It’s Rocket Science
A Kenyan professor of aerodynamics working for NASA in California
has emerged as the mystery man behind Australia’s newest weapon
in the quest to regain the Ashes
“Contrast swing” is the brainchild of Dr Rabi Mehta,
and on Tuesday it reached out 13,000km from his laboratory in California’s
Silicon Valley to play a key role in Australia’s miraculous
second Test win at the Adelaide Oval.
Through Australian bowling coach Troy Cooley, Dr Mehta’s scientific
work guided Australia’s fast bowlers as their reverse and
contrast swing backed up Shane Warne’s spinning blitz to decimate
After reverse swing played a huge part in England regaining the
Ashes last season, contrast swing is set to become the new buzz
word among the world’s fast bowlers.
A leading expert in aerodynamics – specifically aircraft turbulence
– Dr Mehta works at the Ames Research Centre, NASA’s
premier research laboratory, which has supported projects from the
Apollo moon landings to today’s space shuttle missions and
It hardly seems the place to find world cricket’s fast-bowling
guru, but Dr Mehta grew up loving the game from his school days
in British colonial Nairobi.
Educated in England, where he opened the bowling with Imran Khan
at the Royal Grammar School in Worcester, Dr Mehta dreamed of playing
professional cricket in England.
“I used to be able to hurl it down at a fair pace, but my
dad wasn’t very impressed when I told him I wanted to play
cricket,” Dr Mehta told The Sunday Mail on Friday, as his
NASA colleagues concentrated on a space shuttle launch.
A graduate of London’s Imperial College, Dr Mehta combined
his academic and sporting loves to start wind tunnel tests on the
aerodynamics of the cricket ball.
Those experiments have evolved the art of reverse swing into something
completely different from what Pakistani champions Imran and Wasim
Akram pioneered almost by accident on the subcontinent 25 years
Dr Mehta’s interest was sparked in 1980 when Imran told him
he occasionally made the ball swing “the wrong way”,
although he had no idea why it happened.
“At the time I honestly didn’t believe that such a phenomenon
could occur and I could not explain it scientifically,” Dr
Mehta said. “In the following year, when we conducted our
wind tunnel experiments, the mystery was revealed.
“If you take a ball and bowl it with the seam angled towards
first slip it will swing away from the right-handed batsman.
“For true reverse swing, everything is the same but the ball
will swing towards fine leg You can even do it with a brand new
ball if you can bowl at high speeds, over 90mph (145km/h). As the
ball gets older, the speed you need to get reverse swing comes down
as low as 60-70mph (96-112km/h).
“Contrast swing started thanks to talks I had with (then England
bowling coach) Troy Cooley when I was in England during the 2005
“It happens when the seam is held upright and the contrast
between the surface roughness of the ball produces the swing.
“From a batsman’s point of view, if the seam is angled
it is reverse swing and if it is straight up it is contrast swing.”
Tasmanian-born Cooley is credited with schooling England’s
pacemen in the “dark art” of reverse or contrast swing,
which played a huge part of its first Ashes series win in 12 years.
He switched back to his homeland to become Australia’s bowling
coach this year.
While he has not been specifically working on reverse swing with
Glenn McGrath, Brett Lee, Stuart Clark and Co, Cooley notes that
any modern paceman who is not keen to master the skill is being
“You practise every aspect of your trade, and reverse swing
is definitely a key aspect of fast bowling today,” Cooley
“If you’re a fast bowler and you’re not practising
reverse, you certainly should be.
“It is an art to get the ball in the right position, and it’s
one that has to be practised.”
Cooley agreed that, while most cricket followers would be aware
of the results of reverse swing, few understood the mechanics behind
it. That’s because so much of the field is still being researched
by experts like Dr Mehta.
The point at which reverse swing occurs is defined by how fast the
delivery is. Brett Lee’s speed enables him to produce reverse
swing earlier than Stuart Clark or Glenn McGrath.
Contrast swing can be produced at any speed, meaning even military
medium bowlers can use it as a new weapon.
Conventional wisdom has always been that it is easier to reverse
swing the Duke brand balls used in England than Australia’s
Kookaburra ball, but Cooley believes it has more to do with our
“The seams do appear a bit different and that may have an
effect,” Cooley said.
“The Kookaburra is a bit flatter while the Duke seam sits
up a bit more. The different ways they prepare the leather and the
type of leather may also play a part, and not every cricket ball
is perfectly round and you need a very balanced ball to get reverse.
“But really it is the ground condition that plays the biggest
part. If you have a greenish wicket and a well-grassed outfield,
like in Brisbane, no one will get contrast swing with any type of
“You saw what happened in Adelaide where the batters were
on top for four days until the pitch began to break up on the fifth
day, the ball got roughed up and it tripped over to reverse.”
And for young fast bowlers who are struggling to get any movement
at all, Dr Mehta has a final word from the wind tunnel.
“With a new ball, the point between conventional and reverse
swing is 80mph (128km/h).
“But if you bowl at exactly that speed, there is no swing
at all. It does not matter how perfectly the ball is delivered,
it is not possible to swing a cricket ball at 80mph.”