The Boeing B-50 Superfortress strategic bomber is a post–World War II revision of the Boeing B-29 Superfortress, fitted with more powerful Pratt & Whitney R-4360 radial engines, stronger structure, a taller fin, and other improvements. It was the last piston-engined bomber designed by Boeing for the United States Air Force. Not as well known as its direct predecessor, the B-50 was in USAF service for nearly 20 years.