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 Players during the 2010 World Cup in South Africa complained the
'Jabulani' tournament ball, had the tendency to behave in a bizarre
fashion and "knuckle" like a beach ball through the air, prompting
German firm Adidas to come up with a more reliable ball for this
year's tournament.
The result, known as the 'Brazuca' after a slang word for native
Brazilians, should fly with greater stability, said Takeshi Asai, a
professor of sports science and head of the Institute of Health and
Sports Science at the University of Tsukuba just outside Tokyo.
The new ball has just six panels, down from eight of the Jabulani,
and are designed in the shape of a shuriken - the throwing star used
by the ninja - while the seams that held them together were the
secret to its greater stability, he added.
"Despite the reduced number of panels, the total length of the seams
to put them together became longer, which makes the range of the
ball speed that creates low air-resistance become wider," said Asai.
 Asai, who has an engineering PhD, collaborated with John Eric Goff,
a physics professor at Lynchburg College in the United States, to
study the aerodynamics of the Brazuca when it was released last
December.
The two concluded that because the total seam length on the Brazuca
is 68 percent longer than the Jabulani, it will add resistance that
will allow the ball to fly more true at the speeds typically seen at
the World Cup.
The seams are also deeper, which adds drag factor.
Asai, however, found that the air resistance around the Brazuca,
which at 437 grams (15.4 ounces) is a gram lighter than the
Jabulani, is minimised when the ball flies at around 20 metres per
second, the approximate speed of fast passes in professional soccer
games.
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When the Brazuca flies within this range of speed, the air
resistance suddenly drops to help the ball fly fast," he said.
"Because it flies fast with a soft kick, I think it's an optimal
ball for Asian players who kick comparatively softer than western
players with higher physical abilities."
Of course, not everybody will be pleased with the new ball -
especially those who, like Japan's Keisuke Honda or Portugal's
Cristiano Ronaldo, try to avoid putting spin on the ball while
taking free kicks.
"Because the Brazuca has a lower lift force when it flies, the
so-called 'knuckling' effect will be harder to achieve," Asai said.
(Editing by Elaine Lies and Greg Stutchbury)
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