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Old 08-21-2012, 02:03 AM   #21 (permalink)
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Quote:
Originally Posted by ERTW View Post
I still take issue with people who demonize gm for "killing the electric car". They invested one BILLION dollars in r&d, and they're supposed to be happy selling 80 cars at $80k each?!

As to why they can't build a 2700 lb steel version, with a turbo 1.4...it'd be a two seat commuter car for the same price as a cruze. I'd expect 15% lower fuel consumption based on weight and drag. The SIV1 should at least be a 2+2. Gm should have a turbo 1L 3 cylinder soon, and cidi engines which will bring it to prius level economy.

The Shape has to stay the same from the a pillar rearward to keep it aero. Designers would be redundant. You don't want them to lose their jobs, do you?
Thats funny....when i look at all the really ugly cars being built and sold... i think porsche got it close to perfect with 911 design....anyone agree? Z:-D

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Old 08-21-2012, 06:48 PM   #22 (permalink)
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Originally Posted by thomason2wheels View Post
Thats funny....when i look at all the really ugly cars being built and sold... i think porsche got it close to perfect with 911 design....anyone agree? Z:-D
I never got very good with their shifters but otherwise always enjoyed driving them.
Hucho would classify the 911 as a 'pseudo-Jaray' form,with a bit too fast downslope on the roofline in side elevation for this 'Lange' form.Over the years a number of rear spoilers have been employed as a palliative for the flow separation-induced lift.
Today's Porsche is finally getting away from that steep roof.The Panamera and 918 are closer to the K-form.
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Old 08-21-2012, 08:04 PM   #23 (permalink)
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Originally Posted by Sven7 View Post
I've been sketching and 3D modeling.

But mine will probably be a one-off.
They are going to all be one-offs for the reasons that Phil outlined above
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Old 08-21-2012, 09:11 PM   #24 (permalink)
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Originally Posted by freebeard View Post
Behold the Volkhart-Sagitta. Cd of .17 in 1940.
The back is old school and too fast. The full wheel skirts are nice. Very good aero, but not sure i'd buy .17 Cd. Hucho pointed out that lots of these old numbers aren't directly comparable to modern measurements.
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Old 08-22-2012, 04:20 AM   #25 (permalink)
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You may be right , but hey--talking point.

I look at the cowl-line height and the contour around the A-pillar.

Someone with the tool-set could model this and morph the mesh into the Mercedes-Benz 'Boxfish' design and set it to 50%. I wonder what that's Cd would be.
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Old 08-22-2012, 10:57 AM   #26 (permalink)
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This thread started with the statement that 0.3CD is about where the state of the art is for modern cars.

Maybe in Detroit it is, but not in Stutgart or Bavaria.

I'm a merc man (afforable in europe) and can hand on heart post the following

1988 W124 Merc: 0.3CD
1996 W210 Merc: 0.27CD
2002 W211 Merc: 0.27CD
2010 W212 Merc: 0.25CD
2010 W212 Merc Coupe: 0.24CD

I beleive MB are aiming to get their fleet down to around 0.2CD.. helped by their boxfish study.

I beleive BMW with their efficient dynamics is looking to do something similar.

And where MB and BMW go, others inevitably, eventually, follow.

Derek
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Old 08-23-2012, 01:05 AM   #27 (permalink)
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Achieving .159 Cd isn't really that difficult at all. I'd bet that any one of the hundreds of aerodynamicists employed to work on Formula 1 cars could develop a <0.15 Cd shape in no time. In fact, they do it all the time! I'm sure many of you have seen a diagram comparing a small circle to a large airfoil, with the description mentioning they both have the same drag. Any Formula 1 car you see will have airfoil A-arms (wishbones). In fact, when I sat down with the lead engineer on my FSAE team last year, we calculated that we could save around 40 pounds of drag at just 40 mph, just by switching from round tubes to airfoils for our suspension components.

As far as automakers go, it's the market that directs their choices, not good engineering principles, as several of you have already stated. :/

However, if you study what automakers are doing to keep conventional car looks, while improving aero, you'll find that they are getting quite creative! For instance, the Toyota Corolla:
Look at the rear end of the car, it's quite boxy, and looks quite awful for aero, but you don't hear any Corolla owners complaining about trunk space or rear leg room do you? Look closely at the hard line on the outside of the rear reflectors, near the bottom outside edges of the bumper. That hard line is actually a technique that automakers are using to reduce drag by actually inducing turbulence in the boundary layer of airflow early, thereby allowing the air to move into the low pressure area behind the car in a much easier fashion. It's quite clever, keeping the engineers busy, business people happy, and oblivious customers even more happy with their mpg numbers, multitude of passengers, and trunk full of crap.
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Old 08-26-2012, 01:18 AM   #28 (permalink)
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Quote:
Originally Posted by ERTW View Post
I still take issue with people who demonize gm for "killing the electric car". They invested one BILLION dollars in r&d, and they're supposed to be happy selling 80 cars at $80k each?!
No they are expected to lose money to start just like every corporation that introduces something "new" like Microsoft on the Xbox or pilot runs on new foods or countless other products, the idea is that the real world owners provide R&D value in excess of what they can do just paying some guy $50k/year to keep driving test cars around taking notes.

The reason they cost $80k each is because they never went into production afterwards to amortize out the total R&D cost. The people that loved them to the point of wanting to buy them off lease showed there was a market. They performed better than modern electrics by what I can tell. Instead of rolling up production which would drop prices per car they just canned it all.

What i'm saying is I don't see how there was more profit crushing and destroying the EV1's after use instead of SELLING them. Plus considering GM gets handed billion(S) of dollars to do things like go build new factories... in brazil... to create jobs and cars for brazillians instead of doing it here, it's not like they are martyrs over it. I heard most of their EV1 R&D was indirectly subsidized thru some govt program at the time but I cant remember/source that right now so don't quote me. Heck taxpayer subsidies went to hybrid buyers up til last year too, it's nothing new. The only thing that doesn't make sense is acting like GM spent a billion just to come up with a car that couldn't be sold and had no profit potential - the biggest reason it didn't make a profit was they didn't even TRY to sell any end product result of it after having a proven market, full stop.

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