Saturday, 7 May 2011

Top Secret US Stealth Helikopter Down Revealed


One of the most impressive things about Sunday's raid in Pakistan, was the way the Navy Seals managed to penetrate deep into Pakistan without being caught by Pakistani air defenses. Now it looks like a super secret stealth helicopter may be behind this embarrassing security lapse.

The helicopter crashed during landing, and while the team took measures to destroy it before leaving, they missed the tail rotor section which had broken off and fallen outside the compound wall.

This image shows Osama bin Laden

On Monday local children were seen picking up pieces of the silver loaded infrared suppression covering used on the tail rotor surfaces, before Pakistani authorities came and trucked away the remaining bits. Now there is concern that the highly classified materials are on their way to Pakistan's friends in China.

Secret until now, stealth helicopters may have been key to the success of the Osama bin Laden raid. But the so-far-unexplained crash of one of the modified Black Hawks at the scene apparently compromised at least some of the aircraft's secrets.

Part of a damaged helicopter used in the bin Laden raid . . . the vehicle used stealth technology to reach its target.

The assault team that killed Osama bin Laden sneaked up on his compound in radar-evading helicopters that had never been discussed publicly by the US government, aviation analysts said.

The commandos blew up one of the helicopters after it was damaged in a hard landing, but news photographs of the surviving tail section reveal modifications to muffle noise and reduce the chances of detection by radar. The stealth features, similar to those used on advanced fighter jets and bombers, help explain how two of the helicopters sped undetected through Pakistani air defences before reaching the bin Laden compound in Abbottabad.


The two choppers evidently used radar-evading technologies, plus noise and heat suppression devices, to slip across the Afghan-Pakistan border, avoid detection by Pakistani air defenses and deliver two dozen Navy SEALs into the al-Qaida leader's lair. Photos of the lost chopper's wrecked tail are circulating online — proving it exists and also exposing sensitive details.

President Barack Obama traveled Friday to Fort Campbell, Ky., and met privately with the elite Army pilots who flew the daring mission. They are members of the 160th Special Operations Aviation Regiment, nicknamed the Night Stalkers, and he saluted them in public remarks afterward.


The reason one of the helicopters crash landed at the bin Laden compound has not been disclosed, but Daniel Goure, a defense specialist at the Lexington Institute think tank, said Friday it might be explained by the unusual aerodynamics resulting from the aircraft's modifications.

"It could be much more difficult to fly, particularly at slow speed and landing than you would expect from a typical Black Hawk," Goure said.

The U.S. military's first stealth aircraft, the now-defunct F-117 fighter jet, was notoriously difficult to handle in flight, officials have said.


Night Stalker pilots also fly other, publicly acknowledged versions of the Black Hawk that are specially equipped with advanced navigation systems, plus devices allowing for low-level and all-weather flight, day or night. Those are rigged to permit occupants to "fast rope" from the helicopter as it hovers just off the ground — a technique used in the bin Laden assault.

Also taking part in the bin Laden mission were two MH-47 Chinooks, specially modified versions of the heavy-lift Chinook helicoptersthat are widely used by the Army's conventional forces.

The MH-47s are flown by the 160th, the Night Stalkers. Those aircraft are not known to have stealth capabilities, although one was summoned to the scene of the raid after one of the stealthy Black Hawks crash-landed, in order to help ferry the SEAL contingent out of Pakistan.

Graphic showing modified Blackhawk

Many aspects of stealth technology have been known for decades, including the use of angled aircraft edges and composite materials to make aircraft less visible on radar. The Army began a program to build a new class of helicopter with stealth technology in 1992. Known as the RAH-66 Comanche, it was canceled in 2004, in part to speed up development of drone aircraft.

Bill Sweetman, editor-in-chief of Defense Technology International and a long-time student of stealth aircraft development, said the biggest secret behind the stealth helicopter is simply that it existed.

"There was obviously a fairly high risk that you were going to compromise it one way or another the minute you used it," he said in an Associated Press interview.

The decision to use the helicopters reflected the extraordinary stakes involved in eliminating bin Laden, the world's most-wanted terrorist. It is not known whether the choppers have been used in earlier Special Operations raids, but Dick Hoffman, a former Navy SEAL and now a defense analyst at the Rand Corp. think tank, said he had never before heard of their existence.

Hoffman said in a telephone interview that the apparent stealth technology on the choppers boosted the raid's chances for success.

RAH-66 Comanche

"Getting into the target area undetected is hugely important, especially with these terrorist targets and militia targets," he said. He noted that the SEAL team did not arrive at the Abbottabad compound in complete silence, since a resident in the same town was writing on Twitter during the raid that he could hear one or more helicopters and wondered what was happening.

But the modifications that suppressed noise from the helicopters — including the use of extra blades in the tail rotor and placement of a hubcap-like cover on the rotor — may have been sufficient to allow the assault teams to get on the ground before bin Laden and his security guards could mount enough of a defense to slow the SEALS; only one of the defenders was said to have gotten off a shot.

Noise suppression, Goure said, is "a huge advantage in these kinds of strikes."
Some elements of that noise suppression technology were visible in photos of the tail section that was left behind. The main body of the helo was blown up by the SEALs before they left with bin Laden's body, apparently in order to prevent the exposure of other secret stealth components.

A Pentagon spokesman, Marine Col. David Lapan, declined to say Friday whether Pakistan was resisting U.S. efforts to retrieve the remains of the chopper.

Sweetman said it was remarkable that the SEALs managed to swoop into the compound and catch the bin Laden party by surprise.

"They're probably expecting that someday they could get a visit from (U.S.) Special Forces," he said. "But they would also be expecting to hear helicopters for a few minutes before they arrive overhead. If your first warning is that you hear the thing and then you look up and it's right there, you've lost valuable time."

Raid stealth chopper secrets may reach China

There are concerns that the secrets of the stealth helicopter used by US commandos to storm Al Qaeda leader Osama bin Laden's Pakistan hideout may reach China, a media report said here.


The Daily Telegraph reported that the US Navy SEALs had used a previously unseen stealth helicopter for the daring mission in Pakistan's Abbottabad city so that they could evade Pakistani radar and not be heard while reaching the Al Qaeda leader's sprawling mansion.

After a snag developed in the chopper, the commandos lobbed thermite grenades to destroy its main body. The rear section was, however, left intact and it was carted away by the Pakistani military .

The media report said it is feared that if Pakistan refuses a US request to return the tail section, the issue could turn into a diplomatic rift.

The stealth helicopter is probably a modified Blackhawk.

The chopper's stealth capabilities become clear from the fact that Osama's neighbours didn't hear the helicopters till they were directly overhead.

The shape and design of the chopper is similar to that of the RAH 66 Comanche helicopter, believe experts.

It is possible that the technology was adapted and placed into a Blackhawk. The modified tail boom would have lessened noise and appears to be covered in a hi-tech material used on stealth fighters.


"The Americans will be extremely keen to get the wreckage back but there will also be real concerns about the technology finding its way to China," Peter Felstead, the editor of Jane's Defence Weekly, was quoted as saying.

"This kind of technology would be extremely useful to them at this point."

Pakistan is working with China on the JF17 Thunder fighter project.


Helicopter Carrying SEALs Downed by Vortex, Not Mechanical Flaw or Gunfire


A United Technologies Corp. (UTX) Black Hawk helicopter carrying U.S. Navy SEALs to Osama Bin Laden’s hideout was downed by an air vortex caused by unexpectedly warm air and the effect of a high wall surrounding the compound, not mechanical failure or gunfire, according to U.S. officials and a lawmaker.


The Army pilot from the service’s most elite aviation unit executed a hard but controlled landing -- clipping a corner wall -- after the chopper lost lift. The 12 heavily armed SEALs exited the aircraft unharmed.

Senior government officials briefing reporters by telephone on May 1, the day bin Laden was killed, gave conflicting accounts, first saying the chopper experienced a mechanical “malfunction” and then backtracking without an explanation.

The initial administration explanation wasn’t accurate, according to U.S. government officials, a lawmaker and congressional staff briefed yesterday by Vice Admiral William McRaven, leader of the Joint Special Operations Command.

The command includes the Army’s 160th Special Operations Aviation Regiment, which piloted the SEALs of the Navy’s Special Warfare Development Group to the house in Abbottabad, Pakistan. McRaven yesterday briefed the Senate and House armed services and intelligence committees.

Rappelling Mission Ditched

The aviation unit is based at Fort Campbell, Kentucky. President Barack Obama is scheduled to visit the base on Friday and see members of the 160th, said an Army official who spoke on condition of anonymity because he wasn’t authorized to discuss the trip.

Twenty-five Navy SEALS were flown to the bin Laden home by two Black Hawks, CIA Director Leon Panetta told the PBS “News Hour” May 3.

The helicopter that crash-landed was supposed to hover over the compound’s courtyard so that the SEALS would rappel, or “fast rope,” to the ground, Panetta said.

According to two U.S. officials, who praised the skill of the pilot, the chopper lost the lift necessary to hover because it entered a “vortex” condition. At least two factors were at play -- hotter than expected air temperature and the compound’s 18-foot-high walls, they said.

The wall blocked rotor blade downwash from moving down and away as it normally would. This caused disturbed airflow to move in a circular, upward and then downward path back through the top of the rotor, causing insufficient lift for the aircraft.

Hard Landing

The pilot, realizing he had lost lift, landed quickly in a maneuver practiced by pilots to deal with helicopter flight conditions known as “settling with power,” one official said.

Another explained that if a helicopter hovers next to a large enough building at just the right distance, moving air created by the rotors won’t be able to exit freely. Instead, it will hit the wall and have nowhere to go except back into the rotor, robbing lift.

The pilot executed a “hard landing” as a result, House Armed Services Committee ranking Democrat Representative Adam Smith told reporters after a McRaven briefing.

Asked if there was a mechanical failure in the United Technologies’ Sikorsky aircraft, Smith said, “I don’t believe that is what happened.

‘‘As was explained to me, with the temperature and the setting, it came down faster than they anticipated so I don’t believe there was some sort of mechanical failure. It’s just those were tough conditions to land in,” Smith said.

House Armed Services Committee Chairman Representative Howard McKeon of California reiterated in Washington yesterday that “it was not a mechanical failure.”

Wreckage Destroyed


He also said he had “no sense from the military that they had any concerns about” leaving wreckage of the modified Black Hawk, said McKeon.

The commandos detonated an explosive to destroy the helicopter, which the Army Times reports was a specially configured stealth model Black Hawk.

Two 160th additional MH-47 special operations Chinook helicopters provided back-up and assisted in flying out the raiders.

Sikorsky Aircraft spokesman Paul Jackson said the company hasn’t been contacted about any aspect of the raid.

Night Stalkers

Once known as the secret Task Force 160, the aviation regiment was formed in 1981 and has participated in most major U.S. military operations since the 1983 invasion of Grenada. Its pilots are known as the “Night Stalkers.”

Five of its personnel were lost and eight aircraft, including two Black Hawks, were either destroyed or damaged during the October 1993 battle in Mogadishu, Somalia.

The unit’s Black Hawks and the mission to rescue the air crews were the basis of the book and movie “Black Hawk Down.”


The unit flies the Sikorsky MH-60 Black Hawk, Boeing Co. (BA) MH-47E heavy assault chopper, and the Boeing A/H-6M Little Bird, used to ferry Army Delta Force commandos during a raid in the invasion of Panama to free a jailed American businessman, Kurt Muse.


What makes the experts think the aircraft that crashed in Abbottabad was a secret "stealth helicopter?"

The Navy SEALs' helicopter tail rotor assembly came down on the other side of the compound wall.

• "The first thing that stood out, and it may seem like a small thing, is the color scheme. Whereas most Black Hawk Army helicopters are painted olive green, this particular one is gray. Not just any gray; it's infrared-suppressant gray, and the purpose of the IR gray, as it's known, is to help reduce the vulnerability of the helicopter to ground-launched heat-seeking missile systems," Jennings told CNN Pentagon Correspondent Chris Lawrence.

• Photos from Abbottabad show that the chopper had a five-bladed tail rotor. "On a conventional Black Hawk, you have four blades. The addition of the extra rotor blades on the tail rotor hub reduces the acoustic signature of the helicopter there by making it hard to hear, giving the SEALs that extra few minutes to get over the compound before anyone on the ground quite knows what's going on," according to Jennings.

• Those five tail rotor blades are partially covered by a disk-like object that Jennings called a "hub-mounted vibration suppression system." He believes it provides more noise suppression and some possible protection for the tail rotor from bullets of shrapnel. And it's not typical on military helicopters. "No, I've never seen that on an operational helicopter before," Jennings said. But he added that a similar system was part of the Comanche helicopter design.

• The blades on that tail rotor also appear to be shorter and thinner than typical Black Hawk helicopter's blades. One former Army Black Hawk pilot, who asked not to be identified, said, "More blades and shorter blades means the helicopter would make less noise in flight."

It's not just the tail rotor blades that are different. "On the main rotor assembly that was actually destroyed by the SEAL team on the ground the blades themselves are threaded, which signify that these are carbon composite rotor blades as opposed to conventional metal rotor blades, which again signifies aspects of stealth technology that have been incorporated into this particular helicopter," Jennings said.

• Some photos show parts of the helicopter appear similar to non-secret stealth aircraft. "What's left of the tail section of that helicopter, the shape of the fuselage, it's canted. It's angled. It's a shape that's synonymous with fixed-wing stealth fighters such as the F-22, the F-35. Essentially, it's designed to defeat radar. If you eliminate right angles in an aircraft design, radar waves can't bounce back," Jennings said.