Smoooth . . . or not?

Topics relating to Advanced Driving in cars
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StressedDave
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Re: Smoooth . . . or not?

Postby StressedDave » Wed Jan 20, 2016 10:20 am

waremark wrote:I would be surprised if police drivers corner anywhere near the limit of grip, at which smoothness might be an issue. Swift road drivers probably corner at 0.3 or 0.4 g compared with a limit of grip of around 1 g.

If my data is to be believed, 0.5g for a smooth driver, a bit more for someone who goes too deep into things before steering.

waremark wrote:I wonder what is meant by smoothness in the racing driver context. When I see video of racing drivers they are generally working the steering wheel as they corner, whereas most of us smoothly wind the steering on, hold it constant for a bit, and then smoothly wind it off. Is the working at the wheel, or I could call it sawing at the wheel, which the best racing drivers do, smooth?


They have to work the steering - you're constantly balancing the car as the road surface varies in grip level and angle relative to the car. You can add 'not getting it quite right last time' to that. If you're tanking on you are using all of the grip budget so fiddling around with the corner weights using power/deceleration isn't going to give enough of an effect on its own so you use the steering to add an instant effect at the front of the car.

When I'm really tanking on around Millbrook, on certain corners you have to do this. The longer the bend, and there's a cracking triple apex corner halfway round the Millbrook Outer Handling circuit, the more likely you're going to need to mess with both weight transfer and steering. I still do more of the former than the latter, and if I'm doing it right you oughtn't, as a passenger, feel any difference in cornering force.
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Playtent
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Re: Smoooth . . . or not?

Postby Playtent » Wed Jan 20, 2016 10:38 am

https://www.youtube.com/watch?v=SfdgQSkiYIQ

49s on shows how quick his hands are.

https://www.youtube.com/watch?v=tZjAU943BfY

From 3.52s shows all the angles. That's a production car and his hands are giving constant minor inputs.

I imagine his drive would have been much smoother at 60mph for the passenger who didn't seem to bat an eyelid. :shock:

I know there's a video of his footwork as well but I can't find it.

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Mr Cholmondeley-Warner
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Re: Smoooth . . . or not?

Postby Mr Cholmondeley-Warner » Wed Jan 20, 2016 11:33 am

Playtent style braking :mrgreen:

[1:30 onwards]
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Playtent
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Re: Smoooth . . . or not?

Postby Playtent » Wed Jan 20, 2016 11:46 am

Mr Cholmondeley-Warner wrote:Playtent style braking :mrgreen:


It's a lie, I was NOT driving that car!

At least I'm not this bad!

https://www.youtube.com/watch?v=_47utWAoupo

TripleS
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Re: Smoooth . . . or not?

Postby TripleS » Wed Jan 20, 2016 1:36 pm

waremark wrote:Is the working at the wheel, or I could call it sawing at the wheel, which the best racing drivers do, smooth?


I would say no, it isn't smooth, and I guess they do it to feel where they are in relation to the limit of grip. To that extent it may be helpful, but I don't see how it can be smooth, Incidentally, do the best racing drivers actually do that?

Presumably the better scenario is for a driver to have such sensitivity that he knows pretty well where he is relative to the grip level, in which case there should be no sawing at the wheel and therefore more natural smoothness, and indeed higher speed as a result. I would have thought that those who need to be 'sawing at the wheel' may indeed be figuring out where the limit of grip happens to be, and therefore helping to achieve a higher speed than they would otherwise, but it looks to me as if they'll be paying a penalty in speed by unsettling the car and therefore sacrificing some grip that they could otherwise have had.

....or words to that effect. 8-)

Best wishes all,
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Astraist
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Re: Smoooth . . . or not?

Postby Astraist » Wed Jan 20, 2016 2:05 pm

waremark wrote:I would be surprised if police drivers corner anywhere near the limit of grip, at which smoothness might be an issue. Swift road drivers probably corner at 0.3 or 0.4 g compared with a limit of grip of around 1 g.


Well, they better be, unless they want to meet other road users, and not in a sociable way....

waremark wrote:I wonder what is meant by smoothness in the racing driver context. When I see video of racing drivers they are generally working the steering wheel as they corner, whereas most of us smoothly wind the steering on, hold it constant for a bit, and then smoothly wind it off. Is the working at the wheel, or I could call it sawing at the wheel, which the best racing drivers do, smooth?


But than again, race cars are all quite stiff, so it's more about the suspension rocking about rather than trying to use the steering to do anything clever in terms of car dynamics. It's also useful in order to get a better feel through the steering.

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Mr Cholmondeley-Warner
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Re: Smoooth . . . or not?

Postby Mr Cholmondeley-Warner » Wed Jan 20, 2016 2:33 pm

TripleS wrote:I would say no, it isn't smooth, and I guess they do it to feel where they are in relation to the limit of grip.


Here's a 1 lap sample of Lewis Hamilton (arguably one of the best but let's not have the argument):



I would argue:

a) he's exceedingly smooth (and he's in the process of setting a pole position time). Look how he winds on the steering smoothly as waremark described.
b) he's at, or very close to, the limit of grip.
c) he's not feeling for grip, he's correcting for loss of it.

I don't see any deliberate "sawing", only corrections to keep the car going where it's intended to go. The track surface may vary and on bumpier surfaces you'd quite likely see more hand movement, some of this would be correction, as above, some of it would just be the car driving the steering wheel rather than the other way about.

Just my view.
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StressedDave
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Re: Smoooth . . . or not?

Postby StressedDave » Wed Jan 20, 2016 2:53 pm

Mr Cholmondeley-Warner wrote:(c) he's not feeling for grip, he's correcting for loss of it.

In my experience, this... I've done a fair bit of coaching for those who sprint (at an amateur level). In other words they try and drive a short, normally flat course as quick as possible. I see in these people a tendency to saw at the wheel, find the limit of grip on the way out of a corner as they flail around trying not to go off circuit, and generally waste what grip they have.

Anyone sawing at the wheel to find grip then has to waste grip trying to correct their use of too much grip generating either understeer or oversteer (In the true engineering sense).
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Mr Cholmondeley-Warner
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Re: Smoooth . . . or not?

Postby Mr Cholmondeley-Warner » Wed Jan 20, 2016 3:06 pm

Well Lewis has 800 hp under his right foot so the slightest twitch of the toe is likely to result in losses of grip. I think that's what we see in the clip - power, start of slide, correction, more power (and his corrections are pretty much all in a single direction - i.e. he doesn't overcorrect and have to steer back the other way, ever).
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xpc316e
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Re: Smoooth . . . or not?

Postby xpc316e » Tue May 10, 2016 1:14 pm

I wonder what some of the opinions expressed here are based on. Are they based on years of sitting alongside the very best Police drivers, or is it a case of thinking 'well, they are going faster, so they must be coarser'?

As a young man I spent a month at work seated alongside a chap who was the epitome of smoothness. When we were not on a call, it was just like being wafted around in a limousine. When we did get a call, it just got a lot faster, but crucially no less smooth. He ended as a driver of some repute on the Flying Squad. He inspired me to become a Class One Driver, and I went on to spend five wonderful years as an Instructor at Hendon Driving School.

Even there we had testers who thought that if they were being thrown around in a car like a ball bearing in a wok, that they must be going quickly. Coarse is rarely fast in my opinion; it just feels as though it ought to be. The really smooth driver gives the impression that he isn't going very fast; when one glances over at the speedometer though, it is often a case of 'JESUS, WE ARE REALLY TRAMPING ON'.

Smoothness is evidence of better control habits, of course, but it is also a by-product of better visual habits, earlier plans, better anticipation, and improved driving plans.


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