Sorry, been tied up with a bunch of rubbish (work stuff)
Anyhooo..
Silhoute reminded me very much of Bob Hoover's Shrike somehow. It def wasn't a C130, much too quiet!
I don;t know much about drones/UAVs? This had what appeared to be a "normal" layout - staright wings, single vertical stabiliser, low-set tailplane.
I guess it's going to be another one of those little mysteries!