B-50C Superfortress
The aircraft that started as the B-50C eventually came to be designated the XB-54. It's had substantial new design features including four R-4360-43 turbo-compound engines, also known as Variable Discharge Turbine (VDT) engines. These new engines demanded a redesign of the B-50's airframe that gave it a wider wingspan and longer fuselage. This made the takeoff weight of the B-50C 50,000 lbs. greater than previous B-50s.
Late in the year 1948 it was decided that these differences between the B-50C and its predecessors were enough to warrent a new designation. The B-50C became known as the B-54. By this time 14 standard and 29 reconnaissance versions of the plane were on order.
The XB-54 faced shortcomings however. Because it was a derivative design there was little growth potential for the aircraft. It also carried a high price tag and required a wider than standard taxiway. If it were to go into production air bases would have to be modified. The design was also hindered by the fact that jet engines could not be installed without redesigning the aircraft's wings. Finally, installing the K-1 bombing system would require removing the belly turret or redesigning the fuselage.
These problems raised doubts about the feasibility of the XB-54. General Curtis LeMay argued that the program should be scrapped and production of B-36s expanded. However this would have upset a balance of medium and heavy bombers that the Joint Chiefs of Staff had approved. While some, like Air Force Secretary W. Stuart Symington, proposed substituting some B-54s with B-50s General LeMay felt it would be better to cut production for the B-54 entirely and instead order more B-47s. Eventually the Board of Senior Officers agreed with LeMay and the B-54 program was cancelled on April 5, 1949. No aircraft were ever actually produced.
