Badminton’s Spin Serve Banned as Physics Reveals Its Secrets

Serious badminton players have recently encountered a significant rule change regarding the spin serve, a technique considered highly effective and difficult to return. The Badminton World Federation (BWF) imposed a ban on this innovative serve in 2023, citing concerns over potential unfair advantages it provided to players. The BWF’s decision aimed to ensure that international tournaments do not become a testing ground for this technique, which shares similarities with the previously prohibited “Sidek serve.” The ban will remain in place until after the 2024 Paralympic Games in Paris.

The spin serve involves adding a pre-spin just before the racket strikes the shuttlecock, creating a trajectory that many have deemed “impossible to return.” This has prompted a deeper examination of the physics behind the serve, leading to research published in the journal Physics of Fluids by Chinese physicists. Their findings shed light on the unique aerodynamics of the shuttlecock, which differs from other sports projectiles due to its open conical shape and the influence of its 16 overlapping feathers.

Shuttlecocks are designed to decelerate rapidly during flight, resulting in a steep parabolic trajectory. This characteristic requires players to exert considerable force to hit the shuttlecock the full length of a badminton court. Despite these challenges, shuttlecocks can reach speeds exceeding 300 mph. The feather structure also introduces a natural spin, which can be manipulated to enhance various strokes, such as achieving a more effective tumbling net shot.

Understanding the Physics Behind the Spin Serve

A previous study from 2015 focused on the shuttlecock’s aerodynamic behavior, revealing that its geometric properties play a critical role in its flight dynamics. The latest research by Zhicheng Zhang and his team at Hong Kong University of Science and Technology builds upon these insights by investigating how the spin serve specifically affects the shuttlecock’s trajectory.

Zhang noted, “We were interested in the underlying aerodynamics. Moreover, revealing the effects of pre-spin on the trajectory and aerodynamics of a shuttlecock can help players learn the art of delivering a spin serve, and perhaps help players on the other side of the net to return the serve.”

To explore this, the researchers developed a digital model of the commercially available Li-Ning D8 feather shuttlecock and conducted 3D fluid dynamics simulations under three conditions: without pre-spin, with pre-spin in the direction of the shuttlecock’s natural spin, and against it.

The study identified three phases of the shuttlecock’s trajectory: the turnover phase, oscillation phase, and stabilization phase. When using a pre-spin in the opposite direction of the natural spin, players can extend the oscillation phase, leading to a distinctive “dip and sway” pattern. This effect results from a high-pressure region forming on the side facing the flight direction, causing a significant decrease in horizontal velocity.

The authors acknowledged that variations in shuttlecock shape could affect the results and expressed interest in studying different configurations in future research. They also aim to conduct motion capture studies of various badminton serves, including the spin serve, with the goal of helping players refine their techniques.

The ongoing exploration of badminton’s spin serve not only highlights the intersection of sports and science but also underscores the importance of maintaining fairness in competitive play. As players continue to adapt and innovate, understanding the underlying physics will be crucial for both mastering the serve and returning it effectively.