As I recall from literature Sukhoi T-4 shares nothing with B-70 other than specs,from technical POV it shares a lot of technology with Mig-25/31 and some with Tu-144.
It failed for the same reason M-50 failed-technology not advanced fast enough to keep up with what was expected from aircraft.
Regardless of difficulties Russian designers have a talent of making something useful using (by Western standards) outdated tech. Tu-95,Mig-29 and entire line of Antonov airframes are the best examples of just that.
Here is something from days when Russian aircraft design was far ahead from nearly everyone.Tupolev ANT-25.
It failed for the same reason M-50 failed-technology not advanced fast enough to keep up with what was expected from aircraft.
Regardless of difficulties Russian designers have a talent of making something useful using (by Western standards) outdated tech. Tu-95,Mig-29 and entire line of Antonov airframes are the best examples of just that.
Here is something from days when Russian aircraft design was far ahead from nearly everyone.Tupolev ANT-25.

