None of the 25-member U.S. Navy Seal team that killed Osama bin Laden in Pakistan on Sunday were injured during the nearly 40-minute night raid, but one of their transport helicopters was downed, and is now the subject of intense speculation by aviation experts and enthusiasts around the world.
Photos of the tail-end of the aircraft circulated online shortly after the raid suggests it was a secret stealth helicopter -- possibly a highly modified version of an H-60 Blackhawk -- that was designed to fly quietly and to radar, experts say.
"Now we know that the so-called black stealth projects -- secret projects involving new technologies -- are not only rumors or speculation," said David Cenciotti, a military aviation journalist and information security expert based in Rome.
Cenciotti said he noticed something strange about the copter immediately after seeing images of its downed tail section online.
"There was something weird about the design of the tail,” he said. Specifically, the shape and position of the aircraft's horizontal stabilizer and tail rotor were unlike any he had ever seen on a Blackhawk or an Apache helicopter.
The blades were also flatter, and not wing-shaped like in other helicopters, and they were partly obscured by a metal plate resembling a hubcap that Cenciotti speculates could have been anything from a stealth cover to an armor plate or some type of noise reduction device.
The helicopter paint job was also unusual, Cenciotti said. "It reminded me of the same type of anti-radar paint that stealth fighters have," said Cenciotti, who is also a former member of the Italian Air Force.
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Top secret no longer
Excited, Cenciotti called up Ugo Crisponi, an artist at , and the two collaborated to create a sketch of what the full stealth aircraft would have looked like and posted it on Cenciotti's .
"After we issued the first image, we received a lot of interesting comments and feedback that helped us produce a second sketch and give it the final shape," Cenciotti said.
"For sure, we couldn't have made our sketch so quickly without the Internet to help us."
The pair's updated sketch reveals a helicopter that looks like a tougher and sleeker Blackhawk. Painted entirely in matte black, the copter's blades are slightly longer than a Blackhawk's, and the tips of the blades are bent slightly downward.
The stealth copter may also have more blades than a Blackhawk, and the blades may be spaced differently, Cenciotti said, a design tweak that could help muffle the "chop-chop" sound made by conventional helicopters.
Cenciotti noted that NASA is also known to be using motion-control technology to reduce Blackhawk noise, and the strange tail cover on the downed copter could conceivably have been used to house such technology.
Of utmost importance
The U.S. government's willingness to use during the Sunday raid is a measure of the importance it placed on the mission, experts say.
"To use such extra-secret technology to perform such a raid means that [bin Laden] was an extremely important target," Cenciotti said.
"The noise made by this helicopter compared to a conventional helicopter probably reduced the reaction time of all the personnel protecting bin Laden."
It's unclear how or why the stealth copter crashed during the raid. According to the New York Times, lawmakers brief on the mission said the copter had not malfunctioned, but got caught in an air vortex caused by higher-than-expected temperatures and the high compound walls, which interfered with the workings of the rotor blades.
As a result, the copter may have lost its ability to hover over the yard and to make a hard landing, clipping one of the walls with its tails and crashing.
Some of the Seal members reportedly tried to destroy the downed copter to hide its technology, but Cenciotti speculates that the tail section survived because it fell outside of the compound.
Even though the stealth copter may not be as secret as it once was, there are still plenty of things to keep aviation enthusiasts busy.
"We don't know about a lot of the other supporting casts that were involved in such a complex operation," Cenciotti said.