re: Blazing speed is less useful for reconnaissance than many people think
"How much damage could one do by simply whanging over a target (like ground troops) at, say, mach 5?"
No plane can fly at mach 3 at low altitude, you could probably make a missile go this fast. A Phoenix Missile can go around mach 5.
"In excess of 3,000 mph (4,800 kmph)":
http://www.fas.org/man/dod-101/sys/missile/aim-54.htm
