In April 1945 the USAF’s predecessor, the USAAF, had issued its specification for a B-35/B-36 replacement with turbine propulsion.
The Convair submission to the 1945 requirement was the Convair YB-36G, which was in essence the B-36 recast with flying surfaces swept at 35 degrees and with a powerplant of eight Pratt & Whitney J57-P-3 turbojets. The type was redesignated YB-60 before two prototypes were ordered on 15 March 1951.
They retained the basic fuselage of the B-36 with a modified nose and generally similar wing centre-section and landing gear offering a 75 per cent structural commonality with the B-36.
The first was flown on 18 April 1952, but the type failed to gain a production contract, the USAF ordering instead the Boeing B-52.
In addition to its new wings and tail, the YB-60 had a revised landing gear arrangement and a considerably larger fuel capacity. Maximum speed was 550 mph (885 km/h) at 55,000 ft (16765 m), but in all operational aspects the competing Boeing aeroplane was superior, as well as offering far greater development potential.
Engines: 8 x 4080kg J57-P-3
Max take-off weight: 300000 kg / 661390 lb
Empty weight: 150000 kg / 330695 lb
Wingspan: 206 m / 675 ft 10 in
Length: 171 m / 561 ft 0 in
Height: 50 m / 164 ft 1 in
Max. speed: 520 km/h / 323 mph
Ceiling: 45000 m / 147650 ft
Range: 8000 km / 4971 miles