Special Forces soldiers who attacked the villa of Osama bin Laden, the leader caught al Qaeda off guard. However, this operation was a surprise for the armed forces of Pakistan, which have not appeared Radar U.S. helicopters. How do they do it?.
According to experts, this question can be answered as follows: special group first used the latest ' stealth helicopter ', built using technology to reduce the visibility.
Reasons for these findings provide photographs of one of the helicopters that the U.S. ' fur seals ' had to be destroyed before returning to base.
Explosives are not destroyed top-secret helicopter tail section, and it gave aviation experts much food for speculation.
Work up a sweat a few, experts decided that the operation used a helicopter, UH-60 Blackhawk, which is significantly modified to make it less visible to radar.
They believe that the operation against bin Laden - this is the first application of stealth helicopter in real combat conditions.
However, these machines were created in the past. Sikorsky Aircraft Company for the U.S. Army has built several prototypes of helicopters, known as the RAH-66 Comanche. However, in 2004, when the unit is still being finalized, the program was discontinued because of too high cost.
It was really their first combat use - says editor-in Aviation Week. - Previously, we have never seen a stealth helicopters used in this way '.
To make the invisible helicopter, you need to get rid of some form of aircraft that are well known to radar, says Tony Osborne - Deputy Editor Rotary - British Journal of helicopters.
'You must hide its main components, the waves are reflected in different directions, or even absorbed, - says expert. - Tail rotor gearbox is covered. I had never seen this in a helicopter. As we know, various experiments were carried out continuously, but very interesting that all this is already being used in '.
' Completely flattened tail stabilizer, and it probably is covered by nacreous material which, when one looks light silver, while the other - black - continues Osborne. - I saw it only on an invisible aircraft, such material is likely to absorb radar waves. Covered by even the small rivet that can give the helicopter: radars are very sensitive '.
' What remains of the tail boom, suggests that the landing gear was retractable. Again, they are usually fixed by radar, so if you remove them, this will help avoid detection ', - says Osborne. 
' Apparently, the tail rotor has five or six blades. This means that it can rotate more slowly and generate less noise. The noise comes from the fact that the ends of the blades at high speed cut the air ' - explains the deputy editor of Rotary.
The eye can not cheat?.
However, to ' cheat ' radars, helicopters do not even need to resort to such tricks. The fact that the majority of Pakistan's radar is on the ground, and this means that because of the angle it is difficult to detect vehicles, flying at low altitude.
Earlier, Pakistani intelligence official told BBC BBC that during the operation against bin Laden, U.S. helicopters have not appeared on the radar screens, but were spotted by Pakistani military when the country crossed the border from Afghanistan.
According to intelligence, the military saw four low-flying helicopter, after which the air had been raised fighters armed forces.
However, the U.S. military had informed Islamabad that the helicopters are directed to a special operation is extremely important.
www. bbc. co. uk.
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