@smudges – The plane depicted is a SCRAM jet, and that technology definitely exists. The performance and nature of the movie’s Darkstar is almost certainly based on NASA and DARPA programs using the technology which achiever speeds right around Mach 10 for brief moments..
The look of the jet also feels very SR-71 inspired and they are working on an SR-72, a successor to the SR-71 that reportedly will reach Mach 6 and use scramjet technology. You’ll note that’s considerably slower than the prototype scramjets. That’s to be expected since the production model isn’t just a research prototype.
I question whether a successor to SR-71 is a good idea given that multiple countries are claiming to have hypersonic missiles, the speeds of which have estimates between 5 and 10 times the speed of sound. And while Russia is almost certainly exaggerating it’s achievements (they have a long history of doing just that), I believe China’s claim.
But more relevantly, I felt this entire story arc added nothing to the narrative. Why does Maverick have to still be acting like a 20 year old when he’s 60? That story angle took alot of time and… kind of makes Maverick feel a bit one dimensional. It was a main story element in the original, but it felt out of place here. One of many substories that I felt added little to the movie.