Advantages of Over/Understeer

[raymondu999]

Hey all. Just curious here. I want to talk only about the advantages and not of the disadvantages of each. For oversteer, the advantage would undoubtedly be that you can turn in very well. How about understeer? Are there any benefits to understeer? You get a better entry (ish) with oversteer, but you don't get a better exit either do you? And I seem to have read somewhere in a q&a with button I think? I can't find it right now, it would be helpful if someone could post up the link here if they know which Q&A I'm talking about. That he said he set the car to understeer to help take care of the tyres during australia. I'm not sure how this would have helped him?

Thanks!!

[marcush.]

Hey all. Just curious here. I want to talk only about the advantages and not of the disadvantages of each. For oversteer, the advantage would undoubtedly be that you can turn in very well. How about understeer? Are there any benefits to understeer? You get a better entry (ish) with oversteer, but you don't get a better exit either do you? And I seem to have read somewhere in a q&a with button I think? I can't find it right now, it would be helpful if someone could post up the link here if they know which Q&A I'm talking about. That he said he set the car to understeer to help take care of the tyres during australia. I'm not sure how this would have helped him?

Thanks!!

without putting some quantity behind O/S or U/S you canot talk about benefits or disadvantages .

to a degree this is not something you could clear cut.
If your mount is oversteering it will reduce the amount of steering action needed (it could need of course counter steer action then wich reverts the positive into a negative!)wich can be very good on slow and ondulating tracks..but if this is a high speed track with only 2 corners ...oversteer will kill you ..as either you have to slow down untill you are able to avoid a spin or you will crash.
With Understeer on a track with only high speed corners ,what you have to do is turn in earlier and judge your entry speed to still make the corner on the tarmac....

so horses for courses here .but taken to extremes an oversteering car is just slow ,only good for drift challenge .
A understeery dog is slow as well ,but driven extremely you still can wrestle a decent time out of it,given the corners are not only of the slow variation....

[WhiteBlue]

It depends much of the driver's preferences. Schumacher isn't very quick in an understeering car. He wants a very positive front end and a loose rear end. He then takes the corners very close to the edge of adhesion, feels where the car is getting away and slightly lifts the throttle.

Button is probably neutral and wants the car as balanced as possible.

From the top of my head I don't remember a driver who prefers understeer but the following article says most cars are set up for slight understeer. So that implies that many drivers prefer it.

Source for following explanation

Understeer and Oversteer

The forces exerted on the wheels by the weight of the vehicle are not distributed evenly. This means the slip angle for each tyre is different. The ratio between the slip angles on each tyre determine the way the car corners. If the ratio of front to rear slip angles is greater than 1:1 (ie the front tyres do not have as much grip as the rears), the car will tend to understeer. A ratio of less than 1:1 (ie the front tyres have more grip than the rears) will produce oversteer.

Understeer causes the car to go straighter than the trajectory that the driver is trying to take. This is sometimes known as pushing, plowing, or ‘refusing to turn in’. However, the car will be fairly stable as it is not wanting to spin. Understeer can appear under heavy acceleration and through heavy braking. If the brake balance is too heavy at the front (the front brakes are stronger than the rear), the car may understeer because the front wheels lock and lose effective steering. To counter understeer, more rear wing can be added to create more downforce at the back of the car, and the rear suspension softened.

Oversteer is when the rear wheels of a car do not track behind the front wheels. Instead, they tend to slide out towards the outside of the turn. This can easily cause a car to spin. In a race car, particularly open-wheeled cars, oversteering in high speed turns is caused mainly by aerodynamic configuration; A heavy aerodynamic load on the front of the car relative to the rear causes it to oversteer. In low turn speeds, oversteer can be reduced by traction control systems. To overcome oversteer, more front downforce is needed. This is usually achieved by changing the suspension settings.

Although understeer and oversteer can both cause a loss of control, many cars are designed to lean towards understeer as it is generally believed that it is easier to recover from understeer than it is from oversteer.

A car which neither understeers nor oversteers at it’s limit is known as a car with ‘neutral handling’. Race cars are often setup to slightly understeer as accelerating hard after the apex of a corner allows the car to get the maximum amount of speed down the following straight. The car that starts the acceleration soonest will usually have the biggest advantage, so slight understeer will help the driver to maximise the traction on the tyres and help them get a good exit out of the corner. An oversteering car also has a tendancy to be quite ‘twitchy’ meaning the driver is more likely to lose control during the course of a race.

Driving style is a massive factor in whether to setup a car to slightly understeer, or slightly oversteer. Some drivers prefer oversteer as they like to have a car which is more willing to turn into corners. This is why drivers in the same team will often run with different balance settings and also why these settings may be changed during the course of a race.

[timbo]

feels where the car is getting away and slightly lifts the throttle.

From what I remember from vids and articles he rarely modulates his throttle, he would use steering a lot and sometimes gently touch brakes.

From the top of my head I don't remember a driver who prefers understeer.

I remember there were talks that Alonso prefers understeer.

One thing to notice, driver input may provoke one or another.
Generally you would want a bit of oversteer on entry and understeer on exit.

[marcush.]

feels where the car is getting away and slightly lifts the throttle.

From what I remember from vids and articles he rarely modulates his throttle, he would use steering a lot and sometimes gently touch brakes.

From the top of my head I don't remember a driver who prefers understeer.

I remember there were talks that Alonso prefers understeer.

One thing to notice, driver input may provoke one or another.
Generally you would want a bit of oversteer on entry and understeer on exit.

most of the drivers seem at a loss to differentiate between slip angle and oversteer for the backend of the car.

To be at the maximum grip at the rear as on the front a degree of rear slipping is in fact necessary.If slip angle front and rear is equal=this is called neutral steer!
or try it this way around:if you conduct the track very slowly you will need a certain steering angle for each corner you negotiate .If at full flight the steering lock angle gets less: this is called oversteer if it increases:understeer


very often the drivers talk about -walking- at the rear which discribes nothing more than the car building up grip by approching that correct optimum slip angle
in the front that is easy to detect -the steering feedback gets less-

so all these guys with the uncertainty of that walking feeling sensation trying to avoid are all understeer guys ,and most of them are...maybe in F1 not ..but I remember coulthard as one driver who always maintained he NEEDS a planted rear to commit for a corner...just one example..

[RH1300S]

In F1 they tend to be talking about fine degrees of difference from a neutral setup when describing an understeer car or oversteer car.

Obviously this balance can change depending on corner speed and can be changed by driver input.

Also it is very important to describe the cars balance relative to where it is in a corner (entry - mid - exit). A different balance might be good for each.

I like to think of it like this - oversteer can help a car change direction, but makes loss of control more likely and also if on corner exit it surely limits the cars ability to put power down. An understeerer will need putting into a corner on a different arc to compensate and on corner exit understeer can sap power as the tyres are being pushed across the surface creating tyre drag.

[timbo]

Understeer = stability but no control
Oversteer = control but no stability

From Peter Wright's book "Formula 1 technology"

It is not possible to provide the driver with both the stability and control he would like to have at the limit.

[Jersey Tom]

Understeer = stability but no control
Oversteer = control but no stability

Not true.

On the original point of the discussion though.. first thing is you have to define what you're calling 'oversteer' vs 'understeer' or 'tight' vs 'loose.' It's not as straightforward a definition as you'd think, at least in a practical (rather than textbook) sense.

Second, broadly saying a car is 'u/s' or 'o/s' or that a driver prefers one or the other is useless IMO. Measures of balance, stability, and control are a sliding scale, not a binary attribute, and change dramatically with vehicle speed, steering throttle and brake inputs, etc. You can have a car that's free on the brakes and tight on throttle.. or tight on the brakes and free on throttle. Just breaking a corner down into "entry - middle - exit" isn't as insightful as breaking balance down by input. Depending on the type of vehicle, the track, the corner.. varying degrees of vehicle handling can be fast or slow.

For example, having a stock car half sideways through to the center of a tight corner is probably going to have a lot of potential for speed... whereas it would ruin you in an open wheeler.

I would also not agree that 'oversteer' is good for having a car change direction.

In any event, all F1 cars are going to be set up very very close to neutral through most of the lap. If you're not using all of your front or rear tires, you're leaving speed on the table.. period. Preference differences between drivers are going to be very, very slight.

[WhiteBlue]

I believe that driver preferences can make a big difference. Remember the battles Ralf and Trulli fought at Toyota to get the car to their respective preferences which were obviously opposed. When Gascoyne introduced a B-spec car midway through the season suddenly Ralf got results with it and Jarno went nowhere. Next time round it would be the other way again. They never got a car which fitted both drivers.

Ferrari also went to great pain after 1996 employing only drivers who had a similar driving style to Schumacher.

[marcush.]

+1

the big question is here how steep is the grip raising or falling towards the optimum slip angle .If it is a flat curve or plateau for a range of 10° of slip angles ,you would not have a problem with over or understeer ,apart from other losses to go sideways and being lets say imprecise.

If your grip levels peak sharply with optimum slip angle ,dial in the car wrong and you will not be able to make the corner at optimum speed as of course you either find the optimum in the front and have a loose back -oversteer- or a planted rear and the front goes away from you understeer.You just can´t adjust by driving input
neutral steer to something like that.

so to get a time from peaky tyres ,you will need to find a car setup allowing you to drive the car with both ,no all 4 corners at peak grip levels (for the vertical loads applied) = at the slip angles providing peak grip..!as you can´t steer the two front tyres independant ..you are relying on ackerman geometries for this at the frontinside... on the rear it is the bumpsteer behaviour that has to adjust the inside to the best compromise ...

[marcush.]

I believe that driver preferences can make a big difference. Remember the battles Ralf and Trulli fought at Toyota to get the car to their respective preferences which were obviously opposed. When Gascoyne introduced a B-spec car midway through the season suddenly Ralf got results with it and Jarno went nowhere. Next time round it would be the other way again. They never got a car which fitted both drivers.

Ferrari also went to great pain after 1996 employing only drivers who had a similar driving style to Schumacher.

this is not exactly a U/S O/S theme ...as JT elaborated .. you just cannot afford to have the car understeer ing or oversteering as such .you´d be lost ,galaxies away from the leading teams..

[autogyro]

It is DF that has ruined the finer points of O/S U/S in F1.
I liked the comparison with a stock car on a loose surface half sideways through the apex. I remember it well. Looks good to.
The car was thrown sideways into the corner to slip off speed the driver working this out to achieve the highest apex speed to start applying power for the exit.
This was always much faster than the careful balanced method of cornering as used on circuits. Of course to do this on tarmac with high DF would take a superb driver at the speeds needed and would soon wear out the tyres.
The same inherent U/S and O/S factors still apply and to much O/S usualy results in an instant spin. Driver preference was AFAIR mostly for a neutral but pointy car, allowing a simple and not to physical input on the steering wheel and as little as possible unbalance under braking.
There is no point going into depth about mechanical handling in F1 until we stop bowing down to the god of DF.

[marcush.]

It is DF that has ruined the finer points of O/S U/S in F1.
I liked the comparison with a stock car on a loose surface half sideways through the apex. I remember it well. Looks good to.
The car was thrown sideways into the corner to slip off speed the driver working this out to achieve the highest apex speed to start applying power for the exit.
This was always much faster than the careful balanced method of cornering as used on circuits. Of course to do this on tarmac with high DF would take a superb driver at the speeds needed and would soon wear out the tyres.
The same inherent U/S and O/S factors still apply and to much O/S usualy results in an instant spin. Driver preference was AFAIR mostly for a neutral but pointy car, allowing a simple and not to physical input on the steering wheel and as little as possible unbalance under braking.
There is no point going into depth about mechanical handling in F1 until we stop bowing down to the god of DF.

yes and no there are still corners not entirely dominated by DF ,if it were nobody would even talk about Red Bulls rideheight system or cars being stiff where they need to be soaking up the bumps.. right ?

[autogyro]

It is DF that has ruined the finer points of O/S U/S in F1.
I liked the comparison with a stock car on a loose surface half sideways through the apex. I remember it well. Looks good to.
The car was thrown sideways into the corner to slip off speed the driver working this out to achieve the highest apex speed to start applying power for the exit.
This was always much faster than the careful balanced method of cornering as used on circuits. Of course to do this on tarmac with high DF would take a superb driver at the speeds needed and would soon wear out the tyres.
The same inherent U/S and O/S factors still apply and to much O/S usualy results in an instant spin. Driver preference was AFAIR mostly for a neutral but pointy car, allowing a simple and not to physical input on the steering wheel and as little as possible unbalance under braking.
There is no point going into depth about mechanical handling in F1 until we stop bowing down to the god of DF.

yes and no there are still corners not entirely dominated by DF ,if it were nobody would even talk about Red Bulls rideheight system or cars being stiff where they need to be soaking up the bumps.. right ?

Not exactly, the main motivation for ride height control on this occasion is to deal with the DF input on top of the extra fuel weight. I doubt the benefits would be as great with less DF.

[marcush.]

yes of course it is downforce motivated ,as you will undoubtedly find yourself at different parts of the aeromap with a raised static rideheight ,so you will have generally less df with diminishing effects toward higher speeds..so yes you are right.
But of course high or low ,df will not help grip and cornering in the slower bits of a track that much 8with the wings they use, if you optimise the wings for the slow stuff it would of course help tremndously as well)

but my claim was not really contradicting your df thing as I was referring to vertical load ,and this decidedly includes Downforce wich is of course a vertical load.