Fans in the stands and viewers watching on television have no way of telling, but Yonex included four grades of shuttles, from slow to fast, that are deployed based on the conditions at the badminton venue
To figure out which shuttle to use each day in Rio, a tournament referee and a representative from Yonex go to center court before the first match. On a recent morning, as a sprinkling of athletes and fans filed in to the building, Boris Reichel, who works for Yonex, took three No. 2 shuttles and three No. 3 shuttles and went to the service line.
He hit them with a gentle arc to the singles service line on the other side. The shuttles landed a few inches short. He then went to the other side and hit them back again. This time, they all landed closer to the line. Reichel figured that the shuttles had flown farther in that direction because of a draft coming from the doors that were opening on that side of the building.