The significance of all this is that it is an air breathing engine -
not one (like a rocket for example) that also has to bring its
oxidizer along. Yes, it takes a lot of speed to get it in positive
thrust territory, but it accelerated beyond that point to an even
higher speed. The engine is very simple in its construction and has
no primary moving parts - other than a large fuel pump.

There are more than a few details though to be ironed out before Tokyo
will be an hour away...........