Rob Wilson - driver coach?

[Ral]

I'm not a racing driver, nor do I have an engineering degree, but I think your friend is misunderstanding either what Rob Wilson is saying, or what he himself is saying. Because from where I'm sitting, what he's saying has no direct bearing on any of the points you've raised from Rob Wilson in this thread.

While there are of course physics reasons for why certain lines are better than others, I think your friend is too concerned with the mathematical side of things. For example, the slant in the surface road is for all intents and purposes irrelevant, because it's there in all situations, accelerating or braking with or without steering lock and regardless of how much steering lock you put on. So I'm not quite sure why he felt the need to mention it. And while I'm sure most drivers will try to avoid crossing the crown in the track's surface in a corner (if there is one) because of the inherent bumpiness and additional instability that would induce while already suffering lateral load, I don't think it has any bearing on the racingline otherwise unless we are talking significant camber and then only in the additional speed it allows.

Rob Wilson's point, if I understand him correctly, is that a higher apex speed will not necessarily result in a higher average speed on the following straight. This is true, because while the speed measured is in a forward direction from inside the car, from an observer's point of view a not insignificant vector of that speed is not forward in the direction of the track, as a result of centrifugal force commonly mentioned as the g-forces experienced by the driver. Like so. So what Rob Wilson says is to make sure you have to worry about the vector that would take you off-track for as short a time as possible, ie. shorten the corner by making sure you do the actual turning as quickly as possible.

"Warning the car" is something Jacky Stewart also says. As I understand it, you basically load up the tyres by turning a little bit before you want to start the actual turn, so you feel where the limit of grip is beforehand. This makes the car's behaviour during the turn predictable which means you have confidence in what's going to happen which means you will be able to commit to the turn which means you'll be faster than if you had to guess roughly what your car can put up with in that particular corner in the particular conditions when you arrive at that turn.

I would say that, while all of this is eminently sensible from a pure numbers perspective following the laws of physics, there are a couple of problems approaching this from a purely mathematical perspective like raymondu999's friend seems to try to do (and apologies if I misunderstood, which is entirely possible). One is the ever present conundrum of the spherical chicken in a vacuum and the other is the driver. Humans aren't perfect, input processing takes time as does (re)action output. Add mental factors like confidence on the day, in the car and the tyres, the weather and all of that together will mean that basically, while there might be a perfect line for any given car for any given corner, the fastest way through that corner with that car with a particular driver in a particular instant in particular conditions, might not follow that exact line. The numbers will tell you it never can be, and that is of course true, but if you made that driver follow the mathematically perfect line, he might be slower than following his (natural) line. Not necessarily because he can't drive that line, but it might be that he can't modulate the throttle well enough on the exit so he is either taking too long to accelerate or he is getting excess oversteer. Or he might have problems with the trail-braking required to follow the perfect entry line to the apex. Or there might be dust, or marbles on that line. In essence, the act of driving itself isn't a science even though there are scientific guidelines one can follow to make it better overall. If it was perfectly scientific, we'd only have overtaking between vastly different speed cars (didn't the working group say it was 3s a lap or so speed difference required to overtake a car when they started fiddling with adjustable front wings and KERS and DRS?). If it was, robots would be able to race one another around a track faster than humans.

[Cam]

Warning: Science Content

Thought this maybe relevant to the overall concept of turning into a corner and why/what is the best focus to get it right.

http://www.nsf.gov/news/special_reports ... ansfer.jsp

Edit: put in the right URL. Other great videos here too.

[Cam]

Another good read:

http://soliton.ae.gatech.edu/people/dcs ... sie05a.pdf

Edit: Below images are from the PDF from the above URL.

[raymondu999]

If you're into that kind of thing - this is a good read too: http://phors.locost7.info/contents.htm

However unfortunatley none of these guys actually talk about the "shorten corner" line that Rob does.

I'm beginning to wonder if I had misconstrued Rob Wilson's lesson though. I asked (under a pseudonym) Rob about how to find a balance between carrying speed through the apex and onto the exit, and about "shortening" the corner. He says that you should shorten the corner whenever it doesn't sacrifice your minimum speed. So basically, if you have "excess" traction in a corner - use it to turn the car, rather than to carry a wider line through. Which obviously makes just about perfect sense - because to a certain extent, you're power limited rather than grip limited, and obviously you'd make better use of the grip (probably) than if you carried the wider line

He talks of an interesting (though I don't think scientifically correct) analogy - he says holding a half-hot stove, for 10 seconds, does more damage than holding a hot stove for 5 seconds. It describes what he means rather beautifully, though I'm not sure it's scientifically correct.

[mike]

Power limited occur around speeds around 170km/h for a Formula 1 car below that the car is traction limited, so its not so much as that you have excess traction its more like you have more grip to turn the car then grip to put down the power

[raymondu999]

Power limited occur around speeds around 170km/h for a Formula 1 car below that the car is traction limited, so its not so much as that you have excess traction its more like you have more grip to turn the car then grip to put down the power

Holy runon sentences batman!

That's what I said though. You've got traction (aka grip) which you're not using. I'm not just talking about traction on the exit of corners (as people do in conversational vernacular), but the actual definition of traction - grip.

[mike]

hahahahaa
I read the other thread and they seem to say traction as putting down power and grip as sideway stuff.
well you're right at low speeds the car is very traction limited in the rear end, but has the greatest ability to steer. This is all because f1 cars have 54% grip at the rear and when they steer they have 100% available. If F1 cars have 4WD then I'm pretty sure it will be better to speed into the corner. This is probably the reason why too much downforce is bad for F1 because drivers simply dont have to work as hard as before.

[raymondu999]

hahahahaa
I read the other thread and they seem to say traction as putting down power and grip as sideway stuff.

In talking to people - like everyday conversation about motor sports, then yes, people don't talk of sideways as "traction." But in a scientific context - traction is generally grip in any direction.

I think, based on my latest interaction with Rob - that what he means is, for example. If you can take a corner flat out. For example Turn 3 Barcelona, or Turn 8 Turkey, if you're in a 2010 Red Bull - then take as tight a line as you can, so you have a straighter exit.

My question to him (via a pseudonym) was basically asking, "in a circuit as relentlessly busy as Hungaroring, where Sector 2 is practically just corner after corner, how do you balance shortening the corners for a flatter run between corners, versus taking speed through the corner?"
To which his reply was: "You shorten the corners where it doesn't hurt your minimum speed."

Where I think Rob's technique may fall short slightly is that F1 cars have more grip, the quicker you go. If you go slower for a better rotation - then you have less downforce, and then the situation gets dicey - because while you may be freeing up grip for rotating the car, you're robbing yourself of downforce anyways.

If F1 cars have 4WD then I'm pretty sure it will be better to speed into the corner.

Have you tried lapping in a 4WD car mate? I'd recommend the opposite

A 4WD car is a weird beast, from my personal experience. In a slow corner, it's more maneuverable, especially at higher angles of steering lock - it has a better front end, because the front is pulling the car in the correct direction rather than the rear pushing in the wrong direction, and asking the fronts to steer the car. If you tried turning the car through a quick corner - it's got quite a bit more understeer in it than a RWD car, because the "grip" or "traction" of the front tyres is being used to pull the car forward, rather than just to steer it. In a 4WD car, I'd recommend Rob's driving style any day, because the grip is so good - instead of trying to put the power down through 2 contact patches, you have twice the number of contact patches under power.

Mind you this is for static 4WD. Some 4WD cars have racier modes - for example my Audi S5 starts shifting the "power bias" to the rear at higher speeds to kill the high speed understeer. Mind you I've only brought it to a track once - then never again. It's my daily driver anyways... not a track car!

[mike]

I meant in slow speed corners for F1 car, the more traction it has the faster you can speed into the corner. Basically I'm saying it all depends on how well the car can put down its power. If say you cut down 20% of the power it will make more sense to get a earlier apex instead of a higher power car.

[Andrew F]

Hey, really interesting topic and I think raymond is my long lost brother as we seem to think alike

I have read a lot of the topic but as a busy bee, i've scanned some.

I have a few thoughts and questions and i wonder if you can confirm them in a simplistic way. I've read all about traction circle but using formulas isn't for me so straight answers (if possible) help me.

I'm interested in what Rob has to say as I'm interested in learning more about driving styles. I've just started in sim racing so modelling my style on a successful style would be my aim.

Rob notes that lewis likes straight lines. So heavy braking, as late as possible, locking on and off as quick as possible followed by throttle down progressively but as quickly as possible? so in effect, reducing the turn but the overall, large radius of corner is taken?

Jenson....more of a curved corner, so softer inputs, braking more gently, locking on and off slower, more focus on maintaining higher average speed through throttle input in the turn and creating maximum radius through turning?

Question1: rob says lewis made tyres last longer at canada because jenson spent more time in the turn. i've always heard people say that jenson saves tyres by smooth inputs (e.g. braking). so is it better to save tyres using straight lines and braking hard over braking less and scrubbing tyres during longer turns?

i watched this video:
http://www.youtube.com/watch?v=VFlbFZMz1J4

i think somebody mentioned about losing apex speed by braking later and driving straight lines?
in this video, vettel seems to drive straight lines compared to button...button trying to maintain more speed in the turn.
however, altho he does this, he seems slower on entry, slower on exit and usually the same speed or slower at apex.

Question s2: so if you use straight lines, surely you can still achieve same apex speed?

trail braking: i understand the benefits of using more grip through trail braking and all the top drivers seem to do it. lewis seems to trail brake all the time - check out his lap at abu dhabi. however, does trail braking not lend it's to scrubbing more speed and reduces turning potential to a degree at least? surely trail braking should be corner specific?
for example, if you approach a really slow corner (e.g. the corner after the long straight in sector 3 at china) you want to late apex. prost advocates this in his main book ....so sure you would want to use threshold braking, maximum grip for slowing down at the last minute (to maximise speed from the straight) then use maximum grip for turning to create a turn of small radius...followed by maxium grip for acceleration? I would have thought fast rounded corners where you need to carry as much speed into them would suit trail braking more so...

Question 3: Should trail braking be corner specific?

similar theme, "exit speed is nearly always king"...exceptional example: long straight followed fast corner followed by short straight. if this is the case, why do drivers carry speed right up to apex and accelerate from the apex? surely this should be corner specific and most corners would suit accelarating a greater distance from the apex? i.e not necessarly early apexing but even late apexing and turning? surely if you're driving like lewis , brake and turn for as little time as possible (reducing turn radius - like rob wilson advocates) you will have the car rotated at a distance away from the apex?

Question 4: why do so many top f1 drivers brake up to the apex? does this not mean they are braking for longer?

thanks if you can clear up any of my misconceptions. great thread!

[raymondu999]

Hello long lost brother!

About trail braking, it's not about just braking and reducing turning potential. Imagine a traction circle - as you go from straight to cornering, the dot will gently drift from center to the left/right. Let's assume a driver who can maximise the traction circle mid-apex, and so the dot will be sitting on the circle perimeter.

But while you're turning the wheel, the red dot is moving only to the left or right, and it's not on the perimeter until you're at full lock for the corner. So why not use that grip for braking? So basically trail braking is about moving your traction circle usage from full-reverse (braking) and slowly, bit by bit transferring that grip use level to sidewards

Eg. If you could put 30 degrees of steering lock at 220kph (arbitrary numbers) while you're building from 0degrees-29.99 degrees but at 220kph, there's spare grip available. However do note that trail braking up to the apex means you're increasing lock up to the apex and decreasing out of it - geometrically, if you took that line, you'd have more lock at the apex then you would in a smoother, more circular line, which means you carry a slightly lower apex speed across. But remember too that as you brake, the car dives and weight shifts forward, which helps the fronts get a bit more grip. In fact if you have a moderately understeering car, trail braking can sort of help you balance it out.

Here's more on trail braking: viewtopic.php?f=1&t=11603

Basically a more straight-line, short-corner approach sees the driver have a sort of V-shape, while the other driver will get a semicircular shape

[Andrew F]

Thanks raymond, I never thought about it in the sense that the driver keeps turning up to the apex.

I understand the idea that you get maximise grip by say using a percentage of lateral grip at the same time as a percantage of longitudinal grip with trail braking as opposed to one or the other i.e threshold braking versus turning...

however, are we saying that using maximum grip is always faster?

what i mean is, is it possible to brake with threshold (using only grip for braking and slowing quicker) then steer off the brakes using only grip for steering (but turning in quicker than with trail braking - which requires a percentage of both, no matter how small in one) and then being able to accelerate before the apex (because you've turned in later and quicker) using only grip for throttle? so faster exit speed and all round less time braking and in turning? is this possible on certain corners?

couple of questions:
1, are we saying that if you're not using all the latitudinal and longitudinal grip available then you are not maximising speed? i.e. so if i threshold brake i may be slowing quickly, but if i turn in without braking, i am losing speed at this point?

surely at a tight hairpin turn , for example, trail braking would be a poor choice as you need all available brake to brake deep and then all available turn to late apex it? to combine them would mean some level of compromise so...
2. is trail braking not corner specific?

3. i still fail to see how it is always faster to brake up to the apex and throttle from there? surely it can often be faster to brake late but throttle before apex? i will read other thread you've shown but it's not clear. sorry!

p.s. do you do sim racing or something "long lost brother" ?lol

[Andrew F]

i guess i'm thinking as well, if you're late apexing, you don't brake up to the apex do you? you brake later, turn in later but probs on throttle before you hit the "late apex point"? (compared to the geometric apex where you would probs brake up to the apex)

thanks again for any help

[raymondu999]

Trail braking isn't so much a compromising of braking for turning/vice versa... It's managing the transition. For example - even if you were to do threshold braking, followed by "threshold turning" - you would need time, even if it was only 0.001s, to turn the steering wheel, and to stop braking. So why not do both at once anyways, just as long as you don't exceed your available grip?

Threshold braking followed by threshold turning is basically using 100% longitudinal, then 100% lateral. But you need the longitudinal to go from 100-0, and the lateral to go 0-100. So you then transfer the grip demand from longitudinal to lateral, by decreasing the longitudinal demands (from braking) to the lateral demands (of turning) - eg if you imagined two gauges next to each other imagine one labelled (longitudinal) and the other labelled (lateral) - now imagine one decreasing at the same rate that the other is decreasing. Hence why I say trail braking isn't about managing the corner per se - it's about managing the transition of 0-100 turning, and 100-0 braking, at the same time.

On a late apex, you do your turning mostly before you "apex" - but you still generally trail brake up to the point when you do the max turning. i.e. if viewed from above, you could imagine it as basically a regular apex line, but taking an "invisible apex" - same motions, just different speeds and geographic location

I don't quite sim race - my games are more arcady than those - but I have had the good fortune of testing and driving various cars (albeit all road legal, or track-modified versions of road-legal cars, and never open wheeled) on various track days - which I use quite a bit for experimentation.

[gato azul]

I think, what RM999 want#s to say can be illustrated with the "string" analogy.
The string connecting the bottom of the steering wheel with the brake pedal, if you want to turn, you have to lift off the brakes, but you try to keep the string tensioned all the time ( e.g. don't lift the brakes more then necessary)