 The remaining B-29s in service were then redesignated as Training (TB-29), Photo Recon (RB-29/F-13), Air-Sea Rescue (SB-29), and refueling/tanker (KB-29M) aircraft.The last USAF flight was in September 1960.As a stop-gap measure between the Lancaster and Lincoln propeller-driven heavy bombers and new jet V bombers, the Royal Air Force operated 88 leased B-29s in the early 1950s.