The US military may have operated a new classified helicopter type in its recent raid on Osama bin Laden's compound in Pakistan. It was a secretly developed stealth helicopter, probably a highly modified version of an UH-60 Blackhawk.

Specifically, the tail rotor of the crashed helicopter has a five-bladed assembly, whereas the Black Hawk tail rotor has four blades.

First News reports show the remains of what appears to be a Sikorsky UH-60 Black Hawk helicopter that crashed in the US military raid that killed Osama bin Laden early on 2 May.

Images of the wreckage of a helicopter that reportedly crashed during the operation, apparently due to an undisclosed technical malfunction, do not conform to any types that are known to be in service with the US military or in development.

It’s not uncommon for U.S. military forces to destroy an aircraft downed in a foreign land, but U.S. Special Forces had particular cause to blow up the ill-fated helo that participated in Sunday’s raid on Osama Bin Laden’s compound in Pakistan. Apparently, it was a secret stealth helicopter, the design of which U.S. military commanders would not be keen to share with the Pakistanis or anyone else.

Specifically, the tail rotor of the crashed helicopter has a five-bladed assembly, whereas the Black Hawk tail rotor has four blades. Also, where the Black Hawk's vertical tail section tapers towards the top, the helicopter lost in the raid has a vertical tailplane than has an even chord from top to bottom capped off with what appears to be a large aerodynamic surface.

Standard US Army BlackHawk UH-60 helicopter