US probably used classified helo in Bin Laden operation

The US military may have operated a hitherto undisclosed classified helicopter type in its recent raid on Osama bin Laden's compound in Pakistan.

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.

Following the raid on 1 May only the tail section of the helicopter remained - the main body having been destroyed in situ by US special forces - but aspects of its design do not tally with the generally held belief that Sikorsky MH/UH-60 Black Hawk-type helicopters were used in the mission.

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.