From the Marginal Revolution:
"Recall the development of the Polaris nuclear-missile system in the late 1950s. The whole package—a nuclear submarine, a solid-fuel missile, an underwater launch system, a nuclear warhead and a guidance system—went from the drawing board to deployment in four years (and using slide rules).
Today, according to the Defense Business Board, the average development timeline for much less complex weapons is 22.5 years. A case in point is the Ford-class aircraft carrier. The program is two years delayed and $2.4 billion over budget."