Been looking at the odly undercut or backcut shape under the rear bumper on the First Gen. I have searched for an explanation of this probable aerodynamic feature. Anyone seen an explanation of the various contours on the rear of this car?
Personally i think this bit of the car is a bit lame. It should really be a nice abrupt end like the top spoiler.
Infact just like the Prius 2..... would look far better amongst other things. All i see is a nicish curve to promote the air to attach to the rear bumper.
Although its a Kammback, its not really cut off as an aero design would be, i can only assume styling of the time and less understanding along with bumper 5mph regulations guided it.
Since the First Gen Insight enjoys a record low Cd among production cars, I have to believe that non of the features or shapes are without purpose. Some of the aero features are pretty easy to understand, but some of them less understandable. It is certainly true that Honda made some compromises, as any street car must, but they seem to have done a pretty darn good job. Have you seen any analysis of the car's aero features? I searched some, but the aero parts doesn't appear to be well discussed in the literature.
If only there was a kit replica company that could recreate the shape of the EV1, it had somewhere between 0.188 and 0.195 depending on what source I ran into, making it the most aerodynamically efficient vehicle produced. If only it's design could be created again.
I took note of post #10 from RobertSmalls on this thread
So, the EV1/Impact started with a Cd of .188. This drops to 0.167 with a mirror delete, short springs, and some duct tape, and 0.153 with a 16" boat tail.
Alot of the EV1 drag was thanks to it being an EV. No where near the cooling drag effect of a typical ICE engine radiator/condenser/engine bay drag. Then also doesnt have to deal with as much exit air from the bay having to go under the car.
I keep seeing alot of small engine cars in car parks and its obvious that the Insight bumper aperature and grill really is a bit OTT.
Id love to see some foam inserts made up for the aperature to narrow it then just fibreglass over it. Smoothing out the grill extending the bonnet leading edge may pay off aswell.
Thanks jonnyvtec, I do have my eyes on producing an EV, if I were to use any car at all and money wasn't and option and the option to use an EV1 replica shell, I think the EV1 would be my first choice. My second choice at this point(and most likely) would be a Honda Insight purchased with a bad engine, or sold cheaply from an owner who doesn't want to deal with IMA issues, and then I would pull and sell the working engine(likely to someone who needs it here). Third choice would be a Toyota Tercel. I think it would be very cool to do it with a late 60's/early 70's Fiat 500 (F model or similar) as those are only 1,100 pounds. Not sure if it would be better to go with a smaller car and less weight or an Insight with better aero for 60mph travel. I could fit more battery into an Insight though, probably would need to strap the spare tire into the cargo area though.
One huge disadvantage from the first generation lead-acid EV1 is that it was a lead-sled just a hair under 3000 pounds. Thanks to todays Lithium secondary cells that weight would probably be cut in half easily.
The new Merc E class will trump the Insight with 0.24 Cd.
No wheel covers but advanced computational analyisis on the underfloor airflow.
Yes, I've read that about the Mercedes E class. I kinda ignored fact that it ties or perhaps slightly beats the Insight Cd.
Do you have a link to discussion of E class underside?
I'm so interested in the potential aero effect of the Insight rear bumper because of all the discussion of boattails going on just now. "Simple" boattails get so long that I have concerns about their practicality regarding ground clearance. As I think you said earlier, the current thinking seems to be that rears should be square off sharply and perhaps that is correct. I'm certainly no expert.
Mercedes engineers have succeeded in aerodynamically optimizing the body of the new E-Class, achieving an impressive Cd of just 0.24 making the E-Class Coupe the world's most aerodynamic series-production car.
To reduce aerodynamic drag, there is an all-new electro-pneumatically controlled grille closure shutter. Its development is based on the knowledge that the air flowing through the radiator and the engine compartment accounts for up to ten percent of a car body's total aerodynamic drag. The fan shutter allows the engine's cooling air quantity to be limited in line with requirements, thus saving fuel. In essence, this means that, when the engine is running under part load and requires relatively little cooling, the radiator grille is closed by a circular system of louvers located behind the radiator. For minimum cooling, the shutter allows just a small amount of residual air to enter the engine compartment, but opens completely when the sensors signal that more cooling air is required.
When the fan shutter is closed, the Cd falls by 0.013, which is equivalent to a fuel saving of up to 2% when travelling at 80 mph. The fan shutter is fitted as standard on the four-cylinder models and on the E 350 CGI BlueEFFICIENCY Coupe.
When the fan shutter is closed, the Cd falls by 0.013, which is equivalent to a fuel saving of up to 2% when travelling at 80 mph.
Simply slowing to 60mph would decrease aero drag 44% (drag force goes as the square of the speed). Since power to overcome aero drag goes as the cube of the velocity, slowing to 60mph would reduce the power required to overcome aero drag by 58%. Not clear if fuel consumption is linear WRT power output plus there are other losses such as friction and tire rolling resistance, but still that's probably a lot more than 2%.
Cool technology though!!
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2006 MT
MIMA w/FAS module
various mods to driver
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First Gen Rear Bumper Aero Shape?
