By Carlo Platella
So far the ground effect regulations have been stingy for Mercedes, but the Brackley team has never stopped grabbing attention. After the very innovative and unfortunate narrow-bellied bodywork of 2022, the Silver Arrow of 2024 enlivens the discussions with its front wing, the result of a clever interpretation of the regulation. The main technical point of the W15, however, is its rear suspension, which sports a decidedly aggressive strut pattern, also re-proposing a solution already seen during the golden era of the British team.
The debate on suspensions
Since the debut of the 2022 ground effect regulations, suspension geometries have taken center stage. The arrangement of the external elements, in fact, has a double aerodynamic influence. On the one hand, the geometries of the suspension are fundamental for stabilizing the posture of the floor during travel, putting it in a position to work at its best. At the same time, the configuration of the arms influences the flow pattern, especially at the rear where both the air conveyed by the chute bellies and that coming from the lower part of the sides arrives.
The suspension design therefore takes aerodynamics into high consideration, while balancing the advantages with the compromises in terms of kinematics and mechanical behaviour, which affect the use of the tires and agility in slow speeds. Currently the grille is divided into the configuration chosen for the rear group, with the pull-rod maintained only by Ferrari, Haas and Williams. Mercedes, on the other hand, is among the teams that have recently converted to the strut scheme.
The push-rod rod, hooking into the upper part of the gearbox, frees up space in the lower area, favoring the circulation of the flows collected at the bottom by the bodywork. The effectiveness of the compromise between aerodynamics and mechanics, however, does not lie solely in the inclination of the rod, but also in the arrangement of all the surrounding arms. It is the latter aspect in which the new Mercedes stands out from the competition.
The rear of the W15
In 2024 Mercedes switches to the push-rod scheme, moving away from the pull-rod used until 2023, in which the rod reached the spring-shock absorber group in the lower part of the gearbox. However, the strut geometry of the W15 is different from that of its rivals, Red Bull above all. The auction, in fact, presents an almost horizontal inclination, not the best for the transmission of vertical forces between the wheel and the rest of the car. However, the Mercedes push-rod also appears less forward-oriented than the Red Bull strut. All this suggests a different arrangement of the spring-shock absorber group both in comparison with rivals and with the 2023 W14, which required a complete redesign of the transmission case to free up the necessary space.
But the news doesn't end here. In the lower part, Mercedes has separated the front arm from the semi-axle assembly, the latter set back compared to 2023, also a sign of a shift in the differential at the gearbox exit. However, the focus is entirely on the rear arm, moved as far back as possible to better condition the flows towards the beam-wing and the diffuser. This is the most advanced geometry ever in this direction, which recalls the solution present on the Mercedes W11 and W12 of 2020 and 2021, when the rear arm did not attach to the gearbox, but to the impact structure behind it.
Rear under observation
When setting up the W15, Mercedes paid great attention to giving Russell and Hamilton a more benign rear end. “Great care has gone into improve the unpredictability of the rear axle of the previous machine”, technical director Allison's explanation. “We have worked hard to ensure that both axles, but in particular the rear one, can enjoy better tire control than on the W14.” Mercedes is not the only car to fit the new suspension, also purchased by an Aston Martin customer. The other Williams customer, however, preferred to continue with the old pull-rod scheme, mainly with a view to saving costs.
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