In 2010, goalkeepers groused that the official World Cup ball, the Jabulani, gave strikers an unfair advantage because it could be easily manipulated to behave like a knuckleball. When kicked with zero or little spin, the ball would take an erratic course toward the goal, making the goalies work that much harder.
This year, the official World Cup ball is called the Brazuca, which has only six panels (a traditional soccer ball has 32; the Jabulani had eight), features deeper seams than the Jabulani and is covered with tiny bumps. NASA decided to test out the Brazuca and found that it won’t be as easy for strikers to manipulate as the Jabulani was four years ago, giving goalkeepers more of a chance.
Here’s what NASA found:
The overall increased roughness of the Brazuca football will help to decrease the ball’s knuckling tendencies at kicking speeds typically encountered in the World Cup. …
Tests in the wind tunnel and a 17-inch water channel, which uses florescent dye dispensed into the fluid flow under black lights, shows that the speed of greatest knuckling for a traditional ball is around 30 miles per hour (mph). This is well below the typical kicking speed of a World Cup-caliber player, which is about 50 to 55 mph. Interestingly, the Jabulani, a much smoother ball, produced its greatest knuckling effect in that same speed range (about 50 mph), which is why the players in the 2010 World Cup noticed the effect more frequently.
The smoother a ball is, the higher the speed at which the knuckling effect occurs. However, with the increased roughness of the Brazuca, this critical speed for maximum knuckling is reduced to about 30 mph. So it is expected that the 2014 World Cup ball will have a more predictable flight path at typical striking speeds.