Optimising the aerodynamic design process : a parametric study of multi-element rear wings for Formula Student electric vehicles

Abstract

Aerodynamic downforce is crucial to the performance of Formula Student race cars, especially electric vehicles, as the system efficiency and performance optimisation processes are highly complex and critical. Increasing downforce, which is negative lift generated by airflow on vehicles, provides more tyre grip and eventually improves lateral acceleration. For this negative lift, the rear wing assembly is the most crucial part of the vehicle, as it generates the most downforce. Even though such a generation is essential, it also comes with a penalty: increased aerodynamic drag. The inevitable increase in drag can adversely affect both the vehicle's longitudinal performance and battery usage. Given the marginal gains in competitive environments derived from innovation, such as the Society of Automotive Engineers (SAE), a clear understanding of the balance and its optimisation from the rear-wing perspective is critical for effective engineering decision-making.

This study investigates the impact of rear-wing aerodynamic downforce on the performance of the Metropolia Motorsports FS race car for 2026 (HPF026). The study evaluates the effect of different aerodynamic configurations on the rear wing through a dual-path engineering strategy: a systematic retune of the geometric variables of secondary elements of the rear wing, and the modular integration of a pre-existing cascade element onto a baseline rear wing setup.

Specifically, the first path analyses geometric variables, such as secondary flap angles and slot gaps, optimised around a fixed mainplane, with respect to vehicle performance metrics, such as cornering capability, lap time, and total aerodynamic drag. This study used aerodynamic coefficients obtained from steady-state Computational Fluid Dynamics (CFD) simulations as inputs to the developed vehicle performance model. Rather than a detailed component-level design, this study focuses on the performance implications and specific trade-offs between negative lift and drag to support engineering decisions regarding resource allocation and development time.

The results indicate that the rear wing's aerodynamic downforce significantly enhances the vehicle's cornering capability and reduces the estimated lap time, despite the indicated increase in aerodynamic drag being far from linear. To meet the needs of Formula Student competitions that require low-speed technical cornering, the study establishes that maximising the absolute lift coefficient (CL) improves the performance and lap times more than chasing peak aerodynamic efficiency (CL/CD). The comparative vehicle dynamics analysis reveals whether a system retune or a modular upgrade is more beneficial in terms of their return on investment on the track record. The nonlinear results provide quantitative guidance for selecting high-downforce rear wing configurations to maximise track performance while keeping drag manageable in electric Formula Student vehicles.