Hybrid aerodynamics driven by fuel economy
Why does it look like the Prius?The Toyota Prius is the king of hybrid cars. Yet, there are many that hate its design. Thus, now that the world has seen images of both the Honda Insight and the Chevy Volt, there is even more hate in the hybrid world, as these hybrid vehicles have come to resemble the Prius in many ways.
Honda's Chuck Schifsky, a Honda spokesman, adds some insight into this issue. Regarding the Insight design Schifsky recently went on record and stated, "It was done that way because it was the most aerodynamic design, and we were going for fuel economy."
Thus, the Clarity fuel cell vehicle and the CR-Z, another future Honda hybrid, will also share many of these ' prius' design cues. These vehicles, just as the Volt, however, do not resemble the Prius because of its sale's success, but because of an aerodynamic focus on fuel economy.
Labels: Chevy Volt electric vehicle concept, honda insight hybrid, Hybrid Vehicles, toyota prius
posted by Dahcredyns at
6:44 AM
10 Comments:
You know where I stand on this...I'd really have to see hard data to believe this.
Control surfaces of an aircraft have little to no effect at speeds of 40 mph and below. And this is in the regime of full deflections and maximum dynamic pressure for a particular control surface.
I can't believe that aerodynamics play a role at these speeds more than weight...I simply cannot.
Most of the fuel burned is off the line. The one and ONLY factor that improves performance in stop and go traffic is weight...and that is a fact no one can dispute.
So therefore, as I have stated before, these companies are simply setting up their tests in a way that give them the results they want to obtain in order the drive the design they want. That may be hard to swallow but frankly, being in this business and knowing aerodynamics, I simply don't buy their logic.
Well, I'm not sure that you can say aerodynamic drag for airplanes and cars is the same. Cars hug the ground, for instance, aircraft do not.
Also, much American driving is done at speeds above 40 mph.
Right exactly...that's my point. For GM to claim aerodynamics plays a role in the Volt means they have set a few assumptions about vehicle's operating regime which really, to me, makes no sense. If I want to get 40 miles of EV performance in city traffic, WEIGHT should be the issue, not aerodynamics.
I'm hoping to get some face time with a Volt GM engineer tomorrow. I'm going to try to find out some more about this.
Future fuel efficient cars are now starting to look like Prius. Prius in latin means "To go before". It is just a matter of time before a lot of people will start to realize how Prius moved the industry forward with the engine of change called Hybrid Synergy Drive.
Guess what anti-hybrid say why people buy the Prius? They give credit to the unique look that many love to hate. They gave no credit to the aerodynamic and interior room benefit of the shape.
GM is now getting a "taste" of the spread of this mis-information. The Volt does not have to look like a Prius. It can look like a Camry hybrid to be almost as good in term of aerodynamic. Camry Hybrid has 0.27 cd while Prius has 0.26 cd. If you look closely at Volt's front 3/4 pic, it looks like a combination of both Prius and Camry yet Volt's aero drag is said to have 0.28-0.29 cd. It does not add up.
Great points about the Prius, Dennis. Definitely a little irony with the Volt as Bob Lutz loved talking about the Prius as a "science experiment" in terms of its looks.
Still, I don't mind the look of the Volt at all. Of course, I've always thought the Prius was genius, so i guess that isn't saying much.
I'm hoping to talk to some GM engineers, especially those focused on aerodynamics. Have any good questions?
Q1: I read an SAE article by a Volvo engineer that about 30% of the aero drag is due to the cooling system. The air going through the radiator and around the engine compartments. When Volt runs on pure EV mode, do they plan on including active grille that completely blocks off the front (below the bumper since the top is simulation) and open as needed during the range extended mode? This would significantly improve the aerodynamic since Volt will only need to cool down the battery pack and ~98% efficient electric motor. This leads to my second question.
Q2: Will cooling the battery pack and the electric motor be sufficient with the air from the cabin? Prius battery is cooled by the cabin air.
Q3: What kind of combustion cycle does the 1.4L gas engine run on? HCCI? Atkinson?
I know I've been around some of the cooling system discussion, it just didn't stick with me, as I was focused on other issues at the time, but its relationship to aerodynamics has my interest now.
As for your last question. I'm positive its not HCCI. I know that GM is investing heavily in HCCI, but i don't think its yet ready for production. i'd bet its Otto, rather than Atkinson since the engine functions only as a generator, but that's only a guess.
It might actually be the "holy sh*t why didn't I thought of it" idea. A simple open and close mechanism can extend Volt's highway EV range by double digit % (25 -30%?) It may end up saving a few thousand dollars ($5k?) off the battery price.
Another idea. Use a supercharger type air vent (on the hood) to cool the battery and electric motor. It will look more like a muscle car and will be functional. Market it like an electric super charger! Right there, you have the look and coolness that differentiates Volt from every other hybrid. It would be perfect for the concept Volt but not so for the production look.
Dennis-
I found out a little bit about the 1.4 liter, 4 cylinder, naturally-aspirated engine. It's larger than it has to be, but larger because of noise issues. They experimented with a smaller engine, but the RPM band was too high and caused too much noise when generating electricity.
Also, regarding the battery cooling system, it's purely liquid cooled.
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