No understeer on turn-in = not fast enough?
Discussion
I dont know if this is the right forum to bring this up but here goes...
I've been looking into understeer and it's relationship to corner entry speed. In my view, all cars will understeer on turn-in if carrying enough speed, what happens after you hit the loud pedal is a seperate issue.
Is this a fair comment?
If you're turning into a corner and the car is balanced and willing to turn, albiet with tyre squeal, are you too slow?
I've been looking into understeer and it's relationship to corner entry speed. In my view, all cars will understeer on turn-in if carrying enough speed, what happens after you hit the loud pedal is a seperate issue.
Is this a fair comment?
If you're turning into a corner and the car is balanced and willing to turn, albiet with tyre squeal, are you too slow?
If your front tyres are the only turning wheels, and they still have availbale grip then surely more speed can be carried? I realise this is disregarding your exit entirely.
My most satisfying on track moments have been when I have been in an understeery slide but still hitting the apex. I really felt that was the absolute fastest thae car could go round that corner. Granted it was more luck than skill and would need alot of practice to master.
My most satisfying on track moments have been when I have been in an understeery slide but still hitting the apex. I really felt that was the absolute fastest thae car could go round that corner. Granted it was more luck than skill and would need alot of practice to master.
Edited by compocon on Sunday 17th October 12:14
I think it's an appealing idea, but it depends entirely on the setup of the car. It is perfectly possible that your turn-in speed is limited by other effects such as turn-in oversteer.
This is certainly where my Radical clubsport was (on track) this year and what I was trying to dial out. Basically with an entry speed too high, the front would turn in fine, but the back end would step out. You'd then either have to reduce lock a little or use a dab of oppo to correct it. Either way it prevented a good turn in.
The driving solution was to reduce entry speed a little.
Bert
This is certainly where my Radical clubsport was (on track) this year and what I was trying to dial out. Basically with an entry speed too high, the front would turn in fine, but the back end would step out. You'd then either have to reduce lock a little or use a dab of oppo to correct it. Either way it prevented a good turn in.
The driving solution was to reduce entry speed a little.
Bert
compocon said:
My most satisfying on track moments have been when I have been in an understeery slide but still hitting the apex. I really felt that was the absolute fastest thae car could go round that corner. Granted it was more luck than skill and would need alot of practice to master.
Surely if you're losing traction, you're losing time? I know very little about track driving, but common sense says sideways is not the best way to take a corner if you want to improve?In the majority of corners entry speed is ultimately governed by what you can do with the throttle at the apex, too quick ant you have to wait to get back on the throttle, conversely if you can get on the throttle before the apex you might be too slow on entry. ( before I get all you track gods telling me its not so...corner entry is a few tenths the next straight is maybe multiples of seconds, in most situations power on at apex is the quickest)
Just one way of measuring entry speed.
Jimmy
Just one way of measuring entry speed.
Jimmy
parapaul said:
compocon said:
My most satisfying on track moments have been when I have been in an understeery slide but still hitting the apex. I really felt that was the absolute fastest thae car could go round that corner. Granted it was more luck than skill and would need alot of practice to master.
Surely if you're losing traction, you're losing time? I know very little about track driving, but common sense says sideways is not the best way to take a corner if you want to improve?
not at all true.
You can dial out pretty much all turn in understeer with castor, toe and camber settings and also by changing the roll stiffness. Less easy to change aftermarket - but easy enough during the design process - but the position of the roll centres has big effect on roll understeer/oversteer.
You can dial out pretty much all turn in understeer with castor, toe and camber settings and also by changing the roll stiffness. Less easy to change aftermarket - but easy enough during the design process - but the position of the roll centres has big effect on roll understeer/oversteer.
filski666 said:
not at all true.
You can dial out pretty much all turn in understeer with castor, toe and camber settings and also by changing the roll stiffness. Less easy to change aftermarket - but easy enough during the design process - but the position of the roll centres has big effect on roll understeer/oversteer.
Agreed, I guess my question was once all this has been done (say on a top level GT or open wheel race car), if you entered the corner even faster, causing understeer by exceeding the front grip available - would it be any quicker if you're still nailing the apex?You can dial out pretty much all turn in understeer with castor, toe and camber settings and also by changing the roll stiffness. Less easy to change aftermarket - but easy enough during the design process - but the position of the roll centres has big effect on roll understeer/oversteer.
If you are still nailing the apex and are at the correct angle to complete the turn then I would say that the car isn't understeering in the way that I think you mean. (Pedantically, cars that steer in the desired direction before braking traction with the rear wheels are understeering)
Depending on the set up of a car it may be that understeer slows the car down towards the apex allowing the car to turn better as it slows down or allows the steering to be set with regard to changing conditions during a corner e.g. camber, grip.
I have a favourite roundabout where I set the steering on course to collide with the centre upon entry, however due to changes in camber and road polishing the car will understeer to the apex and then steer more tightly (without any change of steering angle) as camber and other influences occur after the apex.
Hope this helps
Depending on the set up of a car it may be that understeer slows the car down towards the apex allowing the car to turn better as it slows down or allows the steering to be set with regard to changing conditions during a corner e.g. camber, grip.
I have a favourite roundabout where I set the steering on course to collide with the centre upon entry, however due to changes in camber and road polishing the car will understeer to the apex and then steer more tightly (without any change of steering angle) as camber and other influences occur after the apex.
Hope this helps
If you are getting understeer, you have overcome the grip of the front wheels Technically you are going "too fast" but that isn't the whole story. The options for correcting this are: Slow down, Adjust your line, or adjust the setup of the car.
It is possible to set a car up with neutral handling; that is that the front and rear should lose traction at the same time. This is not always desirable though. Many drivers like a to tend toward understeer in a RWD car as it usually means more stable handling, and it can be easily corrected with either throttle or braking as required.
On a FWD car the balance for ultimate pace is to tend towards turn in oversteer, which can then be corrected with the throttle as required.
It is possible to set a car up with neutral handling; that is that the front and rear should lose traction at the same time. This is not always desirable though. Many drivers like a to tend toward understeer in a RWD car as it usually means more stable handling, and it can be easily corrected with either throttle or braking as required.
On a FWD car the balance for ultimate pace is to tend towards turn in oversteer, which can then be corrected with the throttle as required.
compocon said:
filski666 said:
not at all true.
You can dial out pretty much all turn in understeer with castor, toe and camber settings and also by changing the roll stiffness. Less easy to change aftermarket - but easy enough during the design process - but the position of the roll centres has big effect on roll understeer/oversteer.
Agreed, I guess my question was once all this has been done (say on a top level GT or open wheel race car), if you entered the corner even faster, causing understeer by exceeding the front grip available - would it be any quicker if you're still nailing the apex?You can dial out pretty much all turn in understeer with castor, toe and camber settings and also by changing the roll stiffness. Less easy to change aftermarket - but easy enough during the design process - but the position of the roll centres has big effect on roll understeer/oversteer.
Fast feels slow.
Just to answer a few points raised:
The maximum grip of a tyre on tarmac is actually when it is "sliding" slightly. Most drivers would interpret this as a slide from the passenger seat if you showed them. Even F1 cars, which look like they're on rails, are in a drift all the way through a corner. The point of maximum grip varies with tyre and tarmac; very generally speaking the higher the levels of grip, the smaller the amount of slide to generate that grip.
What a car does at turn-in depends on the way a driver is driving. The ideal situation is to have both ends of the car at the point of maximum grip (see above), so the car is in a state known as "neutral steer".
To quote the OP "from turn-in until the throttle is hit" isn't really how a car should be driven. The way to get the most out of a car on a race track is to exchange brakes for steering on turn-in, then hold the balance with a steady throttle before then exchanging steering for throttle on the way out. This technique is modified at either end to account for varying setup, or requirements from a corner in the context of the fastest way round the whole track.
The maximum grip of a tyre on tarmac is actually when it is "sliding" slightly. Most drivers would interpret this as a slide from the passenger seat if you showed them. Even F1 cars, which look like they're on rails, are in a drift all the way through a corner. The point of maximum grip varies with tyre and tarmac; very generally speaking the higher the levels of grip, the smaller the amount of slide to generate that grip.
What a car does at turn-in depends on the way a driver is driving. The ideal situation is to have both ends of the car at the point of maximum grip (see above), so the car is in a state known as "neutral steer".
To quote the OP "from turn-in until the throttle is hit" isn't really how a car should be driven. The way to get the most out of a car on a race track is to exchange brakes for steering on turn-in, then hold the balance with a steady throttle before then exchanging steering for throttle on the way out. This technique is modified at either end to account for varying setup, or requirements from a corner in the context of the fastest way round the whole track.
RobM77 said:
The maximum grip of a tyre on tarmac is actually when it is "sliding" slightly.
That's a really interesting statement and something I did not realise with driving at all.Coming at it from a purely engineering standpoint my understanding of grip is that any slide at all is breaking traction so is totally undesirable (if you don't want to exceed the limits of friction that is).
Naturally I have absoutely no experience of track racing so am not challenging your assertion but am genuinely interested in what you've discussed.
Are you talking about something that is almost undetectable to regular drivers (like myself) but more apparent to trained professionals?
Fatman2 said:
RobM77 said:
The maximum grip of a tyre on tarmac is actually when it is "sliding" slightly.
That's a really interesting statement and something I did not realise with driving at all.Coming at it from a purely engineering standpoint my understanding of grip is that any slide at all is breaking traction so is totally undesirable (if you don't want to exceed the limits of friction that is).
Naturally I have absoutely no experience of track racing so am not challenging your assertion but am genuinely interested in what you've discussed.
Are you talking about something that is almost undetectable to regular drivers (like myself) but more apparent to trained professionals?
Basically, there's no such thing as "sliding" and "not sliding"; a car will progress gradually through what most people call a "slide". This graph shows how slip angle (the angle a tyre's pointing compared to the direction of travel) is matched by grip, until grip peaks at a certain point then falls away again:
The whole idea of racing is to seek out the peak point on this graph and use it to corner as fast as possible, and obviously to also use it to brake and accelerate as well as possible too.
As for your last question regarding whether you need to be a "pro" to detect this peak, the honest answer is that I've only ever been me so I've no idea really. I can detect exactly where I am on the above curve as soon as it goes non-linear and then when I'm racing I obviously take the tyre to the peak point and hold it there through the corner, that's just racing and just what I do and have always done. To be honest I have a fair idea where the peak's going to be even before I've taken a new car into the non linear section of the graph. As for other people, I've done a little bit of instruction and you're right, some people do seem to have no idea what's going on until what they call a "slide" occurs (which worries me!). I haven't really sat with a large enough number of people on track to know how many people can feel it, and how it varies with experience etc.
Here's a good video that someone sent me yesterday which proves the point well. Notice how Webber is holding the car at a point where it's "sliding" gently - that is the point of maximum grip.
http://www.youtube.com/watch?v=ZkBtK3aFwvs
Obviously, no surface or camber is perfectly consistent, which is why he has to make corrections with the throttle and steering, but essentially Mark is holding the car at the point of maximum grip through all of those corners.
HTH
BertBert said:
parapaul said:
Interesting that the system of car control translates so literally to track driving, too.
Interesting observation, which part of the system of car control are you thinking of? And which system of car control?Bert
RobM77 said:
The way to get the most out of a car on a race track is to exchange brakes for steering on turn-in, then hold the balance with a steady throttle before then exchanging steering for throttle on the way out..
And I was referring to the Roadcraft system - I wasn't aware there were others.Gassing Station | Advanced Driving | Top of Page | What's New | My Stuff