While as yet it’s unclear just what crashed at Casa Del Osama, chances are it’s a stealthy modification of the Blackhawk. The idea of a radar-stealthy Blackhawk is not a new one. In 1978 Sikorsky released some details of three design studies of Blackhawk fuselages modified for low radar cross section. No details were released about the rotor, but it’s obvious that the rotors and hubs would need a fair amount of work to reduce RCS… perhaps just the sort of modifications visible in the photos.
Note: I have better quality copies of these illustrations elsewhere, but these are what are readily at hand. I’ll add the better ones at a later date if there is interest.
Configuration1: a modification just to the cockpit area.
Configuration2: highly sloped fuselage sides.
Configuration3: sides sloped five degrees
Unsurprisingly, configurations 2 & 3 were found to add noticably to aircraft weight.