Thanks for the input, folks. All appreciated.
As I said in my original post, I am not a professional, but I was intrigued by the bullet shaping of the machine, the very thin wings, and all-moving tailplane being used, and wondered if these things would have enabled it to break the "sound barrier".
Of course, as mentioned, other things probably would not have helped, i.e. lack of fuel, how to get it "up there" in the first place.
But all interesting. Thanks again.
N.Z.