Graining

When tyre grip is insufficient, and the driver does not decrease the pace accordingly, the tyre will slide sideways towards the outside of the corner This produces these small lumps towards the inside of the corner that harm the tyre-road friction.

Blistering

A too high inflation pressure or heating up the tyre too quickly both produce an overheating of the zone right below the tyre surface Air bubbles appear below the surface, making it detach, creating craters. The contact area reduces and gets uneven, harming grip!

So, graining is mainly caused by aggressive driving with cold tyres (e.g. when doing an undercut), while blistering can be due to an inappropriate inflation pressure or heat-up procedure. Pirelli mitigated blistering by reducing the thread width, making its temperature more even.

And that’s it! Did you enjoy the explanation? Let me know in the comments!

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What is ‘Dirty Downforce’?

How is it related to aerodynamic efficiency and car performance?

I explain it in this thread using real examples! Read on!

F1 cars, when moving through the air, produce both drag (the aero resistance force, which slows the car down) and downforce (that pushes the car down, increasing grip.

Downforce is desired; drag, of course, is not.

Both forces grow with the square of speed: if the speed doubles, the forces quadruples.

Each one is linked to speed through a coefficient: the drag coefficient Cd and the downforce coefficient Cl. Ideally, we want low Cd and high Cl! Their ratio e=Cl/Cd is called ‘aero efficiency’.

Engineers can get more downforce at the expense of higher drag.

You can achieve so in different ways, like increasing the angle of attack of the wings.

Doing so, the ‘car’ will move over the blue line, towards the upper-right corner.

The slope of the black straight line, that passes through the origin and is tangent to the blue line, is the maximum efficiency the car can achieve!

Notice that, initially, you’re gaining downforce (Cl grows) with minimum increase in drag (Cd grows minimally).

The more downforce you require, though, the more additional drag you get… until the gained downforce is not worth it anymore! (All low-hanging fruits were taken!)

However, in tracks like Monaco, the teams try to extract all the downforce they can anyway!

The very short straight makes the added drag not much impactful.

You will notice many crazy solutions, like this ‘nosecone wing’ of Verstappen’s (father) Arrows!

Other examples:

‘86 Jordan extra wing

‘97 Tyrrell crazy ‘X-Wings’

‘01 Jordan nosecone wing

For a wing, the increase in drag coefficient Cd is proportional to the SQUARE of the lift coefficient Cl.

So the efficiency e=Cl/Cd decreases rapidly over medium lift coefficient values… but in Monaco it might be worth it for achieving ultimate downforce!

And that’s it! 👍

Did you enjoy the explanation?

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How does the 'Inerter' (J-Damper) work?

FIA banned the 'Inerter' (also called 'J-Damper') in 2022... but WHAT is that? And HOW does it work? 🤔

I will give you the answers in this thread... and explain how it could have mitigated porpoising!

Read on, and get ready to learn! 👇

Car suspensions have two components:

- Spring: applies a force proportional to its deflection➡️'Transfers' the energy of the bump to the car body.
- Damper: force proportional to HOW QUICKLY it deflects➡️Dissipates such energy.

F1 cars also had the Inerter... but what is it for?

The inerter applies a force proportional to the acceleration between its two extremities.

So:
- Suspension Deflection➡️Spring Force
- Deflection Speed➡️Damper Force
- Deflection Acceleration➡️Inerter Force

Invented in 2002 by a professor, F1 teams quickly adapted it to their needs!

A scheme:
When the suspension extends or compresses, the right ring moves relatively to the left ring ↔️

Due to the thread profile, this produces a rotation of the inertial body (in🟥red).

This produces an inertial force proportional to the acceleration between the two rings.

How is this useful?

For any oscillation:
Acceleration: - Deflection*Frequency^2

1) The higher the frequency, the higher the acceleration vs the deflection.
2) The acceleration has OPPOSITE sign compared to the deflection.

So the Inerter 'contrasts' the spring at high frequencies!

So, the Inerter effectively makes the suspension softer at higher frequencies!

This is the 'holy grail':
- Engineers can use a stiffer suspension➡️More stable aero, more responsive car ✅
- At higher frequency (kerbs/bumps), the suspension softens ➡️Less bouncing on unevenness! ✅

A practical example:

Vertical axis: tyre load oscillation (bad!)
Horizontal: frequency.

First, the engineer stiffens the suspension to improve the aero (solid to dashed line)➡️Problem: the peak increases.

Then, they employ the inerter (bold line)➡️The peak reduces significantly!