It's callsign is Gaspipe
Seriously though - I would have thought that the simple laws of physics would suggest that if there is or has been a USAF hypersonic vehicle operating, it would probably have been revealed by now.
Think of the plasma surrounding even a medium sized UAV (or the manned version - which would necessarily be bigger) travelling at Mach 5+.
That's a mile a second at least.
In the infra-red - surely the thing would glow like the rising sun, and there's nothing I can think of that would hide that.
And come to think of it - the same plasma would not only preclude microwave or radio coms and telemetry inks to and from the aircraft would it not - and how would the aircraft's onboard sensors see through the plasma?
Am not a hypersonics, radar or sensor expert - so happy to hear the counterfactual from someone who is.
Did the space shuttle maintain coms all the way through re-entry?
Wouldn't an Aurora be very easy to detect by those it is reconnoitering purely because of its heat - even if it would be very hard to shoot down?
Lockmart are certainly now claiming that they've perfected an operationally feasible scramjet - and there have been credible suggestions that small scale protoypes of an SR-72 have been flying.
Did Aurora ever exist though?
Much as I'd like to think so (how fantastic) I doubt it.