, anyway.

Here's my system for keeping track of the pieces: the section at the highest point of the roof (just behind the driver's head) is Section 0. The first 2" slice (the foam is actually closer to 1 15/16" thick!) forward of this is F1, then next is F2, etc. up to F39. The first slice just behind Section 0 is R1, R2 -- up through R47.

Each section then is made in segments, to best fit on a 24" x 96" sheet, and the part where it meets up with the adjacent segments is made into a 'V' so they will align properly. The position of each segment relative to a clock face will determine the name -- so if it is on the right side about at the 3 o'clock position, it would be called F23-3 or R42-3, etc. If it is on the bottom of the car, then it would be called F7-6 or R16-6, etc.

Now, some parts of the car will work better if I cut the section longitudinally; namely the center of the hood out to the fender chines, and the back foot or so of the car. Anything that tapers more abruptly than 2" thick sections can resolve easily. These are named FL0 - FL13, and RL0 - RL10 (front / rear longitudinal).

Here's the plan view of all the sections


The longitudinal sections will be mirrored and duplicated for the right side of the car.

And here is F1 and F2:


The back of the driver's head is what you see at the centerline of F1. The other bits are the two front passenger's thighs and arms and their seats.

The biggest challenge is to figure out which surfaces are increasing and transfer the profile from the adjacent section, so that there will be enough foam to be able to carve away the step and leave the correct form. To clarify, the top outside of F1 is the section of the model at that point -- but since the bottom of the car gets lower, I'll transfer the profile from section F1 back to F0, and the profile from F2 back to F1, etc. Same thing for the inside of the roof -- the inside profile of F1 (in cyan) has been transferred over to F0 so there will be enough foam to be able to carve it away, to leave the smooth surface.

[NeilBlanchard]

I just found out that the Phlatprinter 3 can *taper* the edges of the sections -- it is a 3D CNC machine!

That is the clincher! This is the ticket to build a composite sandwich structure! The foam will also provide thermal stability inside of CarBEN EV. It cannot do overhangs (it is a 3-axis CNC), but this will be a big help.

Wow.

[wilcorp70]

This is really similar to the project I want to do. Even using the foam core construction. Although mine is more like an SUV than a van.