Why were spaghetti string rackets banned in the game of tennis?

In 1977 a patent was submitted for a 'spaghetti' stringing system which allowed the tennis player to impart considerably more spin on the ball than was possible with a conventionally strung racket. This racket was subsequently banned by the International Tennis Federation. In this paper the difference in the magnitude of spin generated by 'spaghetti' and conventionally strung rackets is quantified. Laboratory tests were conducted which showed that the 'spaghetti' strung racket imparts almost twice as much spin on the ball compared to a conventionally strung racket, for a typical oblique impact. Four conventionally strung rackets were tested using different combinations for string type and tension. There was no significant difference in the magnitude of spin produced by each of these four rackets. By considering the lift and drag forces acting on a ball during flight it can be seen that a difference in ball spin magnitude significantly affects the ball trajectory.