If you tune in to a Formula 1 race, you will probably hear the drivers complain about “dirty air” but what exactly is it and why is it such a problem for teams to mitigate and manage across an F1 Grand Prix race distance?
Dirty air, often called wake too, is a phenomenon that occurs when an F1 car is too close to another car and as a result of that, sees a reduction in air flow to its aerodynamic components. As a consequence, it becomes harder to follow through corners and to maintain competitive lap-times due to a loss of downforce.
Additionally, it causes greater tyre wear as a lack of “free” air means that tyres cannot cool themselves down as much, often forcing F1 drivers to give up lap-time in order to manage the situation by backing off to create space for more free air.
The trade off to a lack of air resistance is that a car becomes quicker in a straight-line whilst chasing, however, the slip-stream is sometimes not enough to replace the time lost around an F1 circuit due to dirty air so a faster car or driver cannot always take advantage.
Dirty air is exacerbated on narrow tracks or street tracks, where there isn’t the space to make a confident overtake meaning that if a driver positions their car to the middle of the road then a move is essentially not going to happen.
This is what Lewis Hamilton found out at the 2021 Hungarian Grand Prix when he tried to repeatedly pass Fernando Alonso on fresher tyres. The faster Mercedes ran out of straights to make an overtake whilst the dirty air/wake and narrow track was enough to ensure he couldn’t use the tyre advantage elsewhere.
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Max Verstappen also encountered the issue at the 2024 Hungarian GP, under the same circumstances, as he found himself forced into two errors whilst trying to pass Hamilton, who managed to hold onto the podium.
How do the ground effect rules fight dirty air?
At the end of 2021, F1 and the FIA threw out the modern concept of generating aerodynamic downforce using the surface of the car and instead reintroduced ground effect, a popular concept from the 1980s.
Ground effect works by directing airflow underneath the car through venturi tunnels to suck the car to the floor instead of pushing the car to the track, whilst the FIA ensured the upper chassis shifted to a simplified concept to reduce wake by re-designed front-wings and the abandonment of bargeboards.
Additionally, a new diffuser and rear assembly structure pushed air flow up above the cars, towards the sky, aiming to minimise the disturbance to chasing cars and ensure closer racing through the corners.
The aim was to reduce development spending as well as take away the reliance on DRS to make an overtake. It also aimed to ensure the tyres would not overheat as easily as previous years to let drivers push harder and for longer whilst trying to race.
