15 replies to this topic

[jtarnstrom]

I'm getting confused about the different driving styles of certain drivers. Some are said to be so called early-turn-in, others are late-turn-in. Most literature on the subject states that for the former category turn-in understeer is to be preferred to keep the car stable under braking. Also, it gives the rear tyres more grip to be used which is helpful if you want a fast getaway out of the turns. Now, I know that Coulthard, ALesi and M. Schumacher are referred to as early-turn-in drivers. Still M. Schumacher is claimed to have a very pointy and "oversteery" setup. Coulthard is known to prefer understeer as did Gerhard Berger.

I've read Autosport, F1 Racing and the books by Carroll Smith on the subject and I see a lot of conflicting arguments. In one instance, F1 Racing -99 it was claimed that drivers like Schumacher, "Providing they have a front end that plugs, drivers like the Schumachers will always turn-in earlier.", is required to have oversteer dialed in to make an early turn-in. Quite the opposite of the theory if you read Carroll Smith for instance. I know this discussion has been brought up before but there's gotta be more people who are confused than me. Having seen Schumachers ability to use the throttle to steer his way out situations
I'm hard pressed to believe that he hasn't got understeer which makes his car a bit easier to handle. Also he does seem to have a good handling car in the wet. A good way of getting a car more reasonable in the wet is to dial in understeer.


Further, would it be more useful to categorise the drivers on two axis? One axis for understeer-oversteer and one axis for early-turn-in and late-turn-in. A driver like M. Schumacher would be high on oversteer and early-turn-in, Coulthard high on understeer and early-turn-in and so on.


Come on people and enlighten me,
Joakim Tarnstrom

[Ross Stonefeld]

I think we have to keep into perspective its all relative.

How "early" or "late" you turn into a corner is quite a small difference. It shows up in the lap time too. .5 seconds difference over a 90 second lap is actually quite a small amount. Try counting out half a second in your head

The best line through a corner depends on the corner, what proceeds the corner, what follows the corner, and the setup and characteristics of the car.

Generally what ever you can do to allow you to put the power down earlier is going to really really help you. The corner exit is the most important phase of the corner, but the corner entry is what determines the exit.

I dont think Schumacher would go very fast in a Mclaren because its not dialed around his "style" of driving. I dont think Hakkinen would go very fast in a Ferrari because its not built around his "style" either.

I seem to recall once watching a program where a computer formulated the ideal line, brake and acceleration points on a track. Emmerson Fittipaldi got into the car, and went faster than the computer said was possible. *throws hands in the air*

Ross Stonefeld
Aztec Group Motorsport

[This message has been edited by Ross Stonefeld (edited 05-24-2000).]

[srf]

.5 seconds per lap is a big difference. Multiply that .5 seconds times 50+ laps and count that in your head. At 120mph .5 seconds is a difference of what, over 80 feet?

[Ross Stonefeld]

Yes I realise that, but the point I was trying to make that the difference between "early" or "late" turning is a small degree. And switching to one or the other wont suddenly put you and your lovely Minardi on the front row of the grid.

Ross Stonefeld
Aztec Group Motorsport

[jtarnstrom]

Thanks for taking interest in my topic but as much as I agree and understand that changing from one style to the other doesn't put your Minardi on the front row it doesn't increase my understanding of the problem. I'm well aware that these differences in styles are hardly noticeable without comparing photographs with each other. The thing is, I don't get the theory to match reality here. I wanna know how to justify oversteer and early-turn-in in terms of theory.

/Joakim Tarnstrom

[PDA]

Early turn in drivers such as DC, JA, MS abhor a car which has alot of understeer. They induce a certain amount of controlled understeer as they turn in (i.e. the front end "plugs"). At the apex, they need to "flick" the car to oversteer, and this is the really difficult bit. MS is obviously very good at it, as he can manage a car which "flicks" to oversteer very quickly. Other drivers call such a car "nervous" and tend to spin off (Alesi and Berger, Benneton 1996).

This cornering technique is claimed to be faster because you can keep on the brakes further into the corner (right to the apex) and therefore brake later, although the speed in the middle of the corner may be lower than a traditional "oversteer" driver such as MH.

The need for controllable oversteer on exit for this style to work is difficult to achieve, as the natural tendency for a car with power on and differential locked is to understeer. Mac and Ferrari (and probably others) have probably developed some very clever torque transferring diffs. to combat this tendency (also the purpose of Macs "fiddle" brake system in 98)

[PDA]

Further info from Nigel Mansell's autobiography (he was very much a front end driver). I quote froom page 35:

"To drive like this I need a car which has a very reesponsive front end and turns in immediately and doesn't slide at the front. I cannot drive on the limit in a car which understeers for example." He goes on to say that he needs a "nervous" car, although that is difficult to control, becasue he needs fast reaction to steering input: "The back end feels like it wants to come around on you, but that's something you learn to live with."

[Ross Stonefeld]

In my experience, when talking with Vector (Formula ford constructor) principal Mick Goldney about mono-shock vs dual-shock suspension...

"a fast setup is a nervous setup"

I'd have to agree. The Mygale I tested that won the British Formula Ford championship was, how shall we say, quite "free" in the balance.

Ross Stonefeld
Aztec Group Motorsport

[jtarnstrom]

bear with me if you start to feel I'm thick. One argument that I've heard is that the Schumacher school of drivers need to feel their front end. What I read into this is that they want to feel if their front end is braking away. If their front end is braking away before the back end like the argument implies, I would call that understeer. I hear you PDA but I see only what I've already read in the same books as you. What you say about the diff is of course very relevant and I have to check into that.

Is this just a matter of drivers expressing themselves in terms of how they think the balance should be in their car? Would anyone agree that a driver of Hakkinens style would prefer more oversteer than a driver of Schumachers style? Is it just in relation to other drivers of the same style that Schumachers settings are considered "oversteery" or even in comparison to Hakkinen?

BTW, I've never heard any driver say they like understeer. They're always battling understeer but it's always in relation to their driving style. Sometimes I think that spills over on the discussion of driving styles and the inherent balance of the car.

Cheers everybody

[tak]

I'm going to muddy the water ALOT, by reminding you all that the drivers fundamental style affects the oversteer/understeer aspect of a car. For example a car that turns in well under trail braking will NOT turn as well under power. The trail braking changes the weight distribution, which changes the handling. The same idea applies to the speed drivers turn in the car (do they flick it into the corner or do they gently bend the car into the corner?).

Fundamentally, I believe that an oversteering car will always be faster than an understeering car--for the very simple reason that the oversteering car REQUIRES throttle to keep from spinning. Comparatively, the driver in an oversteering car will spend more time on the gas.

[PDA]

J - what you say is basically correct, but turn in drivers take a neutral to oversteering car and induce a certain amount of understeer on entry to a corner. They cannot do this if the car is uncontrollably understeering and ploughing past the apex.

When one analyses the comments of the drivers aftrer practice sessions, qualifying or race, they are always talking about getting "balance" in the car. It is my understanding that they are looking for a neutral handling car so that they can induce understeer or oversteer at will.

[jtarnstrom]

I guess we have come to the point where this thread can be summed up in one question to give me the answer I'm looking for: How do they induce understeer with an oversteering setup in terms of weight transfer, slip-angles, braking, steering and so on?

tak, I basically disagree about the notion that an inherently oversteering car would be faster out of corners. Understeer, espescially in the exit of bends leaves more grip in the rear tyres to be exploited by using throttle. Of course, you can't have understeer to the degree that your ploughing out of the turns or have to lift off to stay on the track but that's not what I'm talking about. Also, I don't quite understand the following: "an oversteering car will always be faster than an understeering car--for the very simple reason that the oversteering car REQUIRES throttle to keep from spinning." If anything an oversteering car is more prone to spinning when using too much throttle. Of course you can balance the car with the throttle if your rear starts to slide but that's not the fast way to go anyways. In that situation your also dependent on what your diff allows you to do.

Wish Carroll Smith was on this forum so we could get this straightened out

[Yelnats]

The key to inducing understeer with an oversteering car lies with the braking setup. Brake bias can change an oversteering car to an understeering car just as the throttle can change a understeering car to and oversteering car.

Brakes setup with a bias toward the front will compensate for oversteer when used by a master like Schumacher. An early turner like Schumi will let off the brakes slightly on turn in to unload the front end and allow the front tires to generate side force for the turn. But the front brake bias will make the front slide out more than the rear and balance the car to turn oversteer into understeer during corner entry. As soon as the brakes are released the rear will swing out and apparently this is where Schumi excels in catching and balanceing the car for acceleration out of the turn.

[Yelnats]

jtarnstrom, I aggree with your point about an oversteering car being theoretically slower than an understeering car on corner exit but as I mentioned above, the oversteering car has advantages over an understeerer on corner entry. Also and oversteering car inherently has better steering reponse an as many a racer has commented on and an understeering car is prone to greater attitude swings with throttle modulation as it transitions between understeer and oversteer depending on the trottle opening.

It's a question of degree. I'm not sugesting that that a F1 car be violently and irrevocably as oversteering as the old VW bug. But as an F1 car is going to oversteer on the corner exit due to throttle usage anyway, a basic setup with a little oversteer will smooth the cars response to the trottle and tend to give a speedier, more accurate entry to the corner while providing a more consistant reaction to throttle on corner exit.

As I related topic I thouroughly enjoy watching the F1 racers of the later part of the seventies. They were spectacular to watch and swung violently from understeer to oversteer on the exit of any mid speed corner. Jody Schecter was a particularly adept at this but of course this was in the era of unlimited tire widths when I suspect an entirely different set of paramaters applied.

[MacFan]

jtarnstrom -

I have also been puzzled by the inconsistency between "early turn-in" drivers' reported preference for oversteer or understeer.

You are obvously familiar with Carroll Smith's work, so this may be repeating what you have already read, however to quote the guru himself (from "Drive to Win"

"In order to be able to accelerate in Phase Four (corner exit) while still cornering, in Phases Two and Three (corner entry & mid-corner) the car must have reserve rear tire capacity. This means that every fast car will have a certain amount of Phase One, Two and Three understeer.

Think about it. If you are using up all of the available traction of all four tires in the generation of cornering force, there is nothing left to accelerate with - applying power will produce instant oversteer."

So there you have it - every fast driver's car actually understeers!

It has always struck me, speaking as somebody whose practical racing experience is limited to a few years' kart racing a decade ago, that the fastest way round a corner is to have the vehicle set up to understeer in and understeer out. That way, you are forced to still be braking as you turn into a corner, to transfer weight forward, reduce the dynamic weight on the rear tires, and overcome the vehicle's tendency to understeer. This allows you to enter the corner at a higher speed than the equivalent car set up to oversteer (assuming the understeer has been acheived by adding grip at the rear).

In essence, you set the car up with more rear grip than is conducive to sharp turn-in, and you cancel this out by trail-braking, setting up a four-wheel drift through mid-corner. The maximum possible speed for a four-wheel drifting car through a corner is dictated by rear grip, with the primary task of the front tyres being balancing the slide. This excess of rear grip also helps in the corner exit phase, as described above by Carroll Smith.

Returning to your original topic (I seem to have strayed!), Keke Rosberg said when Senna went to McLaren in 1988 that if the car was an understeerer then Senna couldn't live with Prost. History proved him wrong, but I took this comment to mean that Prost was an understeer driver.

Jim Clark and Stirling Moss also seem to have been understeer (trail-braking) drivers, from reading their biographies.

David Coulthard, while he was in F3 in 1991, seemed to be very much an understeer driver, altough JYS dialled some of this out during the season. However I recall an interview with Coulthard when he was in F3000, in which he said that he quite liked understeer.
Peter Windsor's article in F1 Racing last month seems to dispute this, however DC's well known dislike of a twitchy car (as opposed to an oversteering one) supports my theory that he is the best current example of an understeer driver. (You need confidence in the rear of a car to be able to trail brake).

I believe that the understeer Mansell and the Schumachers dislike so much is mid-corner understeer in fast corners, which scrubs off speed and wears front tyres out. However, only the drivers and those close to them really know the truth. I am still waiting for the definitive article to be written about this.

[Yelnats]

MacFan's quote, "So there you have it - every fast driver's car actually understeers!" An interesting conclusion. Too bad Jack Brabham didn't know about this. Maybe he would have won four WDCs instead only wining two titles with his oversteering Cooper against a field of understeering front engined cars. {;->

I'm afraid your go-cart setups have little relationship to a F1 car because of the vast differences in the ratio of the wheel-base to the height of CG. Braking a go-cart will almost stand the cart on it's nose, whereas a F1 car under full braking on the straight only moves about 25% of the weight to the front so the rear tires do about as much braking as the front. Under trail braking at corner entry the transfer is much less and this is where brake balance is critical. If the balance is too much to the rear, oversteering under trail braking will provoked but with the front brake balance used on F1 cars, this unstable condition is avoided. Biasing the brakes to the front provokes understeer by moveing the front tires closer to the limits of their circle of adhesion than the rear.

Whether the car basically understeers or oversteers under steady state throttle may have a small theoretical effect on corner exit acceleration but far more important is the drivability. A car that swings from understeer to oversteer, depending on the throttle position, is more difficult to control than a car that with a consistant mild oversteer so it will be faster because of better drivability.