 This led to John Boyd's energy–maneuverability theory, which stressed that extra power and maneuverability were key aspects of a successful fighter design and these were more important than outright speed.Through tireless championing of the concepts and good timing with the "failure" of the initial F-X project, the "fighter mafia" pressed for a lightweight day fighter that could be built and operated in large numbers to ensure air superiority.In early 1967, they proposed that the ideal design had a thrust-to-weight ratio near 1