Ferrari SF-23: how new bodywork is designed to tackle rear-end inconsistency

The Spanish Grand Prix marked the introduction of Ferrari’s significant bodywork upgrade. Despite a challenging weekend for the Maranello team at the Circuit de Catalunya in Barcelona especially in terms of race pace, Carlos Sainz emphasized that the upgrade shouldn’t be solely blamed for their performance. Starting from the front row, the Spaniard faded to a fifth-place finish and shared his perspective after not being able to celebrate a podium finish in front of his home fans.

“I believe the upgrades are effective,” he explained – “but we implemented them at a circuit that doesn’t suit us well.”

This season, the Italian side has struggled with inconsistency in the rear of the single-seater, experiencing sudden instability as reported by both drivers. The latest bodywork modifications aim to fix this issue by providing enhanced and consistent aerodynamic loading to the rear of the car.

To achieve this objective, Scuderia Ferrari undertook a complete redesign of the sidepods and lower engine cover. While the sidepods maintain their wide and blunt frontal shape (in contrast to the sharply undercut designs used by other teams), the wide section’s length has been increased when viewed from above.

Furthermore, the width of the sidepods has been reduced. Although the “wide” section remains wide, it is now narrower yet longer. These changes, coupled with the introduction of a new floor, constitute the essence of the transformation.

To comprehend why the Maranello team believes these alterations will deliver the desired outcomes, it is crucial to examine how the “fat” sidepod fronts, introduced in last season’s F1-75 single-seater, operate.

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The absence of an undercut on the bluff front aids in redirecting the airflow away from the car’s surfaces, subsequently drawing it back into the rear where the sidepods gradually merge with the coke bottle area, leading toward the diffuser.

The airflow dynamics in the “coke bottle” area are crucial in determining the behavior of the car. This region, characterized by lower pressure, serves as the mechanism for redirecting the out-washed airflow from the bluff front of the sidepods back towards the car. Ideally, the airflow follows a consistent parabolic curve between these two points.

The approach used by the Ferrari, with its “out-wash and in-wash” concept, aims to induce the airflow to leave and rejoin the car’s surfaces. In contrast, the Red Bull-style undercut sidepod employs a channel carved into the narrower sidepods, guiding the airflow along the lower edges through a downward ramp at the rear of the sidepods. The merging of these flows enhances the energy as the air passes through the gap between the rear wheels and over the diffuser.

While both methods seek to maximize the speed and power of the airflow over the diffuser walls, thereby increasing the suction effect on the car’s underbody, they employ different techniques. Ferrari’s adjustments, narrowing and lengthening the “wide” section of their sidepods, suggest their belief that the intended airflow path, following the curved parabola, is experiencing detachment, causing a dissipation of energy.

Airflow separation occurs when the direction changes abruptly. By narrowing the pod, the curvature of the intended airflow curve becomes shallower. Furthermore, lengthening the wide section contributes to a further reduction in curvature, as could be seen from the images taken during the Spanish Grand Prix weekend at the Circuit de Catalunya.

If indeed the SF-23 car’s rear-end instability is rooted in airflow separation, this alteration in sidepod geometry should enhance stability by minimizing detachment and should allow the Maranello team to improve the behaviour of the car in the upcoming F1 races.