Soccer fans that remember the buildup to the 2010 World Cup will remember the complaints from professional footballers that were set to compete in the tournament about all of the issues with the ill-fated Jabulani ball from adidas.
Claudio Bravo, Chile's goalkeeper, said that Jabulani was "like a beach ball" while Brazil's Julio Cesar called it "terrible... like a ball you'd buy in the supermarket. Italian forward Giampaolo Pazzini referred to it as "a disaster" while Serbia's Vladimir Stojkavic echoed the sentiment by calling it "a catastrophe."
The stem of the complaints was the Jabulani ball's tendency to knuckle in flight (like a Tim Wakefield pitch, for you baseball fans) and thus move unpredictably. This, according to NASA's aerodynamics researchers, happens when "at zero or near-zero spin, the seams of the ball channel airflow in an unusual and erratic manner making its trajectory unpredictable."
So, when the striker hits the ball directly in the center without slicing the top of their foot across it, the ball has the potential to move randomly in the air, fooling the goalkeeper and potentially leading to a goal.
In a bid to determine whether the 2014 World Cup ball, brazuca, is better than its 2010 counterpart, NASA took some samples to the agency's Experimental Aero-Physics Branch at the Ames Research Center in Moffett Field, California.
As a quick refresher, adidas spent years developing the brazuca ball and tested it with hundreds of athletes (both contracted to the manufacturer and not) and did perception testing to see what the stars thought of the new product. brazuca has less panels than any ball before it, reducing the traditional 32-panel shape to just six propeller-shaped interlocking panels.
According to Nasa and Dr. Rabi Mehta, the chief of the Experimental Aero-Physics Branch, brazuca is a marked improvement:
Despite having fewer panels, the finger-like panels on the Brazuca increase the seam length, compared to previous World Cup balls. The seams are also deeper than those of the Jabulani and the panels are covered with tiny bumps; all of these factors influence the ball's aerodynamics.
What seems like common sense about air moving around a simple sphere does not, in fact, bear true. The airflow around a sphere is not smooth; a great amount of drag is created behind the object. An example of this can seen on a golf course, where a smooth golf ball travels much shorter distances than a regular, dimpled golf ball.
Because of the raised nub texture that covers each of the six panels in their entirety and the longer seams on the ball, brazuca is much rougher in texture and that's a good thing. Because of that rougher texture, Dr. Mehta says that "there is a thin layer of air that forms near the ball’s surface called the boundary layer and it is the state and behavior of that layer that is critical to the performance of the ball." So, when the players at the World Cup drive the ball at speeds upwards of 70 miles per hour, brazuca's performance will be noticeably better than that of the Jabulani.
Dr. Mehta concluded by saying that "the players should be happier with the new ball. It is more stable in flight and will handle more like a traditional 32-panel ball."