Boeing B-52D Stratofortress After it became operational in 1955, the B-52 remained the main long-range heavy bomber of the US Air Force during the Cold War, and it continues to be an important part of the USAF bomber force today. Nearly 750 were built before production ended in the fall of 1962; 170 of these were B-52Ds. The B-52 has set numerous records in its many years of service. On January 18, 1957, three B-52Bs completed the first non-stop round-the-world flight by jet aircraft, lasting 45