When any object goes through the air, a thin cushion of air wraps around it that stays relatively still. This boundary layer is why you get dust trapped on your ceiling fan. At slower speeds, the air around a soccer ball moves smoothly over the surface and separates off the sides of the ball at its widest points. Imagine a ball moving from right to left across a clock, Goff explains, so traveling from the 3 to the 9. With laminar flow, the air flows over the surface and then flows off at the 12 and 6, which creates more drag in the air. Drag slows the ball down faster. At higher speeds, the air moves turbulently across the ball’s surface and peels off at the 2 and 4. The wind effectively wraps around the back. This turbulent flow has less drag, which means the ball keeps moving at high speed for longer.
Although the length of kick may end up being a little shorter, the changes make the Telstar 18 more balanced, says Alam. On other balls, Alam and his team have found that there is a difference in how the ball flies based on where it’s kicked in relation to the seams. His tests have found that the Telstar 18 ball doesn’t have as much variation. The total length of seam of the Telstar 18 is 14.1 feet, 3.28 feet more than on the Brazuca. With the longer seam, and more symmetric panels, no matter how the ball is turned there is the same amount of seam exposed. “The other two balls were not like that, they were significantly different,” he says.
Adidas designs every World Cup ball, and on top of being a big seller for them, engineers at the company are constantly a little closer to the perfect ball, Goff says. The ideal soccer ball is a pimple-covered, perfect sphere, its surface just subtly textured enough to keep the airflow around the ball slightly turbulent. Unintuitive as this might sound, the ridges and pimples on the ball make it more aerodynamic, helping the ball to fly through the air more stably.