Steve's Intro

[SteveP]

Hi,

I'm in the SF Bay Area and looking to do an EV conversion in the (perhaps not so) near future and because of my range requirements (30 miles at 70 mph) I am considering aero mods (along with rolling resistance mods) to help achieve it. Yes, I'll need Lithiums to come down a bit in price, too, but that's happening. In the meantime I'm trying to learn everything I can about car aerodynamics--fortunately I have a bit of a head start since I know a little about aerodynamics from rocketry.

For now, I've just finished reading Road Vehicle Aerodynamics by A. J. Scibor-Rylski, the only book on vehicle aerodynamics my local college library has--it's quite good and worth a read. I'm looking for Hucho and the other "classics" and am reading various SAE papers to see what can be gleaned from them. Answer: plenty!

Haven't decided on a donor car yet--and won't until I have a better handle on the aerodynamics. I also plan to go visit an EV1 and hopefully take some measurements--there's a lot we can learn from that car. I've also written a simulator (along the lines of the EV calculators on the net) that helps figure out contributions to drag from rolling resistance and aerodynamics at different speeds, etc. Learned a lot from that, too.

In the meantime, I'll add comments to other threads where I think I've found something that may be helpful....

--Steve

[SVOboy]

Welcome to the site! Do you have any idea what kind of car you want to use for the EV?

[Daox]

Welcome to the site. I look forward to seeing some work get done.

[SteveP]

Thanks guys...

SVOboy: Re vehicle: Light and aerodynamic. An EV1 would do just fine :-)

I've scoured vehicle specs for months. I know what the lighter gliders will be (Swift clones, Tercel, etc.) and have chased down all the CdA numbers I can find (not that they're necessarily accurate). What I'm now wrestling with is what style (sedan, fastback, hatch, etc.) I can most easily mod to get a CdA that will work for me (5 sq ft would be nice--EV1 was 4 sq ft). The problem with modding a sedan (or coupe) is that boattailing the "upper" part (the rear glass) would potentially screw up the trunk. The problem with the hatch is that you have to really extend the whole rear end. I haven't looked at the older fastbacks yet to see what's available and what might work. I would really like something without a trunk since I often haul stuff that fits with a hatch that doesn't fit in a trunk.

Darin mentioned the Honda Insight, but the problem is they're darned expensive around here--more than my total budget, unless I get really really lucky like Red did (I've looked and am not holding my breath).

Also, I'm mindful of the fact that it may just be a lot easier and cheaper (if this process takes long enough) to spring for a couple more battery cells to extend the range than it will be to do the aero mods to accomplish the same thing.

The newer cars are really coming down in Cd, but the A's are getting bigger and the weights are increasing to ridiculous proportions as well (they'd be out of my price range as well, of course). It is very frustrating.....

--Steve

[Daox]

If I were going to convert an EV, I'd really take a good look at a CRX. Great aero, lightweight, and just a nice little car.

[SteveP]

Daox:

I found a CdA of 5.71 sq ft for the 1990 Si--true, that's not a *horrible* CdA, but I'd want to get it down to 5. It's on my short list, though. Unfortunately, they stopped making them in '91 so you don't get airbags and some other features you'd get with something from around '95. You can get them for not much money (2k or less) and older cars around here are less rusty than they are in some areas of the country, so that helps. Also, I'd prefer a decent interior and the older cars (of any make/model) tend to have pretty trashed interiors. Several have been converted to EVs, so I wouldn't be breaking any new ground there (always a plus).

--Steve

[Christopher Jordan]

Craigslist had an EV Aztek kit car last week, a small Bombadier the week before or a boxy Mountain View utility, and many Gems, Xebras, or electric cop car Mustang the other day........constant reading enjoyment for me! Unfortunetly; no EV velomobiles yet.

Oh; by the way- welcome!

countersTrike

[Daox]

Steve, what cars have you found that have a CdA of under 5?

[SteveP]

Doax: Under 5? Nothing (of course). That's why I'm studying the heck out of aerodynamics. The only way I'm getting 5 or below is to get (an affordable) Insight or something that's over 5 and mod the heck out of it. So what I'm trying to do is figure out what mods are most likely to succeed (for a given car), how much effort they are, etc etc. and weigh them against other options. It's just a small matter of homework

--Steve

[Daox]

Would you mind posting a list of the CdA values you have collected?