A Douglas B-45 Tornado, the U.S. Air Force's first operational jet bomber, banks over a mountain range during a training or test flight. Entering service in the late 1940s, the B-45 was America's first four-engine jet bomber and among the earliest aircraft capable of delivering nuclear weapons, bridging the gap between piston-engine bombers and the jet-powered Strategic Air Command fleet of the Cold War. Project: 218216