ST. LOUIS -- Boeing's Defense, Space and Security unit is placing a major bet on the Air Force's next-generation fighter aircraft -- whatever that may be. The company unveiled its new 1.1-million-square-foot, $1.8 billion classified Advanced Combat Aircraft facility to reporters here on Wednesday, nearly two weeks after Air Force Chief of Staff Gen. David Allvin hedged questions regarding the future of the Next Generation Air Dominance program . Boeing broke ground on the manufacturing site about six months ago...