Tinbucket

I wonder if anyone has engineered a deck lid with a wing or whatever for th the C63. With as much potential some of our cars have it seems a good idea to me. It would provide down frce at speed and like some other cars could rise and turn to act as air brake at high speed. Seems some ducting for brakes, up front and venting from engine compartment, for coolers and radiator and to proved down force over the car a good idea also.
Surely someone that cruises the Autobhan in the left lane has though about such things. I'm not capable of designing the hardware fro the spoiler or wing but Renntch and others surely are. Integrating to look part of the car and not a monster stuck to it would be somewhat of a challenge though.
Anyone?

odonnks

Sounds like your talking about a C63 Black Series.
http://www.autoblog.com/2011/11/21/2...-drive-review/

jcfay

Yup, black series. Your wish is AMG's command...

Ingenieur

Does the BS actuly have downforce (negative lift)?

The base c63 is almost neutral
Sportauto tested it and it has <100 lb lift front & rear
I'll see if I can find specifics

C63
Fahrzeugstirnfläche: 2.180 m²
Luftwiderstandsbeiwert: 0.32
Luftwiderstandsindex: 0.69
Vorderachse: 35 kg Auftrieb
Hinterachse: 42 kg Auftrieb


BS
Fahrzeugstirnfläche: 2.190 m²
Luftwiderstandsbeiwert: 0.35
Luftwiderstandsindex: 0.77
Vorderachse: 25 kg Auftrieb
Hinterachse: 13 kg Abtrieb

Still has lift not downforce

jcfay

Dude, I so don't sprechen Deutsche, much less technical German. I assume they test lift (neg/pos) at speed? I guess the point then is relative lift, or less lift. I wonder what F1 car downforce values are? Or even Daytona GT or prototype cars?

jcfay

found this -
"Auftrieb" = lift; "Abtrieb" = downforce

and i'm thinking Vorderachse and Hinteraschse might mean front end and rear end? In that case, the BS does have rear downforce values (yes, front has lift), and certainly improved over the stock C63, right?

edit: guess it's front axle, and rear axle. makes sense

Ingenieur

They put the car on scales in a wind tunnel
I think they test at 124 mph 200 kph
Positive numbers are lift
It's in kg ~ 2.2 lbs
F/R
C63 77/92 lbs
BS 55/29 lbs

So the C63 has lift
If the front weighs 2000 lbs at rest at speed it weighs 2000 - 77 = 1923
That's what they mean by 'getting light'

It's proportional to the square of velocity
So at 186 mph lift would be 1.5^2 x 77 = 173 lbs or so

Ingenieur

Many times downforce or lift is expressed as g force
The major force acting on objects in our world is gravity or g force
Force = mass x accel
Accel due to gravity is g = 32 ft/sec^2 if falling you will accel at that rate
Your mass is not 180 lbs
That is your force on the earth
Your mass is 180/32 ~ 6 slugs

Let a car weighing 4000 lb have 2000 lb of down force
It has 2000/4000 or 1/2 g of downforce
If a 1600 lb car has 4800 lb of downforce = 3 g
Or 2 more units than gravity
It can be driven upside down
It becomes lift and the car flies constrained by the ceiling

Before df was regulated an F1 car could drive upside down at a little over 100 mph

If a car has 4 g of df in theory it can corner at 4 g and brake initially at 4 g
Obviously as the car slows df decreases as the square of velocity and so does braking g force

D C

Found these interesting tidbits....

In 2011, an F1 car will create something in the region of 1200kg of aerodynamic downforce at 155mph

The 2003 Lola Champ Car produced "3039 lbs. @ 150 mph, with 966 lbs. of drag

Ingenieur

http://www.discovery.ca/article.aspx?aid=13512
Mythbusters

Fast cars produce very little drag, and lots of downforce. F1 cars produce so much downforce that theoretically they can drive upside down when travelling at the speed of 150 km an hour. In fact, according to Dr. Suleman, drivers will experience a force of 3 Gs when driving in their F1 cars. That's three times the car's own weight!

Another article
. Such an extreme level of aerodynamic development means that an F1 car produces much more downforce than any other open-wheel formula; Indycars, for example, produce downforce equal to their weight (that is, a downforce:weight ratio of 1:1) at 190 km/h (118 mph), while an F1 car achieves the same at 125 to 130 km/h (78 to 81 mph), and at 190 km/h (118 mph) the ratio is roughly 2:1.

So 1 g at 80 to 90 mph
Wow


Fifty-five
metres is the braking distance a Formula 1 car travels when performing a full stop from a speed of 200 km/h. The process takes 1.9 seconds and creates deceleration forces of up to 5 G.

Our cars take almost the same from 70 mph
And only 1 g or so

m a x i m u s

+1. f1 cars generate thousands of pounds of downforce, so much so that merely snapping out of the throttle at speed feels like slamming on the brakes in a road car.

jcfay

although they did reduce downforce this year, I'm sure it's still astronomical. If you want to see some insane acceleration numbers (gone totally off-topic here...) take a look at drag/funny car numbers. They are totally ridiculous. Talk about intentionally firing an engine to the point of detonation. Not a huge fan but the specs are terribly impressive. For me, though, F1 is where it's at. Indy, with its uniform spec, is much less interesting to me. Still, I'd love to drive any of those rigs.

I also heard that nowadays it is possible to generate >7g forces with F1 aero if the rules allowed it, but this would necessitate driver suits like pilot flight suits, to keep drivers from passing out due to loss of blood flow to the brain. How crazy is that!

rage2

No downforce up front, zero or downforce out back depending on wing settings. From the original press release:

Optimum aerodynamic balance

The basic configuration of the C 63 AMG Coupé Black Series already impresses with its optimum aerodynamic balance. The combination of slight lift at the front and rear axles ensures a high level of driving stability in all driving conditions.

The AMG Aerodynamics package not only boosts the vehicle's appearance but also optimises its aerodynamics even further. The flics on the front apron – basically as found on the SLS AMG GT3 – as well as the integrated centre spoiler lip beneath the front splitter, combine to halve lift at the front axle. The carbon-fibre rear aerofoil is supported on aluminium elements on the on the boot lid and can be manually adjusted by the driver. This requires only a few simple steps, with two levels to choose from: level 1 with a pitch angle of 0 degrees creates what is referred to as "zero lift" at the rear axle; in level 2 with a pitch angle of 4 degrees, the aerofoil achieves effective downforce at the rear axle without the lift at the front axle increasing significantly. Level 2 is recommended when driving on the race track, where driving stability benefits from the higher negative lift force, particularly during fast cornering.

The aerodynamic balance of the vehicle is also further enhanced with the AMG Aerodynamics package, a fact which has been confirmed with tests in the wind tunnel and test drives on a variety of high speed routes. Furthermore, a glimpse at the aerodynamic data reveals that at aerofoil level 1, the AMG Aerodynamics package has barely any negative effect on the drag coefficient and air resistance.

Ingenieur

C 63 BS
Fahrzeugstirnfläche: 2.190 m²
Luftwiderstandsbeiwert: 0.35
Luftwiderstandsindex: 0.77
Vorderachse: 25 kg Auftrieb
Hinterachse: 13 kg Abtrieb

Auftrieb = lift; Abtrieb = downforce

after looking at it again you are correct, I missed the word difference, was expecting to see a negative (-) sign, lol
the front has 55 lbs of lift
the rear has 29 lb of downforce (not knowing how the wing was set)

jcfay

No big deal, but pretty minimal differences in #s IMO between BS and standard C63. Not to knock the BS which is awesome for all sorts of reasons, I guess I'm just somewhat surprised that the #s are so similar. A relatively minor delta in downforce.

Ingenieur

Agreed
Not much when you figure the car weighs 4000
About f/r 2200/1800 or so
Very small percentage