Numerical Analysis of Winglets on Racing Motorcycles Under Slipstream Conditions

ABSTRACT Aerodynamic winglets on modern motorcycles are designed to enhance performance by increasing downforce and mitigating front‐wheel lift. However, their aerodynamic influence on a trailing motorcycle during slipstreaming remains poorly quantified. This study investigates this interaction, specifically focusing on the potential for aerodynamic instability. A Computational Fluid Dynamics analysis was conducted using a steady‐state RANS k‐ω SST turbulence model. The simulation modeled two motorcycles, both with and without winglets, in a tandem formation while varying the inter‐vehicle separation distance across a range of close‐proximity racing scenarios. The results demonstrate notable aerodynamic instability. While a solo motorcycle equipped with winglets generated significant downforce as intended, the trailing motorcycle experienced a significant loss of downforce. At the closest separation distances, the aerodynamic force completely reversed, transitioning from beneficial downforce to a net positive lift. This constitutes a total loss of the winglets' intended function. This phenomenon occurs because the turbulent wake from the leading motorcycle severely disrupts the airflow over the trailing motorcycle's winglets, neutralizing their effectiveness. These findings provide clear evidence that aerodynamic appendages can introduce significant aerodynamic instability in close racing. It is hypothesized that this rapid shift from downforce to lift could impact braking performance, steering response, and front tire loading. Therefore, these results underscore the necessity for regulatory bodies to consider these interactive effects, while highlighting the need for coupled vehicle‐dynamics simulations to fully validate these safety implications.