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Old 07-24-2008, 12:27 AM   #31 (permalink)
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NeilBlanchard -

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Originally Posted by NeilBlanchard View Post
Hi y'all,

My AirTabs came today, and I even managed to stick (most) of the m on. They are much lighter weight than I was expecting -- they are "hollow" ABS. Also, they are pretty stiff, so they must be applied to a near-flat surface. I drive with them a bit tomorrow, and I'll need to fill up soon, so I'll see how the next tankful comes out...

Oh, that's right -- I pick up a sheet of Coroplast tomorrow, if it comes in.
Yeah, sorry about that. I should have pointed that out to you. There is one place on the side that I have been intending to install them, but I think I have to cut the Airtab down the middle to make it attach, and fill the cut with Bondo or something. The alternative is to "build up" a curved base to make it attach properly.

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Old 08-01-2008, 03:35 AM   #32 (permalink)
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Airtabs, shark fins and i thought that this matter was a done and gone affair till today when i saw my neighbours car with vortex generators on her Hyundai Accent, believe it or not thi is a sub comapct and the vortex generators were on the rear bumper at laes at a 35 degree angle sloping upwards off the bumper. Now this is a low end car and VG'S to add drag, i am having second thoughts about that.

I was going to approach this woam but decided against as she is somewhat rotund and may get the impression that i like them short and as heavy as a heavy chevy...........surely there is someone out there who can explain this to me and to others what gives with vg's

I made my own and have nine on the back of the rex.................sure feels different other than the noise that they make, my impression is that i can go further on a coast and if i lay on the gas she is off and running .........most interestingly the gas mileage has not suffered....................there has to be a reasonable explanation why Hyundai placed them on the rear bumper.................someone pleae resolve this issue once and for all...........................if you run a gas sipping car why would one use them there?

Will ask her re car when i see her GULP!
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Old 08-01-2008, 05:43 AM   #33 (permalink)
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Hello,

I'm probably going to remove the AirTabs I put on my xA -- I think they are hurting the FE a bit. It doesn't feel like I coast as well with them, either.

The first tankful with them was pretty lackluster, though I did have more people in the car, and ran the A/C some (43.5mpg) and this second tank is looking to be in the 43-45mpg range. This is less than I'd gotten before.

I have put on taller wheel skirts, and so I would have expected to do better than the 47.5 that I got with my earlier (smaller) wheel skirts.
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Old 08-01-2008, 06:49 AM   #34 (permalink)
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With all due respect I have tried to explain once before possibly to another party that air tabs are for trucks............just a bit big are they?

VG style would be like fins look for a similar design and make your own
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Old 08-01-2008, 08:28 AM   #35 (permalink)
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I would have to disagree with Doax. What the VG's do is to disrupt the streamlines going over the vehichle. Streamlines don't like sharp corners and will only bend at about 10-12 degrees. The VG's disrupt the streamlines and create a layer of turbulance next to the vehicle. There are other streamlines that still travel around the vehicle, but they are pushed farther from the surface by the turbulance layer. This prevents the streamlines from hitting sharp corners and allows it to bend easier.

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Old 08-01-2008, 08:43 AM   #36 (permalink)
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Quote:
Originally Posted by crexcrex View Post
i saw my neighbours car with vortex generators on her Hyundai Accent, ... on the rear bumper at laes at a 35 degree angle sloping upwards off the bumper.

...there has to be a reasonable explanation why Hyundai placed them on the rear bumper.................someone pleae resolve this issue once and for all
There is a simple reason: styling. The structures on the rear bumper are meant to look like a diffuser, and on this vehicle they are utterly useless aerodynamically.
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Old 08-01-2008, 10:05 AM   #37 (permalink)
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Hi y'all,

I pulled all the AirTabs off my xA, and the drive to work confirmed that they were slightly detrimental to the aerodynamics. It now coasts better, and it raised the average MPG by 0.7 in just 45 miles -- I had burned almost half a tank. I'll see how high I can get.

I'm better off without the AirTabs, that's for sure.
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Old 08-01-2008, 05:39 PM   #38 (permalink)
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That's what I was afraid of -- they might produce too much drag to make them worth it. Ah well.
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Old 08-01-2008, 07:26 PM   #39 (permalink)
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Let's not forget that while VG's can theoretically reduce Cd, depending on the vehicle they can also increase A, so the net effect (Cd*A) may be a wash.
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Old 08-01-2008, 07:36 PM   #40 (permalink)
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Unless the A was so big already (as on semi's) that the lower Cd compensates for the slightly increased A. On smaller vehicles, the increased A is more noticeable and cancels out the benefits. Makes sense.


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