L.U.C.I. in the sky - Chris Fox

Maria Haymeyer has an I. Q. of 250, once posed for a Playboy 'Girls of Mensa' feature, and has invented a radical new design for a warplane computer game she calls 'L. U. C. I.' -- short for Light Ultra Chip Intelligence. But someone has stolen her idea, and converted it to bid for a multi-million Joint Strike Fighter contract with the Pentagon.
An unwilling but crucial ally in Maria's search to recover L. U. C. I. is a man called Terry Weston, who, up until now, has pursued an ultra-secret career as a corporate spy. But he is not aware of a critical fact - that L. U. C. I. is a warplane with a built-in Doomsday mechanism.