Thread by @FDataAnalysis

A curious #F1 tech detail - The Anti-Ackermann steering

Someone looked at the instant BEFORE the crash by ALO and noticed, "wait, was the outer wheel turning MORE than the inner?!?"

The answer is yes, and it is something peculiar to F1

Read to know why!
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When cornering, the inner tyre travels along a shorter path, being closer to the turn centre

Consequently, cars have a so-called 'Ackermann steering geometry': when turning the steering wheel, the inner tyre will turn more than the outer

This is NOT what happens in F1
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In F1, performance is the goal: an Ackermann steering minimises tyre slip, but is not ideal for performance

In fact, a tyre must slip laterally to produce a cornering force. The amount of slippage that maximises grip increases as the tyre load increases (see the graph)
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When cornering, the 'centrifugal' force moves part of the load of the inner tyre to the outer

Thus, the outer tyre must slip more than the inner tyre to maximise grip.

This is done with an 'Anti-Ackermann' steering, where the outer tyre turns more compared to Ackermann
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F1 brings this to the extreme: the level of Anti-Ackermann is so high that the outer tyre turns MORE even compared to the inner tyre!

This worsens the wear but improves the lateral grip. In circuits like Monaco, the former is not a big deal, while the latter is crucial
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How do I know about this?

I was the head of Suspension & Dynamics of my local Formula SAE team. We chose an anti-Ackermann geometry for our car too!

Not as extreme as in F1, though: the inner tyre still turned more, but less so than with an Ackermann geometry

I hope you enjoyed the thread!
This is something that often confuses people, as @NaturalParadigm highligted to me. I hope that now the concept is clearer!

Please share it to spread this knowledge further! And comment with further examples and curiosities 😃