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Discussion Starter #1
Is there a good resource, online or elsewhere, to look up the drag
coefficient and frontal area of modern vehicles? (Yes I already know
about the mayfco.com list; it doesn't include any vehicles less than 10
years old, and most are 15 or more years old). So far Google hasn't been
helpful on half the cars I've tried to look up.

Is this the kind of thing for which some kind of publication is
available, that I might find in a library somewhere? I'd even be willing
to pay a reasonable amount for ongoing access to this kind of
information, if it's kept up to date.


--
Christopher Robison
[email protected]
http://ohmbre.org <-- 1999 Isuzu Hombre + Z2K + Warp13!

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Discussion Starter #2
Christopher Robison wrote:
> Is there a good resource, online or elsewhere, to look up the drag
> coefficient and frontal area of modern vehicles?

Not to my knowledge--I went down this path a while back and didn't find
much. Sometimes some of the car mags (Car&Driver, IIRC) have CdA numbers
in their full reviews, but they've only been doing that for a few years,
so there's a real gap in info between the mayfco.com and the car mag
stuff.

--Steve

> (Yes I already know
> about the mayfco.com list; it doesn't include any vehicles less than 10
> years old, and most are 15 or more years old). So far Google hasn't been
> helpful on half the cars I've tried to look up.
>
> Is this the kind of thing for which some kind of publication is
> available, that I might find in a library somewhere? I'd even be willing
> to pay a reasonable amount for ongoing access to this kind of
> information, if it's kept up to date.
>
>

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Discussion Starter #3
Try this:
<http://en.wikipedia.org/wiki/Automobile_drag_coefficients>

--
Martin K

Christopher Robison wrote:
> Is there a good resource, online or elsewhere, to look up the drag
> coefficient and frontal area of modern vehicles? (Yes I already know
> about the mayfco.com list; it doesn't include any vehicles less than 10
> years old, and most are 15 or more years old). So far Google hasn't been
> helpful on half the cars I've tried to look up.
>
> Is this the kind of thing for which some kind of publication is
> available, that I might find in a library somewhere? I'd even be willing
> to pay a reasonable amount for ongoing access to this kind of
> information, if it's kept up to date.
>
>
>

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Discussion Starter #4
Yeah, that first table is from mayfco.com; however, the 2nd table is new
since I last looked. Sadly, the 2nd table lists only the Cd, so you're
left to approximate (guess) what the frontal area is. Sigh....

--Steve

Martin Klingensmith wrote:
> Try this:
> <http://en.wikipedia.org/wiki/Automobile_drag_coefficients>
>
> --
> Martin K
>
> Christopher Robison wrote:
> > Is there a good resource, online or elsewhere, to look up the drag
> > coefficient and frontal area of modern vehicles? (Yes I already know
> > about the mayfco.com list; it doesn't include any vehicles less than 10
> > years old, and most are 15 or more years old). So far Google hasn't been
> > helpful on half the cars I've tried to look up.
> >
> > Is this the kind of thing for which some kind of publication is
> > available, that I might find in a library somewhere? I'd even be willing
> > to pay a reasonable amount for ongoing access to this kind of
> > information, if it's kept up to date.
> >
> >
> >
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev

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Discussion Starter #5
On Thu, 2007-09-20 at 23:02 +0200, [email protected] wrote:
> > From: Christopher Robison <[email protected]
> > Subject: [EVDL] Drag coefficient, frontal area data?
> > Is there a good resource, online or elsewhere, to look up the drag
> > coefficient and frontal area of modern vehicles? (Yes I already know
> > about the mayfco.com list; it doesn't include any vehicles less than 10
> > years old, and most are 15 or more years old). So far Google hasn't been
> > helpful on half the cars I've tried to look up.
>
> http://en.wikipedia.org/wiki/Automobile_drag_coefficients has some.

I had seen this; I probably should have mentioned it too. There are
combined Cd and frontal area measurements for 45 vehicles here. I was
hoping for something comprehensive, a database where I could look up any
mass-produced vehicle including OEM body style variants up to the
current year. (The second list, while longer, only states Cd values,
which aren't very useful without frontal area).

I'll assume such a resource doesn't exist. There are descriptions online
for using the deceleration curve of a vehicle to determine drag values
(and, interestingly, to separate aerodynamic drag from rolling
resistance), but these require that I actually get to drive the
vehicles, on an otherwise vacant road. Maybe I can rent or do test
drives...

Makes me curious though ... some vehicle reviews do contain this kind of
data -- where do they get it? If it's not published somewhere, do they
call the manufacturer? Surely a car review site isn't going to do its
own wind tunnel tests....?

--
Christopher Robison
[email protected]
http://ohmbre.org <-- 1999 Isuzu Hombre + Z2K + Warp13!

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Discussion Starter #6
I'm interested in this too so I propose a team effort -
if you can find front and side drawings or pics with scale,
I'll calculate A and approximate Cd (assuming car is 2d extrusion)
and put it up at
http://imby.biz/saymoo/EvdlGems/DragAndRollingCoefficients
or if u like the nerd stuff I'll find the pics and you do the calcs.

>I was hoping for something comprehensive, a database where I could look up any
>mass-produced vehicle including OEM body style variants up to the
>current year. (The second list, while longer, only states Cd values,
>which aren't very useful without frontal area).
>I'll assume such a resource doesn't exist. There are descriptions online
>for using the deceleration curve of a vehicle to determine drag values
>(and, interestingly, to separate aerodynamic drag from rolling
>resistance), but these require that I actually get to drive the
>vehicles, on an otherwise vacant road. Maybe I can rent or do test
>drives...
>Makes me curious though ... some vehicle reviews do contain this kind of
>data -- where do they get it? If it's not published somewhere, do they
>call the manufacturer? Surely a car review site isn't going to do its
>own wind tunnel tests....?

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Discussion Starter #7
The U.S. gov't EPA databases have some really neat information, like the weight and Cd*A, as well as fuel economy.

Unfortunately, the newer databases only have fuel economy info, but 1996 and earlier there is alot of neat stuff.

http://www.fueleconomy.gov/feg/download.shtml

----- Original Message ----
From: "[email protected]" <[email protected]>
To: [email protected]
Sent: Friday, September 21, 2007 4:26:16 AM
Subject: Re: [EVDL] Drag coefficient, frontal area data?

I'm interested in this too so I propose a team effort -
if you can find front and side drawings or pics with scale,
I'll calculate A and approximate Cd (assuming car is 2d extrusion)
and put it up at
http://imby.biz/saymoo/EvdlGems/DragAndRollingCoefficients
or if u like the nerd stuff I'll find the pics and you do the calcs.

>I was hoping for something comprehensive, a database where I could look up any
>mass-produced vehicle including OEM body style variants up to the
>current year. (The second list, while longer, only states Cd values,
>which aren't very useful without frontal area).
>I'll assume such a resource doesn't exist. There are descriptions online
>for using the deceleration curve of a vehicle to determine drag values
>(and, interestingly, to separate aerodynamic drag from rolling
>resistance), but these require that I actually get to drive the
>vehicles, on an otherwise vacant road. Maybe I can rent or do test
>drives...
>Makes me curious though ... some vehicle reviews do contain this kind of
>data -- where do they get it? If it's not published somewhere, do they
>call the manufacturer? Surely a car review site isn't going to do its
>own wind tunnel tests....?

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Discussion Starter #8
Depending on what the need for aerodynamic data is, I would assume that
you could use highway fuel economy as a scale for how aerodynamic a
vehicle is. If you're just trying to prove that a Honda Civic is more
efficient in general than a Hummer H2. Things change rapidly when you
start talking about hybrids and electric conversions with half a ton of
lead but if you compare the gas-only list it should provide a good
analog. City MPG is not a good comparison of aerodynamics, but it is
directly related to size of engine and weight of vehicle.
--
Martin K

David Dymaxion wrote:
> The U.S. gov't EPA databases have some really neat information, like the weight and Cd*A, as well as fuel economy.
>
> Unfortunately, the newer databases only have fuel economy info, but 1996 and earlier there is alot of neat stuff.
>
> http://www.fueleconomy.gov/feg/download.shtml
>
>

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Discussion Starter #9
In April 2006, Neon John posted a clever low-tech way to measure the
frontal area of a given vehicle.

Start with a frontal photograph of the vehicle. If you are taking the
picture yourself, include a one-foot square, propped up vertically.. If
not, make sure there's something in the photograph, in the plane of the
front of the car, that has a known length. Like a state license plate,
for example.

Now use scissors/hobby knife and cut the outline of the car out of the
photograph.

Then cut out the one-foot square, or calculate what a one-foot square
would look like based on the scale of the known measurement and cut that
out of the same paper.

Weigh the one-foot square on a laboratory scale. This tells you how
much the paper weighs per square (photographed) foot.

Now weigh the cutout of the vehicle. Divide this number by the weight
of the one-foot square, and you have the frontal area of the vehicle in
square feet.

<http://www.mail-archive.com/[email protected]/msg06421.html>

Sometimes I miss that guy.

Later,

Doug

Steve Peterson wrote:
> Yeah, that first table is from mayfco.com; however, the 2nd table is new
> since I last looked. Sadly, the 2nd table lists only the Cd, so you're
> left to approximate (guess) what the frontal area is. Sigh....
>
> --Steve
>
>
Martin Klingensmith wrote:
>
>> Try this:
>> <http://en.wikipedia.org/wiki/Automobile_drag_coefficients>
>>
>> --
>> Martin K
>>
>> Christopher Robison wrote:
>>
>>> Is there a good resource, online or elsewhere, to look up the drag
>>> coefficient and frontal area of modern vehicles? (Yes I already know
>>> about the mayfco.com list; it doesn't include any vehicles less than 10
>>> years old, and most are 15 or more years old). So far Google hasn't been
>>> helpful on half the cars I've tried to look up.
>>>
>>> Is this the kind of thing for which some kind of publication is
>>> available, that I might find in a library somewhere? I'd even be willing
>>> to pay a reasonable amount for ongoing access to this kind of
>>> information, if it's kept up to date.
>>>
>>>
>>>
>>>
>> _______________________________________________
>> For subscription options, see
>> http://lists.sjsu.edu/mailman/listinfo/ev
>>
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>

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Discussion Starter #10
The current administration has made it a policy to pull all non required
info from government websites to make it harder for evinomentalists to
make their cases for alternatives to the oil economy and global
warming.

They literally have destroyed whole offices with reasearch. The congress
issued a injunction to stop some of it.


David Dymaxion wrote:
> The U.S. gov't EPA databases have some really neat information, like
> the weight and Cd*A, as well as fuel economy.
>
> Unfortunately, the newer databases only have fuel economy info, but
> 1996 and earlier there is alot of neat stuff.
>
> http://www.fueleconomy.gov/feg/download.shtml
>
> ----- Original Message ----
> From: "[email protected]" <[email protected]>
> To: [email protected]
> Sent: Friday, September 21, 2007 4:26:16 AM
> Subject: Re: [EVDL] Drag coefficient, frontal area data?
>
> I'm interested in this too so I propose a team effort -
> if you can find front and side drawings or pics with scale,
> I'll calculate A and approximate Cd (assuming car is 2d extrusion)
> and put it up at
> http://imby.biz/saymoo/EvdlGems/DragAndRollingCoefficients
> or if u like the nerd stuff I'll find the pics and you do the calcs.
>
>> I was hoping for something comprehensive, a database where I could
>> look up any
>> mass-produced vehicle including OEM body style variants up to the
>> current year. (The second list, while longer, only states Cd values,
>> which aren't very useful without frontal area).
>> I'll assume such a resource doesn't exist. There are descriptions
>> online
>> for using the deceleration curve of a vehicle to determine drag values
>> (and, interestingly, to separate aerodynamic drag from rolling
>> resistance), but these require that I actually get to drive the
>> vehicles, on an otherwise vacant road. Maybe I can rent or do test
>> drives...
>> Makes me curious though ... some vehicle reviews do contain this kind
>> of
>> data -- where do they get it? If it's not published somewhere, do they
>> call the manufacturer? Surely a car review site isn't going to do its
>> own wind tunnel tests....?
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>
>
>
>
>
>
>
>
> ____________________________________________________________________________________
> Be a better Heartthrob. Get better relationship answers from someone
> who knows. Yahoo! Answers - Check it out.
> http://answers.yahoo.com/dir/?link=list&sid=396545433
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev

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Discussion Starter #11
I suggest an improvement to that method
rather than print it and weigh parts of the image, use a photo app and
color the part that is car in the image all white and the rest all
black. photoshop has a filter called 'average' which is the average
color of the entire image. then pick that color and that intensity is a
percentage of the car area of the picture area. you have your yard stick
(sic) in the picture to determine the 'area' of the picture and 'voila'
you have your cross section

be sure to take the picture from a good distance to closely approximate
isometric view (to avoid perspective distortion of the profile)
even if you can't zoom in to make the car fill the entire frame,
distance will work. of course if you go too far the precision will drop.

Dan


Doug Weathers wrote:

>In April 2006, Neon John posted a clever low-tech way to measure the
>frontal area of a given vehicle.
>
>Start with a frontal photograph of the vehicle. If you are taking the
>picture yourself, include a one-foot square, propped up vertically.. If
>not, make sure there's something in the photograph, in the plane of the
>front of the car, that has a known length. Like a state license plate,
>for example.
>
>Now use scissors/hobby knife and cut the outline of the car out of the
>photograph.
>
>Then cut out the one-foot square, or calculate what a one-foot square
>would look like based on the scale of the known measurement and cut that
>out of the same paper.
>
>Weigh the one-foot square on a laboratory scale. This tells you how
>much the paper weighs per square (photographed) foot.
>
>Now weigh the cutout of the vehicle. Divide this number by the weight
>of the one-foot square, and you have the frontal area of the vehicle in
>square feet.
>
><http://www.mail-archive.com/[email protected]/msg06421.html>
>
>Sometimes I miss that guy.
>
>Later,
>
>Doug
>
>Steve Peterson wrote:
>
>
>>Yeah, that first table is from mayfco.com; however, the 2nd table is new
>>since I last looked. Sadly, the 2nd table lists only the Cd, so you're
>>left to approximate (guess) what the frontal area is. Sigh....
>>
>>--Steve
>>
>>
Martin Klingensmith wrote:
>>
>>
>>
>>>Try this:
>>><http://en.wikipedia.org/wiki/Automobile_drag_coefficients>
>>>
>>>--
>>>Martin K
>>>
>>>Christopher Robison wrote:
>>>
>>>
>>>
>>>>Is there a good resource, online or elsewhere, to look up the drag
>>>>coefficient and frontal area of modern vehicles? (Yes I already know
>>>>about the mayfco.com list; it doesn't include any vehicles less than 10
>>>>years old, and most are 15 or more years old). So far Google hasn't been
>>>>helpful on half the cars I've tried to look up.
>>>>
>>>>Is this the kind of thing for which some kind of publication is
>>>>available, that I might find in a library somewhere? I'd even be willing
>>>>to pay a reasonable amount for ongoing access to this kind of
>>>>information, if it's kept up to date.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>_______________________________________________
>>>For subscription options, see
>>>http://lists.sjsu.edu/mailman/listinfo/ev
>>>
>>>
>>>
>>_______________________________________________
>>For subscription options, see
>>http://lists.sjsu.edu/mailman/listinfo/ev
>>
>>
>>
>
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>
>
>

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