CivicTail project: ginormous aerodynamic tail on '07 Civic sedan

[Fat Charlie]

That was the thread- but I kept getting your Civic thread in my searches.

Post it for sale here- the chance to solve that mystery should add to its value!

[BabyDiesel]

Originally Posted by BabyDiesel

If this test doesn't go better, just send it to North Carolina and I'll put it to good use

My offer still stands

It is roughly ~750 miles up to where you are, Metro... ~30 gallons of gas. So tempting...

[aerohead]

Originally Posted by California98Civic

I am always amazed at your energy for these projects... still 3% would just a little over 1 mpg on the freeway, which is something but so much less than we'd expect. Has the basic Civic body design been so optimized that it has become that difficult to improve upon?

The only thing I've run across had to do with the A-pillars.They were designed to act like a flow straighteners,directing air over the roof rather than allow it around the sides.
So there is a bias towards over-roof flow.How this impacts boat-tailing I've no idea.
Honda seems interested in the more organic contours.

Sure would be nice to have a big wind tunnel.

[aerohead]

Darin,thanks for going the extra distance with the additional mods, testing,and data reduction.It could not have been too much fun!
Only time ahead and what we run across will help explain the boat tail debacle.
Hope the disposition of the car goes easy.

[MetroMPG]

Thanks, Phil! It should be easy to sell. It really is a nice car.

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~30 gallons of gas. So tempting...

Not worth 30 gallons of gas for a cardboard + coroplast boat tail that won't fit your car properly! DIY, baby.

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I posted the fancy test graphs and raw numbers in post #4 (which I had 'reserved' for that purpose when I started the thread).

You'll see in the first graph something that we haven't talked much about: the Kammback section on its own apparently made no difference vs. a bare back end. Very strange, this Civic. (More likely: not optimal, my handiwork.)

[CigaR007]

I noticed on your graphs that there wasn't a "kammback off/tail on" scenario. I know that seems counter-intuitive but it would have been an interesting approach. Perhaps even just for the curiosity of it.

I think the results are due to the notchback design on the civic. Perhaps Honda did a really great job at the rear of the car, meaning a rather "clean" separation after the decklid. I know it is too late now, but I wonder if removing the kammback and leaving the tail might have netted better results. It might have unlocked an untapped synergy.

The kammback certainly improved the flow on top, but it might have been interfering with the c-pillar vortices, causing the net efficiency gain to be somewhat lower than expected. Pressure differentials on the boattail surface might also be the culprit. I believe we want an even pressure recovery.

Given that the rear glass angle and overall design was already optimized by Honda, adding the tail only might have netted better efficiency gains, as it would help the pressure recovery aft of the decklid, where the airflow does usually re-attach in notchback designs.

Food for thought I guess. Thanks again for the hard work; it never ceases to amaze me.

[Cd]

Earlier, I saw a Civic hybrid - same year as this car.
I had to wonder why the heck Honda would install a tiny decklid spoiler if it did noting.

I guess it was just something that they could charge more for, much like the mandatory options that come with a different model of car.

I sense your frustration Metro. That was a lot of work.

[Daox]

Darin made his own lid spoiler in earlier testing.

[BamZipPow]

Originally Posted by Cd

Earlier, I saw a Civic hybrid - same year as this car.
I had to wonder why the heck Honda would install a tiny decklid spoiler if it did noting.

I guess it was just something that they could charge more for, much like the mandatory options that come with a different model of car.

I sense your frustration Metro. That was a lot of work.

One of the things that some of us seems to fergit is that marketing/style is key to sales. If you can't appeal to all the senses regardless of function, then yer sales can fall flat. the spoiler make make it look more sporty than it actually performs as a functioning spoiler. Other examples are the faux diffusers and drilled/slotted rotors on street cars.

I remember a time when most cars didn't have a oil pressure gauge or tachometer. Now they are pretty much standard on all cars.

[MetroMPG]

Actually, the hybrid style spoiler is functional for drag reduction. The "sporty" Civic sedan trim had a different, bigger and blingy-er style spoiler.

When Canada introduced a tax rebate for efficient cars around 2008 (since cancelled), the base 5-speed, non-hybrid Civic sedan originally fell just under the rebate threshold. So Honda revised the car to get it into rebate territory by adding the hybrid rear deck spoiler, hybrid wheels & tires (and a few other mods). There are a lot of Civic sedans running around here that look like the hybrid, but aren't.