Ball-tampering aids reverse swing, claims NASA scientist

London, Sep 3 (UNI) A NASA scientist, who has been studying the effects of ball tampering on cricket, claimed that his experiments have proved the theory that scruffing one half of the ball causes it to swing at lower speeds than an untampered version.

According to media reports in Scotland, Aerodynamics expert Dr Rabi Mehta briefed the England team on the issue after using wind tunnels at NASA's Ames Research Centre, California, to study the flight of tampered cricket balls.

Dr Mehta met England's fast bowling coach Troy Cooley 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.

''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,'' he said.

His 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 to 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.

UNI XC PM YA KP1946