My research student this summer is Chad Hobson, who just completed his first year here at Lynchburg College. Chad will be helping me with Tour de France modeling. He is also a soccer player and avid fan of the beautiful game. We spent part of the afternoon today examining the flight of Brazuca. The photo below shows my ball, which is just like the one my colleagues in Japan tested in a wind tunnel (we published our research on Brazuca a couple of months ago -- go here to download a copy of our paper for free).
Click on the image for a larger view. Note the texturing on the surface. Note, too, the long seam paths, which help make the six-panel Brazuca's surface rougher on average than the eight-panel Jabulani surface. The research I did with my colleagues in Japan shows that Brazuca will be more stable than Jabulani. There should not be so many erratic trajectories this time around!
To get a feeling for how a soccer ball curves, check out the image below (click for a larger view).
Chad kicked the ball with counterclockwise spin as seen from above (also a little topspin component). I show the path the ball takes with the red trajectory curve. Brazuca's spin causes air to be whipped off back and to the right. There is thus a leftward deflection, creating the nice banana trajectory you see above.
It now World Cup time!