ELLSWORTH AIR FORCE BASE, S.D. -- Aerospace propulsion Airmen from the 28th Maintenance Squadron work on a B-1B Lancer engine, Feb. 3. Carrying the largest payload of both guided and unguided weapons in the Air Force inventory, the multimission B-1 is the backbone of America's long-range bomber force. (U.S Air Force photo/Airman 1st Class Anthony Sanchelli)