Air or RF, stealth or not, everything leaves a wake. Commercial weather radars are tracking wind speed and direction, and getting better all the time.
Is the military (ours or theirs) really behind that kind of tech?
I don’t think so. Add in RF and IR and who knows what else; you’re gonna be seen.
A hummingbird traveling at 500+ knots leaving a big ass wake, and a heat signature, is gonna be noticed.
“A hummingbird traveling at 500+ knots leaving a big ass wake, and a heat signature, is gonna be noticed.”
That is why we don’t have supersonic nuke platforms (B-2).