They sound like the sort of tests you do to ensure your drone does *not* do damage
IE before you commit to a design.
BTW 650 is 0.5 Mach, which is pretty damm fast near the ground.
AFAIK the only aircraft with that sort of takeoff speed is the Skylon spaceplane. *
*Which it won't do if if it's "self ferrying" to an equitorial spaceport and only be carrying LH2 for air breathing, hence about 160tonnes lighter than normal. 1