Originally Posted by
LOMCEVAK
I have intentionally been to about 1.05M but I am intrigued to know how HS ever achieved the 1.2M limit!
I asked JF the same thing and his answer was the aircraft had no true airframe mach limit as the aircraft was effectively self-limiting. The absence of a number didn't sit well with the customer though so the M1.2 number offered by the intake/propulsion team was used instead. The actual maximum achieved by HS was M1.17.