CW values for the NC

I've been reading an article on cars and their CW values and what it
means for efficiency. The article is in German but I thought the figures
given for the MX-5 may be interesting so here it goes.

Top down: 0.45 cw
Soft top up: 0.39 cw
Hard top up: 0.37 cw

At 150 KMPH The Hard top uses 0.3 litres of gas less than the soft top
per 100 KM. With the top down 1.4 litre extra gas is used per 100 KM
(also at 150 KMPH). This can of course also be translated to possible
top speeds but the article does not do that - it only comments that no
one drives top down at more than 150 KMPH (Sort of making me "no one" as
I do - it's loud but otherwise fine).

http://www.autobild.de/artikel/autos...al_666465.html
http://www.autobild.de/mmg/mm_bilder...d=0&m =&e=&i=
http://www.autobild.de/mmg/mm_bilder...d=0&m =&e=&i=
http://www.autobild.de/mmg/mm_bilder...d=0&m =&e=&i=

No real surprise that the soft top is a little less smooth or that top
down is even worse when it comes to smooth airflow.

Here are some other figures (also from the article):

The ten most efficient
1. BMW 5er 0,26
1. Mercedes S-Klasse 0,26
1. Lexus LS 460 0,26
1. Toyota Prius 0,26
2. Audi A4 0,27
2. BMW 3er 0,27
2. Mercedes E-Klasse 0,27
2. Mercedes C-Klasse 0,27
2. Mercedes CL 0,27
2. Porsche 911 0,27

And the ten less efficient
1. F1 Race car 1,2
2. 2 Mercedes Actros 0,81
3. 3 Morgan Roadster 0,6
4. 4 Land Rover Defender 0,59
5. 5 Hummer H2 0,53
6. 6 Mercedes G-Modell 0,52
7. 7 Morgan Aero 8 0,51
8. 8 Jeep Wrangler 0,49
9. 9 Jeep Commander 0,41
10. 10 Chrysler PT Cruiser 0,38

Kind regards
Bruno

Biggest Irony in all of that is the model name of one of the cars on the
'worst' list; Morgan Aero 8! That's pretty funny.

Biggest surprise was the F1 car. That just does not jive with common sense
and logic. Seems to me that they have horribly tiny frontal areas and
there's no flat / blunt surfaces. Maybe I just figured it out; the ground
effects intentionally abut a whole bunch of air, with the resulting force of
that air pushing the car downward in order to keep the car on the ground.
Hmmmmmmm, I could be right!?! In effect these cars need the huge HP to
utilize the air to keep them stuck down! Can you imagine how fast these
buggers would be with aero aids that allow them to slice thru the wind?

Chris
99BBB

Why doesn't someone do that? Drive an F1 car upside down! That could get a
crowd excited!

Chris
99BBB

"pws" > wrote in message
...
> Chris D'Agnolo wrote:
>
>> Biggest surprise was the F1 car. That just does not jive with common
>> sense and logic. Seems to me that they have horribly tiny frontal areas
>> and there's no flat / blunt surfaces. Maybe I just figured it out; the
>> ground effects intentionally abut a whole bunch of air, with the
>> resulting force of that air pushing the car downward in order to keep the
>> car on the ground. Hmmmmmmm, I could be right!?! In effect these cars
>> need the huge HP to utilize the air to keep them stuck down! Can you
>> imagine how fast these buggers would be with aero aids that allow them to
>> slice thru the wind?
>>
>> Chris
>> 99BBB
>
> The aerodynamics on the F1 cars produce so much down force that the Indy
> cars can theoretically be driven upside-down as long as you keep the speed
> above 81 mph, since roughly 81 mph is when the down force equals the
> weight of the car.
> They produce roughly 2 times their weight in down force once they hit 118
> mph.
>
> From Wikipedia:
>
> The cars' aerodynamics are designed to provide maximum downforce with a
> minimum of drag; every part of the bodywork is designed with this aim in
> mind. Like most open wheeler cars they feature large front and rear
> aerofoils, but they are far more developed than American open wheel
> racers, which depend more on suspension tuning; for instance, the nose is
> raised above the centre of the front aerofoil, allowing its entire width
> to provide downforce. The front and rear wings are highly sculpted and
> extremely fine 'tuned', along with the rest of the body such as the
> turning vanes beneath the nose, bargeboards, sidepods, underbody, and the
> rear diffuser. They also feature aerodynamic appendages that direct the
> airflow. Such an extreme level of aerodynamic development means that an F1
> car produces much more downforce than any other open-wheel formula; for
> example the Indycars produce downforce equal to their weight at 190 km/h
> (118 mph), while an F1 car achieves the same downforce:weight ratio of 1:1
> at 125 km/h (78 mph) to 130 km/h (81 mph), and at 190 km/h (118 mph) the
> ratio is roughly 2:1. Therefore, theoretically, F1 cars can drive upside
> down from 130 km/h (81 mph).
>
>
> Keeping it on topic, can you imagine how the Miata would drive with that
> kind of down force?
> You would obviously need a lot more power to drive your car that starts to
> "weigh" well over 4000 pounds at highway speed.
> Cornering would be even more fun than ever! :-)
>
> Pat
>

> I wondered that myself. It would require either being able to smoothly
> climb a wall and onto the ceiling at over 81mph, which could be tricky
> or even impossible. (Leon?)

How about an oval track, only vertical? Shoot down the straight to build up
speed, enter a vertical curve at the end which continues until you're upside
down and headed back the other direction. Vertical curve at the other end
takes you back to the ground on the original straight. That would be a hoot
to watch. They could build the grandstand in the middle.

miker

On 2008-05-05, pws > wrote:

>> How about an oval track, only vertical? Shoot down the straight to build up
>> speed, enter a vertical curve at the end which continues until you're upside
>> down and headed back the other direction. Vertical curve at the other end
>> takes you back to the ground on the original straight. That would be a hoot
>> to watch.
>
> That would be very cool.

Not as cool as a möbius strip racetrack...

--
Grant Edwards grante Yow! Why are these athletic
at shoe salesmen following
visi.com me??

Grant Edwards wrote:
> On 2008-05-05, pws > wrote:
>
>>> How about an oval track, only vertical? Shoot down the straight to build up
>>> speed, enter a vertical curve at the end which continues until you're upside
>>> down and headed back the other direction. Vertical curve at the other end
>>> takes you back to the ground on the original straight. That would be a hoot
>>> to watch.
>> That would be very cool.
>
> Not as cool as a möbius strip racetrack...
>

If someone is going to try it with a F1 car they had better do it quick.
I believe regs are going to reduce downforce considerably in 2009.
It would need a strong ceiling. The downforce used at some tracks is huge.

On 2008-05-05, Invisible Man > wrote:
> Grant Edwards wrote:
>> On 2008-05-05, pws > wrote:
>>
>>>> How about an oval track, only vertical? Shoot down the straight to build up
>>>> speed, enter a vertical curve at the end which continues until you're upside
>>>> down and headed back the other direction. Vertical curve at the other end
>>>> takes you back to the ground on the original straight. That would be a hoot
>>>> to watch.
>>> That would be very cool.
>>
>> Not as cool as a m??bius strip racetrack...
>>
>
> If someone is going to try it with a F1 car they had better do it quick.
> I believe regs are going to reduce downforce considerably in 2009.
> It would need a strong ceiling. The downforce used at some tracks is huge.

That's where the moebius strip track has an advantage: once the
field is spread out enough, you'll have cars on both sides of
the strip and the downforces would cancel. Perhaps the staring
lineup could be split so that half the cars start on one side
and half on the other.

--
Grant Edwards grante Yow! I've got an IDEA!!
at Why don't I STARE at you
visi.com so HARD, you forget your
SOCIAL SECURITY NUMBER!!

On 2008-05-07, pws > wrote:
> Grant Edwards wrote:
>
>> That's where the moebius strip track has an advantage: once the
>> field is spread out enough, you'll have cars on both sides of
>> the strip and the downforces would cancel. Perhaps the staring
>> lineup could be split so that half the cars start on one side
>> and half on the other.
>
> To continue this silly thread....
>
> I have to admit to forgetting what a moebuis strip is, thank you for the
> reminder.
>
> Like to keep that vocabulary thing growing, and that is one of the few
> things with a name that does not have at least 15 definitions in the
> English language depending on the context, so I should be able to
> remember it.
>
> How about a Figure 8 Klein Bottle track? ;-)

I've always wanted a Klein bottle.

--
Grant Edwards grante Yow! ! Up ahead! It's a
at DONUT HUT!!
visi.com

In article >,
Jim Hayter > wrote:

> See
> http://www.kleinbottle.com/.

Priceless! Thanks.

> The problem with math jokes is that most
> folks don't get them.

It's the same with classical music jokes (q.v., PDQ Bach's "Concerto for
Horn and Hardart" et al.).

--
Lanny Chambers
St. Louis, MO
'94C

Lanny Chambers > wrote:

> It's the same with classical music jokes (q.v., PDQ Bach's
> "Concerto for Horn and Hardart" et al.).

That's more of a food joke and one that people should get Automat-
ically.... <Ouch!>


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