Slip Angle

Slip Angle

In this video I introduce you to one of the top racing concepts: slip angle. Since the driver is in complete control of this angle it will help you maximize your tire’s ability to grip.

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Video Transcript

Hey everybody Matt Covert here again from howtobecomearacecardriver.com. In this video we’re going to talk about one of my favorite concepts and that is slip angle.

So let’s go ahead and hop right into that. Slip angle is important to understand because I think it is somewhere between three and five, third and fifth most important concepts in the racing world. And that is because it has everything to do with maximizing your tire’s ability to grip.

Alright? And if you’re racing in a stock class or a street category this is extremely important because there aren’t a lot of modifications that are allowed to your vehicle so you have to take advantage of every single bit of traction that your tires can get you, OK? And that’s why this is important. This is all something the driver can control. And if the driver has control over this he can maximize grip and he’s going to have an advantage over everyone else. And that’s obviously what we want.

So let’s talk about what slip angle is. Slip angle is the difference between where a tire is pointed and where it’s actually going. And I’ll explain that in a second but it’s important to understand that the difference is the angle.

So let’s look at an example. So let’s say we have a tire going down a straightaway and it’s not turning at all. It’s going in one single direction so it is going the exactly same way it is point. That tire has a zero degree slip angle. And we’re not worried about that tire.

Slip angle occurs when you go into a corner. So let’s draw on that’s kind of offset here. Oops. There we go. And let’s say it’s connected to the chassis like that, alright? Let’s say that the vehicle is trying to go into a corner this way, alright? And the tire is pointed in this direction there, oops. Let me draw that a little better. The tire is pointed in this direction, but since the car has inertia and momentum and what have you and it’s trying to change direction it’s tendency is to keep going straight, it doesn’t want to turn.

OK? And the result of that is a small difference between where the tire is pointed, let’s say this tire is pointed in this direction, but it’s actually slipping across the driving surface this way. Alright? So rather than, let’s draw the same tire down here. Rather than kind of going in this arc where the tire is pointed it’s actually going to go here so it’s actually sliding across the driving surface if that makes any sense.

The difference between where this tire is pointed and where it’s actually going to slip across the surface is, we’ll go back to this here, is the slip angle. And this is very important to understand because tire are most efficient when they are slipping across the surface at some degree. OK? There is a degree that you can go past so they are less efficient, but it’s important to understand that tires are most efficient when they are slipping and have some angle like this.

So let’s take a look at an example of how much slip angle you can possibly want. Alright? So let’s say that a tire’s optimal slip angle at a certain speed is, two four six eight ten, twelve degrees. That’s a little high but we’re going to go with that as an example OK? So let’s say, oh two four six eight ten twelve, so let’s say that a tire’s slip angle curve looks something like this. OK? Up to a point this tire has the most amount of grip, you can see here, the most amount of grip at this slip angle. We’ll just say, two four six eight, well it ends up being more like tenish.

So let’s just say that a ten degree slip angle is the optimal angle at which this tire makes grip. OK? Now if you go past that, obviously you’re going to start losing grip again. And if you don’t get up to it, then, well, you’re leaving traction on the table because you’ve only gotten up to here or something like that.

And this is very important to understand because this is all something a driver can control. If a driver is not driving a vehicle hard enough he’s going to end up in this range, maybe. And look at all that traction he left on the table. Well a better driver than him is going to get up here and he’s just going to be faster and that’s what we want to avoid. You want to be able to get into the sweet spot which is right about here. Alright? If you go past that, if you’re driving the car too hard then obviously you’re going to be outside the tire’s maximum ability to grip.

And, incidentally, when you’re up here you’re just creating huge amounts of heat because your slip angle is pretty radical. And any time you have a radical slip angle, let’s say it’s pretty crazy, it’s going all the way this way, big angle then you’re just generating a ton of heat from traction and that’s no good.

OK? So this is something that you really need to understand, I know I’ve said that a bunch of times now but this is a very very important concept.

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