Stealth helicopter revealed by bin Laden raid

A downed helicopter may be yielding some information about new stealth technology, as the U.S. tries to get back what remains of their Black Hawk.

One of the Black Hawks flown by an elite Army unit called Task Force 160 - which carried the Navy SEAL commandos - lost lift and was forced into a hard landing at Osama bin Laden's compound in Abbotabad, Pakistan. The pilot nudged the Blackhawk forward into a controlled crash - saving the mission from disaster, but sheering off the helicopter's tail section, reports CBS News national security correspondent David Martin.

The SEALs were able to continue with their raid. Before they left, they left blew up as much of the Blackhawk as they could but had to leave the tail section intact.

That gave aviation expert Bill Sweetman his first good look at a stealth helicopter.

"I think nobody outside the classified community really knew that these existed," he told Martin.

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Black Hawks are manufactured by the Connecticut-based Sikorsky, but the tail section left behind in Pakistan appears modified - possibly with technology developed for a stealth helicopter program that was cancelled, reports The New York Times.

Sweetman points out some of the features that make it stealthy, like special materials covering the tail rotor hub to reduce the helicopter's radar signature.

Sweetman, Editor in Chief for Defense Technology for Aviation Week, has written that published photos of the tail section show stealth-configured shapes on the boom and tip fairings, swept stabilizers, and a silver-loaded infra-red suppression finish.

The tail rotor also has more than the usual number of blades -five or six - which evens out the distinctive whop-whop sound of a helicopter.

"At a range of a couple hundred feet even, if you've got a bit of urban background noise, you're not going to hear it," said Sweetman.

A prototype was built of the Boeing-Sikorsky RAH-66 Comanche helicopter (left), which was to herald a new generation of rotorcraft for the military, but the Army canceled the $8 billion program in 2004.

The Pakistanis hauled the tail section away, so now the secret of the stealth helicopter is blown.

Still, the Pentagon wants its helicopter back, and has asked Pakistan to return it.