Aerodynamic stability ...or lack of
Discussion
What do people think about the high-speed stability of the S?
I've driven four examples and all of them (mine included) seemed to go a little light on the front end at speed. Not enough to be worrying in normal motorway use, but you can feel the steering lightening by about 80mph and over 100 or so it gets distinctly floaty.
It's rock steady at lower speeds and I'm convinced this is an aero issue. Any thoughts?
Mine's not running as low at the front as some which may be a contributing factor I guess, but to a certain extent I think it's a product of the shape. Its '60s-esque lines pre-date widespread knowledge of aerodynamics and Peter Wheeler would probably think stuff like that was for girls anyway.
I've driven four examples and all of them (mine included) seemed to go a little light on the front end at speed. Not enough to be worrying in normal motorway use, but you can feel the steering lightening by about 80mph and over 100 or so it gets distinctly floaty.
It's rock steady at lower speeds and I'm convinced this is an aero issue. Any thoughts?
Mine's not running as low at the front as some which may be a contributing factor I guess, but to a certain extent I think it's a product of the shape. Its '60s-esque lines pre-date widespread knowledge of aerodynamics and Peter Wheeler would probably think stuff like that was for girls anyway.
Chris71 said:
I'm convinced this is an aero issue. Any thoughts?
Just been thinking about this and I reckon not, my reason being that I recently had a bonnet catch come off on one side and I was concerned as I was a few miles from home but watching it at speed it was pressing the Bonnet down not lifting it, just an observation,I'm sure aerodynamics have a bit more to them than that. Chris71 said:
What do people think about the high-speed stability of the S?
I've driven four examples and all of them (mine included) seemed to go a little light on the front end at speed. Not enough to be worrying in normal motorway use, but you can feel the steering lightening by about 80mph and over 100 or so it gets distinctly floaty.
Not mine. If anything it gets better the faster I go. I've driven four examples and all of them (mine included) seemed to go a little light on the front end at speed. Not enough to be worrying in normal motorway use, but you can feel the steering lightening by about 80mph and over 100 or so it gets distinctly floaty.
page3 said:
You'll find above 105mph the S settles down nicely 
... although at 125mph mine spat all its water out the radiator
How is your incontinent S3, Adam? I'm not convinced it was a head gasket.... although at 125mph mine spat all its water out the radiator
Is this a stupid observation?
The tyres (15" ones) by modern high performance standards are not very low profile - so if the tread is a softer compound could the centre of the tyre increase in diameter due to centrifugal force as speed increases?
(Have you ever watched drag racing?)
The result is the middle of the tyre expands and you get slightly less tyre contact with the road?
Completely guessing here.
Chris
The tyres (15" ones) by modern high performance standards are not very low profile - so if the tread is a softer compound could the centre of the tyre increase in diameter due to centrifugal force as speed increases?
(Have you ever watched drag racing?)
The result is the middle of the tyre expands and you get slightly less tyre contact with the road?
Completely guessing here.
Chris
I have similar reservations about my S1 at higher speeds (over 105-110mph), and its got new springs/shocks etc, and has been set up correctly. I wonder if its just me getting older and wiser. In my younger more lairy days, I regularly used to see 120mph in my old S3, and even 140mph once, which when I consider the circumstances was near to insane! However, the car behaved impeccably.
Doing the Marham tackday soon, so will be able to test it properly!
I have been thinking how I could fit a spoiler without upsetting the lines too much. I think those little wings you see on the front corners below the bumpers on Porsche GT2/3`s might be a step in the right direction. The bonnet however is only connected by two hinge bolts, so there is a limit to how much force could be applied, in either direction.
Doing the Marham tackday soon, so will be able to test it properly!
I have been thinking how I could fit a spoiler without upsetting the lines too much. I think those little wings you see on the front corners below the bumpers on Porsche GT2/3`s might be a step in the right direction. The bonnet however is only connected by two hinge bolts, so there is a limit to how much force could be applied, in either direction.
Those bonnet mounts are pretty strong actually. When I had the big splitter on mine there was so much downforce that the middle of the splitter bent far enough to drag along the ground at anything over about 130. Standing on the front of the splitter didn't deflect it far enough to touch the ground ...
GreenV8S said:
Those bonnet mounts are pretty strong actually. When I had the big splitter on mine there was so much downforce that the middle of the splitter bent far enough to drag along the ground at anything over about 130. Standing on the front of the splitter didn't deflect it far enough to touch the ground ...
Mine seems to be a little higher than some of the cars running on adjustables, I wonder if the splitter would be a bit more effective lower down or at a different angle of attack? 
Chris71 said:
Mine seems to be a little higher than some of the cars running on adjustables, I wonder if the splitter would be a bit more effective lower down or at a different angle of attack?
The aerodynamics are quite sensitive to the attitude of the car. Even quite a small amount of nose up attitude will increase the lift substantially.Chris71 said:
I wonder if the splitter would be a bit more effective lower down or at a different angle of attack?
I think there may have been a few different designs on the S. I don't just mean the obvious differences between V8 and V6 bonnets, or even with or without driving lamps. Take a look at my old car parked next to the S3 of Harry1972M on our way to Le Mans. We both had completely straight stripes on, but it highlights the difference in the angle of the front 'splitter' part of the bonnet. The red one is clearly at a steeper angle than the green one.
I have no idea what, if any, effect this would have.
Damn, I miss that car. Any excuse to post a photo! Happy days...
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