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Old 06-09-2008, 01:18 PM   #61
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Interesting paper, but a bit light on technical data. Not surprising.

When I posted "it would be interesting to read that trade study," I was thinking that it would be nice to read Mitsubishi internal data that actually had the *real* design constraints. I wouldn't be surprised to see something from their styling group that laid down an envelope from which the researchers couldn't deviate.
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Old 06-09-2008, 01:24 PM   #62
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Interesting paper, but a bit light on technical data. Not surprising.

When I posted "it would be interesting to read that trade study," I was thinking that it would be nice to read Mitsubishi internal data that actually had the *real* design constraints. I wouldn't be surprised to see something from their styling group that laid down an envelope from which the researchers couldn't deviate.
That's what I meant about the spoiler. All that research to reduce drag on those little bumps after deciding to have that big spoiler.
BTW I just filled up and got 37.3 mpg on this last tank.
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Old 06-09-2008, 04:52 PM   #63
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So, is there a rule of thumb on coupe/sedan shape to prevent this lift?

Should the back glass angle always be more shallow (less slope) than the windshield angle? This seems to be the case on the CRX as well as Prius and even the Nissan 240sx

As you said, there should be a separation point about halfway down the back.

So models with a steeper back glass (Fiero, early 1990's Dodge shadows etc.), will likely have more drag, right?

my LX Civic is very susceptible to lift, and any large truck that blows by me causes my car to sligthly swerve. As RoadWarrior stated the sedan's shape has lift problems as it looks a lot like an airfoil (aircraft wing) that will promote lift which is bad for cars. this can be compensated (form what I read from many different forums) by lowering the car (or adding an air dam) and installing a spoiler. As stated in the article I posted on this thread, the airtabs VGs installed at the bottom front of the car can also reduce this problem. I have ordered 20 airtabs and will experiment on where to place them. I will install the airtabs with magnet sheets instead of just sticking them on the skin of the car so I can move them around and see what works but the ones that I will put on the front bottom would have to be stuck on to the lower lip since it's not metal.
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Old 06-09-2008, 05:42 PM   #64
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That's what I meant about the spoiler. All that research to reduce drag on those little bumps after deciding to have that big spoiler.
BTW I just filled up and got 37.3 mpg on this last tank.
Well, after all, the EVO is a performance car. And Mitsu's alternative to the VGs is the mega-drag inducing roof deflector ala Subaru WRX STI. IMO, that's the beauty of VGs...the passive ability to 'deflect' air with minimal obstruction.

Good tank, BTW!
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Old 06-09-2008, 05:59 PM   #65
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There will be no spoiler on the Cavalier. Performance cars designed to go over 100 mph is bound to have different problems. Down force and lift are not on my list of concerns, but I do need to reduce drag. At least my back window and top part of the trunk lid didn't collect dust as usual ( just a few inches on the top back of the trunk lid and the bumper).
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Old 06-09-2008, 06:26 PM   #66
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I have always wondered if stock Civic Sedans and Civic coupes have better aerodynamics than stock Civic Hatchbacks.

I know the sedans and coupes weigh a little more than the hatchbacks, but they definitely have more of a tear drop shape which ought to have a smaller low pressure area behind when compared to the hatchbacks- which just drop off abruptly.

Any thoughts on this?

If this was true, a 92-95 lightened civic coupe with D15Z1/VX trans might get better highway mpg than a VX hatchback.

I've alwasy wondered this as well, I know the 92-95 civic coupes have very long smoothly sloping back windows. I also once drag coefficient for the european model (same chassis) of .32, a pretty good starting point in my opinion. The sedans rear window seems too steep to be as good, but they still seem like they have to have a smaller bubble than the hatchback models.
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Old 06-16-2008, 09:09 PM   #67
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Sorry to wake up this thread...but on the subject of VG size, I found this pic of the Renault eco2:



I count 16 of the lil' guys.
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Old 06-17-2008, 06:29 AM   #68
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LOL! I thought about just using the spoons but the wife would probably disown the civic if I do!
Ok, I got the airtabs installed. let's see if it works.

If I see even the slightest improvement in FE with these airtabs I'll install them in front of the rear wheel wells as well to improve the aero of the rear wheel wells.
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Old 06-17-2008, 10:35 AM   #69
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They look too close together compared to the photos on airtab.com, and they should also be distributed on the whole width of the car i believe...
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Old 06-17-2008, 10:57 AM   #70
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They look too close together compared to the photos on airtab.com, and they should also be distributed on the whole width of the car i believe...

they seem to work just fine judging from the reaction of water dorplets when it was raining a couple of days ago. the water droplets were zipping down the window a lot faster during the time. I could see the difference between the water droplets reaction on the area where airtabs are installed to areas where no VGs are present. the middle of the window had water dropplets that were zipping down fast, the outer part of the windows (both sides) water droplets were moving down slower.

Airtab do suggest installing them as close as about 4" apart (measured from the middle of each tab to the next tab). I just chose to install them right next to each other.

as far as having them across the roof of the car, I started with just three, then kept adding two. I will add two more after my current gas tank. I'm trying to see if there would be any difference so I'm installing them slowly.
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