Physics Philosophy 101

You misunderstood what I stated. I was implying that excessive understeer is a good teacher if you want to take corners at the correct speed. I see a lot of people (and I am sure that I do this myself more than I would like) trying to take corners far too fast, with obvious results. They try to force the car to make the turn. What works is to slow down enough so that the car can turn through the corner properly, and therefore not feel like it is understeering.

 

Maybe it makes sense to me right now. I'm thinking about Renault curve (Catalunya) for some reason. It is always like that, you enter with too much understeer, then gradually slowdown till car actually rotates, it is fun when sometimes it goes from understeer to oversteer there.

 

Good thing there is such a low amount because in few minutes I heard a lot of crap. If dudes in their "seminars" can spread that kind of stuff no wonder some people's post in forums are so wrong.

 

I find when I roll around a corner is faster then sliding, over or understeer.

 

Care to elaborate?

 

I don't know where the notion of me being this MrDeap guy came from, but okay. I'm surprised people who are not personal friends of mine still remember my name. I guess it's one way to flatter.


MrDeap seems to think that slip angles for the tires are closely linked to each other. He also seems to be missing the point of what happens when tires slip: namely that they just produce forces away from the heading of the wheel hub.

@MrDeap why exactly do you think that front slip angle must decrease if a car rotates around it's center axis? Explain this in detail to me.


While we're at it, tell me, is it possible to slip all 4 tires evenly with the steering completely straight in the middle of the corner? What happens in this case?

Can you produce a high front slip angle with the steering centered?

How is slip angle and traction related? How about load and traction?

Think about these and give us an answer. I'm waiting for further theories.

@PhilS13

It's a bit bold to criticize some educational content without explaining your basis.

 

Because the back tire make the car rotate du to the slip angle. It change the direction of the front slip angle. That's why shorter wheel base car are more twitchy.

Yeah but for a very brief moment(less than 0.05sec) on regular corner. For very large long corner it can hold it longer, yeah it can happen.(nothing is perfect, but I suppose it's about even). The car is in motion & there's a speed change.

Corner elevation change, track positive camber, it can be done.

The more load, the more traction on the slip angle
Less load will result less traction on the slip angle

Answered, I suppose it work like that.

 

Total contact patch area is a constant. No. Quite weird non-linear relation with load in fact.

Weight going to the front is the reason why you are able get some decent over-rotation on entry. Try getting over-rotation while trailbraking with 80% brake bias. Good luck.

Seems like he feels the need to take big juicy shortcuts so that his students go "Ooooooh right". Short term "I get it now" will be causing some misunderstandings down the road. I guess it's one way to introduce people.

 

MrDeap, why exactly is that then? WHY are shorter wheelbase cars more twitchy, apart from that they are more twitchy because the slip angles change faster in relation to each other? I'm gonna give you one hint: it has something to do with rotational inertia, and a lot more to do with a lot more else.

How are better drivers able to slide all 4 tires more or less evenly for several seconds then? You're probably talking about scrubbing speed off in the mid corner, not an actual neutral slide.

What causes the high slip angle in elevation change and positive camber? Are you sure that you can't trailbrake into a corner and cause a big yawing movement and high slip angle even if your steering is centered for the entire corner from the entry onwards? If not, why?

You said that more load = more traction at a certain slip angle.

Okay, let's go with that.

However, how is the slip angle generated, then? Can you have a high slip angle with low load, and if so, how?

 

You seem to be more hardcore about physic.

For the last question. Isn't less load result less traction? How can you get high slip angle without load?

 

Ice.....

 

Maybe deflate the tires but I suppose it's an exploit.

 

I find that a lot of this theory isn't necessary to be a fast driver, heck, do Aliens look at slip angle charts all day? More often than not, this theory is (mis)interpreted in different ways yet every friend I invited over for AC trials got the hang of the drive after 2 hours or so (getting used to the wheel and lack of butt forces) and managing the lack of fear of crashing against the perpetual understeer show you get when overdriving. Understeer is indeed a very useful training tool for most rookies and a basic understanding of the traction circle is more than enough to get most people up to speed. All the rest is very nice for long discussions when people are bored but theory does not replace experience and practice which WILL be the main difference between a fast and a slow driver (alongside talent).

None of these theories will make MrDeap faster than William on NS, yet some years of practice might.

How will you apply all this slip angle theory to driving in the sim? How can you tell the difference between the feel of a lower and a higher sidewall while driving in AC? If I fire up 2 driving sessions for you with the same car on different sidewalls will you be able to tell me which is which? Will you know if you are now at 5% slip or 9%? Or will you just naturally know there is some slip, hear a low pitch squeal and know instantly you are around the limit, helped by a well set up wheel?

Many people consider they know a thing or two about tire dynamics but can be quickly proven wrong, misinformation is all around you in this age of gurus on every blog, forum website and youtube video. Many seminars are filled with loose knowledge and sketchy information delivered as fact. The Skip Barber video is around 25 years old now and tire technology has progressed a lot since then which affects how cars feel, corner, break and generally perform. They use no aero cars, which is almost inexistent in this day and age. How many cars today rely on mechanical grip only? How many AC servers rely on mechanical grip cars? Tire performance is the most talked about factor in sim racing, yet the vast majority of online racing features serious aero cars which pollute tire performance. If you were to start practicing those techniques the closest analog would be the type 25 I suppose, or the KTM to some extent, though even the KTM generates decent downforce at speed. With others cars you can no longer consider tires as THE defining factor as much because of aero. Some aspects of the video are no longer as true as they were back then even if the technique itself holds true today. Are people going to reference it as something valid in another 25 years?

Got carried away with philosophy...

 

Mistery you're pretty much spot on. I think you misinterpret my analysis on the Nordschleife.

Theory can lead to advantage, but you only need to know just enough. The major point where it make the whole difference(in my opinion) is how you interpret the radius on the corner. What bother me is when there's a massive disparity of time & the relation within my current performance... since when I'm challenging William? If I don't understand where I'm doing very wrong. I kind of push knowing what what it is & bluff around, especially where there's a massive lead on several corners. You will probably tell I don't but I think I know. If other get faster or even suddenly get much faster than I am. It make me happy.

I'm not as fast nor faster than you guys.

 

I understand what you're trying to say, but the tires will always be the cars contact with the ground regardless of aero, no?

 

Certainly are. Strange question. My musings only said all the thought put into these tires and how they work (on our part as consumers of a software) are 1) not really helping us going faster and 2) i don't want to say meaningless but somehow soiled by the addition of complicated aero on most cars.

Put it this way. Take a KTM X-Bow which has a version with serious aero recently (base one generates 200kg downforce too) and consider if the tires on the aero car as important to handling as the ones on the base model. And I am saying this in context of this thread which shows us slip graphs etc. The grip and handling characteristics of the aero car are suddenly influenced a lot more by aero at least at any decent speed and the influence or importance of tires has been diminished somewhat.
Or compare a 911R vs a 911GT3. More or less the same car except one is a track oriented big winged animal and the other is a road hooligan. Which one relies on good tires more and which one has better traction even if the tires are starting to wear.

But going back to my point one, about these theories not making a driver faster aside from understanding the basic form of the traction circle, anyone care to share how elaborate tire behaviour theories made them better drivers? OR how these are somehow better than actual time behind the steering wheel.

 

When things get too scientific usually I'm looking at my monitor like this:

 

I´m questioning your philosophy that tires matter less now, and even lesser in 25 years. So, the load changed with adding aero to cars, resulting in the need of redesigning tire compounds and how the work with increased temps etc. The tires still matters just as much, we just added to the equation. At least the way I see it.
Anyway, agree that knowledge on slip angles and so on will not make anyone faster on the fly, but the knowledge behind it can make you learn quicker and practice better. And I still know very little numbers, I just go for the obvious

cheers

 

Tyres always matter, and they're IMMENSELY better than they were even just 10 years ago. Just look at how much grip street cars manage now, even without any significant differences to similar cars from before. Aero just makes those tyres work even better, basically. As long as they can handle the load (which they easily can, street cars dont make "that" much downforce).