>>1241257This!
Only ways to reduce aerodynamic drag are:
>lower frontal areCan't get much lower, even the Concorde's fusselage was tiny in diameter and the wings just large enought for take-off.
>lower coefficient of dragThey are working on it, but I don't expect a miracle.
>lower air densityAir breathing engines can't go much higher and you don't realy get much lift from the wings at a realy high altitude.
So either they go (suborbital) rocketplane or it will never realy get efficient, but that gives you other issues with heat during re-entry.
