Did you know that a smash can reach 565 kilometers per hour? This is what makes badminton the fastest racket sport in the world! Research in sports physics is numerous and aims to understand the scientific phenomena underlying this sporting practice.
Plastic shuttlecocks: less efficient than goose feather shuttlecocks
The characteristics of the steering wheels are studied for several years. Its low weight, combined with its shape, induces a significant friction force in the air. These characteristics make its trajectory very particular.
On a serve, the oblique upward trajectory is practically linear while the shuttlecock then falls vertically, at a constant speed of approximately 24 km/h. The feather shuttlecocks do not deform with speed, which allows optimal control of the game. However, the feathers do not resist the blows imposed by the players for long. This is why they are reserved for professionals.
So, for a single match, around forty goose feather ruffles are sometimes necessary! Synthetic shuttlecocks (nylon), more flexible, were invented to compensate for this lack of resistance. More durable, they are restricted to beginner and leisure use.
However, the game is altered: the deformation of their skirt with the speed in contact with the air makes the trajectories difficult to control. This is the result of an aerodynamic study carried out in India and published in January 2024 in the journal Physics of Fluids. Indeed, the researchers examined the friction forces exerted on the plastic steering wheel at several flight speeds. They observed that from 144 km/h, the skirt crashes. As its contact with the air decreases, the friction force decreases and the steering wheel is then braked much less. Its trajectory becomes more parabolic.
Conclusion: the length of the trajectory of a nylon shuttlecock is more difficult to control than that of a goose feather shuttlecock.
Trajectory of a feather (red) and plastic (blue) shuttlecock. Diagram taken from the article “The physics of badminton” Caroline Cohen et al 2015 New J. Phys. 17 063001
“If the steering wheel is not made with the same material and the same structure, the aerodynamic behavior will be different. It’s like comparing a football with a rugby ball: they don’t follow the same trajectories,” illustrates Vincent Dolique, CNRS research engineer, at the Physics laboratory of the ENS (École Normale Supérieure) in Lyon, and who did not participate in the Indian study.
The authors of this work in aerodynamics hope that one day nylon shuttlecocks will be manufactured whose playing quality will be close to that of feather shuttlecocks. “Our study paves the way for improved designs that would make the nylon steering wheel structurally stiffer so that it more closely replicates the aerodynamic performance of feather steering wheels”enthuses Sanjay Mittal, co-author of the study, in a press release.
In the slice, left-handers have the advantage
23% of badminton players are left-handed. When it comes to racquet sports, it is already accepted that left-handers have physiological advantages. They are particularly used to playing against right-handers, while the opposite is less true.
Moreover, “visual and spatial information is processed in the right hemisphere of the brain, which controls the movements of the left part of the body, which reduces reaction time”, adds Eric Collet, professor at the Rennes Institute of Physics and author of a vast study on the differences between left-handers and right-handers.
His work is published in Physics Reports of the Academy of Sciences: in October 2023, Eric Collet filmed exchanges during the French internationals in Rennes. Using an ultra-fast camera, he demonstrated that the geometry of the steering wheel favors left-handers.
These slow motion videos made it possible to observe the flying in the air, with a resolution of 3700 frames per second. Result: once returned, the steering wheel turns on itself counterclockwise. This rotation results from the chirality of the steering wheel, namely its non-superimposable nature on itself in a mirror. The 16 feathers are hung on the cap and follow one another in the shape of a helix oriented towards the left. The air flow then sets the steering wheel into rotation.
During a slice, players “rub” the shuttlecock from the baseline to send it to one side of the opponent’s court. Right-handers who perform this movement accelerate the natural rotation of the steering wheel. For lefties, it’s a different story. The steering wheel rotates clockwise again, which increases the friction force. Then it stops rotating, then rotates in a natural counterclockwise direction. The shuttlecock then slows down more on a left-handed slice and falls more vertically after the net, which creates more difficulty for the opponent than on a right-handed slice.
Chirality in the synthetic steering wheel?
The synthetic steering wheel is also chiral. If we look more closely, its skirt is a succession of short edges with large holes, and long ones with small holes, again creating a helix. “Without this chirality, the steering wheel would not be able to turn on itself and maintain its trajectory,” recalls Eric Collet.
Indian researchers have indicated that they want to make the rotation of synthetic flywheels a future study object. Will we one day be able to create a durable synthetic shuttlecock offering good trajectory qualities, compatible with the high level? Furthermore, the feather shuttlecock is made by hand, representing cost as well as time. Also, animal welfare also raises questions while the methods of designing feather shuttlecocks remain little known outside of the places where they are manufactured.
To note that Physics Night, the theme of which will be physics and sport will take place on April 2 at the Grand Rex in Paris.
2024-04-02 10:47:41
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