In my opinion it is disingenuous to call any supersonic aircraft sustainable. Independently of any clever aerodynamic design to moderate the drag coefficient, aerodynamic drag always increases like the velocity squared. Doubling the speed will mean applying 4x the force for 1/2 the time, so all propulsive efficiencies being equal, you will expend twice the fuel to go the same distance - at an absolute minimum. In reality engine efficiencies decrease at high-speeds, and you won't be able to completely eliminate the Mach 1 "barrier" (drag peak), or design an aircraft that is equally efficient in takeoff/landing... so the factor will be bigger than that. But x2 fuel consumption is a hard lower bound.
I don't believe this can be called sustainable. Air transport is already a major contributor to CO2 emissions. We as a civilization badly need significantly more efficient ways to fly, not less efficient ways. To even slightly suggest that this might be helping the environment is deplorable.
Also, air transport is already miraculous. Going around the world in a day is not enough for you? Really? Buy a book.
I don't believe this can be called sustainable. Air transport is already a major contributor to CO2 emissions. We as a civilization badly need significantly more efficient ways to fly, not less efficient ways. To even slightly suggest that this might be helping the environment is deplorable.
Also, air transport is already miraculous. Going around the world in a day is not enough for you? Really? Buy a book.