iMiEV CdA?

jennrod12 said:

Cool, let me know how it goes! How many did you get? Hopefully you can post a picture, too.

I think we didn't get the extended hatch cover because our car is wider. I'd really like that hatch cover.

Jenn

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I purchased 9, measured the back of our Miev and it's about 4 feet of mountable space but thought 12 airtabs was overkill, also our antenna in the back probably didn't need an airtab behind it. I also looked at their website and based it on this photo of a Smart car http://airtab.com/gallery/large/11A2.jpg
As you can see they mounted it before the roof-hatch gap. Yes, would have preferred an extended hatch, too bad wasn't an accessory option

Received my airtabs yesterday, ordered 9 but they provided 10 in shipment which actually turned out for the better as I was able to mount 5 on each side of the rear antenna as opposed to having an unbalanced 4/5 setup. Installed per instructions provided and gave it a spin this morning at speeds up to 60mph. Initial impressions: Felt I had improved handling, main reason for getting these were not for FE gains but for better handling as we get some pretty strong winds here on Oahu, especially with all the mountain valleys. It was raining moderately this morning, noticed that rear window had little to no precipitation while driving. Used the same number of bars (4) to get to my destination and back, might require a longer drive to determine if any effect on FE.

Forgot to add that did not notice any additional wind noise, may be due to fact that our Miev already had wind noise at higher speeds and we've gotten used to hearing it.

Thanks OahuMiEV, plz post pics when you can.
I've found a new boat-tail hero. The sheet-metal dutch creation was nice, but had significant body gaps. This foam composite creation looks factory.

https://picasaweb.google.com/threewheeler100/HondaInsightTailExtension#5665767454497591266

oahumiev - I too would be interested in seeing a photo of the airtab installation. Let us know what you think after a few weeks of driving.

jray3 - that is indeed a nicely-done aft extension for the Insight, and I would hope that he gets a measurable mpg improvement at speed.

Wife has the car this weekend so will have to wait until sometime next week for a pic. Waiting for a windy day to really put these airtabs to the test!

Can update that these past few days we've had some pretty strong gusts upwards of 30-40 mph. Did some driving in these conditions which certainly put these airtabs to the test. In the past with similar windspeeds, the Miev did get pushed around a bit at highway speeds of 50-60mph which is the speed limit here. With the airtabs, can say that the car had more control and did not get pushed around very much. Have not noticed any significant FE gains or losses, I do not use any type of FE measuring device other than knowing that my roundtrip to Honolulu and back used to take 12 bars and still takes 12 bars with Airtabs installed. I am satisfied with the Airtabs thus far and will not be removing them from my Miev. Wish I could directly load a picture of installation onto this forum, any thoughts on simplest way to do this without signing up for something?

I tried the AirTabs on my Scion xA and I found they hurt my efficiency a fair bit. I'm going by a couple of tanks, and I ended up removing them.

I bought a bunch, and I still have a few unused, if anyone wants to try them.

The boattail you posted is about the best one I've seen (over at EcoModder.com):

https://picasaweb.google.com/threewheeler100/HondaInsightTailExtension#5557294009769008898

He included lots of construction photos, and it took a lot of effort, but it seems to have helped a lot.

Excellent craftsmanship and a beautiful result!

I'll *bet* he doesn't have to parallel park at work though

Don

Don said:

I'll *bet* he doesn't have to parallel park at work though
Don

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But we wouldn't!
I found myself a half-length parking spot next to an Excursion, and that beast still stuck out further than the i did!

jray3 said:

I found myself a half-length parking spot next to an Excursion, and that beast still stuck out further than the i did!

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You parked facing the curb?

Wee John said:

jray3 said:

I found myself a half-length parking spot next to an Excursion, and that beast still stuck out further than the i did!

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You parked facing the curb?

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Nope, I didn't go end-in a parallel spot, but took an (undesignated) motorcycle space in front of a landscaping planter, and fit just fine.
Let's try some ASCII Art. See if you can spot my i!

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Thanks to Wee John, I'm finally posting pics of my Airtabs install. Have had them for about a month now, wife who drives the car to work daily loves them and definitely notices better handling especially on freeway at 50-60mph. Lmk if any questions regarding install.

If you still need an area for the i MiEV, I can do a polyline in DataCAD. If you have a photo from straight-on with a long(er) lens from the middle, and with a yardstick (or a longer scale) in the photo at the high point of the car, please post it here, and I'll get you an area in CAD.

This is an example of the kind of photo that works best:



The horizontal bar is not needed, but it shows that the vertical scale is at the high point of the roof. Notice that this photo is *close* to straight on, but the rear of the car is slightly skewed to the left side, so this is close enough to be useful, but would not be as accurate at it could be.

The car is a incredibly sleek electric car built by Dave Cloud, called the Dolphin. It has a range of over 200 miles -- using lead acid batteries!

oahumiev, thank you for posting the photos. Those AirTabs sure look large on the iMiEV compared to a truck trailer. Makes me think that a much smaller version would be more applicable to a car, as my understanding is that vortex generation needs minimal protrusion. Certainly doesn't detract from the iMiEV's looks IMO.
Question: do the AirTabs help at all in reducing the amount of dust/dirt accumulating on the aft end of the car?

JoeS said:

oahumiev, thank you for posting the photos. Those AirTabs sure look large on the iMiEV compared to a truck trailer. Makes me think that a much smaller version would be more applicable to a car, as my understanding is that vortex generation needs minimal protrusion. Certainly doesn't detract from the iMiEV's looks IMO.
Question: do the AirTabs help at all in reducing the amount of dust/dirt accumulating on the aft end of the car?

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JoeS, yes, I too wouldn't mind a smaller profile but it does it's job. As to your question, I do notice the rear windows not collecting as much dust/dirt, as for the aft end of the car, it still gets dirty as much of that might come from the rear wheel but in general, I would say the hatch looks cleaner than before.

oahumiev, now that you've had these for almost a half-year, I was wondering what your opinion of the AirTabs is now?

I've been staring at my iMiEV with an eye to making some Cd-reducing mods, and the only things I can come up with are aft wheel skirts and the AirTabs. I can't see any simple way of streamlining the underbody under the rear drivetrain, and I'm not at all inclined to make a boat-tail extension as that would greatly reduce the car's functionality.

JoeS said:

oahumiev, now that you've had these for almost a half-year, I was wondering what your opinion of the AirTabs is now?

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I'm the weekend Miev driver while my wife is the daily commuter, she had driven the car for a few months before putting the AirTabs on and she noticed a big difference in the handling, prior to the AirTabs she complained the Miev would be "nudged" during windy days at freeway speeds which would freak her out. Since putting the Airtabs, haven't heard that complaint once so yes, the Airtabs have helped with stability during windy days at high speeds. As for any FE gains, it takes us 12 bars to get to Honolulu and back home which is the same prior to installation. I've got to imagine that if one drives at higher speeds more frequently than lower speeds, these Airtabs might make a larger impact, we're relegated to 55mph speed limits here, no complaints however as the Miev is perfectly happy not having to get up to 75mph as they do on mainland interstates.

Hi oahumiev, thank you for the update.

It seems that the vortex generator needs only to be minute and not necessarily the sizeable Air Tabs protrusion. Another alternative may be something called a zig zag turbulator, which is a stick-on tape that was developed for sailplanes but is also used on radio-controlled planes, racing cars, motorcycle fairings, wind-gen blades, fin keels of sailboats, etc. I'm still looking for some concrete quantitative test data using this stuff.

NeilBlanchard said:

If you still need an area for the i MiEV, I can do a polyline in DataCAD. If you have a photo from straight-on with a long(er) lens from the middle, and with a yardstick (or a longer scale) in the photo at the high point of the car, please post it here, and I'll get you an area in CAD.

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Neil, how about this photo, courtesy of Motor Trend?
Thanks!

http://www.google.com/imgres?imgurl=http://image.motortrend.com/f/oftheyear/car/1201_2012_motor_trend_car_of_the_year_contenders_and_finalists/39376737%2Bw799%2Bh499%2Bcr1%2Bar0/Mitsubishi-i-MiEV-dimensions.jpg&imgrefurl=http://www.motortrend.com/oftheyear/car/1201_2012_motor_trend_car_of_the_year_contenders_and_finalists/photo_249.html&h=499&w=799&sz=63&tbnid=p39jMD-SidRzCM:&tbnh=72&tbnw=116&zoom=1&usg=__JsK9PQq7MRccWEW0Q6R_4HumPSg=&docid=qGhyBGpuo9cS1M&sa=X&ei=I0xoUb6lComkigL564GwAw&ved=0CJEBEPUBMAs&dur=708

That works very well - I downloaded the full version. Caveat is that the front shot is *not* straight on - the back of the car is shifted to the left (as you look at it) so, the antenna does *not* line up with the Mitsubishi logo. So the outline is not accurate, unfortunately. I did the outline - including the mirrors and the tires - and the total area I measured is 25.447 sq ft.

Then I remembered that the EcoModder CdA list includes the i and they list it as 23.2 sq ft. They may not have included the mirrors (I think it is the convention to *not* include them?) and it is likely that the actual number is in between?



I know how to correct my outline - the 62.4" width dimension scales ~65.6" (even though I calibrated it to the 144.8" length) - I'll make my outline exactly 62.4" (not including the mirrors) and that should be pretty close...

... Okay, the revised measurement is 24.052 sq ft, including mirrors. So, I think the 23.2 sq ft is good for the area without mirrors. Here's the corrected area, shown with a 1 foot square grid hatch pattern, and the horizontal majenta line is *exactly* 62.4" long.