Nasa high-flier briefed England cricket team on ball tampering study

Published on 03/09/2006 00:07

WISDEN, we have a problem. A Nasa scientist has been studying the effects of cricket ball tampering and even briefed the England team on the issue, Scotland on Sunday can reveal.

Aerodynamics expert Dr Rabi Mehta has used wind tunnels at Nasa's Ames Research Centre, California, to study the flight of tampered cricket balls.

Mehta says his experiments have proved the theory that scuffing one half of the ball causes it to swing at lower speeds than an untampered version.

The scientist met Troy Cooley, England's fast bowling coach at the time, to brief him on what causes cricket balls to swing. He also lectured senior officials at the England and Wales Cricket Board (ECB) on the effects of tampering. It is possible the meetings fuelled suspicion among English players that Pakistan cricketers had tampered the ball during the Oval Test two weeks ago.

Umpire Darrell Hair received intense criticism when he awarded five runs against the Pakistani side after claiming they had been tampering with the cricket ball.

Mehta said: "On my last trip to England in December I met Troy Cooley and others from the ECB. Troy invited me out to their academy in Loughborough where I gave some lectures and some tips on swing bowling and reverse swing. We talked about ball tampering, what it is and how it helps."

Mehta's wind tunnel experiments have established that swing is caused by an asymmetric flow of turbulence around the ball which produces a side force.

If the rough side is bowled so it faces the batsman, then the air clings to the ball for longer, creating a pressure difference that allows the ball to swing. This technique requires skill to angle the ball correctly but the rougher the side - particularly through tampering - the greater the effect.

A spokesman for the ECB confirmed Mehta had met Cooley and had discussed ball tampering.