> The drag factor is derived from that force and a reference area.
> Inconsistencies in the way that area is calculated for road vehicles,
> makes drag factor mostly a marketing figure

The biggest reduction in drag in most EV's comes from not having an open
grill.  So how they define the area with and without a grill can make a huge
difference.  Most of the air that hits the grill and goes thought the engine
is almost 100% drag since it does not smoothly recombine with the flow.  I
once heard a GM Volt engineer say something to the effect that "when they
let him close off the grill" it was the best thing done for efficiency on
the Volt.

Bob
-----Original Message-----
From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Paul Compton via EV
Sent: Tuesday, October 17, 2017 6:01 PM
To: Electric Vehicle Discussion List
Cc: Paul Compton
Subject: Re: [EVDL] EVLN: EV Question #19: why do electric vehicles have to
look so ... silly?

Drag factor is a load of crap.

It's drag in terms of force required to propel a vehicle at a given speed
that's important.

The drag factor is derived from that force and a reference area.
Inconsistencies in the way that area is calculated for road vehicles, makes
drag factor mostly a marketing figure.

For vehicles it's frontal area that's used (gross or net?), but wing
profiles generally use plan or surface (wetted) area.

On 17 October 2017 at 16:18, ROBERT via EV <ev@lists.evdl.org> wrote:
> I think the EV1 had a drag coefficient of 0.19.  Does not make the CD =
> 0.24 for a Prius build in 2016 look very good.
>
>
> ________________________________
> From: EV <ev-boun...@lists.evdl.org> on behalf of brucedp5 via EV
> <ev@lists.evdl.org>
> Sent: Tuesday, October 17, 2017 3:59 AM
> To: ev@lists.evdl.org
> Cc: brucedp5
> Subject: [EVDL] EVLN: EV Question #19: why do electric vehicles have to
> look so ... silly?
>
>
>
> https://www.stuff.co.nz/motoring/97760520/car-question-19-why-do-elect
> ric-vehicles-have-to-look-so-silly
> Car Question #19: why do electric vehicles have to look so
> ...<https://www.stuff.co.nz/motoring/97760520/car-question-19-why-do-e
> lectric-vehicles-have-to-look-so-silly>
> www.stuff.co.nz
> OPINION: If you're ambivalent about electric vehicles (EVs), odds-on it's
> down to one of two things: range anxiety or the fact they always seem to
> look a bit silly ...
>
>
> Car Question #19: why do electric vehicles have to look so silly?
> October 12 2017  DAVID LINKLATER
>
> [images
> https://resources.stuff.co.nz/content/dam/images/1/m/7/f/e/u/image.rel
> ated.StuffLandscapeSixteenByNine.620x349.1m7ci0.png/1507768530182.jpg
>
> [https://resources.stuff.co.nz/content/dam/images/1/m/7/f/e/u/image.re
> lated.StuffLandscapeSixteenByNine.620x349.1m7ci0.png/1507768530182.jpg
> ]
>
> You know Nissan Leaf is an EV because it looks silly. But it's less
> aerodynamic than a Mazda3 or Toyota Corolla
>
> https://resources.stuff.co.nz/content/dam/images/1/m/7/f/e/t/image.rel
> ated.StuffLandscapeSixteenByNine.620x349.1m7ci0.png/1507768530182.jpg
>
> [https://resources.stuff.co.nz/content/dam/images/1/m/7/f/e/t/image.re
> lated.StuffLandscapeSixteenByNine.620x349.1m7ci0.png/1507768530182.jpg
> ]
>
> Expect future pure-EVs to look no different to conventional cars. VW
> is doing it already with the e-Golf ]
>
> [image]  Toyota Prius popularised the Kamm-tail body shape for eco-cars:
> smooth lines, chopped-off tail.
>
> OPINION: If you're ambivalent about electric vehicles (EVs), odds-on
> it's down to one of two things: range anxiety or the fact they always
> seem to look a bit silly. Or perhaps both.
>
> To many, electric vehicles are a turn-off because they lack a certain
> visual dignity. But are there good reasons for EVs to look like
> transportation pods from the planet Smorth?
>
> Yes, of course. But not all are entirely scientific.
>
> The most obvious one is aerodynamic efficiency. EVs are all about
> extracting the maximum distance from the limited battery power
> available, so it makes complete sense to have a slippery body shape.
>
> Aerodynamics really ony became a thing for cars in the 1930s, and the
> work of German brainbox Wunibald Kamm from that era is still very
> influential today.
>
> The so-called "Kamm tail" combines long, smooth body contours with an
> abruptly cut-off tail. The best-known Kamm-tail car is also one of the
> most recognisable production-car shapes of modern times: the Toyota
> Prius. Which did not start out as an EV, but its electrified hybrid
> technology did help send the automotive industry down that path two
> decades ago.
>
> That's why so many eco-friendly cars have looked so much like the
> Prius over the years. It's a very clean profile.
>
> Automotive aerodynamics are generally measured by something called
> drag coefficient, represented by a "Cd" number. As a point of
> reference, a modern family car might be in the 0.30-0.35 range.
> Something quite brick-like, such as a Ford Territory SUV, is more like
> 0.38.
>
> The latest Prius is considered extremely smooth for a
> series-production car, with a figure of 0.24. Even the previous (taxi,
> anybody?) model was 0.25.
> The new Hyundai Ioniq EV, which looks very Prius-like, is also 0.24.
> These are very impressive numbers.
>
> Simple, really. A silly shape equals smooth windflow. End of story?
> Not quite.
>
> The thing about the Prius and its ilk looking so idiosyncratic is that
> silly body shapes have become synonymous with cutting-edge
> eco-automobiles, which has in turn made them handy marketing tools for
> makers of EVs. While weird styling might turn off the EV-undecided,
> it'll certainly attract the early adopters who want to make a statement.
>
> So while many plug-in hybrid EVs are simply standard cars with extra
> batteries and a socket (think Mitsubishi Outlander PHEV), the trend
> for pure-EVs that run solely on battery power has been
> standalone/super-weird styling.
>
> The Nissan Leaf is perhaps the prime example. It looks extremely silly
> but it's only moderately slippery by modern standards, with a Cd of
> 0.28. That's still really good, but also inferior to a Mazda3
> hatchback (0.26), Mercedes-Benz C-class (which actually equals the
> eco-champs with a figure of
> 0.24) or Audi A4, which achieves a remarkable 0.23.
>
> Or consider the BMW i3 EV, which is super-strange looking but only
> manages a Cd of 0.29.
>
> Indeed, modern aerodynamic design allows carmakers to produce very
> slippery shapes that are still quite classic and elegant. Tesla's
> Model S sedan is
> 0.24 and the forthcoming Model 3 is claimed to achieve 0.23 (the
> original goal was 0.21, which would have been astonishing). Even the
> next-generation Leaf looks a lot more sporty and conventional than the
> current model.
>
> As EV technology becomes more mainstream and carmakers start to design
> new generations of cars to suit a variety of powertrain options,
> expect pure-electric cars to become less silly looking. Or at least a
> lot less self-conscious.
>
> The humble Volkswagen Golf has a Cd of just 0.27 even in standard form.
> Little wonder that the just-launched e-Golf, which is a pure-electric
> model, uses exactly the same body shape.
> [© 2017 Fairfax New Zealand]
>
>
>
> https://electrek.co/2017/10/11/weird-ev-turns-humans-into-self-driving
> -cars/
> [https://electrek.files.wordpress.com/2017/10/17c820_02.jpg?quality=82
> &strip=all&w=250&h=140]<https://electrek.co/2017/10/11/weird-ev-turns-
> humans-into-self-driving-cars/>
>
> A weird new EV platform ‘turns humans into self-driving
> ...<https://electrek.co/2017/10/11/weird-ev-turns-humans-into-self-dri
> ving-cars/>
> electrek.co
> Self-driving cars face a broad acceptance problem. People are used to cars
> always having been driven by humans, which has been the case for over a
> century, and some ...
>
>
> A weird new EV platform ‘turns humans into self-driving cars’
> 2017/10/11  I’m aware that the headline is pretty much an oxymoron and
> it looks like the stupidest thing from the picture above, but please
> bear with me for a second …
> https://electrek.files.wordpress.com/2017/10/17c820_02.jpg?quality=82&;
> strip=all&w=1024
>
>
>
>
> For EVLN EV-newswire posts use:
> http://evdl.org/evln/
> EVDL EV News Archive - Electric Vehicle Discussion
> List<http://evdl.org/evln/> evdl.org EVLN - EV News Archive Edited by
> Bruce {EVangel} Parmenter: EVLN: home | help | archive | news |
> privacy policy | terms of service
>
>
>
>
> {brucedp.neocities.org}
>
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--
Paul Compton
www.morini-mania.co.uk
www.paulcompton.co.uk (YouTube channel)
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