A post that has people intrested gets into a bloody SELOC thread … hows can that be ?? We were learning, the problem with learning is there is always more than just the books and experience does count a lot, in every walk of life.
Its very clear a road car has to be stuck to the road regardless of aero otherwise too much possible law suits - look at the Audi TT ( OK I know that was the other way around but you get my drift ? )
Anyways, I say we shoudl hire the damn wind tunnel for an afternoon and have some fun with an Exige - I think we could all learn a lot from that, I know from my “contact” that some dramatic changes can be had by subtle changes - what about it ? ( yes, yes it will cost a few quid but whya not ? )
I did start to write a post last night but decided against it.
As this one seems to be getting a bit bitchy now I’ll add some of my experiences.
I’ve spent a bit of time prounding round test tracks etc around the world (although less in recent years) and have spent some time messing around with aerodynmamics as they have quite a big effect on the vehicle handling.
As Andy mentions briefly the Audi TT was a perfect example of how not to do it, the actual shape is very poor at reducing lift, and a mixture of the rear wing and some fancy electronics solved the serious rear stability issue the car had. (It was amusing to watch 2 of them pounding round the N’ring during testing of the fix, car with wing was pristine, car without had loads of dents ).
Back to a proper example. One of the cars I worked on (FWD hatch) had great low-medium speed handling but when it got to high speed it became very loose at the rear. (At high speed I mean 130mph). This was especially prevelant in the Autobahn simulation test, which is basically Vmax and brake mid bend, usually done on a very large tarmac ‘lake’. We had some wind tunnel results for the standard car which showed that there was zero lift at the front, but there was some lift at the rear (sorry I don’t have the figures anymore as it was 6 years ago). The rear lift was partially because they were trying to reduce vehicle drag for fuel economy etc so the wing had been tuned for this. We removed the wing and it improved things slightly, we then jacked the wing up a bit (a-la S160 style) which improved things again. We then stuck on what looked like a long wedge across the back of the roof. This made the car 100% stable during some extreme manouvers but reduced the top speed by approx 20mph.
All solutions were later tested in the wind tunnel and showed that removing the rear wing the car still had a touch of lift, the jacked up wing had zero lift so the car was balanced front to rear, and the wedge had quite a bit of downforce, but also loads of drag.
The finished production car had a re-designed rear wing to replicate the results of the jacked up version, they also added some trips etc under the car to bring the drag back down a bit.
The amount of change in lift between the original and jacked up wing were very small, but it was a very noticeable difference.
The thing is, everything is relative, Randy is used to mega downforce on the Nissan, but most people have never really exprienced proper downforce cars and as such when they drive a car that doesn’t get floaty at speed it gives them a wow factor. The Exige does have downforce, it is a small amount, whether it is the figure that Lotus quote or not is IMHO irelevant, the fact is, it doesn’t have lift like the Elise , and of course it has more drag as it’s got a bigger frontal area for a start.
Seriously, I’m a bit sensitive about people insulting our beloved cars. I was just trying to learn and understand more about the subject from somebody who has a lot more experience than me.
I apologize if my posts came across as bitchy. It was all meant in a spirit of fun and education.
Seriously, I would love to club together and get an Exige in a wind tunnel and find out exactly what it does/doesn’t do, and see what tweaks can help it.
Wouldn’t it be cool to get some meaningful data for the Edwards’ diffuser and splitter? And then there’s loads of other things to experiment with. Anybody happy with me drilling/cutting a few holes in their car in the interest of science?
Guess you were having a bad day? because i’m pretty sure everyone round here values your experience and knowledge gained through your experience (vast in comparison to most of us) racing cars.
However, I have to say i agree with Brendan here… and i don’t quite see why you think he’s hving a go? The relationship between the forces acting on the tyres and the weight acting upon the tyres is a proportional one… agreed its complex (because we aren’t talking about simple static friction forces here) but its still proportional, and I have no reason to doubt Lotus quoted figure of 80kg downforce at 100mph which is around 10% of the cars weight so this must translate into (similar?) noticeable improvements in grip?
Maybe not as much as 10% improved cornering, because there are other factors and probably competing forces but as a rough calculation I wouldn’t think Brendan was far away. And it would seem to me that most of us feel this is backed up at Track days because the average exige/driver deffo goes quicker than the average elise/driver… especially thru’ very fast corners.
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