How do you know you just lost a stealth helicopter?
No one notices that it went down. (I know, I know, bad joke, I won’t quit my day job.)
Top Secret Stealth Helicopter Program Revealed in Osama Bin Laden Raid: Experts
Let’s examine this for a bit. The article cites a former Special Operations aviator who identifies the aircraft as a modified Blackhawk. This makes sense, since that airframe has the capacity to carry large numbers of troops into combat, and extract them. Look at the photo at the top of the article. It appears that there is a disk of some sort covering the center of the rotor assembly. This is likely a major component of the stealth modification, and it’s a shame it wasn’t destroyed.
Consider this: when you move air over a body, if the flow of the air is disturbed, it generates noise. The less disturbance there is, the less noise, so to make a helicopter stealthy you start by reducing airflow over parts or surfaces that disrupt that airflow. That’s what that cover does. It hides the rotor articulation mechanisms from the airflow over the blades, which makes for a quieter flight. Coat the helicopter in a radar-absorbing material and replace the blades with redesigned ones made to reduce the chop-chop-chop sound as it flies along, and you have a stealth chopper for less than the $6.9 thousand-million the Army spent developing the Comanche.
(And no, I didn’t stay at a Holiday Inn last night, I just paid attention to my physics classes, so I have an understanding of the basic science behind the ideas).