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Wednesday, May 18, 2011

Helicopter Experts: Stealth Not Only Reason for Secret Mods

Radar jamming, small arms protection also identified as possible explanations for alterations to the UH-60 tail rotor.

By Andrew Parker, Senior Editor

Pakistan agreed to return the tail section and wreckage of the modified helicopter involved in the raid on Osama bin Laden’s compound in Abbottabad to U.S. government officials on Tuesday. But due to the nature of the classified operation, military rotorcraft experts say it could be years before the full details about the raid and the Sikorsky UH-60’s secret modifications come to light. While images of the wreckage offer a rare visual into what appears to be a classified government program, without some official confirmation, it’s hard to draw definitive conclusions about the modifications.

Rotor & Wing Military Editor Andrew Drwiega takes on the subject in a column for the upcoming June edition of the magazine titled, “Stealth: Just Part of the Story?” According to Drwiega, “it seems that adding stealth properties to a couple of Black Hawks would not answer all of the questions concerning this masterstroke of a mission.” He writes, “Nap-of-the-earth flying is likely to have been involved, communications and other jamming, subterfuge in terms of radio calls or transponder codes perhaps, and even the collusion of some in the Pakistan military who may have looked the wrong way at the right moment.”

Drwiega adds that if the 160th Special Operations Aviation Regiment operates the helicopter that appeared in the photos, “then they would surely have been seen around the Fort Campbell area, the home of the Regiment, or another base throughout the country. Did nobody capture a picture of this aircraft—not even on a cell phone camera?”

Frank Lombardi, a test and evaluation pilot with a master’s degree in aviation systems-flight testing, says that the wreckage appears to show “a tail boom with horizontal stabilator and tail rotor—all the surfaces almost look fake, but that is because rivets and seams are detrimental to being stealthy.”

The “dish-like fairing” over the tail rotor “would be necessary to make stealthy the shaft and linkages,” notes Lombardi, a regular Rotor & Wing contributor. “Right angles are the worst when you want to minimize radar cross-section.”

Editor-at-Large Ernie Stephens, a retired law enforcement helicopter pilot who spent most of his time serving in the police special ops division, studied photos of the wreckage. The images appear to show “a swept horizontal stabilizer with a symmetrical blade foil [and] a vertical stabilizer capped by very hard angles that resemble radar-reflective faceting,” says Stephens, a former editor-in-chief of Rotor & Wing. “Since making just one part of an aircraft low-observable serves no tactical purpose, it’s safe to assume that the rest of the ship was also designed that way.”

The “beanie” that covers the tail rotor hub “appears to make the highly reflective pitch linkages less observable to enemy radar,” he adds. “Since it’s there anyway, it might even offer protection from small arms fire.”

Lombardi also wonders if the military had removed the refueling probe completely, or made it internal. “That would change the game, when it came to where are they launching from/going to,” he says. “Making it internal/retractable would also add weight/complexity to the aircraft. If they can carry only internal fuel, then they are probably quite the heavy aircraft, definitely contributing to their probable settling with power/hard landing going in there.”

Despite many in the aviation community deeming it a UH-60, “the words ‘modified Black Hawk’ didn’t come to mind,” Stephens continued, with this caveat: “There wasn’t enough left to point me towards any specific helicopter known to me.”

Stephens concluded that based on the photos, the helicopter that went down during the raid in Abbottabad “could easily have been a heavily modified version of nearly any medium-twin helicopter, if not a brand new design altogether.” But even if the helicopter was from UH-60 lineage, Stephens cautions, altering its landing gear, main rotor system, engines “and everything else low-observable would require such heavy modifications, it wouldn’t have looked much like a Black Hawk anymore, even if in one piece.”

Like others, Lombardi would like to know how long ago the modifications were designed. “Because the shapes I’m seeing—albeit just a few pics—are in keeping with the [Boeing/Sikorsky] RAH-66 Comanche,” he says. “I wonder if [the helicopter in the bin Laden raid] came about before or after.”

Stephens isn’t surprised that the military has technology that the public hasn’t seen before—it’s not the first time, and won’t be the last. But he reminds those digging for details about why secret programs are kept secret: “You don’t win a high-stakes card game by showing your hand as it's being dealt.”

Drwiega adds, “The problem with second-guessing special operations actions is that you don’t actually find out what really happened until much later. But why should those involved tell the world about their tactics techniques and procedures (TTPs) when they might have to use them again in a similar scenario in the near future?”

More: UH-60 in Raid Features Classified Mods

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