As Lockheed Martin’s Marietta, Ga., plant prepares to begin building the 187th—and last—F-22 super-fighter, the military is already dreaming of its successor. In a query to the aerospace industry earlier this month, the Air Force laid out its wish list, and it wants everything: a plane that can win dogfights, demolish air-defense missile networks, support ground troops, and run surveillance missions; a partial prototype would be ready by 2020, with entry into service by 2030. This may be wishful thinking, given the saga of the current wondercraft, the F-35 Joint Strike Fighter. With a development and production price tag of...