Mechanical and aero grip

[Bill_Kar]

Thing is here, I'm no expert with this field of study, so mistakes should be forgiven.

My way of thinking is.The overall grip of the car is actually mechanical grip and aero grip.
Mechanical grip is produced by elements like dampers or suspension.Basically, the chassis of the car.
Whereas aero grip derives from the rear and front wing and generally components that create downforce or reduce drag.

So, to say a track demands more mechanical grip, factors are:
-Slow corners - When speed comes down, mechanical grip increases
-Vibration zones - This is actually when suspension comes in handy along with rough kerbs
-Street circuits - Well it could have an impact on increasing mechanical grip just by the surface alone being override by cars all year, but almost every street circuit has slow corners and massively bumping zones
-Long straights - That could be disputable, but as I see it, better handling inside the corner would give better speed and traction when you come out of the corner.Plus, when you have better traction, you can run less wing in order to achieve better straight speed.
Of course straight speed can be compromised easily by the engine power, but other things equal.

Basically, the opposite would apply for aero grip.
Having these in mind, we could say that

Mechanical Circuits
-Monaco,Canada,Azerbaijan,Hungary,Singapore

Slightly mechanical
-Australia,Bahrain,Austria,Malaysia,Mexico,Brazil

Aerodynamic Circuits
-UK,Belgium,Italy,Japan

Slightly Aero
-China,Spain,USA,Russia,Brazil

If we accept the above, would it be safe to say that Mercedes has slightly better aerodynamics whereas Red Bull has slightly better mechanical grip in the hybrid era?
As I said, my field of study is no relative to this.So it could be all shabby.I won't misunderstand someone going ape all over me

[mertol]

COTA and Monza are more on the mechanical side. Russia too probably. Hungary is more on the aero side and Spain is heavily on the aero side.

[PlatinumZealot]

In my view there is no such thing as aero-grip. All grip is mechanical IMO. The aero just pushes the tyre down harder. Just a matter of whose suspension works better with whatever tyre and down-force, yaw, speed combination.

[Tim.Wright]

While the tyre grip mechanism is 'mechanical', you can break it down into the component coming from 'aerodynamics' and 'everything-else':

GripForce = FrictionCoeff x (Downforce + mass x gravity)

Downforce = aerodynamic grip
FrictionCoeff = mechanical grip

FrictionCoeff is the radius of your friction circle which is a product of tyre grip, suspension K&C & vehicle mass. The better your suspension - the bigger this number will be.

Downforce is your negative lift - 0.5 rho Cz Ax Vel^2

Note that 'aerodynamic grip' is effectively a multiplier of the 'mechanical grip'. Meaning that if you increase 'mechanical grip' you improve everywhere (high speed and low speed).

[Bill_Kar]

While the tyre grip mechanism is 'mechanical', you can break it down into the component coming from 'aerodynamics' and 'everything-else':

GripForce = FrictionCoeff x (Downforce + mass x gravity)

Downforce = aerodynamic grip
FrictionCoeff = mechanical grip

FrictionCoeff is the radius of your friction circle which is a product of tyre grip, suspension K&C & vehicle mass. The better your suspension - the bigger this number will be.

Downforce is your negative lift - 0.5 rho Cz Ax Vel^2

I Think I've misjudged something.FrictionCoeff (μ) doesn't depend on surface alone?

Note that 'aerodynamic grip' is effectively a multiplier of the 'mechanical grip'. Meaning that if you increase 'mechanical grip' you improve everywhere (high speed and low speed).

Tyre grip doesn't recognise the component that's coming from but having greater aero efficiency is a real thing.You do get better traction in high-speed corners.Of course it's still traction,meaning that it comes down at the tyres, but I don't get how increasing mechanical grip can lead to better high-speed grip.Can you explain that bit?

[mertol]

Because you multiply the friction coefficient and the load on the tire. And downforce is just more load on the tire.

[probenprinz]

The friction coefficient is tire limited, with best setup of suspension all you can get at max is the best coefficient allowed by tires, so over a level you have to work on the weight of the car, better with downforce...

[Tim.Wright]

The FrictionCoeff above isn't the tyre friction coefficient but the effective coefficient of the complete vehicle. Its the measure of how much horizontal grip the car can provide for a given vertical load.

This takes into account the fact that the max coefficient of friction of a tyre isn't fixed. It depends on vertical load, inclination angle and temperature and all of these depend on the suspension & chassis.

[PlatinumZealot]

That side force doesn't have to be aerodynamic it can be anything. Even a quick change of steering input. It is said the shark-fins impart a side load on the car. The tyres still don't care where this force comes from.The suspension itself, I doubt it cares either. The suspension is designed with these aerodynamic loads in mind, but I don't see an aerodynamic factor anywhere on the suspension unless you are going to put wings on the suspension arm lol

[Tim.Wright]

Tyre grip doesn't recognise the component that's coming from but having greater aero efficiency is a real thing.You do get better traction in high-speed corners.Of course it's still traction,meaning that it comes down at the tyres, but I don't get how increasing mechanical grip can lead to better high-speed grip.Can you explain that bit?

Aerodynamics act as a multiplier on the base mechanical grip. If you have a lot of base mechanical grip (i.e. a high FrictionCoeff) then every point of downforce with give you more grip than a car with less mechanical grip.

If you take the original equation and break it into the aero and mechanical components:
GripForce = FrictionCoeff x Downforce (aerodynamic) + FrictionCoeff x mass x gravity (mechanical)

You can see that the aerodynamic part has still got the vehicle's base friction coefficient in it.

[Bill_Kar]

Tyre grip doesn't recognise the component that's coming from but having greater aero efficiency is a real thing.You do get better traction in high-speed corners.Of course it's still traction,meaning that it comes down at the tyres, but I don't get how increasing mechanical grip can lead to better high-speed grip.Can you explain that bit?

Aerodynamics act as a multiplier on the base mechanical grip. If you have a lot of base mechanical grip (i.e. a high FrictionCoeff) then every point of downforce with give you more grip than a car with less mechanical grip.

If you take the original equation and break it into the aero and mechanical components:
GripForce = FrictionCoeff x Downforce (aerodynamic) + FrictionCoeff x mass x gravity (mechanical)

You can see that the aerodynamic part has still got the vehicle's base friction coefficient in it.

Not that I don't believe you, just for my own purposes.Can you help me with finding out more about this friction coefficient?Because all that google gives me is μ (the tyre friction)

[Greg Locock]

A reasonable explanation is given in Peter Wrights Formula 1 Technology book. Basically you are looking at the vgg diagram, which shows how the acceleration in each direction varies as a function of velocity. Obviously if you divide acceleration by 1g you get mu for the vehicle, which is a sort of weighted sum of the mu of each tire, which despite what they told you at high school varies significantly with vertical load (https://en.wikipedia.org/wiki/Lie-to-children).

here's an example that ignores aero and gears but at least has some real data

http://www.temporal.com.au/ggdiag.htm

Although his disdain for trail braking will lose him races.

[Tim.Wright]

Not that I don't believe you, just for my own purposes.Can you help me with finding out more about this friction coefficient?Because all that google gives me is μ (the tyre friction)

As Greg said it's bacially the combination of the 4 friction circles of the tyres into one complete one for the full vehicle. I believe it was covered quite in depth in Milliken (Race Car Vehicle Dynamics). A G-G diagram (expressed in units of 'g') is basically your friction circle.

In terms of terminology it is a bit confusing to refer to a full vehicle friction coefficient (mu) because it's not a simple interaction between two surfaces but there isn't any better words to describe this effect.