It is quite clear the SR-71 flew much faster than the publicly acknowledged Mach 3.
There are clear accounts of it exceeding 2400 mph.
The SR-72 will be unmanned, so what fun is that?
I know a retired flight traffic controller who clocked it at 3500kts. Go figure.
You don’t have to be faster than a missile to out run it. At 90k+ feet they had enough head start that even a missile significantly faster might not catch up.
Just imagine if half the funds spent developing stealth was spent refining the design of the SR71 and Ramjet technology.
Better than stealth, the bad guys would see a plane coming at them and could do absolutely nothing about it. Mach 3.5+.
Talk about sending some people to the negotiating table with their tail between their legs.
One of my college profs was a world expert on hypersonic travel and had classified numbers. He let it slip once in class, Mach 6.1 was a number he let slip and then told us to forget about.