Race Car Vehicle Dynamics book question !

[firasf1dream]

hello everyone,
I hope you all having a good day,
well I am reading in the book Race Car Vehicle Dynamics. I know that this book is a classic and a reference for universities for automotive related majors, but while reading i see that this book unfortunately is inconsistent ! why ? because it talks about subjects that we don't know about yet until later in the book ! let me give an example: in the chapter 2 entitled Tire Behavior which is let's say the first chapter, the author mentions Castor angle without explaining what it is ! I personally know what it is but what if someone with engineering background but totally new to vehicle dynamics would do ?!! It even explains simple things in a way that would not be understood ! it makes simple things complicated without a reason !

So my question is please help me out here with some advice on how to read this book ? for example do I have to read some other chapter before even if the chapter comes later in the order ?

Thank you everyone in advance

[WilO]

I think it's important to note that this book was never intended to be used as a textbook for a university course; the authors state that it was written as a reference for engineers and enthusiasts alike.
Note as well that some of the chapters are the result of papers that have been edited and combined so as to form a complete chapter, and still others were authored by people other than the Millikens.

It began to be used as a course text (which implies that students have the benefit of an instructor to guide the student through the book), which prompted the authors to write a companion book "Problems, Answers, and Experiments". I highly recommend you purchase a copy as this is an excellent way to test your understanding of the material. The latter part of this book also contains sample course outlines from a couple of different professors, it will give you an idea of how they approach it.

[firasf1dream]

I think it's important to note that this book was never intended to be used as a textbook for a university course; the authors state that it was written as a reference for engineers and enthusiasts alike.
Note as well that some of the chapters are the result of papers that have been edited and combined so as to form a complete chapter, and still others were authored by people other than the Millikens.

It began to be used as a course text (which implies that students have the benefit of an instructor to guide the student through the book), which prompted the authors to write a companion book "Problems, Answers, and Experiments". I highly recommend you purchase a copy as this is an excellent way to test your understanding of the material. The latter part of this book also contains sample course outlines from a couple of different professors, it will give you an idea of how they approach it.

Thank you WilO for the reply, ok so for someone who needs to learn this book is not suitable ? can you suggest please a book that can be studied like a university course please ? something useful on vehicle dynamics

[Tim.Wright]

The part where they talk about the caster is not really related to the vehicle dynamics. It's more of a side note.

I found that the book works fine when read in sequence. I always recommend people to read chapters 1, 2 and 5 in order to understand the fundamentals of vehicle dynamics.

You do need to have a reasonably solid grounding in statics, dynamics and mathematics to understand everything though.

[Tim.Wright]

Another good book is The Science of Vehicle Dynamics by M. Guiggiani.

[firasf1dream]

The part where they talk about the caster is not really related to the vehicle dynamics. It's more of a side note.

I found that the book works fine when read in sequence. I always recommend people to read chapters 1, 2 and 5 in order to understand the fundamentals of vehicle dynamics.

You do need to have a reasonably solid grounding in statics, dynamics and mathematics to understand everything though.

Thank you Tim Wright,
what happened is that to understand the slip angle theory with the book i had to watch some videos on youtube and read other sources
I am a postgraduate mechanical engineer but unfortunately we did never even got close to a vehicle or automotive subject
so what would you suggest me to do ? i need to understand the vehicle dynamics

[Tim.Wright]

Everything in Milliken should be understandable with about a 2nd or 3rd year mechanics knowledge.

Slip angle is just the angle between the direction the car is going and the direction it is facing. What's difficult to understand??

[firasf1dream]

Everything in Milliken should be understandable with about a 2nd or 3rd year mechanics knowledge.

Slip angle is just the angle between the direction the car is going and the direction it is facing. What's difficult to understand??

what is difficult to understand is the way it is explained in the book, that is what i meant, and it doesn't say the car, it talks about the wheel and tire
in the book it's not clear i had to make lots of other online research to understand it, what i understood FIRST is that the side force is the force applied by the steering column on the joints of the upright, but THEN I understood by watching some videos that when you turn let's say to the left, there is a side force acting on the outer wheel on the contact patch or contact print pushing the wheel to the right due to centrifugal force, so the tire because it is elastic it has material in contact with the road sticking to the ground, so that deformation will have like let's say vectors on the contact patch pointing parallel to the car direction due to weight distribution to the front, but in fact the wheel is pointing towards the left

[WilO]

I had composed a reply much earlier today, but when I hit 'submit', it simply disappeared. I guess someone at F1T knew the value of my contribution...
I never wanted to imply that RCVD wasn't a good book to learn from, I just think it's necessary to recognize its original intent and use it accordingly. I still think that the "Problems, Answers, and Experiments" companion to RCVD is worth its weight in gold, but that's just me.
As you've found fira, RCVD requires some 'reading around' and consulting other texts/resources, and that is not necessarily a condemnation of the book, you'll likely find this to be the case with other vehicle dynamics texts (Tire and Vehicle Dynamics , Pacejka, comes to mind). It all depends on your background knowledge and experience level, no big deal. Imagine if you had to author such a text: what level of experience, knowledge, and background do you assume of your reader? Not such an easy task.
I will give you just a tiny piece of advice, and I truly hope that you find it helpful, as that is how I intend it: Ask yourself good questions. If RCVD is telling you what's happening at the contact patch of one tire/wheel, ask yourself what this means if the same thing is happening at all four contact patches, or maybe only the front axle, and what this means for the entire vehicle considered as a rigid body. Then ask yourself 'is this true during steady state and transient motion'? About what point is the vehicle rotating when the driver first turns the wheel, and what are the forces in the contact patch? What is the vehicle response when this happens on ice?' You get the idea. And believe me, no one on the planet has spent more time trying to understand this stuff, and made more mistakes and taken more wrong turns, then me, and I'm STILL working on developing what I would call a solid understanding of the basics......

[firasf1dream]

I had composed a reply much earlier today, but when I hit 'submit', it simply disappeared. I guess someone at F1T knew the value of my contribution...
I never wanted to imply that RCVD wasn't a good book to learn from, I just think it's necessary to recognize its original intent and use it accordingly. I still think that the "Problems, Answers, and Experiments" companion to RCVD is worth its weight in gold, but that's just me.
As you've found fira, RCVD requires some 'reading around' and consulting other texts/resources, and that is not necessarily a condemnation of the book, you'll likely find this to be the case with other vehicle dynamics texts (Tire and Vehicle Dynamics , Pacejka, comes to mind). It all depends on your background knowledge and experience level, no big deal. Imagine if you had to author such a text: what level of experience, knowledge, and background do you assume of your reader? Not such an easy task.
I will give you just a tiny piece of advice, and I truly hope that you find it helpful, as that is how I intend it: Ask yourself good questions. If RCVD is telling you what's happening at the contact patch of one tire/wheel, ask yourself what this means if the same thing is happening at all four contact patches, or maybe only the front axle, and what this means for the entire vehicle considered as a rigid body. Then ask yourself 'is this true during steady state and transient motion'? About what point is the vehicle rotating when the driver first turns the wheel, and what are the forces in the contact patch? What is the vehicle response when this happens on ice?' You get the idea. And believe me, no one on the planet has spent more time trying to understand this stuff, and made more mistakes and taken more wrong turns, then me, and I'm STILL working on developing what I would call a solid understanding of the basics......

thank you WilO,
yes you are totally right, i see that some chapters are a little bit better easier in terms of for whom they are for
About the car and what you said, well i see that the wheel goes understeer in the direction of the car nose, i would say in the direction of the vector of tangential acceleration maybe but because there is traction between the rubber and the road that would prevent it
On ice the car will slide straight because no traction

So WilO if you don't mind me asking please, are you a certifide engineer, if yes what field you studied ?

[Tim.Wright]

Everything in Milliken should be understandable with about a 2nd or 3rd year mechanics knowledge.

Slip angle is just the angle between the direction the car is going and the direction it is facing. What's difficult to understand??

what is difficult to understand is the way it is explained in the book, that is what i meant, and it doesn't say the car, it talks about the wheel and tire
in the book it's not clear i had to make lots of other online research to understand it, what i understood FIRST is that the side force is the force applied by the steering column on the joints of the upright, but THEN I understood by watching some videos that when you turn let's say to the left, there is a side force acting on the outer wheel on the contact patch or contact print pushing the wheel to the right due to centrifugal force, so the tire because it is elastic it has material in contact with the road sticking to the ground, so that deformation will have like let's say vectors on the contact patch pointing parallel to the car direction due to weight distribution to the front, but in fact the wheel is pointing towards the left

I don't know where you read about the steering column creating forces in the upright because that's not in milliken. Figure 5.2 shows clearly the slip angle at the vehicle CG. Everything after that shows how this slip angle is related to the tyre slip angles, the steering angle and the vehicle trajectory.

LikeI said, everything you need is in Chapter 2 and 5. All layed out in a logical order. You dont need to know anything other than the laws of physics to understand it.

It's not child's play though. I remember having to read each page 2-3 times when I was a student to understand everything. This isn't the book's fault though. It's not a simple subject if you want to learn it properly.

If you keep cutting corners by watching youtube videos and reading blogs (particularly motorsport ones) you are going to learn everything wrong. You have the bible - you just need to read it until you understamd everything.

[WilO]

No, I'm not a certified engineer, unfortunately, I'm just a guy that has had an interest in the topic for a long time. I really enjoy studying it, and it has furthered my understanding of kinematics, statics, dynamics, control theory, but I'll never stop learning.
So it seems that you have a really strong foundation from which to study vehicle dynamics, and I think you have the right idea regarding what happens when the driver turns the steering wheel. My point with steering on ice was to have you think about which way the contact patch pushes on the road surface, and how the road surface pushes back on the tire.
I enjoy studying the transient stuff, such as where the IC of rotation is located, and how this affects the development of rear slip angle, and how the driver might respond.....

I think Guggiani's book that Tim recommended is really good, as the kinematics of a cornering vehicle are covered in ways that I haven't seen in other texts, using topics from the analysis of four-bar linkages/curvilinear motion (inflection circle, centrodes, velocity and acceleration centers, etc.).

[WilO]

"It's not child's play though. I remember having to read each page 2-3 times when I was a student to understand everything. This isn't the book's fault though. It's not a simple subject if you want to learn it properly.

If you keep cutting corners by watching youtube videos and reading blogs (particularly motorsport ones) you are going to learn everything wrong. You have the bible - you just need to read it until you understand everything."

THIS. Best advice ever. To anyone trying to really understand the topic, print Tim's post out and tape it to your bathroom mirror, read it every day. I find this to be true with most everything Tim writes on this forum.

[firasf1dream]

I don't know where you read about the steering column creating forces in the upright because that's not in milliken. Figure 5.2 shows clearly the slip angle at the vehicle CG. Everything after that shows how this slip angle is related to the tyre slip angles, the steering angle and the vehicle trajectory.

No what i said about the column (I meant the rack but forgot the name) was that first i understood that (which i found later that it is wrong), the miliken doesn't say but i did not get what Side Force mean, but i think now i assume a side force can be a force acting on the vehicle side and it can push the vehicle away without even steering the wheels. I did not reach chapter 5 yet, i am at chapter 2 : Tire Behavior.

LikeI said, everything you need is in Chapter 2 and 5. All layed out in a logical order. You dont need to know anything other than the laws of physics to understand it.

It's not child's play though. I remember having to read each page 2-3 times when I was a student to understand everything. This isn't the book's fault though. It's not a simple subject if you want to learn it properly.

If you keep cutting corners by watching youtube videos and reading blogs (particularly motorsport ones) you are going to learn everything wrong. You have the bible - you just need to read it until you understamd everything.

Well, it's gonna sound funny, but when i printed the book from the PDF I have things became a little bit easier to read because i have the pages in front of me, I can write definitions on it and I can go back easily to pictures and graphs and don't have eyes pain from reading on the laptop. lol


Yes that's what I am doing now and thank you for saying this "I remember having to read each page 2-3 times when I was a student to understand everything" because (and you might laugh) I am the kind of person, unfortunately, that needs someone to say "yes you are doing the right thing" to make good results :/

[firasf1dream]

No, I'm not a certified engineer, unfortunately, I'm just a guy that has had an interest in the topic for a long time. I really enjoy studying it, and it has furthered my understanding of kinematics, statics, dynamics, control theory, but I'll never stop learning.
So it seems that you have a really strong foundation from which to study vehicle dynamics, and I think you have the right idea regarding what happens when the driver turns the steering wheel. My point with steering on ice was to have you think about which way the contact patch pushes on the road surface, and how the road surface pushes back on the tire.
I enjoy studying the transient stuff, such as where the IC of rotation is located, and how this affects the development of rear slip angle, and how the driver might respond.....

Well it's gonna sound funny but i did my engineering thesis on formula 1 design and while designing the upright i took into consideration the caster, kingpin etc but i did not included this part just composites cockpit and basic dynamic study and force applied on the chassis.
I actually had a course called Solid Dynamics ( translated from French "Dynamique des solides") which talks about the dynamic basics of solid objects like IC and all those things.
By the way, how do you manage to keep what you learn in your head ? because for me i forget a lot so everytime i have to check the notion i learned again and again