NSX aerodynamics

Hapa88 said:
What you need is to put golf ball dimples all over the car! :biggrin:
Click to expand...

that was a great Mythbusters story ... can't understand why all the big car designers haven't come out with dimpled cars ... so we can top 190mph instead of just 175 :eek:
 
So I think we should all take our NSXs to the driving range and parking them in the middle of the range! That's the easiest way to get a dimple effect I think. Golf ball dimples made by golf balls! That should raise our gas mileage for sure! :rolleyes: LOL
 
Bumping one of my favorite topics and threads and adding this for comparison:

KEY:
frontal surface area (A)
cw (cd)
air drag index (cd x A)
at 200km/h (125mph)
lift front axle
lift rear axle


Because at the GT-R datasheet discussion at factory claimed cd of 0.27 and sportauto clocked 0.31 on one of the most modern windtunnels in the world I thought it would be interesting to compare the sportauto results to manufacturer claims..

Important... not cd is important.. the airdragindex is the important number... the combination of cd and the size of the vehicle.. the lower cd x A the better is the aerodynamic of a car...
a other sidenote... many "noseheavy" cars can become nearly weightbalance neutral at higher speeds if the lift at the front axle is greater than it is at the rear



Honda NSX-R (2002)
(A): 1.7800 m²
(cd): 0.34
(cd × A): 0.60
at 200km/h
downforce front 32kg
downforce rear 5kg



Audi R8 V10 5.2
(A) 2.024m²
(cd) 0.36
(cd x A) 0.72
at 200km/h
lift front 23kg
downforce rear 3kg



Ford GT
(A) 1.92 m²
(cd) 0.35
(cd × A) 0.67
at 200km/h
downforce front 44kg
lift rear 2kg




Nissan GT-R
(A) 2,30 m²
(cd) 0,31
(cd × A) 0,71
at 200km/h
lift front 3kg
downforce rear 8kg



Lamborghini Gallardo LP 560-4
(A) 1.93 m²
(cd) 0.35
(cd × A) 0.67
at 200km/h
downforce front 4kg
lift rear 37kg



Corvette ZR1
(A) 2.059 m²
(cd) 0.32
(cd × A) 0.66
at 200km/h
lift front 39kg
lift rear 14kg



Corvette C6 Coupe
(A): 2.0 m²
(cd): 0.29
(cd × A): 0.59
at 200km/h
lift front 54kg
lift rear 28kg




Corvette C6 Z06
(A): 2.1 m²
(cd): 0.308
(cd × A): 0.647
at 200km/h
lift front 49kg
lift rear 22kg



McLaren MP4-12C
(A): ______ m²
(cd): 0.34
(cd × A): 0.___
at 200km/h
downforce front 2kg
downforce rear 62kg



Ferrari 360 Challenge Stradale
(A): 2.0 m²
(cd): 0.31
(cd × A): 0.62
at 200km/h
downforce front 10kg
lift rear 21kg



Ferarri F430
(A): 2.04 m²
(cd): 0.34
(cd × A): 0.70
at 200km/h
lift front 11kg
lift rear 6kg



Ferrari 430 Scuderia
(A): 2.02 m²
(cd): 0.33
(cd × A): 0.66
at 200km/h
lift front ???kg
lift rear 4kg



Ferrari 458 Italia
(A): 2.02 m² ?
(cd): 0.34
(cd × A): 0.69
at 200km/h
front lift 32kg
downforce rear 31kg



Ferrari 599 GTB Fiorano
(A): 2.23 m²
(cd): 0.33
(cd × A): 0.73
at 200km/h
lift front 41kg
lift rear 24 kg



Ferrari 575 M Maranello
(A): 2.09 m²
(cd): 0.32
(cd × A): 0.66
at 200km/h
lift front 61kg
lift rear 40kg



Porsche 996 GT3 RS
(A): 1.94 m²
(cd): 0.30
(cd × A): 0.58
at 200km/h
lift front 19kg
downforce rear 26kg



Porsche 997 Carrera S facelift
(A): 2.02 m²
(cd): 0.29
(cd × A): 0.59
at 200km/h
lift front 24kg
lift rear 14kg




Porsche GT3 facelift
(A) 2.04 m²
(cd) 0.32
(cd × A) 0.66
at 200km/h
downforce front 15kg
downforce rear 19kg



RUF RT12
(A): 2.04 m²
(cd): 0.33
(cd × A): 0.67
at 200km/h
lift front 11kg
downforce rear 34kg



Porsche Carrera GT
(A): 1.95 m²
(cd): 0.37
(cd × A): 0.72
at 200km/h
downforce front 49kg
downforce rear 40g



Porsche 997 Turbo old
(A): 2.04 m²
(cd): 0.29
(cd × A): 0.59
at 200km/h
lift front 9kg
downforce rear 12kg



Lamborghini Murcielago LP 640
(A): 2.04 m²
(cd): 0.35
(cd × A): 0.71
at 200km/h
downforce front 30kg
downforce rear 11kg



Gumpert Apollo Sport
(A): 1,99 m²
(cd): 0,57
(cd × A): 1,14
downforce front 20kg
downforce rear 176kg



Pagani Zonda F
(A): 2,08 m²
(cd): 0,36
(cd × A): 0,74
at 200km/h
downforce front 1kg
downforce rear 25kg



Koenigsegg CCR
(A): 1,86 m²
(cd): 0,35
(cd × A): 0,64
at 200km/h
downforce front 13kg
lift rear 11kg



BMW e46 M3 CSL
(A): 2.07 m²
(cd): 0.33
(cd × A): 0.68
at 200km/h
lift front 1kg
lift rear 10kg



Alpina B3 Coupe
(A): 2.14 m²
(cd): 0.29
(cd × A): 0.63
at 200km/h
lift front 12kg
lift rear 13kg




BMW e92 M3
(A): 2.17 m²
(cd): 0.33
(cd × A): 0.71
at 200km/h
lift front 10kg
lift rear 23kg




BMW e92 M3 GTS
(A): 2.17 m²
(cd): 0.32
(cd × A): 0.70
at 200km/h
downforce front 7kg
downforce rear 30kg



Mercedes C 63 AMG
(A): 2.18 m²
(cd): 0.32
(cd × A): 0.69
at 200km/h
lift front 35kg
lift rear 42kg



Lexus IS-F
(A) 2.22 m²
(cd) 0.30
(cd × A) 0.67
at 200km/h
lift front 31kg
lift rear 7kg



Audi S5
(A): 2.18 m²
(cd): 0.31
(cd × A): 0.67
at 200km/h
lift front 52kg
lift rear 34kg



Aston Martin DBS
(A): 2.11 m²
(cd): 0.36
(cd × A): 0.76
at 200km/h
lift front 11kg
lift rear 10kg



Mitubishi Evo VII
(A): 2.12 m²
(cd): 0.37
(cd × A): 0.79
at 200km/h
downforce front 37kg
downforce rear 8kg



BMW X6 M
(A) 2.85m²
(cd) 0.38
airdragindex (cd x A) 1.07
at 200km/h (125mph)
lift front axle 69kg
lift rear axle 48kg



Mercedes SLR
(A): 2.07 m²
(cd): 0.37
(cd × A): 0.77
at 200km/h
downforce front 19kg
downforce rear 35kg



Mercedes CLK DTM AMG
(A): 2.15 m²
(cd): 0.34
(cd × A): 0.73
at 200km/h
lift front 37kg
downforce rear 12kg



Mercedes SL 65 AMG
(A): 2.1 m²
(cd): 0.31
(cd × A): 0.65
at 200km/h
lift front 29kg
lift rear 33kg



Mercedes SL 65 AMG Black Series
(A) 2.17 m²
(cd) 0.37
(cd × A) 0.80
at 200km/h
lift front 56kg
downforce rear 22kg



Mercedes SLK 55 AMG
(A): 1.95 m²
(cw): 0.32
(cw × A): 0.625
at 200km/h
lift front 23kg
lift rear 31kg



Maserati Coupé Cambiocorsa
(A): 2.016 m²
(cd): 0.34
(cd × A): 0.68
at 200km/h
downforce front 55kg
downforce rear 45kg
(I'm suspect on this)



Lotus Exige (Mk I)
(A) 1,631 m²
(cd) 0.43
(cd x A) 0.70
at 200km/h
downforce front 20kg
downforce rear 58kg



Lotus Exige S
(A): 1.62 m²
(cd): 0.44
(cd × A): 0.71
at 200km/h
downforce front 5kg
downforce rear 24kg



Opel Speedster Turbo
(A): 1.61 m²
(cd): 0.38
(cd × A): 0.61
at 200km/h
downforce front 23kg
lift rear 19kg



Opel Corsa OPC
(A): 2.15 m²
(cd): 0.36
(cd × A): 0.78
at 200km/h
downforce front 23kg
lift rear 22kg
 
Last edited:
Thanks for the extensive update. Really a nice concentrate of pics and data.

I've studied an aerodynamic book in the meanwhile but I'm afraid to say that my ZE1 was the one who was modified aerodynamically even though the NSX would have profitted much more by tuned aerodynamics than the nearly perfect ZE1.

Nice to see that the NSX-R is still on of the benchmark cars.
 


Honda Civic Type R
(A): 1.93 m²
(cd): 0.326
(cd × A): 0.63
at 200km/h
downforce front 19kg
lift rear 44kg



BMW Z4 3.0si Coupé
(A): 1.94 m²
(cd): 0.33
(cd × A): 0.64
at 200km/h
lift front 28kg
lift rear 43kg



Ford Focus RS
(A) 2,35 m²
(cd) 0,36
(cd × A) 0,86
at 200km/h
downforce front 8kg
lift rear 4kg



Abarth Grande Punto esseesse
(A): 2.21 m²
(cd): 0.34
(cd × A): 0.75
at 200km/h
lift front 26kg
lift rear 31kg



Audi TT-S
(A) 2.10 m²
(cd) 0.32
(cd × A) 0.68
at 200km/h
lift front 42kg
lift rear 17kg



Mini Cooper S John Cooper Works
(A) 2.05 m²
(cd) 0.36
(cd × A) 0.73
at 200km/h
lift front 17kg
lift rear 20kg
 
Last edited:
I've witnessed anywhere from 5-20% difference between the two.

Rotating wheels can provide a big effect. My phat fives not only have a low MOI, but the large face also helps ensure a low drag coefficient. Yeah baby.

Dave
 
jwmelvin said:
I don't know why one would think you can get accurate results with a fixed floor. It's borderline absurd.
Click to expand...
It's not completely inaccurate. Windtunnel testing is very expensive. The underbody in even fast streetcars is overvalued. It's very different from a racecar like an Indy or F1. The hype of underbody-tuning is related to the fact that up to the 90ies the underbody of streetcars has been poorly neglected. Aerotuning in fast streetcars is a very demanding occupation. How to create a car that is able to drive at high speed with good control over it. The NSX-R is still one of the ones who stand out, still nowadays.

Wheels: the bigger, the more exposed, the more open holes (the 'sportier') -> the worse. The NSX with his smaller wheels has an advantage here.
 
The point is that even with this relatively crude evaluation, you are attempting to draw conclusions about the relative performance of cars but you have no idea which ones are more affected by the inaccuracies of the fixed-floor tunnel. By your logic above, it seems to me that the cara with larger wheels are suffering a larger penalty from this tunnel because of their larger wheels.

I understand the expense and challenges of a rolling road tunnel. There are few in the world that will accommodate a full size car. But that's no reason to assume that a fixed-floor tunnel gives accurate, or even meaningful results. Have you ever compared results between two tunnels? I know someone I can ask about that.
 
The magazine Sport Auto, which stuntman quoted, carries out all of their wind tunnel tests in Mercedes' large fixed floor wind tunnel in Untertürkheim, Germany. BMW's new rolling road wind tunnel in Munich would surely measure front and rear lift more accurately but that wind tunnel only opened in 2009. For the sake of consistency, since Sport Auto started measuring aerodynamics in 1997, they have always used Mercedes' Untertürkheim facility.

It's too bad that wind tunnel doesn't have a moving floor but I think it's borderline absurd to think that the measurements carried out in Mercedes' wind tunnel are meaningless. Personally, I'm glad that Sport Auto didn't switch facilities because as a result, the aerodynamic drag they measured for our NSXs way back when can still be validly compared to all of the measurements they carried out more recently - see stuntman's posts above. Had Sport Auto switched facilities, the comparison would be problematic.
 
I agree completely that comparisons can only be made within a single tunnel, and for that reason there is some benefit to sticking with the original tunnel.

I didn't say that the measurements are meaningless, only that I think it's unwise to assume otherwise unless you have experience with wind tunnel results. (I did find your parallelism to my post cute, though.) I did say that it was borderline absurd to think the measurements would be accurate. There is an important difference between accuracy and comparability, which I imagine you appreciate. While (to my understanding) one wouldn't want to think that results on any wind tunnel are accurate (particularly one with a fixed floor), a tunnel may still provide plenty of ability to compare two different cars. And that's much of the point of the tests above. So far so good; perhaps I shouldn't have bristled at the idea of a fixed-floor tunnel. But comparing cars should be done when you can characterize the differences between them and that is where I see the fixed-floor tunnel as falling short.

We know that there are real effects from (1) road moving under the body and (2) spinning wheels. By eliminating both of those factors and drawing conclusions about the relative performance of cars, you are assuming that they affect all cars the same. I doubt that is true; my knowledge, however, is far from what would be required to answer this question.
 
jwmelvin said:
The point is that even with this relatively crude evaluation, you are attempting to draw conclusions about the relative performance of cars but you have no idea which ones are more affected by the inaccuracies of the fixed-floor tunnel. By your logic above, it seems to me that the cara with larger wheels are suffering a larger penalty from this tunnel because of their larger wheels.
Click to expand...
I fully agree that having a rolling floor in the wind tunnel gives you more accurate results but I accept that they were not readily available back then. In F1 a rolling floor tunnel is much more important because the wheels spin freely in the air. From the benchmark point of view it's more valueable to the magazins reader to have ceteris paribus condition (or the same tunnel) than a switch in design. The alternative would have been a retest in a rolling floor tunnel all cars that some of have rusted away in the meantime :). Aero-testing IS expensive. As the underbody and the front wheels account for around 1/3 of the whole car I would expect substantional differences. But I won't defend a German car magazin, oh no, even though Sport Auto is the most serious of them all.

Wheels: Size, design and offset play and an important role. That's were the 'unsporty' (to some people) 02+ wheels are expected to perform better at high speeds than most todays sportcars. Due to this I except the NSX-R to perform even better to the other mentioned sport cars (except the Lotus and the McLaren).
 
liftnot said:

Sauber F1 Wind tunnel Explained
Click to expand...

that's just brilliant, and he's an Aussie :cool: thanks for posting!

stuntman, I looked through many of your great aero graphics and only spotted one cdA better than the NSX's 0.60 (Corvette C6: 0.59) but I'm lazy so please save me the trouble - does the NSX rank 2nd or worse across all those vehicles?
 
Last edited:
Sport Auto has tested more than one car that has a better Cd x A than an NSX. See post #70 back on page 3 of this thread for a few more examples. To save you the trouble of looking for the post, here's a link. :smile:

Last summer, Sport Auto carried out its 200th "supertest", in which they take a car to the Nürburgring, put it in Mercedes' wind tunnel, etc. There's probably a full list of the results somewhere so you could check how the NSX's Cd x A compares to all the other cars Sport Auto has tested.

It would be cool to put a VW XL1 into Mercedes' Untertürkheim wind tunnel and see what Cd x A that yields. Since it's not a sports car, Sport Auto is probably never going to do it, though.
 
Last edited:
greenberet said:
Sport Auto has tested more than one car that has a better Cd x A than an NSX.
Click to expand...
...but not many. 2.0 will be higher than 0.6 I guess.

It's not difficult to build a car with a low cdxA value. The Corvette is a good example AND at the same time a very bad one to create so much lift at 200 km/h. Sportcars should not be called sportcars with aero lift at speed IMHO.
 
Last edited:
Very interesting information here, also shows how good a NSX-R compares to much later cars.
And on the note for the Maserati 42GT being suspect, I also believe that to be a typo although they do have a nice large diffuser in the rear and a some watt of a splitter in the front they are absolutely not that good.
I know i have them in the shop often enough.
 
Hapa88 said:
You guys are getting this aerodynamic stuff all wrong! What you need is to put golf ball dimples all over the car! :biggrin:
DimpleCar.jpg
Click to expand...

The 200+ mph Ford GT full underbody tray is dimpled like a golfball.
 
goldNSX said:
Sportcars should not be called sportcars with aero lift at speed IMHO.
Click to expand...

Ouch! Using that strict definition, the 2002 NSX-R would be a sportscar but the other NSXs would just be coupes.

According to Honda, the 2002 NSX-R generates front and rear downforce, the regular 2002 NSX generates front and rear lift, and the pre-facelift NSXs generate overall lift. When Sport Auto put a 2002 NSX-R into Mercedes' fixed floor wind tunnel, they measured front and rear downforce but when they put a regular 1997 NA2 coupe in there, they measured front and rear lift. Not much, but there was some (at 200 km/h, the 1997 coupe generated 78.7 Newtons of lift at the front and 134 Newtons at the rear).
 
greenberet said:
Ouch! Using that strict definition, the 2002 NSX-R would be a sportscar but the other NSXs would just be coupes.
Click to expand...
I was aware of that when I wrote my lines. But I would apply it to new sportcars only. I'm not one of those who think a car designed in the late 80ies is the benchmark forever. BUT if 2.0 would show lift at speed I'd cause the aero team of not having done the math. But I'm pretty sure they'll do it right. :wink:
 
greenberet said:
Ouch! Using that strict definition, the 2002 NSX-R would be a sportscar but the other NSXs would just be coupes.

According to Honda, the 2002 NSX-R generates front and rear downforce, the regular 2002 NSX generates front and rear lift, and the pre-facelift NSXs generate overall lift. When Sport Auto put a 2002 NSX-R into Mercedes' fixed floor wind tunnel, they measured front and rear downforce but when they put a regular 1997 NA2 coupe in there, they measured front and rear lift. Not much, but there was some (at 200 km/h, the 1997 coupe generated 78.7 Newtons of lift at the front and 134 Newtons at the rear).
Click to expand...
Source?
 
stuntman said:
Source?
Click to expand...

Honda's front and rear lift figures for 2002 NSX and front and rear downforce figures for a 2002 NSX-R:
http://www.honda.co.jp/auto-archive/nsx/2005/mechanism/index.html

Honda's front and rear lift figures for a 1991 NSX:
http://www.honda.co.jp/factbook/auto/NSX/19900913/ns90-031.html

Sport Auto's front and rear lift figures for a 1997 NSX: Issue 8/1997, page 23

Sport Auto's front and rear downforce figures for a 2002 NSX-R: issue 8/2002, page 16 and the test has been put online here:
http://www.auto-motor-und-sport.de/supertest/honda-nsx-r-sehr-r-freulich-1041188.html?show=2
 

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