Crudely streamlined Honda Civic reduces drag
Clay Roe says:
While browsing for horn modifications for my '08 Honda Civic Hybrid, I came across this extreme body modification to a 1992 Honda Civic CX. It may look like an Aptera's older road-weary brother; but the builder claims to have increased his drag coefficient from 0.34 to 0.17! Resulting in over 90 mpg! Just like my expensive hybrid!*"Home-made super-aerodynamic Honda Civic* - (With the wind. Downhill. With the AC off.)
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He claims that when he hits a deer, the front end "scoops them up and over, with minimal damage to both deer and car", and backs the claim up with this video of a racecar hitting a deer:
http://www.youtube.com/watch?v=rGJ0fJN10YY
It's almost better than the site itself.
Parallel parking and changing flat tires may be issues.
That said, I want one.
The quote says:
Shouldn't that say "decreased his drag coefficient"?
Hell, why park at all? This thing probably gets better gas mileage at 50 than most cars do stopped!
So, in the future, we may all actually be driving cars that look like this? I haven't been so excited about something since I was 12. (Ok, that last sentence was a lie.)
I think he is compensating for something...
Lowered drag coeficient gets you 90mpg in a '92 Honda? I find that hard to believe.
Hmmm I remember seeing something on Wikipedia here:
http://en.wikipedia.org/wiki/Kammback
which implies that you don't have to complete the teardrop to get good aerodynamics... I imagine there's an interesting sweet spot of added weight of the teardrop vs aerodynamics of the lighter Kammback (which the car already had).
I wonder if the front scoop is doing more of the work?
http://www.carbodydesign.com/concept-cars/2005-06-23-mercedes-bionic/2005-06-23-mercedes-bionic.php
Timothy @6 - a high drag coefficient on his dick?
The pointy end is the BACK of the car (unless his Civic came with suicide doors for the back seat!).
It seems his skills as a body man are matched well to his skills as data documentor.
I suspect that at the first speed bump he'll 'leave it all behind'.
[quote]This thing probably gets better gas mileage at 50 than most cars do stopped![/quote]
Hrm...
90 miles driven / 1 gal fuel = 90mpg
0 miles driven / 1 gal fuel = 0 mpg
"While browsing for horn modifications for my '08 Honda Civic Hybrid..."
I'm sorry, "horn modifications"?
The pointy rear does a lot. With a flat back, the car creates a zone of low pressure behind it which has a rearward force due to the differential with the higher pressure in front. The tapering tail eliminates this induced drag, which is substantial. It's not going to reduce fuel usage that much, though.
Needs black and yellow paintjob and stinger.
CALLING THE MYTHBUSTERS!
AeroCivic is an Ecomodder icon! I Love the obnoxious look that's true grit!
http://ecomodder.com/forum/showthread.php/aerocivic-how-drop-your-cd-0-31-0-a-290.html
Super low drag cars don't necessarily have to look like this one:
http://www.treehugger.com/files/2005/06/daimlerchrysler.php
The problem I have with this guys car is, what if in 30-40 MPH traffic he suddenly stops his car? What would have been a bad fender bender becomes a battering ram to the face of the other driver.
@18
SUVs are a much bigger problem for motorcyclists...also, don't tailgate in city traffic and you wont have the "guy in front of me had to stop so i rearended him" problem.
Also this car is
a) real...not a concept you'll likely never see
b) has a lower drag coeficient than the concept, even with how poor the body work is.
c) the aerocivic could have an even lower CD if the guy soothes out the underbody and shaves the door handles.
How did he measure the Cd, before and after?
How does the weight increase offset any improved aero.
What about brake cooling?
What about the low clearance and speed humps rocks n other rubbish on road?
Some of the worst fabrication and ugliest mods I have ever seen. Looks like it will fall off
What price looking like a dick and people laughing at you everywhere you go?
Ever since I was a little kid and first grasped the concept of drag, I've always been surprised at how un-aerodynamic most car designs are. It doesn't surprise me at all that he gets these results from a simple reshaping of his car.
And, #18, I don't think it would be much of a battering ram. That rear end looks very light-weight and would almost certainly crumple against your grill. Also, see "Safe Following Distance".
That is pretty awesome. Ugly but awesome. Smooth everything out and it'd just be awesome - but hey, he only spent $400! You can bet he's more than met his goal of "everything I did to the car had to pay for itself in fuel savings within two year's time."
And #19, he did:
#20, Government regulations require cars to not be as aerodynamic as possible. The front and rear have to have at least x amount of flat bumper space, the windshield has to be at least be at least at an x degree angle, must have at least x clearance under the car, etc. Almost everyone of those regs were put into place due to safety concerns. Some of the other things are due to convenience of the operator (door handles, uncovered wheels).
As neat as this car looks, it wouldn't get government approval for mass production for road use.
@#18,
The pointy back of the car is just an aerodynamic fairing. It pretty much only has to be stiff enough to hold its own shape, since the air loads pulling on it won't be very strong (that's the whole point). It could practically be made of foam. Even in jet aircraft, aerodynamic fairings are pretty flimsy.
@#8,
As #14 and #20 pointed out, cars are very very draggy primarily because they are bluff bodies: The steep (pretty much perpendicular to the airflow) back surfaces cause separation (i.e. the air stops following the surface, "unsticks", and flows straight back) and thus a huge low-pressure wake. (As the great Paul MacCready once said, "Most cars would be much more aerodynamic going backwards instead of forwards"). You can reduce separation by decreasing the angle of the surface relative to the airflow, which is done to a small extent in cars like the Prius and Insight. (But even they have a small vertical surface at the back, though, so there is separation around its edge. The only way to prevent separation entirely is to taper all the way down to a point or a wedge). Now, as you increase the size of the teardropping pointy back end (and thus decrease its angle relative to the airflow, making separation less likely), you also add surface area, which increases your viscous drag. The "sweet spot" is where the angle is barely shallow enough to prevent the air from separating. That's because if you increase the teardropping past that point, you don't really reduce bluff-body drag anymore (separation is prevented), but you keep increasing viscous drag.
codereduk, July 16, 2009 7:54 PM
"While browsing for horn modifications for my '08 Honda Civic Hybrid..."
I'm sorry, "horn modifications"?
Yeah. Have you HEARD the horn on a Civic Hybrid?!?!
Meeeeeep meeeeeeeeeeeeeeep.
Ugh.
-Radiodork
The under-car panels probably do more for his gas milage than anything. Imagine how unareodynamic the top of your car would be if you glued green army action figures all over the top of it. That's pretty much what the under side of your car looks like, and why Tesla is making such a big deal out of their completely flat bottom on their new sedan.
I always thought it would be interesting to invent and patent a big nylon windsock that attached to the back of semi truck trailers. At highway speeds air from the top and sides of the truck would fill the cone/wedge/pyramid and create a smooth convergence of air behind the truck. If you've ever been stranded on the side of the road and "felt" a semi truck go by, that's the turbulence created by the big flat spot on the back of the trailer.
I think you're all being perfectly horrid. OK, maybe the quality of his workmanship leaves a little to be desired, but at least he's having a go.
It would be more convincing if there was someone who didn't make the thing writing about results and impressions. As it is, I think the pride of craft (er, making) and an eccentric bent may be tinting his rose colored glasses.
Is that the rear window from a 1971 Buick Riviera? Didn't have time to read his info page.
The Volkswagen Bug looks like that for a reason.
And that reason is not actually comedy value.
The front of that car not only will scoop deer, but also other slightly higher vehicles. There was an accident in which the front bumper of the car was too low, and when it hit a higher vehicle, instead of crumpling the hood, it scooped the rear end of the vehicle right up into the driver's seat.
You can imagine the mess THAT made.