According to Wikipedia: "The Boeing Model 450 B-47 Stratojet was a long-range, six-engine, jet-powered strategic bomber designed to fly at high subsonic speeds and at high altitudes to avoid enemy interception. The B-47's mission was primarily to drop nuclear bombs on the Soviet Union. With its engines carried in pods under the swept wing, the B-47 was a major innovation in post-World War II combat jet design, and helped lead to modern jet airliners."