Photo: Victoria Feliniak
Shuttlecocks used in major competitions such as the Olympics and the World Cup have long been made of goose feathers. The aerodynamic properties have been considered superior to those shuttles made of synthetic material, especially in smash and net games, but that is changing.
Challenges with traditional shuttlecocks
Shuttles made of goose feathers require a large amount of needlework and are made in Asia, often under doubtful working conditions. The feathers are harvested, cleaned and sorted according to length and angle, then they are fixed in a shuttlecock which is tested with many manual operations during all manufacturing steps. The shuttlecocks also require careful handling. They must be stored in regulated humidity and temperature to maintain their performance. Another problem is that they have a relatively short life in games. Manufacturers are now looking for alternatives with shuttles made of synthetic material.
Manufacturers in need of scientific tests
The test methods used for shuttlecocks uses professional players who have smashed the shuttlecocks a certain number of times and they have also tested games by the net to assess ball paths. The method works acceptably for shuttlecocks, but when synthetic balls were to be tested, one began to realize that the methods were too subjective. A more scientific approach was desired.
BWF started looking for solutions and talked to the company that tests shuttlecocks for them, Polyfor AB. It’s run by former elite player Christer Forsgren. He studied chemical engineering at Chalmers and has been active for seven years as an adjunct professor of industrial materials recycling at the Department of Chemistry and Chemical Engineering. Through his company, he has tested and approved balls for BWF for about 35 years. For Christer Forsgren, the contact with Chalmers was his first choice.
“Research in fluid dynamics and Chalmers' investment in sports technology is a good combination for developing test methods" says Christer Forsgren.
The contact with Chalmers resulted in a research project that BWF decided to fund.
Tests in Chalmers’ Laboratory of Fluids and Thermal Sciences
Valery Chernoray is a research professor at the Department of Mechanics and Maritime Sciences and led the project with testing, that was performed by Satheesh Kaviladhikarakunnathu Puthanveeti, a former masters student at Chalmers. Valery says that they figured out and tested many different variants of test methods. They summarized everything in a report that BWF now uses to show that Chalmers' methods work, are objective and based on science and research.
“We have developed reliable methods for testing two performance characteristics that interest BWF. One is smash resistance or shot resistance which can be described as durability during repeated smashes and tumbling which is about performance in net games” says Valery Chernoray.
The rig built at Chalmers can simulate smashes up to 200 km / h. A professional racket is mounted on a carbon fibre arm that is driven by springs that are pulled up with a winch. The shuttles are held in place using a thin plastic tube and vacuum. The smashes are then filmed with a high-speed camera.
"With help from the films, we first check that the shuttle is smashed in a correct way and then we calculate the smashing speed. After each smash, we photograph the ball and measure how far the ball has flown to see if the damage to the ball has affected the performance. After ten smashes, the shuttles are packed and sent to RISE, Sweden’s research institute, for material testing" says Valery Chernoray.
For tumbling, they use a stationary ball and an angled racket that moves along an angled path. The test shuttles are filmed with a high-speed camera and the images are processed to calculate how many times the balls tumble.
The manufacturers work in the direction of synthetic shuttlecocks
All major manufacturers such as Yonex and Mizuno are now working intensively towards synthetic shuttles and the synthetic shuttles produced today are much better than a few years ago and are considered very good by both professional players and test teams.
“They are still a bit too fragile and can only handle two to four powerful smashes from the strongest elite players. But they could already be approved for, for example, Junior World Cup games” says Valery Chernoray.
Christer Forsgren explains the two shortcomings in today's synthetic shuttles. One is smash resistance. The shuttle becomes soft and does not return to its original shape fast enough, which is why it does not brake enough in the air for the smash to be returned. The second limitation is tumbling at nets. If the player hits the impact part, the cork, with the racket a little crooked, the shuttle can start to tumble, which makes it difficult to hit the shuttle towards the baseline with a controlled hit. But Christer Forsgren is hopeful that the synthetic shuttlecocks will be used.
“I'm a little doubtful about if there will be synthetic shuttles for the Olympics in Paris 2024, but I think there will be synthetic shuttles in the Olympics in Los Angeles 2028” says Christer Forsgren.