"XB-1 met all of its test objectives, including safely and successfully achieving an altitude of 7,120 feet and speeds up to 238 knots (273 mph)."
Seems just a bit shy of the speed of sound (760 mph).
Seems just a bit shy of the speed of sound (760 mph).
It's fairly likely they'll find things that need changing along the way, which may also result in the need for additional regulatory oversight, so, double impossible to know if this will be flying at design speeds in a year or ten years or ever.
I'm sure we'll get a HN post about it when it does however.
Flight testing will slowly and very methodically expand the flight envelope until it meets or fails its design objectives.
It would very much be an unusual exception, in that era and now. First flights rarely even raise the landing gear, let alone push the performance envelope. Flight testing programs are designed to be incremental to manage risk as well as learn things in a deliberate vs yolo way.
Rockets are really where you see the opposite being the norm, because it's hard to do a rocket launch half way.
That relies on assumptions (ideal gas, adiabatic compression) that might break down for supersonic jets, but it's pretty close for the speed of sound.