High Quality Content by WIKIPEDIA articles! The Rockwell (now part of Boeing) B-1 Lancer is a four-engine variable-sweep wing strategic bomber used by the United States Air Force (USAF). First envisioned in the 1960s as a supersonic bomber with sufficient range and payload to replace the Boeing B-52 Stratofortress, it developed primarily into a low-level penetrator with long range and supersonic speed capability at high altitude.