MPH: Why science alone can't unlock secrets of ground effect F1 cars
F1
As F1 enters the final year of its ground effect era, teams are discovering that success now depends as much on intuition and adaptability as on traditional engineering precision, as Mark Hughes explains
The current rules cycle is coming to an end this year
In this final year of the current ground effect regulations – and probably for much of last year too – the technical game which has ruled in F1 for decades has changed. It used to be you’d find more downforce in the wind tunnel, make the parts, put them on the car and you’d go faster. Today that correlation is a little more nebulous – and that has changed the route to success. The best minds are adapting to how they approach car design and development as others are still labouring under age-old assumptions and finding ever-more stubborn non-correlations as a result.
The dynamics of airflow at the tiny ground clearances of the choke point of a ground effect floor are so volatile. They can change so much at a crucial point that even the texture of the track’s surface can completely alter how the car is working. Couple that with the contortions of suspension design required to fully exploit the floor and the wild front-rear balance changes at different speeds from a car with the choke point so far back, and the airflow does things in reality which are completely different from what correlation tools such as the tunnel and the simulator predict.
The tunnel, CFD and the simulators are not even agreeing with each other, let alone with the track. Then there’s the almost-impossible-to-model behaviour of the tyres and how they react to different car balances, tracks and temperatures. You can appreciate how it has spiralled way beyond even the most sophisticated modelling.
Teams have had to adapt to new processes to get the best out of their cars
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These waters are further muddied by the fact that there probably aren’t any further downforce gains to be made – for anyone. The laptime gains are now in how that downforce is distributed and how the aero balance transitions between different speeds and attitudes. This is where that irritatingly unpredictable non-linear performance factor – the driver – can play a crucial role. But more of that later.
Clearly, there’s imperfection in the modelling if it’s not reflected in track reality, and every team is suffering from this phenomenon to a greater or lesser extent. But the difference is occurring at such a granular level it’s impossible to even know how to improve the model. All they know is that it’s not working.
So as most have doubled down on attempting ever-more intricate modelling or ever-more intricate attempts at decoding the mystery, more agile minds have changed their approach. Andrea Stella signposted this direction at the end of ’23 and it’s probably not a coincidence that McLaren has flourished more than any other in this new age of uncertainty. They’ve done this by more comfortably accepting the discrepancies between the modelling tools and the track and tailoring developments until they more nearly agree with each tool, discarding anything which may show an improvement on one but is retrograde on another.
This can slow the pace of development down, but when new pieces eventually go onto the car they invariably work. Even if you don’t know exactly why. That has very much been the pattern of McLaren development over the last couple of years and in the process, they have steadily moved towards the front – and then improved further once they got there.
Verstappen’s driving matches what the wind tunnel says
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In this new era, you just find what works, even if you cannot know the exact reasons why. In this way the process is almost quantum-like in its characteristics, reflecting how quantum physics tells you with certainty either the position or speed of a particle – but never both simultaneously; when you isolate with certainty one of those variables, the other is only ever a probability. That’s just how reality works at a sub-atomic level. That isn’t what’s going on here, but the acceptance of uncertainty it engenders is the same.
This more freewheeling attitude to development – accepting where science can’t give you the answers and just working around the uncertainty – probably goes against every fibre in the being of most engineers. Those rare engineers with an artistic temperament – people like Stella and Adrian Newey – would probably accept this more comfortably.
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By
Mark Hughes
It was interesting hearing Newey say in Monaco last week that the driver-in-loop simulator is now a far more important development tool than the wind tunnel which he likened to an engine dyno in that it just gives you an output, not any insight.
Which brings us to the input of the driver in this whole process of uncertainty. It has made drivers far more instrumental in development directions than before. Max Verstappen is one of the few drivers who can happily drive a car in the way a wind tunnel insists is the best. Most drivers hate how such a car feels in the simulator – far too unstable – and that’s one of the key reasons these two tools frequently disagree. Even more so in the ground effect era.
To get around their inherent low-speed understeer/high-speed oversteer, set-ups generally have evolved in the simulator to a point where the driver can get the low-speed rotation so essential to a quick time. But in the real world, that rotation comes at the expense of mid-corner understeer (ie, the reverse of the original problem, with no sweet spot in between).
As the regulations have placed the cars in an ever-narrower window of balance, human intuition, both in and out of the cockpit, has assumed greater importance. Which is not a direction anyone was expecting.
