Conventional (speed) airflow is so difficult that the quiet bathroom fan is still just a gleam in this insomniac'a eye. If multi flow variable shock cone combustion ends up being confined to one airflow speed do you think that a Sanger type atmosphereic skipping profile would be called for? (See X-20, Wikipedia)

Does the engine intake encounter alot of "atmospheric air" molefcules up there at 530km? You know, that is 329.32673 miles or 1,738,845.1 feet and WAY above the altitude of the ISS. wow.