There's no comparison. The XB-70 was intended for high altitude supersonic penetration, attack, and escape. The concept that became the XB-70 goes back to January 1954, but the aircraft did not actually fly until 1964. By then, mainly because the manned bomber program was being deemphasized in favor of intercontinental ballistic missiles, the XB-70 had been reclassified from an operational aircraft to a test and development role. As completed they had no provisions for weapons and only two crew. Despite the loss of the second aircraft in 1966 (through no fault of the XB-70 itself) the test program went on until 1969 when the remaining prototype was retired.
The point is that Concorde was a staggeringly expensive program and was kept alive all these years by the British and French governments for prestige purposes. There's nothing inherently wrong with that, but the XB-70 program (as built) was intended for testing of large high performance aircraft at high supersonic speeds. Once the test program was done, the aircraft itself was done. One can't really consider it to be a parallel with Concorde.
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There's no comparison. The XB-70 was intended for high altitude supersonic penetration, attack, and escape. The concept that became the XB-70 goes back to January 1954, but the aircraft did not actually fly until 1964. By then, mainly because the manned bomber program was being deemphasized in favor of intercontinental ballistic missiles, the XB-70 had been reclassified from an operational aircraft to a test and development role. As completed they had no provisions for weapons and only two crew. Despite the loss of the second aircraft in 1966 (through no fault of the XB-70 itself) the test program went on until 1969 when the remaining prototype was retired.
The point is that Concorde was a staggeringly expensive program and was kept alive all these years by the British and French governments for prestige purposes. There's nothing inherently wrong with that, but the XB-70 program (as built) was intended for testing of large high performance aircraft at high supersonic speeds. Once the test program was done, the aircraft itself was done. One can't really consider it to be a parallel with Concorde.