Traction Circle - Explained

What determines a car's lateral grip? Description of tyre (tire) grip and the traction circle. How much traction does a tyre have and how much frictional force can it supply to keep the car from sliding? A car can withhold the greatest sum of forces when it equates the acceleration/braking forces with the horizontal turning forces.

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[EngineeringExplained]

Because accelerating at 1g takes a tremendous amount of power. Resistances build, friction builds, and inertia losses add up as you keep your foot down. You keep getting quicker and resistance keeps increasing, making it nearly impossible to accelerate at a constant 1g. The Veyron comes pretty close.

[tactablet]

watching this in 2020 and loved the video, please get back to doing more videos like this. absolutely loved it. great work

[PepePL]

As an engineering student who has little knowledge about cars I really like how you use physics and math to explain things. Most of the other videos on You Tube tell you that "this is going to happen when you do this", where my next question is always why. I never thought I am gonna say that but it actually makes much more sense with all those equations :) You got my sub:)

[EngineeringExplained]

Correct. Say a formula car was experiencing 1g of downforce on top of it's current weight (it's weight is effectively doubled, for frictional purposes) this means the maximum g force the car could withstand in a corner (assuming the tires are only producing 1 g of lateral grip) would be 2G. As you probably know, Formula 1 cars have seen 3-4g's regularly, so this tells you about the tire compound, as well as the downforce these vehicles are creating.

[EngineeringExplained]

Thanks for watching, glad you enjoy the videos!

[jadenjaden]

From a 3rd year engineering students perspective I think your explanation is very detailed, amazing you did a great job.. I've never seen this explained in the form you have shown here but it makes a lot more sense and it is easily understood with the drawings you have done..You explain better than my profs do haha.. Good job man

[EngineeringExplained]

@phanofmuzik I was simply explaining the basic principles behind a "perfect" turn, allowing one to go around a corner at the greatest speed. It's an explanation, not a recommendation. Hope that's clear; always good to clarify though I suppose! Thank you!

[EngineeringExplained]

It's simply because the equation F=uN doesn't take into consideration what happens at a microscopic level, where the rubber of the tire sinks into the pavement, thus your grip exceeds the theoretical grip. A wider tire allows for more tire to sink in (to a point), and thus will have slightly more grip.

[maccarioandrea]

Actually, for the forces applied it is more an elliptical model rather than a circle. The maximum lateral force that can be handled by the tire being different from the longitudinal one. Fx0 being the maximum longitudinal force the tire can handle, and Fy0 lateral. (FX/FX0)² + (FY/FY0)² = 1

[davidvenegasramirez]

Coming back to these videos brings back the golden years of YouTube 🥹👏

[akshaysankarshana]

@EngineeringExplained
Hey, Jason! As old, low budget and simple these videos might be, they helped me a lot in understanding basic concepts such as this one. Could you pls tell us a book reference to learn all this from? Would love that. Appreciate your work. Thanks.

[EngineeringExplained]

@KillerZero259 I certainly have. I want to eventually do a video on engine parameters (there's a bunch!), and cover the basic engine cycle thermal analyses. Unfortunately I'm quite busy, so I'll be sticking with easier topics until the earliest being summer.

[EngineeringExplained]

Weight + downforce, which means you can exceed a 1 g turn with proper downforce (or sticky tires).

[EngineeringExplained]

@raymondu99 Correct, the magnitude of the two forces is still 1000, but if you look at the individual components their sum is greater than if you were at any other point on the circle. Example: the very top. 1000 acceleration, 0 turning friction force, sums to 1000, magnitude is 1000.

[EngineeringExplained]

The numbers were kinda arbitrary for this example, so that it could possibly add to 1g in forces. Thanks for watching!

[EngineeringExplained]

Yep, I've heard the same; not really sure how to visualize that, but point is you don't want your car sliding, it has much more grip when it is not.

[EngineeringExplained]

It's all driver feel. They know when they're reaching the edge of adhesion (some better than others) and they attempt to keep the car there.

[EngineeringExplained]

The video is pretty accurate, although there are some assumptions made. A 3000 lb. car will have greater friction than a 1000 lb. car, so the later force it withstands is a larger force, but not larger when you compare the g's the car can withstand. Each car may hold 1 g (plus or minus). The heavier car will have some losses, however, so the lighter car will more accurately follow the friction formula.

[arsnakehert]

Just found out about this traction circle in the reference manual in a used copy of Gran Turismo 1! lol
From what I understood of it, each tire can be represented with one of those circles. Aside from that, when you accelerate or decelerate your car, the weight of the car is distributed differently to the front and rear tires, which affects the normal force on them and therefore how much friction they can withstand before sliding. But, of course, the friction is also distributed between the "task" of steering and that of braking/accelerating. So, the manual says, in order to enter a corner, you have to first brake hard before the corner so the weight of the car is shifted to the front (and so you don't enter the corner too fast), in such a way that the amount of friction the front wheels can use is increased, and then brake much more softly while steering on entering the corner. If you brake too hard, the friction will be distributed much more to braking than to steering, and you'll go straight through the corner. If you don't brake, your weight won't be shifted forward and your steering won't be as effective.

[EngineeringExplained]

@raymondu99 If you watched to the end I mentioned that they are not perfect circles.