Stealth helicopter? What stealth helicopter?

We know that the SOF team that retrieved enormously important al Qaeda hard drives and documents from Osama bin Laden's house, incidentally killing bin Laden as they did so, flew out of Abbottabad with one fewer helicopters than they went in with.

We also know that the helicopters belonged to the US Army's 160th Special Operations Aviation Regiment, based at Fort Campbell, Ky.

The 160th specializes in airborne special operations missions. It falls under the U.S. Army Special Operations Command at Fort Bragg, N.C., and includes about 1,400 soldiers, most of whom are based at Fort Campbell.

The 160th has become known as the Night Stalkers because of its capability to strike undetected during darkness.

Tail boom of the US helicopter left behind
at bin Laden's compound

The circumstances of the crash are unclear. It has been reported that the tail boom of the downed chopper, reportedly a specialized UH-60 Black Hawk, struck the wall around bin Laden's compound as it came into land. Photos appearing on ABCNews' site support this conclusion - the photo at right shows the tail boom next to the wall. The SOFs destroyed the rest of the helicopter, leaving it a charred pile of ashes and molten aluminum.

Queries to the Defense Department on the identity and nature of the aircraft are rebuffed with a polite version of, "no comment." Nonetheless, other photos from the compound reveal interesting details of the bird. One of them shows the tail rotor closeup.

Tail boom closeup

The disk at the lower right of the photo is what intrigues. It covers the central hub the tail rotor (the boom is lying sideways) and speculation is all over the place about what it reveals about the rest of the aircraft.

Most analysts say that the disk is mainly intended to suppress rotor noise. ABCNews reports,

But photos of what survived the explosion -- the tail section of the craft with curious modifications -- has sent military analysts buzzing about a stealth helicopter program that was only rumored to exist. From a modified tail boom to a noise reducing covering on the rear rotors and a special high-tech material similar to that used in stealth fighters, former Department of Defense official and vice president of the Lexington Institute Dan Goure said the bird is like nothing he's ever seen before.

There are undoubtedly many other stealthy characteristics of the aircraft. But for nighttime flying, noise suppression is most crucial. The choppers would be flying dark, of course, and very, very low, making their detection by radar extremely difficult. But typical helicopters can be heard coming from kilometers away. Not these, though.

Neighbors of bin Laden in Abbottabad, Pakistan, told ABC News they didn't hear the helicopters the night of the Sunday raid until they were directly overhead. The rotor covering, along with a special rotor design, suppressed the choppers noise while inbound, Bill Sweetman, editor and chief of Defense Technology International, said.

Pakistan and China have close military ties. That this tail boom and most of the burned wreckage will wind up in Beijing seems a foregone conclusion. That is not a good thing.