Why Mercedes-AMG has fallen from the top of Formula 1

Red Bull leads Mercedes in Australia, a common sight in 2022

Three races in and the previously all-conquering German team is struggling. Don't expect a rapid fix

Were Formula 1 to award a word of the year, the winner in 2022 would be 'porpoising', a phenomenon responsible for the eight-year domination of F1 by Mercedes-AMG coming to a juddering halt.

The repeated bouncing motion of a porpoising F1 car is familiar to anyone who has worked on race cars with powerful ground-effect underfloor venturi tunnels. The name comes from the aquatic mammal’s reputation for skipping in and out of the surface of the water as it travels, a movement echoed by the oscillation of the rise and fall of a car.

This is the result of the downforce increasing rapidly as speed rises and the growing low pressure beneath the floor sucking the car closer to the ground. The underfloor aero then stalls, either because of airflow separation at speed or the floor striking the track surface hard. It can even be set off by hitting bumps. The car then rises, because the downforce is briefly reduced, then is sucked down again as the underfloor works as intended again. The cycle then repeats, hence the bouncing motion.

All of this new breed of F1 cars suffer from porpoising to a greater or lesser extent. But porpoising on the straight isn't necessarily a problem, provided that it's controlled and not so savage that it damages the car or driver. It’s a question of how quickly the porpoising stops when you reach a corner and what compromises you make to the set-up to control the phenomenon.

The dynamics of a car at corner entry are everything, doubly so on one whose performance is dominated by aerodynamics. This requires a compliant, consistent mechanical platform and an aero-balance shift as you enter the turn that's both controllable and reliable. A bouncing car is unpredictable.

“You can’t really stop it; the only thing you do is come off the gas and just drive slower,” said seven-time champion Sir Lewis Hamilton. “But when the car’s going up and down, it’s bouncing, and if you’re turning in at 200mph and the car is loaded and unloaded, you can imagine it can be quite unstable.”

Hamilton was talking about the behaviour of the car into the high-speed left-right turns nine and 10 in Australia, which followed the long, flat-out blast where porpoising was manifesting itself most clearly.

The Ferrari was actually porpoising more vigorously there than the Mercedes, but Charles Leclerc was able to qualify on pole position and win. That’s because Ferrari had to make far smaller set-up sacrifices and the effect it carried into turn nine was much reduced – although it could be felt. By contrast, the Mercedes drivers visibly have to be more conservative into fast corners to let the car at least partially settle.

Mercedes has to make far bigger compromises to its set-up in terms of ride height. This means sacrificing downforce – and hence lap time – all around the lap, because its porpoising problem triggers at a lower speed than the Ferrari. It also comes at the cost of increased drag. That’s why its strongest circuit so far this season was Bahrain, with its largely lower-speed corners that allowed the Mercedes to run a little lower than in Saudi Arabia or Australia.

So why is it so difficult to prevent porpoising? Well, it isn’t, but it costs performance. And that’s the problem: you can raise the ride height to mitigate the porpoising, as it reduces the effectiveness of the aerodynamic ‘seal’ and therefore the overall level of downforce of the car by effectively ‘venting’ low pressure – particularly at the point where that grows rapidly as the floor gets close to the ground. And downforce is performance, with the grip it produces dwarfing what is achievable mechanically.

Simulating porpoising is difficult, because you can’t run the car too low to the rolling belt in the windtunnel or it will damage it. And as effective as CFD is, the complexity of its calculations multiplies alarmingly and breaks down when simulating objects very close to the ground. The data that Mercedes has gathered has helped it build better models, but it’s only by running the car that it can explore the problem and its potential solutions fully.

The combination of F1’s cost cap, set at a baseline level of $140 million (£107m) in 2022 and the lack of testing means Mercedes neither has the cash for endless trial-and-error fixes nor the track time.

The solution likely lies in a combination of modifying the aero in terms of floor design and potentially even the floor structure. This is because the flexing of the floor can exacerbate the problem. F1’s new regulations have also simplified suspension systems, eliminating inerters and hydraulic assistance that would have made controlling the porpoising easier.

So fixing it is going to take time, with team principal Toto Wolff repeating his mantra that there’s “no magic bullet” at every opportunity and driver George Russell stressing there will only be “incremental” changes to the car in the immediate future.

Mercedes might be managing expectations with a solution close to being found, but the team has become markedly less bullish about fixing its problems as time has passed. And its leading rivals are privately confident that it's going to take a while for Mercedes to solve its problems.

Therefore, even though F1 is only heading into its fourth race out of 23 at Imola this weekend, it’s difficult to see Mercedes re-emerging as a championship threat this year, even though it has been a clear third best of the 10 teams in each grand prix.

Don’t bet against it becoming a front-running force again later in the season. But by then, it might only be fighting for face-saving wins and making a nuisance of itself in a Ferrari-versus-Red Bull title fight.

Edd Straw